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Department of Soil Conservation and Watershed ManagementKathmandu, June 2016
(Asar 2073)
Guideline on Landslide Treatment and Mitigation
Department of Soil Conservation and Watershed ManagementG.P.O. BOX 4719, Babar Mahal, Kathmandu, NepalT: 977-1-4220828/4220857 | F: 977-1-4221067
E: dscwm2031@yahoo.com/info@dscwm.gov.npW: www.dscwm.gov.np
Guideline on Landslide Treatment and Mitigation
Department of Soil Conservation and Watershed Management
Kathmandu, June 2016
(Asar 2073)
| Guideline on Landslide Treatment and Mitigationii
PublisherDepartment of Soil Conservation and Watershed Management,
Ministry of Forests and Soil Conservation,
Babar Mahal, Kathmandu, Nepal
Cover photo credit
Landslide in Rasuwa©Mr. Jagannath Joshi
Credits
© Department of soil Conservation and Watershed Management (DSCWM)
Kathmandu, Nepal
Landslide Treatment and Mitigation Sub-GroupCoordinator: Mr. KesharMan Sthapit (FAO Nepal Office)
Members:
Mr. GehendraKeshariUpadhyaya (DSCWM)
Dr. Jagannath Joshi (DSCWM)
Mr. Deepak Bhardwaj (DSCWM)
Mr. Shanmukhesh Chandra Amatya (Department of Water Induced Disaster Management)
Ms. Laxmi Thagunna (Department of Environment)
Ms. Racchya Shah (IUCN Nepal)
Mr. Bhawani Shankar Dongol (WWF Nepal)
Mr. Sanjay Devkota (Forum for Energy and Environment Development)
Mr. Deo Raj Gurung (ICIMOD)
Advisor: Mr. Purna Chandra Lal Rajbhandari (UNEP)
Citation
DSCWM (2016), Guideline on Landslide Treatment and Mitigation.Department of soil Conservation and Watershed
Management, Kathmandu, Nepal.
We are very thankful to USAID funded Hariyo Ban Program, WWF Nepal for providing support to edit,
format and print this guideline.
Guideline on Landslide Treatment and Mitigation | iii
| Guideline on Landslide Treatment and Mitigationiv
Guideline on Landslide Treatment and Mitigation | v
Preface
The working group on “Landslide Treatment and Mitigation” was established following the recommendations of the
consultative workshop on “Landslide Inventory, Risk Assessment, and Mitigation” organized by the Department of Soil
Conservation and Watershed Management (DSCWM) from 28-29 September 2015 at Kathmandu. FAO, ICIMOD, IUCN, UNDP,
UNEP, and WWF collaborated in the workshop. The first Coordination Meeting of Partner Organizations held on 14 October
2015 established the working group that Food and Agriculture Organization-Nepal will coordinate.
FAO designated Mr. Keshar Man Sthapit (Former DG of DSCWM) as coordinator. The members include Mr. Gehendra Keshari
Upadhyaya, Dr. Jagannath Joshi, and Mr. Deepak Bhardwaj, DSCWM; Mr. Shanmukhesh Chandra Amatya, Department of
Water Induced Disaster Management; Ms. Laxmi Thagunna, Department of Environment; Ms. Racchya Shah, IUCN Nepal; Mr.
Bhawani Shankar Dongol, WWF Nepal; Mr. Sanjay Devkota, Forum for Energy and Environment Development (FEED); and Mr.
Deo Raj Gurung, ICIMOD. Mr. Purna Chandra Lal Rajbhandari from UNEP was assigned as advisor.
The “Landslide Treatment and Mitigation” working group held its first meeting on December 18, 2015 and second meeting
on January 29, 2016.
The working group prepared this Guideline through a desk review of pertinent literature, guidelines, and relevant
documents on nationally and internationally adopted practices, and through extensive consultation workshops and
meetings with experts and practitioners. Eventually, it finalized the guideline after incorporating comments and suggestions
made by various experts and District Soil Conservation Officers at a national level validation workshop on June 19, 2016.
The terms of reference of the working group are in Annex 1. This Working Group 3 (Landslide treatment and
mitigation) produced this report describing the guideline, including assessment of landslides for urgency of treatment,
recommendations for treatment, landslide mapping, different techniques used, and basic surveying required for designing
techniques. The report also provides a training schedule for building the capacity of field professionals and a format for
documentation of the lessons learned.
The coordinator appreciates the valuable contributions of the members of the working group.
Keshar Man Sthapit
Coordinator
Landslide Treatment and Mitigation Sub-Group
Guideline on Landslide Treatment and Mitigation | vii
Acronyms and Abbreviations
DG Director General
DSCO District Soil Conservation Office
DSCWM Department of Soil Conservation and Watershed Management
FAO Food and Agriculture Organization of the United Nations
FEED Forum for Energy and Environment Development
GoN Government of Nepal
GPS Global Positioning System
Ha Hectare
MRE Mountain Risk Engineering
NARMSAP Natural Resource Management Sector Assistance Programme
ICIMOD International Centre for Integrated Mountain Development
ILO International Labour Organisation
IUCN International Union for Conservation of Nature
UNDP United Nations Development Program
UNEP United Nations Environment Program
VDC Village Development Committee
WWF World Wildlife Fund
Guideline on Landslide Treatment and Mitigation | ix
Table of Contents
Foreword iii
Preface v
Acronyms and Abbreviations vii
1. Background and Objectives of Landslide Treatment 1
1.1. Main Objectives of Landslide Treatment 1
1.2. Scope of Landslide Treatment 1
2. Urgency and Recommendation for Treatment 3
2.1. Assessment of Urgency and Recommendation 4
3. Landslide Mapping and Surveying to Identify Key Problems 7
3.1. Detailed Mapping of Landslides 7
3.2. Landslide Survey 8
3.3. Problem Identification 9
4. Treatment and Mitigation Measures for Landslides 11
4.1. Landslide Treatment Techniques 11
4.2. Treatments for Specific Zones of the Landslide 11
4.2.1. Upstream and Side Periphery Zones of the Landslide 11
4.2.2. Downstream Zone of Landslide 12
4.2.3. Catchment Area 13
4.2.4. Main Landslide 13
4.3. Practical Considerations and Approaches 14
4.3.1. Landslide Treatment Approach and Working Season 14
5. Capacity Building and Lesson Learned Documentation 15
6. References 17
| Guideline on Landslide Treatment and Mitigationx
viii
List of Tables
List of Annexes
Table 1. Definition of Common Terms 3
Table 2. Treatability Status 4
Table 3. Evaluation Matrix for Assessment of Urgency for Treatment Existing Landslide 5
Table 4. Assessment of Recommendation for Treatment 6
Annex 1. Terms of Reference: Sub-group 3. Landslide Treatment and Mitigation 19
Annex 2. Mapping Steps (Modified after NARMSAP/DSCWM, 2004 and 2005) 21
Annex 3. Basic Surveying 24
Annex 4. Landslide Treatment Techniques 26
Annex 5. List of Commonly Used Species 67
Annex 6. Proposed Training Module for Capacity Building in Landslide Treatment 69
Annex 7. Landslide Inventory 71
Annex 8. Format for Documentation of the Lessons Learned 74
Guideline on Landslide Treatment and Mitigation | 1
Landslide is a general term describing a mass of material
that has slipped downhill under the influence of gravity.
In mountainous terrain, such as Nepal, landslides happen
relatively frequently, especially when the soil is saturated
with water1 as during the heavy monsoon rains.
Landslides cause damage to lives and settlements,
development infrastructures, agricultural fields, and
forests. They occur because of complex forces in
conjunction with the slope morphology, hydrology, and
geotechnical parameters of the material. They occur
when the shear stress exceeds the shear strength of the
material. Other terms to refer to landslide events include
‘mass movements’, ‘slope failures’, ‘slope instability’, and
‘terrain instability’.
The causes of landslides and the problems they create
in the hazard areas determine the types of landslide
treatment and mitigation. Generally, landslide treatment
focuses on the immediately affected areas to fix the sliding
and reduce immediate adverse impacts on the surrounding
area. Mitigation focuses on minimizing the longer-term
occurrence of landslides in a whole watershed.
For example: Immediate or short term measures
includes drainage management, slope stabilization with
engineering structures, such as retaining or toe walls, or
riprap, to address the immediate effects of a landslide.
Medium and long-term measures cover a whole watershed
to improve cultivation practices, and better manage crops,
water, pasture, and watershed vegetation cover through
afforestation.
Therefore, landslide treatment is done every year to
protect property and lives in Nepal. Landslide treatment
refers to the vegetative and structural measures applied
in the landslide area and its influential catchment that
aim to reduce soil erosion and mass movement from
landslide and reduce the devastating effects on the areas
downstream and surrounding the landslide.
1.1. Main Objectives of Landslide Teatment are to: • prevent further movement of slopes by controlling
runoff and erosion
• prevent damage upslope and down slope
• improve water quality and management
• stabilize the landslide area for productive purposes.
1.2. Scope of Landslide TreatmentLandslide treatment stabilizes the landslide and reduces
the adverse impacts upstream and downstream of the
landslide. These activities include managing land and
water resources upstream of the landslide and periphery
area, stabilizing the slope within the landslide, protecting
and improving land use downstream of the landslide, and
protecting the area. It includes bioengineering techniques
to reduce erosion, and water management activities to
dispose water safely and reduce moisture in the landslide
area.
Landslide treatment measures can be categorized into
three general measures:
• proper land husbandry through land use improvement
practices,
• managing water through proper drainage
management and maintaining appropriate soil
moisture, and
• strengthening slope stability through bio engineering
techniques.
1Chapter
Background and Objectives of Landslide Treatment
1 Soil Conservation Society of America-1982, Resource Conservation Glossary Third edition.
2 DSCWM 1992, Soil Conservation and Watershed Management Activities (Definition, Objective, Scope and Working Strategy). Department
of Soil Conservation and Watershed Management, Kathmandu, Nepal.
| Guideline on Landslide Treatment and Mitigation2
Stream bank stabilization by fascine. © Keshar Man Sthapit
Guideline on Landslide Treatment and Mitigation | 3
2Chapter
Urgency and Recommendation for Treatment
An analysis of a landslide, in terms of the urgency to
treat them and recommendations for their treatment, is
essential to better use the resources available. Table 1
gives definitions to create a common understanding of
landslides and the hazards involved.
Table 1. Definition of Common Terms
Landslide hazard3
Probability of a landslide event happening at a certain magnitude, described by:
• Triggering mechanism
• Type of landslide event
• Magnitude of landslide event
Triggering mechanisms are generally categorized as:
• Toe cutting, steep slope
• Lack of water management, heavy rain, steep slope
• Cracked rocks, steep slope, earthquake
Types of landslides
Most common types of landslides in Nepal and their consequent phenomena are:
• Rock fall: Abrupt movements of rocks that free fall or roll or bounce
• Debris slides: Down slope movement (sliding) of debris caused by shear failure (rotational)
on a distinct surface or by sliding shallow debris without a distinct slip surface (translational).
• Debris flow: Rapid down slope movement by vicious fluid debris without a slip surfaces.
• Sedimentation: Deposition of fine sediment washed down by the landslide.
Landslide vulnerability
Degree of damage or loss resulting from the landslide event, a function of:
• Magnitude of event, and
• Types of elements at risk
Element at risk is categorized as:
• Settlements and lives
• Development infrastructure
• Agriculture
• Forests, shrubs or grasslands
Risk
Expected degree of losses to the element at risk, because of a landslide event within a given
area and time.
Risk is a product of the combination of a landslide event, vulnerability, and quantification
(degree) of damage to the elements at risk.
Quantification (degree) of damage to the element at risk may be categorized as high,
moderate, or low.
3 Presentation on “Landslide Risk Assessment” by Xuanmei Fan, Runqiu Huang, and Cees Van Western. May 25, 2016. State Key
Laboratory of Geo-hazards Prevention and Geo-environment Protection, Changdu University of Technology.
Of the two concepts, URGENCY, relates to the level
of risk to human assets or natural resources, and
RECOMMENDATION refers to the feasibility of treating a
landslide.
| Guideline on Landslide Treatment and Mitigation4
Urgency of treatment
Urgency of treatment is based on:
• type of landslide event and consequent phenomena,
such as rock fall, sliding debris, debris flow, or
sedimentation
• probability of another landslide occurrence, whether
high, moderate, or low
• elements at risk, such as settlements, development
infrastructure, agriculture or forests, and shrub or
grasslands
• degree of losses (high, moderate or low) to the
element at risk from the landslide event.
Recommendation for treatment
Once the urgency of treatment is determined, it is
important to know whether to recommend the landslide
for treatment.
Recommendation for treatment is based on:
• element at risk and urgency for treatment due to
potential damage to settlements, development
infrastructure, or to agriculture, forests, shrub, or
grassland
• major factor triggering or enlarging the landslide,
such as toe cutting on a steep slope; lack of water
management on a steep slope after heavy rain; or
cracked rocks on a steep slope after an earthquake.
The steepness of the slope is a triggering factor.
• treatability status of the landslide -- the feasibility of
how easily the landslide can be treated based on the
criteria in Table 2.
2.1. Assessment of Urgency and Recommendation Steps to assess the urgency of treatment
1. Determine which type of landslide event is prevalent
and the probability of its occurrence.
2. Determine the elements at risk and/or damage
caused to settlements, development infrastructure,
agriculture land, or forests, shrub, and grassland
3. Assess the degree (quantify) of damage to the
element at risk whether high, moderate, or low.
4. Decide the urgency of treatment of the existing
landslide by matching the above information in the
corresponding rows and columns of the evaluation
matrix in Table 3 below.
Steps to determine the recommendation for treatment:
1. Determine the element at risk and potential damage
2. Assess the treatability status using Table 2 below
3. Assess the major factors triggering or enlarging
the landslide, such as toe cutting, lack of water
management and heavy rain, or cracked rocks due to
earthquakes
4. Based on the urgency for treatment from Table 3,
decide upon the recommendation for treatment of the
landslide using the matrix in Table 4.
Table 2. Treatability Status
Treatability Status Criteria
Easily Easily treatable with bioengineering measures within two years.
It includes shallow seated landslides on moderate slopes, less than 60%
Moderately Moderately treatable with some engineering structures and bioengineering measures within five
years
It includes shallow seated landslides on steep slopes, more than 60%
Difficultly Difficultly treatable with large engineering structures and longer than five years
It includes deep-seated landslides on steep slopes, more than 60%
Note Shallow seated: Movement of earth mass down to the C horizons (Soil’s Parent materials). This type of landslide is treatable using bioengineering techniques with reasonable resources and time, when landslides affect settlements and livelihoods (agriculture, forests, and grazing land). No bedrock is disturbed or moved.
Deep seated: Movement resulted in cracks in the bedrock and bedrock movement. Treatment of such landslides requires large structures, with reinforced concrete and grouting, using vast resources, and needing a long time. These landslides are treated when they affect infrastructure of high economic value, such as highways, hydropower, and large settlements.
Remarks: When the recommendation for treatment is low or very low, that is, treatment of the landslide is not recommended, it does not mean that the situation does not require any action. If the analysis shows that the urgency of treating the landslide is very high, high, or moderate, the recommended action may be the relocation of the settlement or infrastructures, or realignment of the road or irrigation canal. The urgency of the treatment determines the level of relocation or realignment.
Guideline on Landslide Treatment and Mitigation | 5
Tabl
e 3.
Eva
luat
ion
Mat
rix f
or A
sses
smen
t of
Urg
ency
of
Trea
tmen
t Ex
istin
g La
ndsl
ide
Haz
ard
Type
Elem
ent
at r
isk
Type
of
land
slid
e
even
t an
d
cons
eque
nt
phen
omen
a
Prob
abili
ty
(Cha
nces
)
of
occu
rren
ce
Sett
lem
ent
and
lives
Dev
elop
men
t in
fras
truc
ture
sA
gric
ultu
reFo
rest
s/Sh
rub
/G
rass
land
s
Qua
ntifi
catio
n (D
egre
e) o
f da
mag
e to
the
ele
men
t at
ris
k
HM
LH
ML
HM
LH
ML
Rock
fal
lH
igh
V. H
igh
V. H
igh
Mod
erat
eV.
Hig
hH
igh
Mod
erat
eM
oder
ate
Low
Low
Mod
erat
eLo
wV.
Low
Mod
erat
eH
igh
Hig
hM
oder
ate
Hig
hM
oder
ate
Low
Low
V. L
owV.
Low
Low
V. L
owV.
Low
Low
Hig
hM
oder
ate
Low
Mod
erat
eLo
wV.
Low
Low
V. L
owV.
Low
V. L
owV.
Low
V. L
ow
Slid
ing
/
Deb
ris fl
ow
Hig
hV.
Hig
hV.
Hig
hH
igh
V. H
igh
Hig
hM
oder
ate
Mod
erat
eM
oder
ate
Low
Mod
erat
eLo
wV.
Low
Mod
erat
eV.
Hig
hH
igh
Mod
erat
eH
igh
Mod
erat
eLo
wM
oder
ate
Low
V. L
owLo
wLo
wV.
Low
Low
Hig
hM
oder
ate
Low
Mod
erat
eLo
wV.
Low
Low
V. L
owV.
Low
V. L
owV.
Low
V. L
ow
Sedi
men
tatio
nH
igh
Hig
hH
igh
Low
Hig
hH
igh
Low
Mod
erat
eM
oder
ate
Low
Low
Low
V. L
ow
Mod
erat
eH
igh
Mod
erat
eV.
Low
Hig
hM
oder
ate
V. L
owM
oder
ate
Low
V. L
owLo
wV.
Low
V. L
ow
Low
Mod
erat
eM
oder
ate
V. L
owM
oder
ate
Mod
erat
eV.
Low
Low
V. L
owV.
Low
V. L
owV.
Low
V. L
ow
Sym
bol:
H: H
igh,
M: M
oder
ate,
L: L
ow,
V. H
igh:
Ver
y H
igh,
V. L
ow: V
ery
Low
| Guideline on Landslide Treatment and Mitigation6
Tabl
e 4.
Ass
essm
ent
of R
ecom
men
dati
on f
or T
reat
men
t
Elem
ent
at r
isk
Trea
tabi
lity
stat
usM
ajor
fac
tors
tri
gger
ing
/ E
nlar
ging
land
slid
e
Toe
cutt
ing,
Ste
ep s
lope
Lack
of
wat
er m
anag
emen
t, H
eavy
rai
n, S
teep
slo
peCr
acke
d ro
cks,
Ste
ep s
lope
, Ear
thqu
ake
Urg
ency
for
tre
atm
ent
V. H
.H
igh
Mod
.Lo
wV.
L.
V. H
.H
igh
Mod
.Lo
wV.
L.
V. H
.H
igh
Mod
.Lo
wV.
L.
Sett
lem
ent
Easi
lyV.
S.R.
V.S.
R.V.
S.R.
S.R.
M.R
.V.
S.R.
V.S.
R.V.
S.R.
S.R.
M.R
.V.
S.R.
S.R.
M.R
.R
N.R
.
Mod
erat
ely
V.S.
R.V.
S.R.
S.R.
M.R
.R
V.S.
R.V.
S.R.
S.R.
M.R
.R
V.S.
R.S.
R.M
.R.
Not
Rec
omm
ende
d./
Rese
ttle
men
tD
ifficu
ltly
S.R.
/
Rese
ttle
men
t
M.R
. /
Rese
ttle
men
t
R/
Rese
ttle
men
tN
.R./
Res
ettl
emen
tS.
R. /
Rese
ttle
men
t
M.R
. /
Rese
ttle
men
t
R/
Rese
ttle
men
t
N.R
.N
.R.
S.R.
/
Rese
ttle
men
t
M.R
. /
Rese
ttle
men
t
R /
Rese
ttle
men
t
Dev
elop
men
t
infr
astr
uctu
res
Easi
lyV.
S.R.
V.S.
R.V.
S.R.
S.R.
M.R
.V.
S.R.
V.S.
R.V.
S.R.
S.R.
M.R
.V.
S.R.
S.R.
M.R
.R
N.R
.
Mod
erat
ely
V.S.
R.V.
S.R.
S.R.
M.R
.R
V.S.
R.V.
S.R.
S.R.
M.R
.R
V.S.
R.S.
R.M
.R.
Not
Rec
omm
ende
d./
Real
ignm
ent
Diffi
cult
lyS.
R. /
Real
ignm
ent
M.R
. /
Real
ignm
ent
R/
Real
ignm
ent
N.R
./ R
ealig
nmen
tS.
R. /
Real
ignm
ent
M.R
. /
Real
ignm
ent
R/
Real
ignm
ent
N.R
./ R
ealig
nmen
tM
.R. /
Real
ignm
ent
M.R
. /
Real
ignm
ent
R/
Real
ignm
ent
Agr
icul
ture
Easi
ly
Not
Rel
evan
t
S.R.
M.R
.R
Not
Rel
evan
t
S.R.
M.R
.R
Not
Rel
evan
t
RN
ot R
ecom
men
ded
Mod
erat
ely
M.R
.M
.R.
RM
.R.
M.R
.R
Not
Rec
omm
ende
d /
Land
use
cha
nge
Diffi
cult
lyR
/ La
nd u
se
chan
ge
N.R
.N
.R.
R /
Land
use
chan
ge
N.R
. / L
and
use
chan
ge
Fore
sts,
Gra
ss la
nd a
nd
Rock
y ar
ea
Easi
ly
Not
Rel
evan
t
S.R.
RN
.R.
Not
Rel
evan
t
S.R.
RN
.R.
Not
Rel
evan
t
Not
Rec
omm
ende
d
Mod
erat
ely
RN
.R.
N.R
.R
N.R
.N
.R.
Diffi
cult
lyN
.R.
N.R
.N
.R.
N.R
.N
.R.
N.R
.
V. H
. = V
ery
Hig
hM
od. =
Mod
erat
eV.
L. =
Ver
y Lo
w
V.S.
R. =
Ver
y st
rong
ly r
ecom
men
ded
S.R.
= S
tron
gly
reco
mm
ende
dM
.R. =
Mod
erat
ely
reco
mm
ende
d
R =
Reco
mm
ende
d /
Land
use
cha
nge
to P
erm
anen
t ve
geta
tion
N.R
. = N
ot r
ecom
men
ded/
Lan
d us
e ch
ange
to
Perm
anen
t ve
geta
tion
Sym
bol:
Guideline on Landslide Treatment and Mitigation | 7
3Chapter
Landslide Mapping and Surveying to Identify Key Problems
Designing landslide treatment and mitigation measures
requires field investigations to identify the different
features and the key problems of the landslides.
Information from the landslide inventory and landslide
mapping are the basis for further field investigation of the
different zones of the landslide. See Annex 2 for landslide
mapping tips.
When investigating a landslide, it is divided into zones:
4 Main landslide at the center
4 Upstream zone: Upstream of the main landslide area
where probable cracks developed.
4 Side periphery: Land on either side of main landslide,
which may slide if cracks developed or the surface
deformed.
4 Downstream zone:
Fans: Area at the outlet at the lower end of the
landslide, where course debris deposited.
Sedimentation zone: Further down from the fan,
where fine and medium size particles washed down
and deposited.
3.1. Detailed Mapping of Landslides Mapping of upstream and side periphery zones of
the landslide: Generally, this zone includes crack zones
and the catch area. Crack zones are usually close to the
scarp of the landslide and very sensitive, demanding
urgent treatment. In this zone, it is essential to seal
cracks, manage drainage, and ensure proper land use for
erosion control. Crack zones are more prominent above
the landslide head than in the periphery. Mapping of the
catch area needs to show the different land uses requiring
different treatments; gullies demanding treatment; water
sources such as springs, irrigation canals, ponds, and
drainage channels; and settlements showing houses.
Mapping downstream of the landslide: While further mapping
the downstream zone of the landslide, map the fan where
course debris from the landslide has deposited and show the
main flow path. Any element in the fan area will be at risk.
Mapping of the sedimentation zone: Further, down on the
fan of debris deposition, is the area with medium and fine
sediment deposition. As the slope lessens, there is further
deposition of washed out soil materials. Map the area
affected by medium and fine sediment deposition showing
the different land uses and infrastructure, including the
houses. Sediment deposition may have adverse effects on
crops and settlements. The degree of the damage depends
on the quantity of sediment, its size, and runoff.
Mapping of the main landslide: Landslides have four
zones -- the crack zone, failure zone, transport zone, and
depositional zone (fan and sedimentation zone). When
mapping a landslide, show the following features on the
map.
4 Hanging rock and earth mass: Falling rock or earth
may endanger life and property down slope. It is
essential to knock off hanging rock or earth masses to
avoid this threat.
4 Cracks or hollow: Any crack within the landslide
indicates that the ground is under tension and still
subject to slope failure. While mapping cracks and
| Guideline on Landslide Treatment and Mitigation8
hollows, assess the width and depth of the cracks.
Wide, deep cracks or hollows show a possible serious
slope failure.
4 Scarps or cliff: Scarp slopes and cliffs are common in a
landslide close to the rim of the landslide and within
the landslide where localized slips happened.
4 Benches and terraces: Map where rotational slides
created benches or terraces within the landslide area.
Benches are usually below the scarp / cliff and show
the previous land use.
4 Irregular surface: Map any irregular or undulating
surface area where water may accumulate and help
to trigger more landslides.
4 Water features: Map water features such as springs,
potholes, and spring lines, to show water movement
within the landslide. Darker colored soil and plants
(especially water loving plants) point out dampness
and moisture. Whether a spring is perennial
or seasonal needs to be marked on the map.
Depressions or hollows with accumulated water in the
landslide show the seriousness of the slope failure
and slumping.
4 Drainage line: Map all drainage lines including rills
and gullies and show the portion of the drainage or
gully requiring treatment. Assess the total length of
the rills and the length, width, and slope of the gullies
and drainage requiring treatment.
4 Rock outcrop: Show any rock outcrop within the
landslide because rock outcrops help to assess the
rock type, soil depth, and depth of the slide.
4 Colluvial slope: Indicate where any colluvial deposits
are within the landslide and assess their average
slope and stone size.
4 Barren slope: Show any barren slope requiring re-
vegetation.
4 Toe of the slope: The ‘toe’ supports every slope
and toe protection is essential to stabilize the
slope. Identify the toe line of the slope so it can be
protected from cutting, erosion, sliding, and moisture
saturation. The indicator of the toe of the slope is any
change in the angle of the slope, mostly from steep
to less steep.
4 Path: Sometimes landslide encompasses the path,
although it might be disturbed by the sliding.
Generally, path line is more stable than other sloping
part within the landslide .
3.2. Landslide SurveyApart from the landslide mapping, some measurements in
the field are required to specify the distance, profile, plan,
and cross section. How to measure the distance, plan,
profile, and cross section is given in Annex 3.
Although best measured in the field, distance and plan can
be measured using Google Earth. If the plan is prepared
in Google Earth, the area for different treatments to be
applied can be estimated using http://www.earthpoint.us.
Plan
Cross Section
Guideline on Landslide Treatment and Mitigation | 9
For structural measurements (diversion canals, check
dams, or retaining walls), it is most appropriate to do
field measurements using measuring tapes and surveying
equipment, such as clinometers, clino-compass, level,
theodolite, Global Positioning System (GPS), etc.
3.3. Problem IdentificationMeasures to treat and mitigate landslides need to analyze
the cause triggering the problem. All earth material has
an angle of repose. However, when the slope angle of
an earth mass becomes greater than angle of repose, the
slope fails and the material moves downslope.
The angle of repose changes depending upon underlying
materials, moisture conditions, and conservation status.
With time, weathering changes the underlying material
from rock to soil, with rain, the moisture increases, and
with different human activities, the conservation status
changes. Therefore, with changes, the slope has to change
to be in a stable position again.
A slope that is stable today may not be stable tomorrow
as factors affecting its angle of repose change. For slope
stabilization, it is necessary to understand the dynamics of
these factors in the slope to design and apply conservation
measures appropriately.
Key problems
Some key problems causing slope failure include:
} Slope cutting
l To construct infrastructure, people cut the slope
increasing the angle of the slope to be greater
than its angle of repose. As a result, the slope
fails and earth slips downslope.
l Rivers and streams erode their banks at the toe of
the slope increasing its angle to be greater than
the angle of repose. Consequently, the slope fails.
} Over saturation
l Rain adds the water to the slope, saturating the
earth mass and decreasing the cohesion of slope
materials. The result can be a slope failure.
l Pore water pressure in the slope increases with
the addition of moisture, which can create
downward pressures causing slope failure.
l Mismanagement of drainage: In the process of
building infrastructure -- roads, irrigation, ponds
and reservoirs, etc. -- the natural drainage may
not tolerate adding more water or moisture in
certain places, resulting in slope failure.
} Excess weight
l The construction of infrastructure, such as
buildings, roads, heavy retaining walls, etc. may
add weight beyond what the slope can support,
resulting in slope failure.
l Growth of big trees on the slope can add weight
that eventually triggers slope failure.
l Addition of water in the earth mass adds weight,
resulting in slope failure.
Stabilization of landslide by wattling.© Keshar Man Sthapit
Guideline on Landslide Treatment and Mitigation | 11
4Chapter
Treatment and Mitigation Measures for Landslides
Various different measures for landslide treatment
depend on the features identified or mapped that are
causing problems. The following are specific techniques
for addressing various problems in landslides and general
recommendations for treating the various zones of
landslides.
4.1. Landslide Treatment Techniques4 Different techniques can address the various problems in
the landslides. Measures and techniques appropriate for
addressing different problems of the landslide treatment
are as follows:
a) Land use improvement: Techniques include
conservation plantation, grass plantation, on-farm
conservation, agro-forestry, safe water drainage, and
runoff harvesting ponds or dams in the catchment.
b) Drainage management: To prevent runoff from
flowing into landslides and to drain the excess water
from landslides, drainage management is essential.
Drainage management may be surface and sub-
surface drainage management.
l Surface drainage management: Techniques
applied include construction of diversion
waterways, sealing of tension cracks so that
rainwater cannot get inside and build up pore-
water pressure, rip-rap (stone or vegetative or
combined) of the waterways. These techniques
are appropriate for controlling shallow slides.
l Sub-surface drainage management: Techniques
applied include sub-surface drainage trenches
filled with gravel, perforated drainage pipes
(vertical and horizontal), which are appropriate
for reducing pore-water pressure along failure
planes.
l Conservation ponds to store and divert excess
run-off.
c) Surface erosion control: Techniques applied include
grass or tree sapling planting, jute netting, mulching,
wattling, and brush layering
d) Erosion control in rills: Techniques applied include
fascine, contour grass planting, rip-rap, and palisade
(wide rills).
e) Erosion control in gullies: Techniques applied include
palisade (small gullies), and check dams made of
brushwood, stone, boulders, gabions, masonry, or
concrete.
f) Slope failure due to slope cutting or steep slope:
Techniques applied include crib walls of bamboo, poles,
or concrete), retaining or toe walls of stone, gabion,
masonry, or concrete. Anchoring may be used in a deep-
seated landslide to bolt the rock bed but this is not easy
and is generally not used unless the landslide affects
national structure, such as hydropower or a highway.
g) Slope failure due to heavy load on slope upstream
of landslide: Techniques applied include excavation to
remove rock and soil from the head of a landslide to
reduce the driving force, and filling rock at the toe of
the landslide to increase resistance against movement.
h) Slope failure due to toe cutting by stream / river:
Techniques applied include revetment, spurs, or a rip-
rap toe wall to prevent cutting by the stream or river.
i) Protection of the landslide area from biotic
interference: Generally used soil conservation
techniques in landslide treatment are described in
Annex 4. Different species are used in the applying
conservation techniques. List of local names and their
botanical names and vice versa of commonly used
species are given in Annex 5.
4.2. Treatments for Specific Zones of the LandslideThe following are specific techniques and measure for
treating the various zones of landslides.
4.2.1. Upstream and Side Periphery Zones of the Landslide
This includes the crack zone above the landslide and the
catch area.
4 DSCWM 2004, Soil Conservation and Watershed Management Measures and Low Cost Techniques. Soil Conservation and Watershed
Management Component (SCWMC), Natural Resource Management Sector Assistance Programme (NARMSAP), Department of Soil
Conservation and Watershed Management (DSCWM), Babar Mahal.
| Guideline on Landslide Treatment and Mitigation12
Crack zoneCrack sealing: Runoff water entering cracks saturates
the land mass, reducing its cohesion as the pore water
pressure increases and makes the slope more subject to
failure. The runoff water entering the land mass through
cracks is more serious than surface runoff. Therefore, a
prime treatment in the crack zone is sealing cracks with
any available material, but preferably clay soil.
Water management: Diverting surface runoff from
the crack area close to the landslide is very tricky and
sensitive. A crack area is prone to movement when it
becomes wet, so construction of a diversion channel
may create more hazard than good if cracks develop in
the channel and the diverted water enters the landslide
through the cracks. Any depression where water
accumulates in a crack zone needs to be filled or reshaped
to drain surface runoff and stabilize the slope.
Load management: In the crack zone, any heavy load may
lead slope failure. It could be advantageous to remove
any heavy structure, such as a house, retaining wall, or big
trees. In the crack zone, it is best to grow grass, shrubs,
and bushes.
Cultivation in the crack zone close to the rim of the
landslide should not be allowed. However, when the crack
zone has expanded well above the rim of the landslide, it
is difficult to prevent people from cultivating crops there.
To avoid adverse impacts in such cases, it is important
to promote safe disposal of runoff, improved cultivation,
crop management, proper pasture management, and
afforestation on the barren and degraded slope.
Rills and gullies need to be treated with bioengineering
techniques, such as fascines, palisades, brush layering,
brushwood check dams, wattling, loose stone check dams,
vegetative rip-rap, and grass planting.
4.2.2. Downstream Zone of Landslide
Downstream Zones of landslides have two main parts.
The fan of course debris at the base of the landslide and
the sedimentation area further down with medium to fine
sediment flow.
Fan (of course debris): Below the main landside, course
debris will have deposited in the fan. Any mass movement
in the landslide will endanger everything in this area so
it is a high-risk zone. Generally, a stream or river will be
flowing at the end of the fan. If the stream or river is
cutting the toe of the fan, the primary treatment will be
protecting the toe of the fan.
Contour bunding with large stones (preferably boulders)
and leveling of the land behind the bunding (in another
word, terracing) could be an appropriate treatment. Where
there is a debris flow, contour bunding will dissipate the
energy of the debris flow to avoid damage downstream.
It is also beneficial to do contour planting of grass, shrubs,
and trees so that the vegetation will reduce the movement
of the sediment flow downstream through the fan.
Toe protection: If a stream is eroding the toe of the fan,
it is important to construct a protection wall to stop the
stream from eroding the end of the fan. This will help
stabilize the fan and the slope above it in the landslide.
To help protect the fan from erosion, other structures may
need to be constructed such as retaining walls, toe walls,
embankments, and spurs.
Protect fan from cutting or erosion: Terrace building and
vegetation growth in the fan will protect it from erosion
and reduce any further movement of debris. In cases
where a road passes through the fan of a landslide, the
removal of materials falling onto the road is almost like
toe cutting the fan slope, which makes the fan unstable.
Roads at top of debris fan: It would be most appropriate
to run the road at the top of the debris deposition in the
fan rather than clearing the debris to cut through the
middle of the fan. This increases the road slope, but the
increase in the depth of deposition in the fan supports
the upslope of the landslide. If the landslide is active, any
treatment in this area may be subject to damage. If there
is a prominent channel in the fan, it is best to maintain the
channel, so that water and sediment flow are confined to
the channel, reducing damage to the fan.
Sedimentation zone (Deposition zone of medium and
fine sediment): Generally, a landslide will carry medium
and fine sediment further down from a fan to deposit it on
the gentle slope area below. A sedimentation zone is more
prominent if there is no stream or river flowing at the end
of the fan. If there is a stream or river originated from
other catch area flowing at the end of the fan, it will be
difficult to delineate the sedimentation area clearly.
Treatment measures: The conservation measures to
protect the area and treat the landslide will be to trap
sediment in the fan, establish a buffer strip across the
sedimentation area, and safely channelize the flow from
the fan into a major river. The most appropriate treatment
would be channelization of the flow with a protection
wall, revetment, and spurs, and rehabilitation of reclaimed
land by planting of grass, shrubs and trees, and on-farm
improvement behind the protection wall. Rehabilitate
agricultural land by removing the debris (rocks, stones,
Guideline on Landslide Treatment and Mitigation | 13
pebbles, gravel, etc.), digging and bringing the buried soil
to spread on top, and adding good sediments (silt, clay,
organic matter) from outside the area.
4.2.3. Catchment Area
Land use improvement: The catchment area above the
crack zone generally requires proper land use and safe
disposal of runoff water. Conservation techniques to apply
in the catchment area include plantation of trees and
grass, on-farm conservation, and a safe drainage network.
Therefore, the catchment area needs to be mapped
specifying different land uses that demand different
treatments; gullies demanding treatment; water sources
such as springs, irrigation canals, ponds, and drainage
channels; and settlements showing houses.
Improved cultivation includes planting of trees and grass
on waste areas between the farmlands, protecting from
raiser failure by planting grass or building stonewalls,
leveling of sloping agricultural land, and improving the
drainage network in the farmland.
Crop management includes changing from crops requiring
too much moisture to crops requiring less moisture. For
example, changing from wetland paddy to the system
of rice intensification (SRI), wheat, millet, or maize, and
changing from seasonal cereal crops to more perennial
crops, such as fruit trees or agro-forestry orchards.
Rills and gullies need treatment with bioengineering
techniques such as fascines, palisades, brush layering,
brushwood check dams, wattling, loose stone check dams,
vegetative rip-rap, and grass planting.
Drainage management: The safe disposal of water from
the catchment area that enters the landslide plays a key
role in landslide treatment. The key measures to divert
water from entering to the landslide are construction of a
drainage network and a diversion canal in the catchment
area to divert water away from the landslide area. A
conservation pond and a series of water holding trenches
could help manage water in the catchment area so long as
they are not close to the landslide.
Practical considerations for drainage and waterways improvement
} Always design drainage systems to run along natural
drainage lines
} Never use contour drains because they can block very
easily and are susceptible to subsidence. A blocked or
cracked drain can create terrible damage because of
concentrated water flow in the landslide.
} Design and construct drains in such a way that water
can enter easily from the higher side into the canal
but not seep out of the canal from the lower side.
} Diversion waterways must be well above the
crack zones. Waterways must be wide enough to
accommodate the maximum runoff and be earthen or
lined, depending on the site condition.
} Precautions must be taken to dispose the diverted
runoff safely in the stable natural drainage system so
that no new gully or landslide is created.
} Regular cleaning of drainage and prevention of
leakage in the diversion channel is essential for safe
disposal of water.
4.2.4. Main Landslide
Treatment of the main landslide depends on its different
features and the most feasible treatment for each feature.
However, it is important to note that suggested treatments
must not be adapted blindly without considering the
overall situation of the landslide. This is also not an
exhaustive list of suggested treatments.
Hanging rocks and earth mass: Knock down all possible
hanging rocks and earth mass as a first step. This will avoid
the risk to life and property from falling rock and earth
masses.
Cracks and hollows: Seal all cracks as soon as possible to
prevent runoff water from entering into the earth mass,
which results in greater risk of mass movement.
Scarp and cliff: Stability of the scarp slope depends on
the composition of the material. If the scarp slope seems
stable, keep it as it is. If the scarp slope is not stable,
reshape it to 35 to 45º. Hold the debris from reshaping the
scarp slope by constructing a contour bund or wall at the
foot of the scarp slope. One concern is if the heavy load
of a bund or wall will enlarge the landslide. Stabilize the
reshaped slope using wattling, vegetative riprap, brush
layering, grass seeding, or planting grass slips and tree
saplings.
Benches and terraces: Do not disturb a bench unless
there is a depression holding water. If so, the fill the
depression with debris and plant the surface with grass
and bush. Construction of conservation structures such as
contour bunding and catch wall in the benches could be
considered if appropriate.
Irregular surfaces: Irregular or undulating surface areas need
to be smoothed so that no water is accumulates on them.
Water features: Springs, potholes (depressions including
ponds), and seepage lines are major water features in a
| Guideline on Landslide Treatment and Mitigation14
landslide other than the drainage line. Water management
is the key activity in landslide treatment.
} Spring: Collect water from the spring and drain it
through the drainage network as soon as possible.
Draining spring water through inclined perforated
pipes under the surface may help in the management
of spring water.
} Pothole: Fill potholes (depressions) holding water.
} Seepage line: The seepage line is the weakest part
of the landslide and shows the toe line for the slope
above. It is essential to construct a toe wall to drain
water from the seepage line. It may help to drain
the water from the seepage line through inclined
perforated pipes under the surface.
} Drainage line: The safe disposal of runoff water
is a key activity in landslide treatment. Some
recommended activities for drainage protection are
vegetative stone pitching of the drainage line and
construction of a series of low height check dams.
If the drainage slope is steep, a structure with step
drops is appropriate for the safe disposal of runoff. In
an area with big runoff, a cement or concrete lined
channel or drop structures may be required.
Colluvial slope: Stabilize the colluvial slope with contour
bunding, contour leveling with appropriate spacing, and
growing vegetation.
Barren slope: Protect barren slopes from surface erosion
by diagonal grass planting, jute netting/mulching, and
planting seedlings and cuttings. Stabilize slopes with
retaining walls, contour bolsters, contour stone bunding,
bush layering, wattling, and vegetative riprap.
The moisture concentration in a slope can be managed
by laying stone filled sub-surface drainage in a with
herringbone pattern. Rills and gullies in the barren slopes
can be treated with bioengineering techniques, such as
fascines, palisade, brush layering, brushwood check dams,
wattling, loose stone check dams, vegetative rip-rap, and
grass planting.
Toe of the slope: Each slope has its own toe usually seen
where the slope changes from steep to less steep. Protect
the toe by constructing a toe wall, vegetative pitching the
toe area, and draining moisture from the toe line.
Path: Improvement of the path will help the activities
carried out for landslide treatment.
4.3. Practical Considerations5 and Approaches Landslide treatment is a complex activity because each
landslide is different from all others. Different site-specific
techniques are based on the problem analysis. Landslide
treatment has the most successful results when the
recommended techniques are implemented as a package.
This package may be expensive so if the resources are not
available to implement all the recommended techniques as a
package, it is advisable to implement the activities in phases.
It may also be necessary to implement the techniques over
several years, rather than as a one-time activity. The landslide
situation may also change over time, so the techniques and
measures may need to be changed. Therefore, landslide
treatment needs to be viewed as a dynamic process.
Expensive structures should not be used to treat geological
(natural) landslides unless and until they affect habitation
or infrastructure (e.g. roads and hydropower projects).
4.3.1. Landslide Treatment Approach and Working Season
Community involvement is integral to successful landslide
treatment, which should include with the protection of
settlements including educational centres, initiatives to
reinstate livelihoods, water resource infrastructures such as
irrigation and drinking water source, and agriculture land.
} Any time when workers are available or during
farmers’ slack season for structural works. However,
the rainy season is risky for the construction of
structures.
} During the dry dormant season if the site is moist.
Vegetative work should be done just before the
monsoon for the best results.
5 DSCWM 2004, Soil Conservation and Watershed Management Measures and Low Cost Techniques. Soil Conservation and Watershed
Management Component (SCWMC), Natural Resource Management Sector Assistance Programme (NARMSAP), Department of Soil
Conservation and Watershed Management (DSCWM), Babar Mahal.
Guideline on Landslide Treatment and Mitigation | 15
5Chapter
Capacity Building and Lesson Learned Documentation
Several government organizations and NGOs are working
with the Department of Soil Conservation and Watershed
Management on landslide treatment and mitigation
activities. After the earthquake of April 25, 2015, the need
for landslide treatment has increased greatly in Nepal. The
need is enormous compared to the monetary and human
resources available. There is a serious lack of technical
skills in landslide treatment and mitigation among the
available human resources. Therefore, it is essential to
build the capacity of field professionals in survey, design,
and implementation of the landslide treatment and
mitigation activities.
Annex 6 gives a proposed training module and schedule
for capacity building on landslide treatment. Annex 7 gives
a proposed format for the documentation of lesson learned
from the implementation of the landslide treatment
activities. Landslide treatment measures are site specific so
there is a need for continuous upgrading of technologies,
knowledge, and skill in landslide treatment and mitigation.
| Guideline on Landslide Treatment and Mitigation16
Broom grass plantation to stabilize slope.© Keshar Man Sthapit
Guideline on Landslide Treatment and Mitigation | 17
6Chapter
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Website for the presentation in the Consultative
Workshop Landslide Inventory, Risk Assessment
and Mitigation in Nepal: http://www.icimod.org/
landslideworkshop2015
Guideline on Landslide Treatment and Mitigation | 19
Annexes
Annex 1. Terms of Reference: Sub-group 3. Landslide Treatment and Mitigation
} Recommend the best approach for the execution of
the landslide treatment and mitigation to Nepalese
context.
Scope of work:
} Collect and review all the related documents,
information, guidelines, methodologies, initiatives,
and tools on the landslide treatment and mitigation
measures.
} In line with the workshop’s resolution, the sub-group
should prepare methodology / guidelines considering
the following points:
o Local: It should directly involve the local
communities with the possibility of maximum
use of local materials.
o Simple and easy to use: the method should be
relatively simple having not complex design
consideration, structural parts.
o Guidelines should stress complete treatment of
the landslide using bio engineering techniques
(integration of vegetative techniques with small
scale engineering structure) suitable to the
ecosystem. The sub-group should list the best
suitable species and their characteristics to be
used in the context of Nepal.
} Prepare guidelines with clear methodology for survey,
design, estimation, and costing of landslide treatment
and mitigation measures.
} The sub-group should work on the software part
(training) about the information of landslide risk, its
prevention and safer activities to avoid landslides.
} DSCWM, DSCO will be helping on the field testing,
assessment of the structural components.
Methodology:
This working group has liberty to use varieties of widely
accepted and scientific methods and tools to accomplish
the given task. Team should first assess the different
6 Testing of the methodology and documentation of the lesson learned in the implementation will be responsibility of the implementing
organizations. However, the sub group will prepare format for documentation so that the leaning could be used to update the guideline.
Background:
The consultative workshop recognized the need for close
coupling of treatment work with inventory and hazard
zonation. This should facilitate categorization of landslides
that require mitigation. This should come from the national
landslide inventory and local hazard assessment. It was
felt that priorities should be given both at the community
level as well as for large infrastructures. A strong coupling
of mechanical, biological, and ecosystem based strategies
is suggested. The landslide stabilization should focus on
reinforcing livelihood and food security based on the available
ecosystem services. A formal coordination agency to take
the lead role with operational support from public, private,
civil society and community is also pointed out. Community
participation, Proper land use planning, Establishment of an
early warning system at the local level, Awareness raising,
Capacity building are considered as enabling elements and be
integrated as part of the total project cycle.
Objective of the assignment:
The broader objective of this task is to come up with
methodology (sequential steps) to be followed in applying
landslide treatment and mitigation measures that will be
most appropriate to Nepalese context and can be uniformly
used by different agencies and experts as per their needs.
The specific objectives are:
} Explore and evaluate the methodologies and tools
used for landslide treatment and mitigation in Nepal
and other countries.
} Based on experience and available document
recommend guidelines (sequential steps) for
pragmatic methods in applying landslide treatment
and mitigation measures.6
} Recommend the required survey, design and practical
considerations/ materials required / format for
estimation and conditions to use the methods and
guidelines.
| Guideline on Landslide Treatment and Mitigation20
guidelines/methods used on the subject matter and keep
themselves informed of the relevant studies and workouts
available regarding the job.
Supervision and coordination:
The Sub-group will closely work with and report to the
main working group and/ or liaison person assigned.
Overall technical advice will be provided by the
consortium of the partner organizations or DSCWM and
S.No. Deliverables
1 Field assessment guideline for landslide treatment and mitigation
2 Survey, design, and implementation guidelines for different techniques to be applied in the landslide treatment
and mitigation.
3 List of reference materials
4 Training framework to enable the practitioners to apply the guideline and techniques.
5 Framework for documentation of lesson learned of the different techniques.
other related agencies as per decision of the partners’
meeting.
Deliverables:
Electronic copies of tools and methodology of landslide
treatment and mitigation should be submitted to
the coordinator of the working group in report form.
Particularly, the sub-group should produce and support for
the following deliverables.
Guideline on Landslide Treatment and Mitigation | 21
Annex 2. Mapping Steps (Modified after NARMSAP/DSCWM, 20047 and 20058)
Steps in a suggested procedure Draw, Measure or describe
Step 1 Prepare map of about 1:1000 – 5000 scale (Depending upon the size to the
landslide)
Draw, describe, measure
If it is not possible to prepare such a map, make a sketch map (sketch the site
from a good observation point most preferably in A4 size paper) or use Google
image (wherever possible):
Observe and record physical condition
• Note the exact location of landslide so that other people can easily locate
the site with the help of the note if necessary,
• Mark landslide boundary
• Indicate the presence of an old landslide if any,
• Indicate the features like road, streams, springs, canal (irrigation canals or
drainage structures), that may either have caused it in the first place, or they
may be contributing to future failure.
• Indicate catchment area including major land use types requiring treatment,
• Indicate houses, roads, or other structures in close proximity
• Landmarks on the site, such as prominent trees, etc.
Step 2 Geomorphic situation Draw, describe
Look at the general locality and situation of the site:
• Record in which part of the slope the landslide has originated from i.e.
upper part (upper concave part) of the slope, middle part or lower part
(convex) of the slope.
• Note if it is in a part of the landscape where instability would be expected
Step 3 Landslide zoning Draw
• Mark
• Crack zone outside the main landslide area (look and mark cracked area
on the top and around sides of the landslide)
• Scarp zone
• Transportation zone
• Deposition zone i.e. fan and sedimentation zone
Step 4 Mapping of main landslide
• Indicate hanging rock or earth mass to be knocked down before
implementing any conservation measures
• Indicate main scarp mostly found around the rim of the landslide
• Indicate individual scarp and measure its slope and length and width
• Mark any less steep benches and measure the length, width, and slope
• Mark and measure any back tilted slope, where water may collect
• Mark path passing through the landslide
• Mark any rock outcrop
7 DSCWM 2004, Soil Conservation and Watershed Management Measures and Low Cost Techniques. Soil Conservation and Watershed
Management Component (SCWMC), Natural Resource Management Sector Assistance Programme (NARMSAP), Department of Soil
Conservation and Watershed Management (DSCWM), Babar Mahal.
8 DSCWM, 2005. Training handout on Bioengineering and Survey, Design and Estimation of Soil Conservation Activities- SCWMC, NARMSAP,
DSCWM, Kathmandu, Nepal.
| Guideline on Landslide Treatment and Mitigation22
Steps in a suggested procedure Draw, Measure or describe
Step 5 Mark and measure the surface water body and drainage Draw
• Mark and measure surface drainage pathways (springs, canals) that may
require diverting away from the landslide
• Mark and measure drainage network (stream, rills and gullies) that may
require conservation measures for safe disposal or protection
• Mark and measure any seepage line, spring, swamp, pot holes that may
need to be drained
• Irrigation canals or drainage structures, especially masonry drainage
ditches.
Step 6 Mapping of depositional zone
• Map the fan
• Mark the boundary of the fan
• Indicate the drainage lines in the fan
• Assess the materials types (Alluvium, Colluvium)
• Measure the average slope, dimension (Length and width) and stone size
• Assess broadly the wetness category (Moist, Wet or Dry)
• Map the sedimentation zone
• Assess the material type (Fine, medium or course)
• Measure the average slope and dimension of sedimentation zone
• Indicate the land use type
Step 7 Slope material examinations (Slope forming material and debris) Draw, describe
• Colluvial slope: Slope of material moved downhill mainly by gravitational
force and deposited lower on the slope. The materials are angular
fragments and alluvial in parts. Assess the average slope, dimension, and
stone size in the colluvial deposition.
• Barren slopes: Any slope in the landslide devoid of vegetation. Assess the
average slope and dimensions.
• Assess the wetness of the slopes (Moist, wet and dry).
Step 8 Rock: Look the bed rock surface wherever exposed Draw
• Note the uniformity or layering (bedding) of the rock units:
• Mark alternating hard and soft rocks if any
• Assess hardness of the rocks (weathering): Soft and Hard rock
• Note degree of fracturing of rock, especially any open fracture
• Note the orientation of the rock fracture
• Note any signs of water movement along fractures
Step 9 Prepare profile and cross section Draw, measure
• Sketch a slope profile of the landslide from top to bottom.
• Measure the slope of different zones and places where treatment is
required
• If slope measurement is not possible, make an ocular estimate. Angles may
not be actual, but should indicate relative steepness.
• Survey the longitudinal profile and cross section of the landslide area,
where the check dams, retaining wall and toe wall, etc. that need to be
installed.
Guideline on Landslide Treatment and Mitigation | 23
Steps in a suggested procedure Draw, Measure or describe
Step 10 Record history and life progression of landslide Describe, draw
Step 11 Identify causes and mechanisms of landslide Describe, draw
• Mark problems of toe cutting
Step 12 Assess and design landslide treatment activities Describe
Remarks:} Trees leaning in different directions often indicate a
slow creep of surface materials down slope without
imminent slope failure.
} Fresh debris indicates a landslide upslope.
} Most landslides enlarge with time. Generally, the area
studied should be 2 – 3 times wider and longer than
the landslide area.
} Analyze geology, topography, drainage, and other
natural and man-made elements to understand the
processes of the landslide to design optimal measures
to treat the landslide.
| Guideline on Landslide Treatment and Mitigation24
Annex 3. Basic Surveying
1. Introduction to surveying
Surveying is the art of making measurements (of the
relative positions) of natural and man-made features on
the earth’s surface for presentation either graphically
or digitally. Basically surveying consists of linear
measurement of horizontal distances, bearings indicating
direction of the measurement with north, and elevation
of the measured points corresponding to sea level as a
reference. Basics of surveying are as follows:
a. Linear measurement
Linear measurement is measuring the distance between
two points and expressed in the horizontal distance. If the
measurement is carried out in the slope the measured
distance in the slope need to be converted into horizontal
distance.
Benchmark is a surveyor’s mark on a permanent object
of predetermined position and elevation used as a
reference point. In surveying with bearing and distance
measurements, objects and points are located with respect
to bench marks in a horizontal plane.
Fore and back bearing
The bearing of a line differs accordingly whether the
observation is made from one end of the line or from
the other. If the bearing of a line AB is measured from A
towards B, it is forward bearing or fore Bearing (F.B.). If
the bearing of the line AB is measured from B towards A, it
is known as backward bearing or Back Bearing (B.B.), since
it is measured in backward direction.
Back bearing of line AB is fore bearing of line BA that is
equal to 180° +AB
. Similarly, the back bearing of line CD is
b. Bearing
Bearing of a line is measured with magnetic north (or with
south) in clockwise direction. The value of the bearing thus
ranges from 00 to 3600. A prismatic compass is graduated
in this system.
Bearing and distance allow us to locate the point with
respect to a benchmark.
fore bearing of line DC that is equal to CD
–180°. Thus, in
general, it can be stated that B.B. = F.B. ± 180°, using plus
sign when F.B. is less than 1800 and minus sign when F. B.
is greater than 180°.
HS A B
Horizontal Ground A
B
Ө
SL
H
Horizontal Distance Measured in Sloping ground, HS = SL * Cos Ө
Guideline on Landslide Treatment and Mitigation | 25
c. Elevation
For many purposes, location of the object or point is
required with respect to elevation. For which measurement
in distance, bearing, and elevation is required.
Generally, surveying is done to know the distance, bearing
and elevation of an object or point.
2. Survey information
When designing soil conservation and watershed
management activities, one needs to know distance, plan,
profile, cross section, and area.
a. Distance: Linear measurement between two points
expressed in horizontal distance.
b. Plan: Map indicating different points and objects in
the horizontal plane.
c. Profile: A vertical section of the Earth’s crust showing
the different horizons or layers. It is a map or drawing
showing the horizontal distance and elevation of
different objects / points.
Field measurement for profile leveling (with
Abney’s level or clinometer and measuring tape) -
Take two rods or sticks of the eye height. From the
upper selected site target a clinometer on the top of
the rod at the first site and read the slope in percent
holding the clinometer at the tip of the rod upstream.
E
1 Ro
P
Rod
P
3 Rod
P
2
Rod
H
1
Tape
H”2
Tape H
’2
Tape
E
2
Point P1 to P
2P
2 to P
3P
3 to P
4
Horizontal Distance H1
H2 = H’
2 + H”
2
Slope in % S1
S2
Magnetic Bearing B1
B2
Elevation Diff. E1
E2
Note the slope in percent and measure the horizontal
distance with a tape. While measuring the distance,
keep the tape horizontal. If the distance is too long
or the elevation difference is too high for any person
to hold horizontally, either measure the horizontal
distance in steps or measure the sloping distance and
later convert into horizontal distance for plotting. Also,
measure the bearing, preferably magnetic bearing.
d. Cross section: A section formed by a plane cutting
through an object, usually at right angles to an axis.
Cross section is a dimension measured generally
perpendicular to profile.
How to measure?
To measure the cross- section, stretch a measuring
rope at right angles to the main line of section at a
height of more than 5 meters depending upon the
condition of the site. Then, with a measuring rod start
from one end, to measure the depth of the gully bed
considering the rope as base line and distance from
one end as starting point. The distances are measured
left and right from the center peg. The readings are
entered in tabular form in Table with solved example.
Plotting of the depth and distance will give the cross
sectional profile. Always, it is important to start the
measurements from one side for all sections.
| Guideline on Landslide Treatment and Mitigation26
Annex 4. Landslide Treatment Techniques9
Landslide treatment and mitigation uses several
different conservation techniques that may be broadly
categorized into vegetative and structural techniques.
Vegetative techniques include: grass planting, mulching,
bamboo planting, buffer strips, conservation plantation,
fascine, palisade, brush layering, and wattling. Structural
techniques include rip-rap, waterways, bolster, retaining
wall, check dam, and conservation pond.
9 Source: Modified from DSCWM 2004, Soil Conservation and Watershed Management Measures and Low Cost Techniques. Soil
Conservation and Watershed Management Component (SCWMC), Natural Resource Management Sector Assistance Programme
(NARMSAP), Department of Soil Conservation and Watershed Management (DSCWM), Babar Mahal.
Guideline on Landslide Treatment and Mitigation | 27
Titl
e: G
RASS
PLA
NTI
NG
Wha
t is
it?
Plan
ting
of g
rass
(se
ed, c
lum
p, r
hizo
me,
cut
tings
). P
lant
ed in
con
tour
, ver
tical
or
diag
onal
Sket
chFu
ncti
onLi
mit
atio
n
•
Arm
or (
Prot
ects
sur
face
fro
m r
aind
rops
by
prov
idin
g gr
ound
cov
er).
• Im
prov
e in
filtr
atio
n th
us r
educ
ing
runo
ff.
• Ca
tch
soil
mat
eria
l and
rei
nfor
ce s
lope
s.
• La
bor
inte
nsiv
e.•
Onl
y go
od f
or s
hallo
w s
mal
l lan
dslip
s.•
Som
e sp
ecie
s m
ay s
prea
d as
wee
d.
Type
Cont
our
Vert
ical
Dia
gona
l
Adv
anta
geIn
crea
ses
infil
trat
ion
and
catc
hes
soil
mat
eria
l. Pr
oduc
es f
orag
e.Ch
anne
lizes
run
off
and
less
infil
trat
ion.
Pr
oduc
es f
orag
e.Co
mbi
nes
the
best
fea
ture
s of
bot
h co
ntou
r an
d ve
rtic
al.
Prod
uces
for
age.
Dis
adva
ntag
eCa
n tr
igge
r liq
uefa
ctio
n du
e to
in
crea
se in
infil
trat
ion.
sCa
n de
velo
p ri
lls d
own
the
slop
es d
ue t
o ru
noff
. Ca
n de
velo
p sm
all r
ills
dow
n th
e sl
opes
on
wea
k m
ater
ial.
Som
e sp
ecie
s m
ay s
prea
d as
wee
d.
Plan
ting
ste
ps
• Pr
epar
e th
e si
te w
ell i
n ad
vanc
e fo
r pl
antin
g. F
ill t
he d
epre
ssio
ns a
nd c
lear
pro
trus
ions
. Sm
ooth
the
sur
face
so
that
the
re is
now
here
for
ero
sion
to
star
t. If
the
site
is
ba
ckfil
l mat
eria
l, it
shou
ld b
e th
orou
ghly
com
pact
ed, p
refe
rabl
y w
hen
wet
.•
Alw
ays
star
t pl
antin
g gr
ass
at t
he t
op o
f th
e sl
ope
and
wor
k do
wnw
ards
.•
Mar
k th
e lin
es w
ith s
trin
gs w
here
gra
ss is
to
be p
lant
ed. E
nsur
e th
at t
he li
nes
follo
w t
he c
onto
ur o
r de
sire
d an
gle
(Ver
tical
or
diag
onal
).•
Split
the
gra
ss s
lips
to m
axim
ize
the
amou
nt o
f pl
antin
g m
ater
ial.
Trim
off
long
roo
ts a
nd c
ut t
he s
hoot
s at
abo
ut 1
0 cm
abo
ve g
roun
d le
vel.
Wra
p th
e sl
ips
with
dam
p
he
ssia
n to
kee
p th
em m
oist
unt
il th
ey a
re p
lant
ed. R
emem
ber
that
you
will
nee
d tw
o sl
ips
per
drill
(pl
antin
g ho
le)
if th
e gr
ass
is a
fibr
ous
root
ing
type
(e.
g. b
abiy
o,
ka
ns, k
har,
phu
rke,
etc
.) b
ut o
nly
one
if it
is r
hizo
mat
ous
(e.g
. am
liso,
pad
ang
bans
, etc
.) a
nd o
nly
one
stem
cut
ting
(roo
ted)
or
seed
ling.
• W
ith a
pla
ntin
g ba
r, m
ake
a ho
le ju
st b
ig e
noug
h fo
r th
e ro
ots/
rhiz
omes
/cut
tings
. Pla
ce t
he g
rass
into
the
hol
e. F
ill t
he s
oil i
n ar
ound
the
m, p
ress
the
soi
l gen
tly
with
your
fing
ers.
•
If co
mpo
st o
r m
anur
e is
ava
ilabl
e, s
catt
er a
few
han
dful
s ar
ound
the
gra
sses
. Thi
s is
esp
ecia
lly im
port
ant
on v
ery
ston
y si
tes,
whe
re c
ompo
st o
r m
anur
e ca
n he
lp t
o
im
prov
e ea
rly
grow
th. Y
ou m
ay h
ave
to in
corp
orat
e co
mpo
st in
to t
he s
urfa
ce m
ater
ial t
o pr
even
t it
bein
g w
ashe
d of
f.•
If it
look
s ra
ther
dry
and
the
re is
no
pros
pect
of
rain
for
a d
ay o
r tw
o, c
onsi
der
wat
erin
g th
e pl
ants
by
hand
.
•
Mat
eria
lsSp
ecie
s To
ols
Gra
ss p
lant
s (c
lum
p,
rhiz
ome,
cut
ting)
Th
ysan
olae
na m
axim
a, E
ulal
iops
is b
inat
a, N
eyra
udia
rey
naud
iana
, Sac
char
um
spon
tane
um, T
hem
eda
spec
ies,
Cym
bopo
gon
mic
roth
eca,
Vet
iver
ia la
wso
ni,
Aru
ndo
clon
ax, P
enni
satu
m p
urpu
reum
, Him
alay
acal
amus
hoo
keria
nus,
Aru
ndue
lla
nepa
lens
is, N
eyra
udia
aru
ndin
acea
, Dre
pano
stac
hyum
inte
rmed
ium
, Vet
iver
, Cy
nodo
n da
ctyl
on, e
tc.
• Sh
ort
plan
ting
bars
•
Line
str
ing
/ Ta
pe m
easu
re (
30 m
eter
s)•
A m
eans
of
tran
spor
ting
plan
ts t
o si
te•
Hes
sian
and
wat
er t
o ke
ep t
he p
lant
ing
stoc
k m
oist
until
pla
ntin
g
Spac
ing:
Wit
hin
row
s: 1
0 cm
apa
rt e
xcep
t pa
dang
, am
liso
and
tite
niga
lo b
ans,
whi
ch s
houl
d be
spa
ced
30-5
0 cm
Plan
ting
per
iod
Row
Spa
cing
: Dep
ends
larg
ely
on t
he s
teep
ness
of
the
slop
e
Row
spa
cing
• D
urin
g th
e do
rman
t se
ason
if t
he s
ite is
moi
st.
• Ju
st b
efor
e m
onso
on if
the
site
is d
ry (
May
- Ju
ne)
Cont
our
Vert
ical
Dia
gona
l
Slop
e <
30
: 100
cm
Slop
e 30
– 4
5 :
50
cmSl
ope
> 45
:
30
cm
50 c
m50
cm
On
agric
ultu
re la
nd, fi
nd a
com
prom
ise
betw
een
ease
of
cult
ivat
ion
and
redu
ctio
n of
soi
l and
wat
er m
ovem
ent.
A
ver
tical
inte
rval
of
2 m
eter
s or
mor
e is
gen
eral
ly a
dequ
ate.
Mai
nten
ance
Pr
ecau
tion
sSc
ope
(Sit
e fo
r ap
plic
atio
n)
• In
volv
es p
rote
ctio
n, w
eedi
ng, a
nd c
uttin
g fo
r ne
w g
row
th.
• Re
gula
rly
trim
the
gra
ss p
lant
ed o
n ri
ser
to p
reve
nt
th
em f
rom
sha
ding
and
spr
eadi
ng o
n fa
rmla
nd.
• Pr
otec
t ar
ea f
rom
the
fire
• En
sure
tha
t th
e ro
ots
have
not
tan
gled
or
have
cur
ved
back
to
the
surf
ace.
• Ta
ke c
are
to a
void
leav
ing
air
pock
et b
y th
e ro
ots
durin
g
pl
antin
g.
• A
lmos
t an
y sl
opes
less
tha
n 65
. Mos
tly
wel
l dra
ined
soi
ls w
here
incr
ease
in in
filtr
atio
n is
unl
ikel
y to
caus
e pr
oble
ms.
• Ri
ser
/ ri
m o
f th
e cu
ltiv
ated
fiel
ds.
Refe
renc
es: D
OR,
199
9. F
AO
and
IIRR
, 199
5, D
SCW
M 2
004.
| Guideline on Landslide Treatment and Mitigation28
Titl
e: M
ULC
HIN
G F
OR
SLO
PE S
TAB
ILIZ
ATI
ON
Wha
t is
it?
Tech
niqu
e of
cov
erin
g so
il su
rfac
e te
mpo
rari
ly in
ord
er t
o m
aint
ain
soil
moi
stur
e, p
rote
ct s
eeds
fro
m w
ashi
ng, a
nd c
reat
e
favo
rabl
e co
nditi
ons
for
plan
ts t
o es
tabl
ish.
Sket
chFu
ncti
onLi
mit
atio
n
•
Prot
ects
soi
l fro
m r
aind
rop
eros
ion,
hea
t, f
rost
, and
win
d.
• Re
duce
s ev
apor
atio
n th
us c
onse
rves
moi
stur
e.
• A
rmor
s so
il te
mpo
rari
ly.
• Co
ntro
ls w
eeds
.
• Re
quir
es h
uge
quan
tity
of m
ulch
ing
mat
eria
l.
• La
bor
inte
nsiv
e.
Not
e: P
last
ic m
ulch
is n
ot c
onsi
dere
d to
be
very
pra
ctic
al
for
slop
e st
abili
zatio
n.
Adv
anta
ges
Dis
adva
ntag
es
• O
rgan
ic m
ulch
incr
ease
s or
gani
c m
atte
r, m
icro
bial
act
ivity
,
m
oist
ure
in s
oil,
thus
incr
ease
s pr
oduc
tion.
• H
elps
see
d ge
rmin
atio
n.
• La
bor
dem
andi
ng d
urin
g co
llect
ion
• M
ay in
crea
se in
sect
s (t
erm
ite)
and
pest
s (r
oden
t)
• Ri
sk o
f fir
e ou
t br
eak
• •
Mul
chin
g st
eps
• Pr
epar
e th
e la
nd
• Co
llect
and
cho
p m
ulch
mat
eria
ls
• So
w t
he g
rass
see
ds t
hen
spre
ad t
he m
ulch
to
cove
r th
e en
tire
surf
ace.
• If
the
slop
e is
mod
erat
e to
ste
ep o
r th
e ar
ea h
as p
reva
iling
win
ds, m
ulch
nee
ds t
o be
pro
tect
ed f
rom
blo
win
g. P
rote
ct t
he m
ulch
ei
ther
with
w
ide
mes
h ju
te n
et a
s sh
own
in t
he p
ictu
re a
t to
p or
tie
d to
geth
er w
ith s
ticks
as
show
n in
mid
dle
pict
ure.
• In
usi
ng P
last
ic F
ilm (
PF),
aft
er s
prea
ding
pla
stic
she
et, p
ress
the
edg
es w
ith w
et s
oil a
t le
ast
10 c
m, (
to p
reve
nt f
rom
bei
ng b
low
n
of
f by
the
win
d)
• • • •
Mat
eria
ls
Tool
s
• M
ulch
ing
mat
eria
l: Pl
ant
resi
dues
(st
raw
, sta
ck, h
usk,
and
stu
bble
),
leaf
litt
ers,
saw
dust
/ash
, wee
ds e
tc.
• Sp
read
ing
Rake
• D
oko
(Bam
boo
bask
et)
••
Sick
le
Spec
ifica
tion
Cons
truc
tion
per
iod
Slop
e >
30 Æ
cove
r m
ulch
with
wid
e m
esh
jute
nett
ing
(150
*500
mm
mes
h) t
o ho
ld m
ulch
.
• M
ulch
ing
befo
re t
he m
onso
on t
o pr
otec
t so
il an
d se
eds
from
wat
er e
rosi
on
Mai
nten
ance
Pr
ecau
tion
sSc
ope
(Sit
e fo
r ap
plic
atio
n)
• Sp
read
out
the
mul
ch if
it a
ccum
ulat
ed in
pl
aces
.
• D
on’t
use
pla
nt p
arts
car
ryin
g se
eds
(as
this
may
beco
me
a w
eedi
ng p
robl
em)
Prev
ent
from
fire
or
win
d an
d co
ntro
l rod
ents
.
• H
arsh
are
as (
Red
soil,
Dry
and
fro
st p
rone
are
a)
• U
p to
45 Æ
slo
pes
and
wel
l dra
ined
soi
ls
• N
urse
ry
Refe
renc
es: D
OR,
199
9. F
AO
and
IIRR
, 199
5. R
ongs
en, L
u, 1
994.
, DSC
WM
200
4.
Non
mul
ch a
rea
mul
ch a
rea
Guideline on Landslide Treatment and Mitigation | 29
Titl
e: B
AM
BOO
PLA
NTI
NG
Wha
t is
it?
Pla
ntin
g of
bam
boo
for
soil
cons
erva
tion
and
wat
ersh
ed m
anag
emen
t.
Sket
chFu
ncti
onLi
mit
atio
n
• Re
info
rces
soi
l aga
inst
ero
sion
.
• Pr
ovid
es e
xcel
lent
sup
port
to
the
slop
e if
pl
ante
d at
the
bas
e /
toe
slop
e.
• Re
duce
s th
e ve
loci
ty o
f ru
n-of
f w
ater
.
• Tr
aps
soil
erod
ed f
rom
up
slop
e.
• W
orks
as
a fe
nce.
• N
othi
ng e
lse
can
grow
clo
se t
o ta
ll ba
mbo
o, m
ainl
y du
e to
sh
adin
g an
d nu
trie
nts
and
moi
stur
e co
mpe
titio
n.
• Ba
mbo
o se
eds
are
rare
ly s
ets;
see
ds m
ay n
ot b
e av
aila
ble
du
ring
nee
d fo
r se
edlin
g pr
oduc
tion.
Adv
anta
ges
Dis
adva
ntag
es
• Fo
dder
ava
ilabl
e fo
r an
imal
s (D
. hoo
keri
, B.
nu
tans
/ c
upal
ata
and
Am
pelo
cala
mus
pate
lla
ris
bans
).
• M
ater
ials
for
bas
kets
, Dok
o, M
ats
etc.
(Am
pelo
cala
mus
pate
llar
is, D
. hoo
keri
)
• Po
les
and
bam
boo
stra
ps u
sefu
l for
hou
se
co
nstr
uctio
n. (
D. h
ooke
ri, N
igal
o, B
. nut
ans
and
B.
nut
ans
/ cu
pala
ta B
ans)
• Ed
ible
sho
ots
(Den
droc
alam
us h
amilt
onii
Bans
)
• Pr
ovid
e op
port
uniti
es f
or IG
A
• La
rge
clum
ping
nat
ure
• Ba
mbo
o ca
sts
shad
e to
nea
rby
plan
ts
• H
abita
t fo
r pe
sts
• W
hole
pla
nt d
ies
afte
r se
edin
g
• G
row
th f
rom
the
see
d is
ver
y sl
ow
Prop
agat
ion
step
s
Bam
boo
Prop
agat
ion
Vege
tativ
e pr
opag
atio
n by
Clu
mp
cutt
ing
• O
ff-c
ut s
tem
s w
ith a
por
tion
of r
hizo
me
with
bud
fro
m 1
-1.5
m o
f 1-
year
-old
cul
m.
• Tr
ansp
lant
dir
ectl
y to
a fi
eld
site
or
to a
nur
sery
for
the
use
as
mot
her
stoo
l. Th
is m
etho
d is
si
mpl
e an
d us
ed f
or t
hose
spe
cies
tha
t fo
rm c
lum
p.
Vege
tativ
e Pr
opag
atio
n fr
om N
odal
cut
ting
• Se
lect
the
6-1
0-m
onth
old
cul
m,
• Cu
t th
e ba
mbo
o be
low
the
firs
t no
de w
ith a
bud
,
• Tr
im b
ack
all t
he m
ain
side
bra
nche
s.
• Tr
im o
ff a
ll ot
her
smal
ler
bran
ches
(pr
efer
ably
with
a s
ecat
ure
/ s
aw).
• Cu
t th
e cu
lm in
to p
iece
s (p
refe
rabl
y w
ith s
aw)
with
tw
o-no
des.
Spe
cies
with
larg
e br
anch
es li
ke T
aru
Bans
si
ngle
nod
e cu
ttin
g is
rec
omm
ende
d.
• Ke
ep a
ll pr
epar
ed s
egm
ents
in t
he s
hade
and
und
er m
oist
jute
sac
k or
wet
pap
er u
ntil
they
are
pla
nted
.
• Tr
ansp
ort
them
to
the
nurs
ery
as s
oon
as p
ossi
ble
afte
r pr
epar
atio
n.
| Guideline on Landslide Treatment and Mitigation30
• Fi
ll th
e ho
llow
spa
ce o
f th
e cu
ttin
gs w
ith w
et m
ud a
nd p
lace
cut
tings
hor
izon
tally
in t
renc
hes
in t
he n
urse
ry
be
ds a
nd b
ury
2.5-
15 c
m b
elow
the
sur
face
of
the
soil
imm
edia
tely
. In
two-
node
cut
tings
, a h
ole
can
be m
ade
in
the
cen
tral
inte
rnod
es a
nd fi
lled
with
wat
er. I
f th
ere
is t
erm
ite p
robl
em, t
reat
soi
l with
app
ropr
iate
pes
ticid
e.
• Pr
epar
e th
e so
il of
the
nur
sery
bed
in a
dvan
ce (
best
mix
is 3
:1:1
, soi
l, sa
nd, c
ompo
st).
• Co
nstr
uct
the
shad
e co
ver
stan
d at
80
cm h
igh.
• Th
e bu
d or
bra
nch
shou
ld f
ace
upw
ards
in s
ingl
e-no
de c
uttin
gs a
nd s
idew
ays
in d
oubl
e no
de c
uttin
gs.
• Th
e nu
rser
y be
d sh
ould
be
wat
ered
imm
edia
tely
and
kep
t m
oist
. Flo
od ir
riga
tion
prev
ents
ter
mite
att
ack.
• Li
ft n
odal
cut
tings
whe
n ne
w s
hoot
s gr
ow t
o ab
out
1 m
tal
l. Th
us p
repa
red
noda
l pla
nts
can
be p
lant
ed in
just
be
fore
or
duri
ng m
onso
on.
Sket
chPr
opag
atio
n st
eps
N
odal
cut
ting
is s
uita
ble
for
the
larg
er, c
lum
p fo
rmin
g sp
ecie
s th
at g
row
adv
entit
ious
roo
ts f
rom
nod
al b
uds
fair
ly
easi
ly. H
owev
er, t
his
tech
niqu
e ne
eds
cons
ider
able
car
e in
the
nur
sery
.
Pack
ing
for
tran
spor
tatio
n: C
ut d
oubl
e-no
de c
uttin
gs in
to s
epar
ate
plan
ts. T
rim
off
old
par
ent
inte
r-no
de m
ater
ials
clos
e to
the
nod
e. If
the
tra
nspo
rtat
ion
dist
ance
is lo
ng, w
rap
with
wet
new
spap
er o
r ju
te s
ack.
The
see
dlin
gs
shou
ld b
e pl
ante
d im
med
iate
ly a
fter
the
ir a
rriv
al a
nd ir
riga
te t
hem
just
aft
er p
lant
ing.
The
rate
of
surv
ival
in t
he fi
eld
will
be
mor
e th
an 8
5% if
the
y re
ceiv
e w
ater
reg
ular
ly a
nd a
re w
ell l
ooke
d af
ter
Prop
agat
ion
by s
eed:
Seed
s ar
e co
llect
ed in
late
spr
ing.
Sep
arat
e so
und
seed
s by
floa
ting
off
dead
see
ds a
nd u
nwan
ted
mat
eria
ls in
a
buck
et o
f w
ater
. (25
,000
-35,
000
seed
s pe
r kg
). S
eeds
sho
uld
be s
own
as s
oon
as p
ossi
ble
afte
r co
llect
ion.
The
y
cann
ot b
e st
ored
for
a lo
ng t
ime
(2-3
mon
ths
afte
r ha
rves
ting)
.
Sow
see
ds d
irec
tly
into
pre
pare
d se
edbe
d (u
sing
a s
oil m
ix o
f 3:
1:1
soil,
san
d, &
com
post
). G
erm
inat
ion
will
beg
in
one
wee
k af
ter
sow
ing.
Kee
p w
ell-
wat
ered
. Tra
nspl
ant
to 4
” *
7” p
olyp
ots
whe
n th
e se
edlin
gs a
re 5
to
10 c
m t
all.
The
seed
ling
shou
ld b
e tr
ansp
lant
ed w
hen
they
are
one
-yea
r-ol
d or
abo
ut 7
5-90
cm
tal
l.
Mat
eria
lsSp
ecie
s To
ols
Bam
boo
culm
Seed
Culm
with
rhi
zom
e
That
chin
g m
ater
ials
Den
droc
alam
us h
amilt
onii
(Tam
a ):
300
-200
0 m
, gro
ws
best
in m
oist
and
shad
y si
tes,
not
goo
d in
sou
th f
ace
belo
w 1
200
m L
arge
leav
es,
thin
cul
m, h
eavy
bra
nchi
ng, c
ulm
spl
it ea
sily
D. h
ooke
ri (
Kalo
): 1
200-
2500
m, H
eavy
bra
nchi
ng a
nd b
row
n ha
ir
Bam
busa
bal
cooa
(D
hanu
): T
erai
to
1600
m, l
arge
clu
mpi
ng, t
hin
and
heav
y br
anch
ing
stra
ight
cul
m)
B. n
utan
s /
cupa
lata
(M
al):
Ter
ai t
o 15
00 m
, St
rong
and
str
aigh
t
culm
Am
pelo
cala
mus
pate
llar
is (
Gho
pi):
120
0-20
00 m
, Sm
alle
r bl
uish
culm
B. n
utan
s (
Taru
): T
erai
to
1500
m, s
tron
g
Dig
ging
too
ls
Saw
Shar
p to
ol f
or
cutt
ing
Wat
er c
an
Dok
o
Sack
Dou
ble
node
cut
ting
wit
h ho
le f
or w
ater
ing
Dou
ble
node
cut
ting
wit
h sh
oots
and
roo
ts.
Guideline on Landslide Treatment and Mitigation | 31
Spec
ifica
tion
Plan
ting
per
iod
5 *
5 m
Plan
t du
ring
spr
ing
(Feb
ruar
y -
May
) se
ason
if s
ite is
moi
st.
Just
bef
ore
mon
soon
(Ju
ne)
if th
e si
te is
dry
Mai
nten
ance
Pr
ecau
tion
sSc
ope
(Sit
e fo
r ap
plic
atio
n)
Prot
ect
from
ani
mal
s, c
arry
out
wee
ding
, and
allo
w n
ew s
hoot
s to
grow
for
5 y
ears
.
Mak
e pr
ovis
ions
for
dra
inag
e.
Culm
har
vest
sho
uld
star
t fr
om t
he
olde
st o
ne (
Culm
mat
ures
in a
roun
d
2.5-
3 ye
ars
of a
ge.)
Care
mus
t be
tak
en t
o pr
otec
t th
e no
des
and
the
buds
on
the
rhiz
ome
duri
ng
digg
ing
and
tran
spor
tatio
n.
Culm
mus
t be
pro
tect
ed f
rom
dis
turb
ance
(sh
akin
g) a
fter
pla
ntin
g.
Bam
boo
shou
ld n
ot b
e ha
rves
ted
duri
ng t
he s
prou
ting
seas
on.
Prot
ect
plan
ting
stoc
k fr
om d
irect
sun
light
dur
ing
tran
spor
tatio
n.
Stee
p ba
nks,
gul
lies,
foo
t of
the
slo
pe, l
ive
chec
k da
m, b
rush
woo
d
chec
k da
m, a
nd w
attl
ing.
Aro
und
farm
hous
e as
fen
cing
(ei
ther
live
or
dead
).
Refe
renc
es: M
cCra
cken
, I. J
. (ed
.), 1
992,
DSC
WM
200
4.
| Guideline on Landslide Treatment and Mitigation32
Refe
renc
e: -
Bhi
may
a, C
.P. 1
976;
Cos
tin, E
., 19
76; D
anie
ls, R
. B.,
and
J. W
. Gill
iam
. 199
6; F
AO
, 197
6; H
ai C
hunx
ing,
Wan
d D
ongm
ei, W
ang
Yaol
in, 2
007.
; DSC
WM
200
4; T
he C
hine
se S
oil a
nd W
ater
Cons
erva
tion
Soci
ety,
198
7.; B
uffe
rs a
nd V
eget
ativ
e Fi
lter
Strip
s M
atth
ew J.
Hel
mer
s.
Titl
e: B
UFF
ER S
TRIP
Wha
t is
it?
Plan
ting
of a
per
man
ent
belt
of
eros
ion
resi
stan
t ve
geta
tion
(tre
es, s
hrub
s an
d gr
ass)
gen
eral
ly a
cros
s th
e sl
ope.
Sket
chFu
ncti
onLi
mit
atio
n
• In
terc
epts
run
off
and
sedi
men
t fr
om a
djoi
ning
(up
-slo
pe)
land
s an
d re
duce
impa
ct o
n
do
wn-
slop
e ar
ea f
rom
run
off
and
sedi
men
t•
Prot
ects
adj
oini
ng la
nd f
rom
ban
k er
osio
n su
ch a
s al
ong
the
stre
am o
r la
ke o
r se
a.•
crea
tes
effe
ctiv
e ba
rrie
r to
red
uce
impa
cts
such
as
pollu
tion
• Re
duce
s sa
lt d
amag
e if
the
loca
lity
is n
ear
the
sea.
• D
ifficu
lt t
o es
tabl
ish
in s
teep
slo
pes.
(>50
deg
rees
)
Adv
anta
ges
Dis
adva
ntag
es
• Co
nser
ves
soil
and
moi
stur
e fo
r be
tter
pro
duct
ion
• Sh
rubs
and
gra
sses
hel
p to
slo
w fl
oodi
ng a
nd p
rote
ct c
rops
fro
m fl
ood
dam
age,
• Re
duce
s m
aint
enan
ce o
f di
tch
from
sed
imen
tatio
n.•
Whe
re w
ind
is a
fac
tor,
tre
es a
nd s
hrub
s gr
owin
g in
the
buf
fer
incr
ease
the
buf
fer’
s ab
ility
to
prev
ent
win
d fr
om e
rodi
ng v
alua
ble
tops
oil.
Impr
oves
aes
thet
ic lo
oks
• O
ccup
ies
prod
uctio
n la
nd•
Shad
es a
nd c
ompe
tes
with
cro
ps f
or
nu
trie
nts
and
wat
er.
• H
abita
t fo
r bi
rd a
nd in
sect
s•
Obs
truc
ts f
ree
mov
emen
t of
mac
hine
ries
Plan
ting
ste
ps
• U
sing
“A
” fr
ame
mar
k th
e lin
es t
o be
pla
nted
. •
Prep
arat
ion
of la
nd f
or p
lant
ing
• Se
ed t
reat
men
t (S
eed
is s
oake
d in
wat
er t
o en
hanc
e ge
rmin
atio
n)•
Plan
t th
e tr
ees,
shr
ubs,
and
gra
ss s
aplin
gs o
r se
ed•
If av
aila
ble,
use
com
post
/man
ure
or f
ertil
izer
for
initi
al g
row
th.
Mat
eria
lsSp
ecie
s To
ols
Plan
ting
mat
eria
l: Se
ed, S
eedl
ing,
cut
tings
, sl
ips
Crite
ria f
or s
elec
tion
of s
peci
es: -
• Fa
st g
row
ing
• D
eep
root
ing
syst
em (
Dee
p ro
oted
gra
ss,
sh
rubs
and
tre
es)
• A
bilit
y to
cop
pice
• Ec
onom
ic v
alue
.
Som
e sh
rubs
and
bus
hes
conv
enie
nt t
o pl
ant
on r
ipra
p (H
owel
l, et
al
. 199
1):
Adh
atod
a va
sica
(as
suro
), D
uran
tha
repe
ns (
Nilk
andh
a), E
upho
rbia
ro
ylea
na (
Siul
i), J
atro
pha
curc
as (
Sajiw
an),
Vite
x ne
gund
o (s
imal
i),
Salix
, Aca
cia
penn
ata,
But
ea m
inor
Som
e re
com
men
ded
gras
ses
to p
lant
:A
rund
o cl
onax
(N
arka
t); P
ogon
athe
rum
pan
icum
(M
usek
haru
ki);
Cy
nodo
n da
ctyl
on (
Dhu
bo);
Vet
iver
spe
cies
; Thy
sano
laen
a m
axim
a (A
mlis
o); C
ymbo
pogo
n m
icro
thec
a (K
har)
• ‘A
’ Fr
ame
• M
easu
ring
tap
e•
Stri
ng•
Dig
ging
Hoe
or
spad
e
Spec
ifica
tion
Plan
ting
per
iod
• Se
vera
l diff
eren
t co
mbi
natio
ns o
f ve
geta
tion
vary
ing
from
sim
ply
gras
s to
com
bina
tions
of
gr
ass,
tre
es, a
nd s
hrub
s.•
Buff
er s
trip
with
den
se g
rass
, shr
ubs,
and
tre
es is
mor
e ef
fect
ive.
• Se
ed s
owin
g or
see
dlin
g tr
ansp
lant
ing
shou
ld b
e do
ne w
ith t
he o
n-se
t of
mon
soon
.•
Cutt
ing
duri
ng w
inte
r
Mai
nten
ance
Pr
ecau
tion
sSc
ope
(Sit
e fo
r ap
plic
atio
n)
• Re
plac
emen
t of
dea
d se
edlin
g•
Nec
essa
ry p
runi
ng a
nd w
eedi
ng t
o pr
omot
e un
derg
row
th o
f gr
ass
• Pe
st a
nd d
isea
se c
ontr
ol•
Onc
e bu
ffer
str
ip is
est
ablis
hed,
it r
equi
res
min
imal
mai
nten
ance
• Pr
otec
tion
of b
uffe
r st
rip f
rom
ille
gal c
uttin
g an
d gr
azin
g
• En
sure
buf
fer
stri
p is
alo
ng t
he c
onto
urs
for
inte
rrup
ting
runo
ff a
nd
se
dim
ent
from
ups
lope
• Th
e ve
geta
tion
on b
uffe
r st
rip
mus
t no
t be
dis
turb
ed b
y gr
azin
g
an
d ill
egal
cut
ting
• Th
e ve
geta
tion
mak
es m
inim
um c
ompe
titio
n w
ith a
djoi
ning
cro
ps
• A
long
the
ban
k of
the
str
eam
/ri
ver/
lake
/se
a•
Alo
ng t
he f
oot
slop
e w
here
run
off
and
sedi
men
t flo
w f
rom
ups
lope
is c
omm
on.
• A
cros
s th
e sl
ope,
inte
rcep
t ru
noff
and
sedi
men
t flo
w.
Guideline on Landslide Treatment and Mitigation | 33
Titl
e: C
ON
SERV
ATI
ON
PLA
NTA
TIO
NW
hat
is it
? Pl
antin
g of
tre
e an
d sh
rub
spec
ies
usin
g so
il an
d m
oist
ure
cons
erva
tion
tech
niqu
es t
o pr
otec
t la
nd f
rom
deg
rada
tion
and
to im
prov
e th
e en
viro
nmen
t fo
r th
e pl
ant
grow
th.
Plan
ting
tec
hniq
ues
Cont
our
bund
s or
on
mou
nds
Hor
izon
tal p
latf
orm
or
benc
hes
Plan
tati
on o
n ba
sin
pit
Cons
erva
tion
con
tour
tre
nche
sSt
rip
plan
tati
on
Prob
lem
Wat
er lo
ggin
g or
ver
y w
et
cond
ition
s.
• Cr
eepi
ng o
f lo
ose
mat
eria
ls
• M
oist
ure
stre
ss.
Dry
and
har
sh s
oil c
ondi
tions
Dry
and
har
sh s
oil c
ondi
tion
Hig
h gr
ass
and
wee
ds
Sket
ch
Obj
ecti
ve•
To p
rote
ct s
eedl
ings
fro
m
floo
ding
and
impr
ove
aera
tion
• To
dra
in e
xces
s w
ater
• To
pro
tect
see
dlin
g fr
om
de
bris
• To
impr
ove
infil
trat
ion
and
so
il m
oist
ure.
• To
cat
ch r
ain
wat
er f
or p
lant
s
• To
impr
ove
infil
trat
ion
rate
an
d so
il m
oist
ure
• To
tra
p th
e er
oded
soi
l,
• To
cat
ch r
ainw
ater
for
pla
nts.
• To
ove
rcom
e pr
oble
ms
of
hi
gh g
rass
and
wee
ds.
Site
pre
para
tion
• Pr
epar
e m
ound
s or
ridg
es
w
ell i
n ad
vanc
e by
scr
apin
g
th
e to
p so
il an
d pi
ling
50-6
0 cm
hi
gh o
r ab
ove
the
high
wat
er
le
vel.
• If
the
soil
is s
alin
e, a
dd
gy
psum
.
• Pr
epar
e ho
rizon
tal p
latf
orm
60
–10
0 cm
wid
e at
st
agge
red
patt
ern,
• Co
nstr
uct
a rid
ge o
n
do
wns
lope
sid
e
• Sp
ace
plat
form
s 3
m a
part
.
• Sp
ace
the
plan
ts p
refe
rabl
y
2
m a
part
in t
he p
latf
orm
.
• Pr
epar
e sm
all r
ound
bas
ins
to
ca
tch
rain
wat
er in
a
st
agge
red
patt
ern
for
in
divi
dual
pla
nts,
pile
the
ex
cava
ted
soil
on t
he
do
wnh
ill s
ide
to h
old
ra
inw
ater
.
• Sp
acin
g be
twee
n pl
ants
is
us
ually
2 m
. It
coul
d va
ry t
o
su
ite t
he s
ites.
• D
ig c
onto
ur t
renc
hes
of 0
.4m
w
idth
, 0.5
m d
epth
,
an
d 4m
leng
th in
a
st
agge
red
patt
ern.
• D
ig a
pit
30cm
dee
p an
d
30
cm d
iam
eter
at
the
end
of
th
e tr
ench
.
• Sl
ope
the
tren
ch t
owar
ds t
he
en
d to
div
ert
the
harv
este
d
ra
in.
• Le
ave
1.5
- 3
m s
pace
be
twee
n th
e tr
ench
es.
• Re
mov
e gr
ass
in 3
m w
ide
co
ntou
r st
rips
• Pr
epar
e pi
ts in
the
str
ips
• Pl
ant
larg
e se
edlin
gs o
r bi
g
si
ze s
tem
cut
tings
• Pr
epar
e th
e si
te w
ell i
n ad
vanc
e (1
–2
mon
ths
befo
re)
• D
ig a
pit
of 4
5cm
x 4
5 cm
x 4
5cm
for
pla
ntin
g
• If
poss
ible
, fill
the
pits
with
goo
d so
il, c
ompo
st, a
nd c
ompl
ete
fert
ilize
r (N
PK).
Add
gra
ss, s
traw
, and
org
anic
mat
ter
in t
he p
its t
o re
tain
moi
stur
e (r
ecom
men
ded)
.
Plan
ting
tim
eBe
st a
t th
e en
d of
rai
ny s
easo
n in
wat
erlo
gged
are
as.
• Ca
rry
out
plan
tatio
n pr
ogra
m in
the
beg
inni
ng o
f th
e m
onso
on w
hen
the
soil
has
suffi
cien
t
m
oist
ure
to s
uppo
rt t
he e
stab
lishm
ent
of s
eedl
ings
.
• Pl
antin
g in
the
win
ter
is p
refe
rred
for
a c
uttin
g /
ste
m p
lant
atio
n.
Hig
h w
ater
leve
l
50-6
0 cm
| Guideline on Landslide Treatment and Mitigation34
Care
& m
aint
enan
ce•
Sele
ct s
eedl
ings
of
optim
um s
ize
with
wel
l-de
velo
ped
root
sys
tem
. Tri
m s
appy
sho
ots
and
leav
es t
o re
duce
tra
nspi
ratio
n.
• If
poss
ible
, wat
er t
he p
lant
s in
dry
per
iods
, use
man
ure
if th
e so
il is
ver
y po
or, a
nd p
ut m
ulch
to
redu
ce e
vapo
ratio
n an
d pr
otec
t th
e pl
ant
from
col
d or
hea
t.
• D
o re
gula
r w
eedi
ng f
rom
July
to
Oct
ober
at
leas
t fo
r th
e fir
st 3
yea
rs. P
rote
ct t
he s
ite a
gain
st g
razi
ng, fi
re h
azar
ds, a
nd d
amag
e by
peo
ple.
Oth
er c
onsi
dera
tion
s•
Site
s w
ith lo
ose
and
cree
ping
mat
eria
ls: s
elec
t pl
ant
spec
ies
that
can
dev
elop
roo
ts f
rom
ste
m (
will
ow, s
imal
i, kh
irro
). S
uch
plan
ts c
an t
oler
ate
inju
ry b
y de
bris
fro
m
up
slop
e to
som
e de
gree
.
• Ta
ke s
afet
y pr
ecau
tions
whi
le w
orki
ng o
n st
eep
slop
es.
• In
col
d an
d w
indy
pla
ces
like
Mus
tang
, pla
ntin
g of
1-2
m lo
ng a
nd 1
0-15
cm
dia
met
er c
uttin
g gi
ves
good
res
ults
.
• W
hile
pla
ntin
g cu
ttin
gs, t
he t
ip o
f cu
ttin
g ne
eds
to b
e w
axed
to
avoi
d de
sicc
atio
n.
• Pl
antin
g in
pot
s is
bet
ter
than
bar
e ro
ot p
lant
atio
n in
har
sh s
ites.
• O
n ro
cky
site
s, s
eedl
ings
can
be
plan
ted
on t
he b
est
avai
labl
e sp
ots
inst
ead
of r
egul
ar s
paci
ng.
• G
row
ing
legu
min
ous
spec
ies
alon
g w
ith o
ther
spe
cies
is r
ecom
men
ded
to r
ecla
im d
egra
ded
land
.
• Be
tter
to
use
loca
l fas
t gr
owin
g sp
ecie
s w
ith d
eepe
r ro
ot s
yste
ms.
• D
ispo
se o
f th
e po
ly b
ags
safe
ly.
Sket
chFu
ncti
onLi
mit
atio
n
•
Prot
ects
soi
l sur
face
fro
m r
aind
rops
by
prov
idin
g gr
ound
cov
er
• In
crea
ses
infil
trat
ion,
rec
harg
ing
the
grou
nd w
ater
, and
eva
po-t
rans
pira
tion
th
us r
educ
ing
runo
ff
• Re
duce
s th
e ve
loci
ty o
f th
e ru
noff
by
obst
ruct
ing
it
• Re
info
rces
slo
pes
• Re
cycl
es n
utrie
nts
from
dee
per
laye
r of
the
soi
l
• Fr
ee g
razi
ng c
anno
t be
allo
wed
,
• Fi
re o
utbr
eaks
may
dam
age
the
plan
ts.
• Ri
sk o
f di
seas
e &
pes
ts in
mon
ocul
ture
Adv
anta
ges
Dis
adva
ntag
es
• Re
duce
s er
osio
n an
d im
prov
ed la
nd q
ualit
y (p
hysi
cal,
chem
ical
, and
bio
logi
cal
pr
oper
ties
of s
oil)
• Im
prov
es w
ater
yie
ld (
qual
ity a
nd r
egim
e)
• M
akes
mul
tiple
out
puts
ava
ilabl
e --
Fue
l woo
d, f
odde
r, t
imbe
r, &
leaf
litt
ers
et
c.
• Im
prov
es b
iolo
gica
l div
ersi
ty
• Ro
ots
may
ope
n ro
ck jo
ints
and
cre
ate
unst
able
sl
opes
.
• Lo
ad o
f th
e la
rge
tree
s co
mbi
ned
with
the
dyn
amic
fo
rces
of
the
win
d ca
n in
duce
slo
pe f
ailu
re
• Ta
kes
time
for
esta
blis
hmen
t of
pla
ntat
ion
• Lo
ss o
f w
ater
thr
ough
tra
nspi
ratio
n
• La
rge
wat
er d
rops
fal
ling
from
the
leav
es m
ay
cr
eate
ero
sion
.
Plan
ting
ste
ps
• Id
entif
y th
e pl
antin
g si
te t
oget
her
with
loca
l peo
ple
• D
ivid
e th
e si
te in
to d
iffer
ent
area
s re
quir
ing
diff
eren
t pl
antin
g te
chni
ques
• Se
lect
sui
tabl
e sp
ecie
s is
bas
ed o
n ad
apta
bilit
y, m
ultip
le u
se, s
oil q
ualit
y, a
nd p
refe
renc
e of
the
loca
l peo
ple.
• Pr
epar
e th
e si
te (
site
sur
vey,
site
cle
aran
ce a
nd a
lignm
ent
of t
he p
lant
ing
pits
and
pitt
ing)
wel
l in
adva
nce
(1 –
2 m
onth
s be
fore
).
• If
poss
ible
, put
com
post
at
the
bott
om o
f pl
antin
g ho
le in
poo
r so
ils o
r ad
d a
good
for
est
soil,
and
leav
e fo
r fe
w w
eeks
to
cons
olid
ate
th
e lo
ose
soil
• Re
mov
e po
lyth
ene
bag
from
the
see
dlin
g by
cut
ting
the
side
car
eful
ly.
• Pl
ace
seed
ling
into
the
pit
and
pres
s th
e so
il fir
mly
aro
und
the
seed
ling
Guideline on Landslide Treatment and Mitigation | 35
Mat
eria
lsTo
ols
Seed
lings
, cut
tings
, see
d et
c. d
epen
ding
on
the
prop
agat
ion
met
hod
of s
elec
ted
spec
ies
Surv
ey: M
easu
ring
tap
e /
rop
e /
com
pass
/ A
bney
’s
leve
l / p
egs
/ fi
eld
book
/ r
angi
ng r
od
Plan
ting
: Dig
ging
too
ls
Spec
ifica
tion
sPl
anti
ng p
erio
d
• Pi
t si
ze o
f 30
cm
dee
p an
d ab
out
30 c
m in
dia
met
er. (
Dee
per
pit
is b
ette
r)
• Sp
acin
g: 2
*2 m
for
tre
e an
d 1*
1 m
for
shr
ubs
• G
ener
ally
, see
dlin
g si
ze m
ust
be >
30
cm in
hei
ght.
• Pr
epar
e pl
antin
g pi
ts s
ome
wee
ks b
efor
e
pl
anta
tion.
• Ca
rry
out
plan
ting
at t
he o
nset
of
mon
soon
.
• W
inte
r pl
anta
tion
is b
ette
r fo
r th
e cu
ttin
g /
ste
m
pl
anta
tion
Mai
nten
ance
Pr
ecau
tion
sSc
ope
(sit
e fo
r ap
plic
atio
n)
• W
eed
and
wor
k th
e so
il fo
r a
favo
rabl
e gr
owin
g
en
viro
nmen
t
• Re
gula
r th
inni
ng a
nd p
runi
ng t
o al
low
the
un
derg
row
th t
o gr
ow
• Ca
rry
out
enric
hmen
t pl
anta
tion
in t
he f
ollo
win
g
ye
ars
to fi
ll th
e ga
ps.
• Pr
otec
t th
e pl
anta
tion
site
aga
inst
gra
zing
, fire
haz
ards
, and
dam
age
by p
eopl
e
• Pl
ant
mix
ed s
peci
es t
o m
inim
ize
risk
of
mon
ocul
ture
• Se
lect
spe
cies
with
hig
h su
rviv
al r
ates
, fas
t gr
owin
g, s
ever
al la
yers
, and
hig
h
cr
own
cove
r de
nsity
.
• Pl
antin
g af
ter
mon
soon
or
duri
ng t
he f
all h
as lo
w s
urvi
val r
ate
• Tr
ansp
ort
seed
lings
car
eful
ly a
nd m
ake
sure
tha
t pl
antin
g st
ock
is n
ot a
llow
ed
to
dry
in t
he s
un
• Kh
arba
ri /
Gra
zing
land
s
• Co
mm
unity
and
pub
lic b
arre
n la
nds
• G
ully
and
land
slid
e
• Ri
ver
bed
• Ro
ad s
lope
s
• Co
mm
unity
for
est
Suit
able
spe
cies
For
impr
ovin
g so
il
fert
ility
& o
rgan
ic m
atte
r
For
dry
and
ston
y si
tes
For
poor
soi
l con
diti
ons
For
moi
st s
ites
For
swam
py s
ites
For
fodd
erFo
r ea
sy p
ropa
gati
on
Asu
ro, D
hain
cha,
Khi
rro,
Flem
engi
a, D
esm
odiu
m,
Utis
, Sis
au, R
ahar
, Ipi
l-
ipil,
Tep
hros
ia
Phal
edo,
Am
ala,
Chila
une,
Ket
uki,
Khirr
o
Am
ala,
bay
er, K
etuk
i,
Khai
r, B
akai
no, B
abul
,
sim
ali,K
alo
Siris
,
Teph
rosi
a, C
asua
rina
,
Siss
o, K
hirr
o
Bain
s, U
ttis
, Chi
laun
e,
Lalig
uras
Euca
lypt
us, L
ages
troe
mia
,
Spec
iosa
, Cas
uari
na
glau
ca, w
illow
spe
cies
.
Bada
har,
Bed
ulo,
Bhi
mal
,
Ipil
Ipil,
Dab
dabe
,
Dud
hilo
, Gog
an Jh
inga
t,
Flem
ingi
a, K
utm
iro,
Phal
edo,
Tank
i, Ko
iral
o,
Khan
yu, K
abro
,
Dab
dabe
, Jhi
ngar
t, s
imal
i,
Asu
ro, P
hale
do, K
hirr
o,
Bain
s, S
aru,
Sim
ali
Refe
renc
es: C
ampb
ell,
Gab
riel J
. and
Jean
nett
e D
enho
lm (
edt.
), 1
992.
Dat
ta, S
. K. 1
986.
DO
R, 1
999.
Hud
son,
N. 1
981.
Sax
ena
N. C
. and
Vis
hwa
Bal
labh
–19
95. T
ingf
u, G
uo, 1
992,
DSC
WM
200
4.
| Guideline on Landslide Treatment and Mitigation36
Titl
e: F
ASC
INE
Wha
t is
it?
Layi
ng o
f a
bund
le o
f liv
e br
anch
es b
ound
tog
ethe
r in
a s
hallo
w d
ug d
itch
or t
renc
hes
and
cove
ring
with
soi
l for
sp
rout
ing.
Sket
chFu
ncti
ons
Lim
itat
ion
• Ca
tche
s de
bris
• A
rmor
s an
d re
info
rces
the
slo
pe•
Incr
ease
s in
filtr
atio
n •
Prov
ides
fas
cine
sub
-sur
face
dra
inag
e on
slo
pes
• It
doe
s no
t fo
rm a
phy
sica
l bar
rier
imm
edia
tely
and
req
uire
s
a
peri
od o
f gr
owth
to
beco
me
effe
ctiv
e.•
The
max
imum
slo
pe w
here
it c
an b
e us
ed is
abo
ut 4
5Æ•
Onl
y su
itabl
e fo
r ri
lls a
nd s
mal
l gul
lies
Adv
anta
ges
Dis
adva
ntag
es
• Pu
t ou
t ro
ots
and
shoo
ts f
orm
ing
a st
rong
line
of
vege
tatio
n.•
Sim
ple
and
low
cos
t er
osio
n co
ntro
l mea
sure
s.
• Co
nstr
uctio
n ca
uses
dis
turb
ance
to
the
slop
es
• Re
quir
es a
larg
e am
ount
of
plan
t m
ater
ial
Cons
truc
tion
ste
ps
• Pr
epar
e th
e si
te w
ell i
n ad
vanc
e.•
Mar
k th
e lin
e, w
here
fas
cine
s ar
e to
be
inst
alle
d. E
nsur
e th
at t
he li
nes
follo
w t
he c
onto
ur o
r de
sire
d an
gle
or r
ills.
• D
ig t
renc
hes
abou
t 30
cm
dee
p an
d up
to
50 c
m w
ide.
Cle
ar a
ll lo
ose
mat
eria
l and
pro
trus
ion
and
firm
ly in
fill d
epre
ssio
ns.
• A
lway
s co
nstr
uct
fasc
ines
fro
m t
he b
otto
m o
f th
e sl
ope,
and
wor
k up
war
ds.
• D
ig a
bout
5 m
eter
s lo
ng t
renc
h at
a t
ime
and
lay
the
fasc
ine
bund
les
toge
ther
with
the
ir e
nds
over
lapp
ing
and
fill t
he
tr
ench
. Thi
s en
sure
s th
at t
he s
oil i
n th
e tr
ench
is e
xpos
ed o
nly
for
shor
t pe
riod
the
reby
min
imiz
ing
the
loss
of
soil
moi
stur
e.•
Prep
are
fasc
ine
bund
les
cons
istin
g of
5 –
8 b
ranc
hes
with
a m
inim
um d
iam
eter
of
one
cm e
ach.
The
com
plet
ed b
undl
es
sh
ould
be
15 t
o 20
cm
in d
iam
eter
, with
all
the
grow
ing
tips
orie
nted
in t
he s
ame
dire
ctio
n.•
Tie
the
fasc
ine
bund
le t
oget
her
with
1.5
to
2.0
mm
wir
e or
jute
or
coir
str
ing
at 5
0 cm
inte
rval
s.•
If th
e fa
scin
e lin
e is
ste
eper
tha
n 25Æ
, peg
the
fas
cine
with
a li
ve o
r de
ad p
egs
of a
t le
ast
60 c
m le
ngth
at
50 c
m a
part
.•
Back
fill t
he t
renc
h as
soo
n as
pos
sibl
e, c
over
the
fas
cine
s w
ith a
3-4
cm
of
soil,
and
tra
mp
the
soil
firm
ly.
Mat
eria
lsSp
ecie
sTo
ols
• Br
anch
es o
f di
ffer
ent
spec
ies
of
ro
otin
g pl
ants
6 t
o 18
mon
ths
old,
2
to
5 c
m d
iam
eter
, and
at
leas
t
1m lo
ng
• Sp
rout
ing
woo
den
pegs
(3-6
cm
dia
and
50-
100
cm lo
ng).
• Bi
ndin
g w
ire/
rope
Adh
atod
a va
sica
(as
suro
), E
ryth
rina
arbo
resc
enes
(Ph
aled
o), F
icus
laco
r (K
avro
), Ip
omea
fist
ulat
a (s
aruw
a),
Lant
ana
cam
ara
(phu
l kan
da),
Vite
x ne
gund
o (s
imal
i), S
alix
spe
cies
(b
ains
), G
agru
ga p
inna
ta (
dabd
abe)
, Se
pium
inse
gne
(khi
rro)
, etc
.
• H
essi
an a
nd w
ater
to
keep
the
cut
ting
moi
st u
ntil
plan
ting
• To
ols
to d
ig t
renc
h
Spec
ifica
tion
Cons
truc
tion
per
iod
• Sp
acin
g be
twee
n co
ntou
r fa
scin
es d
epen
ds o
n th
e st
eepn
ess
of t
he s
lope
.
Use
a 4
m in
terv
al f
or le
ss t
han
30Æ
slo
pe a
nd 2
m in
terv
al f
or
30Æ
45Æ
slop
e.•
If fa
scin
es a
re u
sed
on r
ills
or s
mal
l gul
lies,
it ju
st f
ollo
ws
the
rills
or
gulli
es.
• Th
e tr
ench
sho
uld
be a
bout
30
deep
and
up
to 5
0 cm
wid
e.•
For
each
fas
cine
, the
re s
houl
d be
at
leas
t fo
ur b
ut n
ot m
ore
than
eig
ht
br
anch
es.
• D
urin
g do
rman
t se
ason
if t
he s
ite is
moi
st•
Befo
re m
onso
on r
ain
if th
e si
te is
dry
(May
-Jun
e)
Guideline on Landslide Treatment and Mitigation | 37
© WWF Nepal, Hariyo Ban Program/ Nabin Baral
Mai
nten
ance
Prec
auti
ons
Scop
e (S
ite
for
appl
icat
ion)
• In
spec
t th
e ar
ea d
urin
g th
e fir
st r
ainy
seas
on. R
epai
r an
y ex
posu
re /
bre
ak o
f
the
fasc
ines
• O
ccas
iona
l thi
nnin
g an
d pr
unin
g m
ay b
e
re
quire
d af
ter
a fe
w y
ears
.
• T
he b
utt
end
of t
he b
ranc
hes
shou
ld a
lway
s po
int
in t
he
sa
me
dire
ctio
n.•
If tr
ench
is d
eepe
r th
an 4
0 cm
fill
the
tren
ch w
ith g
rave
l.
• En
sure
tha
t w
ater
can
not
run
unde
r th
e bu
ndle
s an
d sc
our
them
out
.•
Fasc
ine
drai
n m
ust
conn
ect
to n
eare
st s
uita
ble
drai
nage
syst
em.
• Fa
scin
es a
re e
ffec
tive
on t
he s
hallo
w g
ullie
s or
dee
p ri
lls li
nes.
• Be
st u
sed
on c
onso
lidat
ed d
ebri
s or
sof
t cu
t sl
opes
.•
On
wel
l-dr
aine
d m
ater
ial,
use
cont
our
fasc
ines
; on
poor
ly d
rain
ed m
ater
ials
, a
he
rrin
gbon
e pa
tter
n of
fas
cine
s im
prov
es d
rain
age.
• Pr
otec
t sl
opes
fro
m s
hallo
w s
lides
(30
– 6
0 cm
dep
th).
Refe
renc
es: D
OR,
199
9, F
AO
, 198
5, D
SCW
M 2
004.
| Guideline on Landslide Treatment and Mitigation38
Titl
e: P
ALI
SAD
EW
hat
is it
? Li
ve s
prou
ting
cutt
ings
pla
ced
acro
ss t
he s
lope
or
smal
l gul
ly u
sual
ly f
ollo
win
g th
e co
ntou
r.
Sket
chFu
ncti
onLi
mit
atio
n
• Fo
rms
a st
rong
bar
rier
acr
oss
a gu
lly
• Re
info
rces
the
slo
pe
• Ca
tche
s de
bris
mov
ing
dow
n th
e sl
ope
• W
eak
to s
uppo
rt b
ig v
olum
e of
deb
ris.
Adv
anta
ges
Dis
adva
ntag
es
• Si
mpl
y an
d ea
sily
bui
lt w
ith im
med
iate
eff
ect
• Fo
rms
a st
rong
low
cos
t ba
rrie
r bu
ilt w
ith t
he m
inim
um d
istu
rban
ce t
o th
e sl
ope
• Li
ving
che
ck d
am f
or g
ullie
s w
ith p
erio
dic
flood
s. G
ood
mea
sure
aga
inst
gul
ly e
rosi
on
he
lps
to r
epai
r an
d fil
l the
gul
lies.
• U
sefu
l onl
y fo
r sm
all a
nd n
arro
w g
ullie
s
Cons
truc
tion
ste
ps
• A
lway
s st
art
at t
he t
op o
f th
e sl
ope
and
wor
k do
wnw
ards
. Mar
k th
e lin
es t
o pu
t th
e pa
lisad
e.
• U
sing
a p
oint
ed b
ar o
r cr
owba
r, m
ake
a ho
le b
igge
r th
an t
he c
uttin
g an
d de
ep e
noug
h to
tak
e at
leas
t tw
o-th
ird
of it
s le
ngth
.
• D
ig a
tre
nch
deep
eno
ugh
to t
ake
at le
ast
two-
thir
d of
leng
th o
f th
e cu
ttin
g ac
ross
the
gul
ly.
• Pl
ace
a cr
oss
beam
(10
cm
dia
met
er a
nd 2
m lo
ng)
to s
uppo
rt t
he c
uttin
gs.
• A
ncho
r th
e cr
oss
beam
with
peg
s (3
-6 c
m d
iam
eter
and
50
cm lo
ng).
Use
live
bea
ms
if av
aila
ble.
• Ta
ke 0
.5-1
m lo
ng c
uttin
gs f
rom
6-1
8 m
onth
s ol
d br
anch
es 3
to
5 cm
dia
met
er.
• Cu
t th
e br
anch
es a
t ri
ght
angl
e at
top
to
redu
ce d
ryin
g an
d at
45Æ
at
bott
om t
o gi
ve m
ore
spac
e fo
r ro
otin
g. If
pos
sibl
e, t
ake
the
cu
ttin
gs t
he s
ame
day
that
the
y ar
e to
be
plan
ted.
• Pl
ace
the
cutt
ings
sid
e-by
-sid
e (5
cm
apa
rt)
in t
he h
ole
so t
hat
at le
ast
1/3
is a
bove
gro
und
and
2/3
in t
he s
oil.
• Ti
e th
e st
akes
with
jute
or
coir
wir
e w
ith c
ross
bea
m
• Fi
ll an
d fir
mly
tra
mp
the
soil
arou
nd it
. Cle
ar a
ny lo
ose
or e
xces
s m
ater
ial d
own
slop
e.
• Su
ppor
t pa
lisad
e w
ith s
tone
and
soi
l fro
m lo
wer
sid
e on
ste
ep s
lope
.
• If
a do
uble
line
is u
sed,
the
n a
seco
nd li
ne is
pla
ced
10 c
m b
ehin
d th
e fir
st a
nd w
ith t
he in
divi
dual
cut
tings
off
set
to c
oinc
ide
with
th
e ga
ps b
etw
een
the
cutt
ings
in t
he fi
rst
line.
Mat
eria
lsSp
ecie
sTo
ols
• 0.
5 –
1 m
. lon
g cu
ttin
gs o
f di
ffer
ent
spec
ies
fr
om 6
-18
mon
ths
old
bran
ches
of
3
to 5
cm
dia
met
er
• Li
ve c
ross
bea
m o
f 10
cm
dia
met
er a
nd
2
m lo
ng
• G
abio
n w
ire
Adh
atod
a va
sica
, Ipo
mea
fist
ulat
a,
Lant
ana
cam
ara,
Vite
x ne
gund
o, S
alix
spec
ies,
Gag
ruga
pin
nata
Sep
ium
insi
gne
• H
essi
an a
nd w
ater
to
keep
the
cut
ting
m
oist
unt
il pl
antin
g
• Po
inte
d pl
antin
g ba
rs o
r cr
owba
rs t
o
m
ake
hole
s fo
r pl
antin
g
Spec
ifica
tion
Cons
truc
tion
peri
od
• Sp
acin
g be
twee
n pa
lisad
es d
epen
ds o
n th
e st
eepn
ess
of t
he s
lope
: 2 m
inte
rval
for
sl
ope
less
tha
n 30Æ
slo
pe a
nd 1
m in
terv
al f
or 3
0Æ-
45Æ
slop
e.
• W
ithin
the
pal
isad
es li
nes,
spa
cing
bet
wee
n th
e cu
ttin
gs is
2 t
o 3
cm.
• D
urin
g do
rman
t (N
ovem
ber-
Janu
ary)
se
ason
if t
he s
ite is
moi
st.
• Ju
st b
efor
e m
onso
on if
the
site
is d
ry
(M
ay-J
une)
Pa
lisad
e
Guideline on Landslide Treatment and Mitigation | 39
Refe
renc
es: D
OI,
1992
. DO
R, 1
999.
FA
O, 1
985,
ITEC
O, 1
990,
DSC
WM
200
4.
Mai
nten
ance
Pr
ecau
tion
sSc
ope
(Sit
e fo
r ap
plic
atio
n)
• In
spec
t th
e ar
ea d
urin
g th
e fir
st r
ainy
sea
son.
Rep
air
and
stre
ngth
en a
ny e
xpos
ure
or b
reak
s of
the
st
akes
to
allo
w g
row
th o
f ve
geta
tion
to t
ake
plac
e.
• So
me
thin
ning
may
be
requ
ired
afte
r a
few
yea
rs.
• Si
te w
ith p
oorl
y dr
aine
d m
ater
ial
su
bjec
t to
hig
h ra
tes
of s
mal
l sca
le
sl
umpi
ng s
houl
d be
avo
ided
.
• M
ake
sure
cut
tings
do
not
dry
in t
he
su
n.
• Ca
n be
use
d on
a w
ide
rang
e of
site
s up
to
abo
ut 6
0Æ s
lope
. Eff
ectiv
e on
ste
ep
la
ndsl
ide
debr
is.
• G
ood
for
stee
p, n
arro
w g
ullie
s.
| Guideline on Landslide Treatment and Mitigation40
Titl
e: B
RUSH
LA
YERI
NG
Wha
t is
it?
A la
yer
of li
ve w
oody
cut
tings
pla
nted
in li
ne a
cros
s th
e sl
ope,
usu
ally
fol
low
ing
the
cont
our
Sket
chFu
ncti
onLi
mit
atio
n
Re
info
rces
the
slo
pe
Catc
hes
mat
eria
ls m
ovin
g do
wn
the
slop
e, a
nd h
elp
bio-
terr
acin
g
If an
gled
, hel
ps t
o dr
ain
out
wat
er
Cons
ider
able
dis
turb
ance
to
the
slop
e
Adv
anta
ges
Dis
adva
ntag
es
Prov
ides
a v
ery
stro
ng a
nd lo
w-c
ost
barr
ier
on lo
ose
debr
is s
lope
Sim
ple
and
easi
ly b
uilt
with
imm
edia
te e
ffec
t
In lo
ng t
erm
, a s
mal
l ter
race
will
for
m
Adv
entit
ious
roo
ting
guar
ante
es s
econ
dary
rei
nfor
cem
ent
Dig
ging
of
terr
aces
dis
turb
s th
e sl
ope
cons
ider
ably
Brus
h la
yeri
ng s
houl
d be
use
d on
slo
pes
cons
istin
g of
loos
e m
ater
ial
Plan
ting
ste
ps
Star
t 50
cm
fro
m t
he b
ase
of t
he s
lope
and
wor
k up
war
ds
Mar
k th
e co
ntou
r lin
es f
or t
erra
ce d
iggi
ng
Mak
e 50
– 1
00 c
m w
ide
terr
aces
with
an
incl
inat
ion
of a
t le
ast
10 –
20
% in
war
d
Lay
the
cutt
ings
cro
ssw
ise
at 5
to
10 c
m in
terv
al. P
lace
the
bra
nche
s cr
ossw
ise
on t
he t
erra
ces
to p
erm
it th
e us
e of
long
er
bran
ches
At
leas
t on
e bu
d an
d 1/
3 to
1/4
of
the
bran
ch s
houl
d ex
tend
ove
r th
e ed
ge o
f th
e te
rrac
e an
d 3/
4 in
side
Use
bra
nche
s (6
to
18 m
onth
s ol
d of
2 t
o 4
cm d
iam
eter
) of
diff
eren
t sp
ecie
s, o
f di
ffer
ent
ages
, and
dia
met
ers.
Thi
s al
low
s
grea
ter
chan
ces
of s
urvi
val a
nd p
rodu
ces
mix
ed v
eget
atio
n.
If po
ssib
le, t
ake
the
cutt
ing
the
sam
e da
y th
at t
hey
are
to b
e pl
ante
d.
Fill
the
low
er b
ench
with
the
mat
eria
l exc
avat
ed f
rom
the
abo
ve t
erra
ce a
nd c
ompa
ct it
rea
sona
bly
wel
l with
gen
tle
foot
pres
sure
.
Mat
eria
lsSp
ecie
s To
ols
Bran
ches
of
root
ing
plan
ts o
f di
ffer
ent
spec
ies
6 to
18
mon
ths
old,
2 t
o 4
cm d
iam
eter
, and
75 t
o 10
0 cm
long
Cut
the
bran
ches
at
righ
t an
gles
at
top
and
at
45Æ
at
bott
om
Adh
atod
a va
sica
, Ipo
mea
fistu
lata
, Lan
tana
cam
ara,
Vite
x
negu
ndo,
Sal
ix s
peci
es, G
agru
ga
pinn
ata,
Sep
ium
nsi
gne,
Erit
hrin
a
varie
gate
, Mor
us a
lba,
Dur
anth
a
repe
ns, J
atro
pha
curc
as
Hes
sian
and
wat
er t
o ke
ep t
he c
uttin
g
moi
st u
ntil
plan
ting
Shov
els
and
pick
axe
s to
mak
e th
e
slop
ing
terr
aces
for
pla
ntin
g
Line
str
ing
/ T
ape
(30
m)
Plan
ting
Peri
od
Spec
ifica
tion
sPl
anti
ng p
erio
d
Spac
ing
betw
een
brus
h la
yer
depe
nds
on t
he s
teep
ness
of
the
slop
e:
2 m
inte
rval
for
less
tha
n 30Æ
slo
pe a
nd 1
m in
terv
al f
or 3
0Æ -
45Æ
slop
e
Dur
ing
dorm
ant
seas
on if
the
site
is m
oist
z
Spac
ing
depe
nds
on t
he s
tabi
lity
of t
he s
oil m
ater
ial a
nd m
ay v
ary
from
2-5
m in
terv
al
Just
bef
ore
mon
soon
if t
he s
ite is
dry
(M
ay -
June
)
Bru
sh L
ayer
ing
Guideline on Landslide Treatment and Mitigation | 41
Mai
nten
ance
Prec
auti
ons
Scop
e (S
ite
for
appl
icat
ion)
Beca
use
the
spac
ing
of p
lant
s in
bru
sh la
yerin
g is
ver
y de
nse,
ther
e is
unl
ikel
y to
be
a ne
ed f
or r
epla
cing
fai
lure
s
Insp
ect
the
area
dur
ing
the
first
rai
ny s
easo
n. R
epai
r an
d
stre
ngth
en a
ny b
reak
s of
the
sta
kes
to a
llow
gro
wth
of
the
vege
tatio
n to
tak
e pl
ace.
Som
e th
inni
ng o
f sh
rubs
may
be
requ
ired
afte
r fe
w y
ears
.
Ensu
re t
he li
nes
run
alon
g th
e co
ntou
rs a
nd d
o no
t co
ncen
trat
e ru
noff
.
Mak
e su
re t
hat
cutt
ings
are
not
allo
wed
to
dry
in t
he s
un.
Avo
id u
sing
thi
s te
chni
que
on p
oorl
y dr
aine
d ar
ea s
ubje
ct t
o sm
all
scal
e sl
umpi
ng.
Suita
ble
for
wet
slo
pes
or s
teep
and
roc
ky s
lope
s no
t
subj
ect
to s
lum
ping
Wid
e ra
nge
of s
ites
up t
o ab
out
45°
and
high
emba
nkm
ents
Effe
ctiv
e to
sta
biliz
e lo
ose
debr
is s
ites
and
fill s
lope
s
Effe
ctiv
e in
pre
vent
ing
shal
low
slid
ing
Refe
renc
es: D
OR,
199
9, D
OI,
1992
. FA
O, 1
985.
ITEC
O, 1
990,
DSC
WM
200
4.
| Guideline on Landslide Treatment and Mitigation42
Titl
e: W
ATT
LIN
GW
hat
is it
? W
attl
ing
is r
ows
of f
ence
mad
e ou
t of
veg
etat
ive
mat
eria
ls (
pref
erab
ly li
ve c
uttin
gs)
plac
ed a
cros
s th
e co
ntou
r of
the
slo
pe.
Sket
chFu
ncti
onLi
mit
atio
n
• • • • • • • • • • • •
• Ca
tche
s de
bris
mov
ing
dow
n th
e sl
ope
• Re
info
rces
the
slo
pe
• M
odifi
es t
he s
lope
• A
pplic
able
onl
y on
a s
lope
with
a li
mite
d vo
lum
e of
deb
ris
flo
w
• D
ange
r of
bre
akin
g be
caus
e of
fal
ling
rock
s
Adv
anta
ges
Dis
adva
ntag
es
• Fa
st a
nd s
impl
e pr
otec
tion
• La
bor
and
mat
eria
l int
ensi
ve
• Es
tabl
ishe
s a
mic
ro-s
ite f
or o
ther
pla
nts
• D
rivi
ng s
take
s lo
osen
s th
e so
il
Cons
truc
tion
ste
ps
• Pr
epar
e th
e si
te w
ell i
n ad
vanc
e of
pla
ntin
g. C
lear
all
loos
e m
ater
ial a
nd p
rotr
usio
n, a
nd fi
rmly
infil
l dep
ress
ions
.
• M
ark
on t
he s
lope
the
line
s w
here
wat
tle
fenc
es a
re t
o be
inst
alle
d to
ens
ure
that
the
line
s fo
llow
the
con
tour
.
• D
ig a
hol
e fo
r pl
acin
g st
akes
with
cro
wba
r or
aug
er. P
lace
1 m
long
sta
kes
at in
terv
als
of a
bout
1 m
alo
ng t
he li
nes;
and
pla
ce t
wo
50
cm
long
sta
kes
in b
etw
een
the
long
sta
kes.
Sta
kes
shou
ld p
rotr
ude
abou
t 20
- 3
0 cm
.
• D
ig o
ut a
gro
ove
alon
g th
e co
ntou
r be
twee
n th
e st
akes
; it
shou
ld b
e at
leas
t 15
cm
dee
p.
• Pl
ace
the
cutt
ings
with
the
ir lo
wer
end
s in
the
gro
ove,
ben
ding
the
m d
own
alon
g th
e lin
e of
the
fen
ce. W
eave
the
m in
and
out
be
twee
n th
e st
akes
. Fir
m t
he s
oil b
ack
into
the
gro
ove.
• Th
e br
ush
wea
ving
sho
uld
be a
lmos
t ho
rizo
ntal
ly a
bove
eac
h ot
her,
but
with
the
end
s fir
mly
pla
nted
in t
he s
oil.
• Fi
ll th
e so
il be
hind
the
wat
tles
for
the
pla
ntat
ion
of t
rees
, gra
ss s
eedl
ings
, and
cut
tings
.
Mat
eria
lsSp
ecie
s To
ols
• St
akes
1 m
long
, 8-1
0 cm
di
amet
er, a
nd 5
0 cm
long
, 6-8
cm
dia
met
er. S
harp
en a
ll st
akes
at
the
bot
tom
.
• W
oody
cut
tings
of
long
and
fle
xibl
e pl
ants
whi
ch r
oot
easi
ly
(m
ore
than
150
cm
long
and
3 –
5
cm d
iam
eter
)
• If
spro
utin
g m
ater
ials
are
not
av
aila
ble,
mat
eria
l lik
e ba
mbo
o
co
uld
be u
sed.
• Ju
te o
r co
ir st
ring
or
wir
e to
bin
d
• Li
ve s
tack
for
anc
hori
ng s
take
s: E
ryth
rina
arbo
resc
enes
, Sal
ix
sp
ecie
s, G
agru
ga p
inna
ta, P
opul
us, P
lum
eria
acu
min
ate,
Fi
cus
laco
r, S
epiu
m in
segn
e, e
tc.
• Bu
shes
, Shr
ubs:
Adh
atod
a va
sica
, Dur
anta
rep
ens,
Ipom
ea
fis
tula
ta, J
atro
pha
curc
as, S
alix
spe
cies
, Lan
tana
cam
ara,
Vi
tex
negu
ndo,
etc
.
• To
ols
to d
ig t
renc
h
• Cr
ow b
ar a
nd h
amm
er t
o dr
ive
st
akes
• H
essi
an a
nd w
ater
to
keep
the
cu
ttin
g m
oist
unt
il pl
antin
g
Spec
ifica
tion
Cons
truc
tion
per
iod
• Sp
acin
g be
twee
n lo
ng s
take
s 1
m
• A
vera
ge h
oriz
onta
l dis
tanc
e be
twee
n w
attl
ing
is 1
-2m
on
stee
p
sl
ope
• D
urin
g do
rman
t se
ason
if t
he s
ite is
moi
st
• Ju
st b
efor
e m
onso
on if
the
site
is d
ry (
May
, Jun
e)
Guideline on Landslide Treatment and Mitigation | 43
Prec
auti
ons
Scop
e (S
ite
for
appl
icat
ion)
• A
void
spl
ittin
g th
e st
akes
by
plac
ing
a pi
ece
of s
tron
g w
ood
on
th
e to
p of
the
sta
ke w
hen
it is
bei
ng d
rive
n in
• U
sefu
l in
the
smal
l sha
llow
sho
rt le
ngth
slid
es
• In
est
ablis
hing
the
gul
ly h
eads
slo
pes
• In
com
bina
tion
with
oth
er m
easu
res
usef
ul f
or b
ank
prot
ectio
n
Mai
nten
ance
• Si
nce
the
spac
ing
of p
lant
s in
wat
tle
fenc
es is
ver
y de
nse,
the
re is
unl
ikel
y to
be
a ne
ed f
or r
epla
cing
fai
lure
s. H
owev
er, r
egul
ar
pr
otec
tion
from
gra
zing
and
hum
an in
terf
eren
ce is
nee
ded.
• In
spec
t th
e ar
ea d
urin
g th
e fir
st r
ainy
sea
son.
Rep
air
and
stre
ngth
en a
ny b
reak
s of
the
sta
kes
gro
wth
of
to a
llow
veg
etat
ion
to t
ake
pl
ace.
• So
me
thin
ning
of
shru
bs m
ay b
e re
quir
ed a
fter
few
yea
rs.
Refe
renc
es: D
OI,
1992
, DO
R, 1
999.
DSC
WM
, 198
3, F
AO
, 198
5, D
SCW
M 2
004.
| Guideline on Landslide Treatment and Mitigation44
© WWF Nepal, Hariyo Ban Program/ Nabin Baral
Titl
e: V
EGET
ATI
VE R
IP-R
AP
Wha
t is
it?
Ston
e pi
tchi
ng f
or s
urfa
ce p
rote
ctio
n w
ith m
ainl
y gr
ass
inte
r-pl
ante
d be
twee
n th
e st
ones
.
Func
tion
Lim
itat
ion
Rein
forc
es a
nd a
rmor
s th
e sl
ope
agai
nst
eros
ion.
Allo
ws
seep
age
to fl
ow o
ut b
etw
een
the
ston
es.
Lim
ited
cons
truc
tion
heig
ht, l
engt
h, a
nd s
lope
Cann
ot b
e us
ed in
gul
ly b
eds
with
cop
ious
deb
ris
flow
Adv
anta
ges
Dis
adva
ntag
es
Ston
es a
re n
ot d
islo
dged
onc
e th
e ve
geta
tion
is e
stab
lishe
d.
Goo
d dr
aina
ge t
hrou
gh w
all b
y th
e pl
ants
Rege
nera
tion
is o
bstr
ucte
d by
the
sto
nes
Rela
tivel
y ex
pens
ive
to c
arry
out
in la
rge
scal
e
Cons
truc
tion
ste
ps
Reta
inin
g or
toe
wal
l as
terr
ace
rais
er
• Sm
ooth
the
slo
pe
• Co
nstr
uct
the
toe
wal
l nor
mal
ly
• M
ake
sure
the
re is
ple
nty
of s
oil i
n ba
ck o
f th
e w
all
• Pr
ovid
e a
foun
datio
n as
nec
essa
ry
• Fi
ll th
e vo
ids
with
soi
l and
sm
all s
tone
s
• W
ait
until
the
rai
ns f
or p
lant
ing
cutt
ings
s or
see
ds
• Ta
ke c
are
that
the
bar
k or
see
d co
at is
not
dam
aged
.
Gul
ly H
ead
• Re
shap
e th
e gu
lly h
ead
to a
n ev
en s
urfa
ce
• O
ther
ste
ps s
ame
as g
ully
bed
s
• Pr
ovid
e an
apr
on a
t th
e bo
ttom
to
prev
ent
scou
ring
• Pr
otec
t to
e of
the
gul
ly h
ead
with
a c
ylin
dric
al m
esh
wir
e fil
led
w
ith s
tone
s or
gra
vel
Gul
ly b
edSt
ream
ban
k
• Cl
ean
the
gully
floo
r co
mpl
etel
y of
all
debr
is, e
xcav
ate,
and
sha
pe
un
til a
firm
bas
e is
exp
osed
or
com
pact
the
soi
l.
• Pr
ovid
e fo
unda
tion
as n
eces
sary
• La
y ou
t st
ones
kee
ping
the
flat
test
sid
es o
n th
e su
rfac
e
• Re
duce
gap
s to
a m
inim
um a
nd p
ack
all v
oids
with
soi
l and
sm
all
st
ones
• Th
e st
one
pitc
hing
sho
uld
have
con
cave
cro
ss-s
ectio
n fo
r w
ater
flo
w a
nd t
o pr
even
t sc
ouri
ng a
t th
e si
des
• Th
ickn
ess
of r
ipra
p sh
ould
be
a m
inim
um o
f 15
cm t
hick
• Pl
ace
the
heav
iest
roc
ks a
long
the
bot
tom
.
• Ex
tend
the
pitc
hing
2 t
o 3m
bey
ond
the
area
of
activ
e er
osio
n
• En
tren
ch t
he b
otto
m r
ow o
f st
one
into
the
str
eam
bed
to p
reve
nt
un
derc
uttin
g.
• pl
ant
cutt
ings
, slip
s, o
r se
eds
of g
rass
or
brus
h at
the
sta
rt o
f th
e
ra
in
• Id
eally
, sm
alle
r gr
asse
s sh
ould
be
plan
ted
in t
he m
ain
chan
nel,
w
ith la
rger
gra
sses
or
brus
hes
alon
g si
des
• Tr
im t
he a
rea
to a
n ev
en s
urfa
ce. R
emov
e al
l fre
e lo
ose
debr
is.
Co
mpa
ct t
he s
oil.
It s
houl
d no
t ha
ve a
ny p
ocke
ts o
f fin
er
m
ater
ials
, whi
ch w
ould
flus
h ou
t an
d w
eake
n th
e st
ruct
ure.
• Pl
ace
a hi
ghly
per
mea
ble
and
appr
opri
atel
y si
zed
geo-
text
ile
fil
ter
fabr
ic o
n th
e pr
epar
ed s
lope
to
prot
ect
the
soil
from
w
ashi
ng. T
ake
care
not
to
tear
the
filt
er f
abri
c du
ring
inst
alla
tion.
• Pl
ace
a la
yer
(15
cm m
inim
um)
of g
rave
l or
smal
l roc
k on
the
ge
o-te
xtile
filt
er f
abri
c. T
he u
nder
layi
ng g
rave
l or
ston
e ne
ed
to
be
size
d ap
prop
riat
ely
so it
will
not
was
h ou
t th
roug
h th
e
ga
ps b
etw
een
the
ripr
ap s
tone
s.
• Bu
ild t
he s
tone
pitc
hing
car
eful
ly, fi
ttin
g th
e st
ones
tog
ethe
r
fir
mly
as
if it
is a
dry
mas
onry
wal
l. St
ones
sho
uld
be
pe
rpen
dicu
lar
to t
he s
lope
, with
the
mai
n po
int
or n
arro
w s
ide
do
wn.
• Th
e th
ickn
ess
of t
he s
tone
pitc
hing
sho
uld
be 1
.5 t
imes
the
th
ickn
ess
of t
he la
rges
t st
one,
on
top
of t
he g
rave
l. Th
e he
avie
st
ro
cks
shou
ld b
e pl
aced
alo
ng t
he b
otto
m.
• Ex
tend
the
rip
rap
2 to
3 m
on
eith
er s
ide
of t
he a
ctiv
e er
osio
n
ar
ea t
o pr
even
t fu
rthe
r er
osio
n be
yond
the
str
uctu
re
Vege
tati
ve r
ip-r
ap a
t To
e w
all,
Wei
ldt,
197
6
Veg
etat
ive
rip-
rap
on g
ully
bed
Ripr
ap in
gul
ly b
ed (
How
ell,
et a
l. 19
91)
Vege
tati
ve r
ip-r
ap
Guideline on Landslide Treatment and Mitigation | 45
• W
hen
only
rip
rap
is b
eing
use
d fo
r ba
nk s
tabi
lizat
ion,
the
top
of
th
e ri
prap
sho
uld
exte
nd 1
m a
bove
the
ord
inar
y hi
gh w
ater
m
ark.
• En
tren
ch t
he b
otto
m r
ow o
f st
one
into
the
gro
und
to p
reve
nt
un
derc
uttin
g.
• D
esig
n ri
prap
str
uctu
res
for
stre
am b
ank
stab
iliza
tion
to b
e st
able
fo
r fu
ll flo
ws.
•
Mat
eria
lsSp
ecie
s To
ols
• A
ngul
ar o
r irr
egul
ar e
dges
on
hard
sto
nes
for
go
od in
terl
ocki
ng.
• Lo
ng s
trai
ght
stem
s or
cut
tings
or
seed
s of
su
itabl
e sh
rubs
(bu
t no
t of
larg
e tr
ees)
, tha
t
ro
ot e
asily
or
gras
s sl
ips
• G
ener
ally
, gra
ss s
eeds
are
not
use
d
Som
e sh
rubs
and
Bus
hes
to p
lant
on
ripr
ap:
Adh
atod
a va
sica
, Dur
anth
a re
pens
,
Euph
orbi
a ro
ylea
na, J
atro
pha
curc
as, V
itex
negu
ndo,
Aca
cia
penn
ata,
But
ea m
inor
Som
e gr
asse
s to
pla
nt a
mon
g ri
prap
in
gulli
es (
Use
d in
Nep
al):
Pog
onat
heru
m
pani
cum
; Cyn
odon
dac
tylo
n; T
hysa
nola
ena
max
ima;
Cym
bopo
gon
mic
roth
eca
• Sh
ovel
s, h
amm
er a
nd p
ick
axes
to
pitc
h
st
ones
,
• Sh
ort
plan
ting
bars
• H
essi
an a
nd w
ater
to
keep
the
pla
ntin
g
st
ock
moi
st u
ntil
plan
ting
Spec
ifica
tion
Cons
truc
tion
per
iod
• To
e w
all u
p to
2 m
hei
ght
and
laid
bac
k at
an
angl
e of
abo
ut 6
0Æ
• La
yout
of
the
ripra
p sh
ould
be
conc
ave
to c
once
ntra
te w
ater
in t
he m
iddl
e
• If
plan
ts c
an b
e gr
own
betw
een
all s
tone
s, it
wou
ld b
e be
nefic
ial
• Ri
prap
sto
ne w
all c
an b
e bu
ilt a
t any
tim
e
• Pl
ant
cutt
ing
duri
ng d
orm
ant
and
se
edlin
g be
fore
mon
soon
sea
son
Mai
nten
ance
Pr
ecau
tion
sSc
ope
(Sit
e fo
r ap
plic
atio
n)
• In
spec
t im
med
iate
ly a
fter
the
firs
t an
d ev
ery
la
rge
stor
m
• Re
pair
any
disp
lace
d ri
prap
• Re
gula
r cu
ttin
g of
gra
ss a
nd p
runi
ng o
f sh
rubs
/
bush
es is
ess
entia
l to
prom
ote
root
sys
tem
s
an
d to
avo
id fl
ow o
bstr
uctio
n
• So
me
thin
ning
of
shru
bs m
ay b
e re
quir
ed a
fter
fe
w y
ears
.
• A
void
rou
nd s
tone
s
• Pl
antin
g m
ust
be d
eep
enou
gh t
o av
oid
dr
ying
up
• O
nly
2-3
cm o
f cu
ttin
gs s
houl
d be
ex
pose
d ou
tsid
e th
e w
all
• Pl
antin
g sh
ould
not
dam
age
the
bark
or
se
ed c
oat
• Lo
w s
lope
toe
wal
ls o
f up
to
2 m
in
he
ight
• G
ully
floo
rs w
ith a
max
imum
slo
pe o
f
45Æ
/ R
oad
drai
nage
• G
ully
hea
d af
ter
resh
apin
g
• Ro
ad o
r tr
ail s
lope
s
• St
ream
or
rive
r ba
nk w
ith m
ediu
m fl
ow
Rip-
rap,
Wei
ldt,
197
6
Vege
tati
ve r
ip-r
ap o
f G
ully
Hea
d W
eild
t, 1
976
Stone rip-rap on slope
Stone rip-rap on
drainage lines
Refe
renc
es: -
BIW
MP,
200
3, D
OI,
1992
., D
OR,
199
9, IT
ECO
, 199
0, S
thap
it, K
. M.,
1998
. Wei
dlt,
H.J.
(co
mpi
led)
, 197
6. O
hio
Dep
artm
ent
of N
atur
al R
esou
rces
. Rip
rap
Reve
tmen
t. w
w.o
hiod
nr.c
om/
wat
er/p
ubs/
fs_s
t/st
fs16
.htm
, DSC
WM
200
4.
| Guideline on Landslide Treatment and Mitigation46
Titl
e: W
ATE
RWA
YSW
hat
is it
? W
ater
cour
se m
ade
for
the
safe
dis
posa
l of
runo
ff w
ater
or
dive
rtin
g w
ater
out
of
an a
ctiv
e la
ndsl
ide
or g
ully
into
a s
afe
outl
et
Gra
ss w
ater
way
sG
rass
wat
erw
ays
with
dro
psSt
one
lined
wat
erw
ays
Wat
erw
ays
plan
ted
with
low
and
rhiz
ome
type
gras
s. G
ener
ally
mad
e in
par
abol
ic s
hape
.
Gra
ss w
ater
way
s w
ith s
mal
l dro
ps k
eep
the
flow
from
sco
urin
g th
e be
d.
Wat
erco
urse
line
d w
ith s
tone
to
prot
ect
the
bed
from
ero
sion
.
A w
ater
way
sho
uld
not
be u
sed
until
the
gras
s co
ver
is p
rope
rly
esta
blis
hed.
Dro
p st
ruct
ures
pre
ferr
ed t
o be
bel
ow 1
m h
eigh
t
but
neve
r ta
ller
than
1.8
m.
15-3
0 cm
dia
met
er s
tone
s sh
ould
be
keye
d in
the
gro
und
Func
tion
Lim
itat
ion
of g
rass
wat
erw
ays
• Sa
fely
dis
pose
of
runo
ff
• D
rain
exc
ess
runo
ff t
o a
safe
and
sui
tabl
e si
te.
• Pr
even
t su
rfac
e ru
noff
fro
m e
nter
ing
the
area
to
be
st
abili
zed
(Gul
lies
and
land
slid
es).
• Ca
n on
ly b
e us
ed f
or s
mal
l am
ount
of
runo
ff.
• Ca
nnot
be
used
whe
re t
here
is a
con
tinuo
us fl
ow o
f w
ater
.
• Ca
nnot
be
used
unt
il th
e gr
ass
cove
r is
pro
perl
y es
tabl
ishe
d.
Adv
anta
ges
Dis
adva
ntag
es
• Lo
w c
ost
• Ea
sy t
o m
aint
ain
• Fr
agile
and
eas
ily d
estr
oyed
if n
ot p
rope
rly
mai
ntai
ned
and
prot
ecte
d.
Cons
truc
tion
ste
ps
• Cl
ear
the
site
. Mar
k th
e lin
es w
ith s
trin
gs w
here
wat
erw
ays
are
to b
e co
nstr
ucte
d. E
nsur
e th
at s
lope
of
the
alig
nmen
t pr
oper
ly s
o th
at t
he
ru
noff
spe
ed is
wel
l bel
ow t
he s
cour
ing
velo
city
.
• D
ig t
he w
ater
way
s gi
ving
uni
form
sha
pe (
cros
s-se
ctio
n) a
nd s
lope
. See
des
ign
step
s fo
r ca
lcul
atio
n of
the
siz
e an
d sl
ope
of t
he w
ater
way
s
fo
r di
ffer
ent
runo
ff.
• Pl
ant
the
gras
s pr
efer
ably
loca
lly a
vaila
ble,
rhi
zom
e, o
r so
d fo
rmin
g gr
ass.
If s
eedi
ng is
don
e, p
lant
ing
of s
eed
shou
ld b
e do
ne w
ith s
hallo
w
di
tchi
ng a
nd m
ulch
ing
at t
he b
egin
ning
of
the
rain
y se
ason
. Pro
vide
sod
ding
at
the
junc
tion
of t
he e
arth
and
the
str
uctu
re t
o av
oid
wat
er
tu
nnel
ing.
• Co
nstr
uct
loos
e st
one
drop
str
uctu
re s
o th
at r
unof
f sp
eed
is w
ell b
elow
the
sco
urin
g ve
loci
ty. T
he h
eigh
t of
the
loos
e st
one
drop
str
uctu
re
sh
ould
not
be
mor
e th
an ½
met
er.
• Pr
ovid
e su
ffici
ent
and
stro
ng f
ound
atio
n an
d ap
ron
for
the
drop
str
uctu
re.
• Pr
ovid
e w
ing
wal
l to
dire
ct fl
ow t
o th
e w
eir
of t
he s
truc
ture
.
• A
fter
the
str
uctu
re is
bui
lt, t
ram
p ea
rth
solid
ly b
ehin
d an
d ar
ound
it t
o pr
even
t cr
acki
ng.
Des
igni
ng w
ater
way
s
• Su
rvey
the
wat
ersh
ed t
o es
timat
e th
e pe
ak r
unof
f. Be
st t
o us
e Ra
tiona
l For
mul
a fo
r ru
noff
est
imat
ion
• Ru
noff
in c
umec
s, Q
= D
imen
sion
less
run
off
coef
ficie
nt (
c) *
Rai
nfal
l int
ensi
ty (
mm
/hr
) fo
r de
sign
fre
quen
cy f
or t
ime
of c
once
ntra
tion
* A
rea
in
ha
(A)
• Ta
ke p
erm
issi
ble
velo
city
of
1.2
to 1
.8 m
/sec
for
den
se g
rass
dep
endi
ng u
pon
the
dens
ity
• Co
mpu
te a
ppro
xim
ate
cros
s-se
ctio
nal a
rea
of t
he c
hann
el t
o ca
rry
out
desi
gn r
unof
f : Q
= A
(A
rea
of w
ater
way
s) *
V (
Perm
issi
ble
velo
city
)
• A
rea
calc
ulat
ion
for
para
bolic
cro
ss s
ectio
n: A
= (
2/3)
*T*d
, W
here
, T =
Top
wid
th, d
= d
epth
of
para
bolic
sec
tion
at t
he m
iddl
e
• Co
mpu
te t
he w
ette
d pe
rim
eter
for
the
cro
ss s
ectio
n, P
= T
+ (
8/3)
* (
d2 /T)
Gra
ss w
ater
way
s
Gra
ss w
ater
way
s
wit
h dr
ops
Ston
e lin
ed
wat
erw
ays
Para
bolic
Cro
ss S
ecti
on o
f W
ater
way
s
Guideline on Landslide Treatment and Mitigation | 47
• Co
mpu
te t
he h
ydra
ulic
rad
ius
for
the
cros
s se
ctio
n, R
= A
/ P
• Co
mpu
te t
he w
ater
vel
ocity
in t
he w
ater
way
s us
ing
Man
ning
’s F
orm
ula,
V =
(R2/
3 *
S1/2 )
/n
,
W
here
,
•
S =
wat
er S
urfa
ce s
lope
cor
resp
ondi
ng t
o hi
gh w
ater
leve
l = It
is t
he r
atio
of
vert
ical
dro
p to
the
leng
th o
f th
e st
ream
.
•
N =
rou
ghne
ss c
oeffi
cien
t, 0
.035
-0.0
45 (
0.04
) fo
r lo
osel
y gr
asse
s an
d 0.
040-
0.06
0 (0
.05)
for
den
sely
gra
ssed
wat
erw
ays.
• If
calc
ulat
ed V
is b
elow
the
per
mis
sibl
e ve
loci
ty, t
he d
esig
n cr
oss
sect
ion
is s
afe
from
bed
sco
urin
g or
ero
sion
• Ca
lcul
ate
the
flow
the
des
ign
cana
l acc
omm
odat
e, Q
= A
(Cr
oss
sect
ion
Are
a of
des
ign
wat
erw
ays)
* V
(Ca
lcul
ated
vel
ocity
usi
ng M
anni
ng’s
Fo
rmul
a
• If
calc
ulat
ed fl
ow t
hat
can
be a
ccom
mod
ated
by
the
wat
erw
ay is
mor
e th
an e
xpec
ted
max
imum
run
off,
the
des
ign
sect
ion
of t
he w
ater
way
is
saf
e/go
od.
Mat
eria
lsSp
ecie
sTo
ols
• Lo
cally
ava
ilabl
e so
d-fo
rmin
g ty
pe g
rass
.
• H
ead
size
d st
ones
Cyno
n da
ctyl
on, P
aspa
lum
and
Cen
tiped
e gr
ass,
etc.
Shor
t pl
antin
g ba
rs
• Li
ne s
trin
g /
Tap
e (3
0 m
eter
s)
• Sh
ovel
s an
d Pi
ck a
xes
to m
ake
the
w
ater
way
s
• M
eans
of
tran
spor
ting
plan
ts t
o si
te
• H
essi
an a
nd w
ater
to
keep
the
pla
ntin
g
st
ock
moi
st u
ntil
plan
ting
Spec
ifica
tion
Cons
truc
tion
per
iod
• Cr
oss-
sect
ion
of t
he w
ater
way
sho
uld
be s
hallo
w a
nd in
the
par
abol
ic s
hape
.
• G
roun
d sl
ope
not
mor
e th
an 2
0 %
,
• Th
e gr
ass
wat
erw
ays
shou
ld n
ot b
e lo
nger
tha
n 30
m;
• Pr
ovid
e dr
op s
truc
ture
s if
long
er w
ater
way
s.
• D
rop
stru
ctur
e no
t m
ore
than
50
cm h
igh.
Use
big
flat
sto
nes
in c
onst
ruct
ion.
• M
aint
ain
3% s
lope
bet
wee
n tw
o dr
op s
truc
ture
s.
• Si
de w
alls
for
the
dro
p st
ruct
ure
mus
t be
hig
h en
ough
to
dire
ct t
he fl
ow t
o th
e w
eir.
• D
urin
g do
rman
t se
ason
if t
he s
ite is
m
oist
.
• Ju
st b
efor
e ra
in if
the
site
is d
ry.
• •
Mai
nten
ance
Prec
auti
ons
Scop
e (S
ite
for
appl
icat
ion)
• In
spec
t th
e w
ater
way
s re
gula
rly
(mai
nly
du
ring
the
first
rai
ny s
easo
n). R
epai
r an
y
da
mag
e (s
uch
as b
reak
s, t
unne
ling)
bef
ore
it
gets
wor
se.
• Re
mov
e br
ush
or la
rge
wee
ds b
efor
e th
ey
w
eake
n th
e gr
ass.
• Re
gula
r gr
ass
cutt
ing
• Sh
arp
turn
s an
d su
dden
fal
ls s
houl
d be
avo
ided
un
less
wat
er c
olle
ctin
g ba
sin
or d
rop
stru
ctur
e
is
pla
nned
.
• Th
e w
ater
mus
t go
ove
r th
e st
ruct
ures
and
not
go
aro
und
them
.
• Th
e w
ater
way
s sh
ould
not
be
used
suc
h as
pa
ths.
• Fa
rm la
nds
• D
egra
ded
area
| Guideline on Landslide Treatment and Mitigation48
Div
ersi
on w
ater
way
s: C
onst
ruct
to
dire
ct r
un-o
ff
away
fro
m g
ully
hea
ds
• W
ater
way
s m
ust
be a
t le
ast
at a
dis
tanc
e tw
ice
th
e w
idth
of
the
gully
/ la
ndsl
ide
from
the
gul
ly
/
land
slid
e he
ad.
• W
ater
way
s si
ze m
ust
be la
rge
to a
ccom
mod
ate
m
axim
um r
unof
f.
• Ta
ke p
reca
utio
ns t
o sa
fely
dis
pose
of
the
di
vert
ed r
unof
f an
d no
t to
cre
ate
a ne
w g
ully
.
Den
sely
Gra
ssed
Wat
erw
ays
Tabl
e: S
ize
of c
atch
dra
ins
(cas
es)
Para
bolic
II
IIII
IIIIII
IVIV
VV
VIVI
VII
VII
VIII
VIII
IXIX
XX
XIXI
XII
XII
XIII
XIII
XIV
XIV
Qm
ax in
cum
ecs
0.10
0.10
0.15
0.15
0.20
0.20
0.25
0.25
0.30
0.30
0.35
0.35
0.40
0.40
0.45
0.45
0.50
0.50
0.62
0.62
0.75
0.75
0.80
0.80
0.87
0.87
0.99
0.99
t =
Top
wid
th in
m.
0.60
0.60
0.60
0.60
0.60
0.60
0.80
0.80
0.80
0.80
0.80
0.80
0.90
0.90
1.00
1.00
1.00
1.00
1.20
1.20
1.20
1.20
1.20
1.20
1.25
1.25
1.25
1.25
d =
Dep
th in
m.
0.30
0.30
0.30
0.30
0.40
0.40
0.40
0.40
0.40
0.40
0.50
0.50
0.50
0.50
0.60
0.60
0.60
0.60
0.70
0.70
0.70
0.70
0.70
0.70
0.80
0.80
0.80
0.80
s =
Cha
nnel
slo
pe0.
040.
080.
040.
080.
040.
080.
040.
080.
040.
080.
040.
080.
040.
080.
040.
080.
040.
080.
040.
080.
040.
080.
040.
080.
040.
080.
040.
08
Refe
renc
es:-
CSW
CS, 1
987.
DO
R, 1
999.
FA
O, 1
977.
Sth
apit,
K. M
., 19
98, D
SCW
M 2
004.
Guideline on Landslide Treatment and Mitigation | 49
Titl
e: G
AB
ION
WIR
E B
OLS
TER
Wha
t is
it?
A g
abio
n tu
be fi
lled
with
sto
ne a
nd p
lace
d in
sha
llow
tre
nche
s ac
ross
in t
he s
lope
Func
tion
Lim
itat
ion
Prev
ent
surf
ace
scou
ring
and
gul
lyin
g
Prov
ide
supp
ort
to t
he s
hallo
w s
urfa
ce s
lippi
ng
Expe
nsiv
e co
mpa
red
to b
io-e
ngin
eeri
ng t
echn
ique
s
Adv
anta
ges
Dis
adva
ntag
es
Form
s a
stro
ng a
nd lo
ng la
stin
g st
ruct
ure
to a
rmor
a
slop
e su
rfac
e ag
ains
t gu
lly e
rosi
on.
If it
fails
it p
ulls
the
soi
l sur
face
aff
ectin
g ar
ea o
f its
appl
icat
ion.
Act
s as
sub
-sur
face
dra
inag
e if
plac
es in
her
ring
bone
patt
ern.
Dig
ging
of
tren
ches
dis
turb
s th
e so
il in
ste
ep s
lope
s.
Cont
our
wir
e bo
lste
rH
erri
ngbo
ne w
ire
bols
ter
Pl
ace
bols
ters
alo
ng a
con
tour
mai
nly
to r
educ
e gu
lly
eros
ion
and
stab
ilize
the
slo
pe. P
lace
on
wel
l-dr
aine
d
slop
es.
Plac
e bo
lste
rs in
a h
erri
ngbo
ne s
tyle
mai
nly
to r
educ
e
surf
ace
eros
ion
and
drai
n th
e ar
ea. P
lace
on
poor
ly
drai
ned
slop
es.
Co
nstr
ucti
on s
teps
Cons
truc
tion
ste
ps
Trim
the
are
a to
an
even
slo
pe w
ith n
o pr
otru
sion
s an
d
depr
essi
ons
Star
ting
from
the
bot
tom
of
the
slop
e, m
ark
out
a
cont
our
line
acro
ss t
he s
lope
Dig
a t
renc
h al
ong
the
line,
abo
ut 3
0-40
cm
wid
e an
d
30 -
40cm
dee
p (F
igur
e a)
Lay
a ga
bion
bol
ster
pan
el le
ngth
wis
e al
ong
the
tren
ch
(Fig
ure
b). E
nsur
e th
e ed
ge o
f th
e ga
bion
on
the
low
er
side
is in
line
with
low
er e
dge
of t
he t
renc
h.
Fill
the
bols
ter
with
sto
nes
larg
er t
han
the
mes
h si
ze.
Fold
the
upp
er e
dge
of t
he p
anel
ove
r th
e st
ones
and
join
it t
o th
e lo
wer
pan
el e
dge
(Fig
ure
c).
Leav
e a
10 c
m fl
ap f
rom
the
upp
er e
dge
exte
ndin
g ov
er
the
low
er e
dge.
Join
abu
ttin
g bo
lste
rs a
cros
s th
e sl
ope
into
con
tinuo
us
lines
; clo
se t
he e
xtre
me
ends
with
wir
e;
Star
ting
from
the
top
, bac
kfill
the
mat
eria
ls a
roun
d th
e
bols
ters
, com
pact
it a
nd c
lean
aw
ay d
ebri
s (F
igur
e d)
Trim
the
are
a to
an
even
slo
pe w
ith n
o pr
otru
sion
s an
d
depr
essi
ons;
Star
ting
from
the
bot
tom
of
the
slop
e, m
ark
out
the
lines
for
the
bol
ster
s; t
here
sho
uld
be o
ne v
ertic
al li
ne
and
slop
ing
lines
join
ing
vert
ical
line
mak
ing
an a
ngle
of 4
5º w
ith e
ach
line
abou
t 5
met
ers
long
.
Dig
a t
renc
h al
ong
the
line,
abo
ut 3
0-40
cm
wid
e an
d
40 -
60cm
dee
p;
Lay
a sh
eet
of b
lack
pol
ythe
ne a
long
the
bot
tom
and
low
er s
ide;
but
not
the
upp
er s
ide
of t
he t
renc
h.
Lay
the
gabi
on b
olst
er p
anel
s le
ngth
way
s in
the
tren
ches
. Ens
ure
the
edge
of
the
gabi
on o
n th
e lo
wer
side
is in
line
with
low
er e
dge
of t
he t
renc
h.
Fill
the
bols
ter
with
sto
nes
larg
er t
han
the
mes
s si
ze.
Fold
the
upp
er e
dge
of t
he p
anel
ove
r th
e st
ones
and
join
it t
o th
e lo
wer
pan
el e
dge;
the
sla
ntin
g lin
es a
t th
e
end
are
clos
ed.
Repe
at u
ntil
all s
lant
ing
lines
mee
t th
e ve
rtic
al li
ne.
Onc
e th
e sl
antin
g lin
es a
re c
ompl
ete,
dig
a v
ertic
al
tren
ch s
trai
ght
dow
n th
e sl
ope
and
inst
all a
ver
tical
bols
ter
to c
olle
ct w
ater
fro
m t
he b
otto
m.
Ben
d th
e to
p fl
ap o
ver.
Dri
ve a
pie
ce o
f st
eel b
ar in
to t
he
grou
nd im
med
iate
ly b
elow
the
com
plet
ed b
olst
ers.
Fill
the
pane
l wit
h st
one.
Lay
a bo
lste
r pa
nel
into
the
tre
nch.
Exca
vate
a t
renc
h.
| Guideline on Landslide Treatment and Mitigation50
Dri
ve 1
met
er lo
ng s
teel
bar
s, a
ngle
s, o
r sp
rout
ing
pole
s
into
the
gro
und
at r
ight
-ang
le t
o th
e sl
ope
ever
y 2
met
ers
alon
g th
e bo
lste
rs. P
ositi
on t
hem
imm
edia
tely
belo
w a
nd t
ouch
ing
the
bols
ters
, and
dri
ve t
hem
in
far
enou
gh s
o th
at t
hey
cann
ot b
e pu
lled
out
by h
and.
(Fig
ure
e).
Tie
the
vert
ical
bol
ster
with
sla
ntin
g bo
lste
rs.
Back
fill t
he m
ater
ials
aro
und
the
bols
ters
, com
pact
it
and
clea
n aw
ay d
ebri
s.
Dri
ve 1
met
er lo
ng s
teel
bar
s, a
ngle
s, o
r sp
rout
ing
pole
s in
to t
he g
roun
d at
rig
ht-a
ngle
to
the
slop
e ev
ery
2 m
eter
s al
ong
the
bols
ters
. Pos
ition
the
m im
med
iate
ly
belo
w a
nd t
ouch
ing
the
bols
ters
, and
dri
ve t
hem
in f
ar
enou
gh s
o th
at t
hey
cann
ot b
e pu
lled
out
by h
and.
Impl
emen
t bi
o-en
gine
erin
g w
orks
thr
ough
out
the
site
.
Mat
eria
lsSp
ecie
sTo
ols
• G
alva
nize
d ga
bion
she
et 1
0cm
m
esh
of r
equi
red
leng
th.
• A
ngul
ar s
tone
s fo
r co
ntou
r an
d
ro
unde
d st
ones
for
her
ring
bone
bo
lste
r of
mor
e th
an 1
0 cm
di
amet
er.
• 16
mm
iron
rod
s of
2m
long
iron
ro
ds /
angl
es
• 8-
10 c
m d
iam
eter
spr
outin
g po
les.
Spro
utin
g su
ch a
s Sa
lix s
peci
es,
Popu
lus,
Vite
x ne
gund
o G
agru
ga
pinn
ata,
Sep
ium
inse
gne
etc.
• To
ols
for
digg
ing
tren
ches
and
for
w
orki
ng w
ith g
abio
n w
ire;
• Sl
edge
ham
mer
s;
• Fo
r he
rrin
gbon
e bo
lste
r, t
hick
(2
0 ga
uge)
bla
ck p
olyt
hene
she
et.
•
Spec
ifica
tion
Cons
truc
tion
per
iod
• Pl
ace
bols
ters
at
vary
ing
inte
rval
s of
5 –
10
met
ers.
Th
e st
eepe
r th
e sl
ope,
the
clo
ser
the
bols
ters
sho
uld
be
inst
alle
d.
• Co
ntou
r bol
ster
use
d ro
unde
d ga
bion
of 3
0 - 4
0
cm
dia
met
er, w
here
as h
errin
gbon
e bo
lste
r use
d
re
ctan
gula
r gab
ion
box
30 to
40
wid
e -4
0 to
60
deep
cm
.
• Pr
efer
ably
dur
ing
dry
peri
od f
or in
stal
ling
the
bols
ters
.
• A
t th
e st
art
of t
he r
ain
afte
r so
il is
moi
st f
or
ve
geta
tion
to g
row
for
bio
-eng
inee
ring
wor
ks.
Mai
nten
ance
Pr
ecau
tion
sSc
ope
(Sit
e fo
r ap
plic
atio
n)
• O
peni
ng o
f th
e ga
bion
tub
e sh
ould
be
regu
larl
y ch
ecke
d af
ter
ever
y ra
in
an
d cl
osed
imm
edia
tely
• St
one
dent
ition
in a
ny r
ills
deve
lope
d be
twee
n th
e bo
lste
rs
• A
ny r
ill d
evel
oped
bel
ow t
he t
ube
mus
t be
clo
sed.
• La
ying
of
thic
k bl
ack
poly
then
e sh
eet
alon
g th
e
bo
ttom
and
low
er s
ide,
but
not
the
upp
er s
ide
of t
he
tr
ench
is e
ssen
tial i
n ca
se o
f he
rrin
gbon
e bo
lste
r.
• M
ust
avoi
d ri
ll fo
rmat
ion
betw
een
cont
our
bols
ters
.
• O
n m
ost
long
, exp
osed
slo
pes
betw
een
35º
to 5
0º
w
here
the
re is
a d
ange
r of
sco
urin
g or
gul
lyin
g on
th
e su
rfac
e.
• Co
ntou
r bo
lste
r is
use
d on
wel
l-dr
aine
d sl
ope
and
he
rrin
gbon
e bo
lste
rs a
re u
sed
on p
oorl
y dr
aine
d
sl
opes
with
a r
isk
of s
lum
ping
.
Cont
our
Bol
ster
Her
ring
bone
Bol
ster
Refe
renc
es: H
owel
l, et
. al.,
199
1.
Guideline on Landslide Treatment and Mitigation | 51
Titl
e: R
ETA
ININ
G W
ALL
Wha
t is
it?
A r
etai
ning
wal
l is
a w
all b
uilt
to
resi
st t
he la
tera
l pre
ssur
e of
the
ear
th b
ehin
d it.
Func
tion
• W
ithst
ands
late
ral e
arth
pre
ssur
es
• Su
ppor
ts t
he e
arth
or
fill m
ater
ial o
r cu
t ea
rth
slop
es a
nd
• Su
ppor
t m
ount
ains
ide
slop
es f
or r
oad,
irri
gatio
n ca
nal,
and
othe
r in
fras
truc
ture
con
stru
ctio
n
• Pr
even
ts t
he t
oe c
uttin
g
• Pr
even
ts b
ank
eros
ion
Type
bas
ed o
n m
ater
ials
Crib
wal
l (B
ambo
o/W
oode
n)Lo
ose
ston
eG
abio
nM
ason
ry /
Con
cret
e
Gen
eral
cha
ract
eris
tics
• M
ade
of w
oode
n po
les
or b
ambo
o
an
d br
ush.
• Th
ey a
re c
heap
and
can
be
mad
e
w
ith lo
cally
ava
ilabl
e m
ater
ials
.
• M
ade
of lo
ose
ston
e
• St
abili
ty a
nd s
tren
gth
depe
nds
on
si
ze o
f st
ones
and
con
stru
ctio
n
qu
ality
• Co
mm
only
use
d in
slo
pe s
tabi
lizat
ion
w
orks
• M
ade
with
larg
e re
ctan
gula
r ga
bion
bo
xes
fille
d w
ith s
tone
s. P
refe
rabl
e
w
here
flat
big
sto
ne a
re n
ot
av
aila
ble.
• Co
mm
only
use
d in
the
slo
pe
st
abili
zatio
n w
orks
• ad
e of
cem
ent
mor
tar
or c
oncr
ete
• Pe
rman
ent
stru
ctur
es
• U
sed
to p
rote
ct im
port
ant
in
fras
truc
ture
, suc
h as
roa
d, b
uild
ing.
Adv
anta
ges
• U
ses
loca
l mat
eria
ls, s
impl
e, a
nd
lo
w c
ost
• O
nce
root
s an
d sh
oots
are
put
out
,
fo
rms
a lo
ng-t
erm
bar
rier
• U
ses
loca
l mat
eria
ls, s
impl
e an
d
lo
w c
ost
• Pr
ovid
e go
od d
rain
age;
flex
ible
;
re
lativ
ely
low
cos
t
• Pr
ovid
e go
od d
rain
age;
flex
ible
and
re
lativ
ely
low
cos
t.
• Su
itabl
e, w
here
who
le la
nd m
ass
is
m
ovin
g.
• Pe
rman
ent
stru
ctur
e
• Lo
oks
good
Dis
adva
ntag
e/ L
imit
atio
n•
Take
s tim
e to
roo
t.
• Su
itabl
e fo
r ge
ntle
slo
pe a
nd s
hort
er
sl
ope
leng
th
• N
ot s
uita
ble
whe
re la
nd m
ass
is
m
ovin
g.
• Su
itabl
e
- w
here
goo
d qu
ality
(fla
t an
d bi
g)
s
tone
is a
vaila
ble
- f
or t
he s
hort
er s
lope
leng
th
- f
or s
mal
l mas
s m
ovem
ent
• Co
stly
• Co
st o
f th
e ga
bion
leav
es t
he
co
mm
unity
.
• N
eeds
ski
lled
labo
r fo
r co
nstr
uctio
n
• Co
stly
and
Cos
t of
mat
eria
ls (
cem
ent,
ro
ds)
leav
es t
he c
omm
unity
• N
eeds
com
plic
ated
eng
inee
ring
de
sign
and
ski
lled
labo
r.
• Po
or d
rain
age
• Ca
nnot
tol
erat
e se
ttle
men
t of
gro
und
| Guideline on Landslide Treatment and Mitigation52
Des
ign
/ C
onst
ruct
ion
spec
ifica
tion
Crib
wal
lLo
ose
ston
e re
tain
ing
wal
lG
abio
nM
ason
ry /
Con
cret
e
• Th
e cr
ib w
all s
houl
d no
t be
hig
her
than
4m
for
pol
e or
2m
for
ba
mbo
o
• Pl
ace
woo
den
pole
or
thre
e ba
mbo
os t
ied
toge
ther
in a
tria
ngul
ar
sh
ape
(A)
alon
g th
e fr
ont
side
of
the
crib
wal
l.
• Pl
ace
a po
le /
bam
boo
(B)
ever
y 1
to 2
m a
t a
dist
ance
apa
rt
pe
rpen
dicu
lar
to t
he h
oriz
onta
lly p
lace
d po
le /
bam
boos
in a
do
wn
slop
ing
angl
e of
15-
30 d
egre
e an
d tie
it t
oget
her
with
the
ho
rizon
tally
pla
ced
pole
/ b
ambo
os. F
or t
his
use
galv
aniz
ed w
ire.
• In
cas
e of
bam
boo
crib
wal
l, dr
ive
a liv
ing
/ ba
mbo
o po
le in
fro
nt
of
the
crib
wal
l to
prot
ect
the
horiz
onta
lly p
lace
d ba
mbo
os.
• In
cas
e of
woo
den
pole
crib
wal
l, th
e po
le p
lace
d pe
rpen
dicu
lar
to
the
hor
izon
tally
pla
ced
pole
s is
gro
oved
at
the
end,
so
that
th
e ho
rizon
tally
pla
ced
pole
can
res
t on
it. T
here
fore
, no
pegg
ing
in
fro
nt is
req
uire
d.
• Th
e to
p w
idth
of
the
reta
inin
g w
all
sh
ould
not
be
less
tha
n 60
cm
for
st
one
mas
onry
and
55
cm f
or b
rick
w
alls
.
• Th
e fo
unda
tion
shou
ld b
e de
ep
en
ough
to
safe
guar
d ag
ains
t
w
eath
er a
nd s
houl
d be
at
leas
t
h/
10+3
0 cm
bel
ow t
he g
roun
d
le
vel.
• Th
e fr
ont
face
sho
uld
have
a b
atte
r
of
at
leas
t 1h
:2v,
with
max
imum
of
1h
:6v.
• Th
e ba
ck s
houl
d be
left
rou
gh o
r
bu
ilt in
ste
ps t
o in
crea
se f
rict
ion
be
twee
n th
e w
all a
nd t
he b
ack
fill
• Pr
even
t w
ater
pre
ssur
e be
hind
the
w
all b
y ba
ckfil
ling
prop
erly
with
co
arse
mat
eria
l and
allo
win
g
dr
aina
ge w
ith w
eep
hole
s.
• Th
e ba
ckfil
l sho
uld
be c
ompa
cted
af
ter
ever
y fil
ling
of 1
0 cm
to
15 c
m
th
ick
laye
r.
• Th
e no
rmal
wid
th t
o he
ight
rat
io is
:
w
idth
= ½
hei
ght
+ 0.
5.
• En
sure
dra
inag
e is
pro
vide
d fr
om t
he
lo
wes
t po
int
of t
he f
ound
atio
n.
• Si
ze o
f th
e G
abio
n Bo
x: U
sual
ly
in
Nep
al g
abio
ns a
re 3
m x
1.5
m x
0.
75 m
mad
e of
8-g
auge
gal
vani
zed
w
ire
with
15
cm b
y 15
cm
mes
h.
Yo
u ca
n de
sign
the
gab
ion
boxe
s of
yo
ur o
wn
size
. For
pra
ctic
al p
urpo
ses
th
e di
men
sion
of
the
boxe
s m
ust
be
m
ultip
le o
f 15
cm
in c
ase
of 8
-gau
ge
ga
bion
box
es o
r 10
by
10 c
m in
cas
e
of
10-
gaug
e ga
bion
box
es.
• Sa
me
dim
ensi
ons
as lo
ose
ston
e
re
tain
ing
wal
l.
• Th
e w
eep
hole
s ar
e ev
en m
ore
ne
cess
ary
for
mas
onry
wal
ls t
han
fo
r dr
y ru
bble
ret
aini
ng w
alls
.
• Th
e w
eep
hole
s sh
ould
be
4 in
ch
sq
uare
, and
pla
ced
ever
y 3
feet
ap
art
hori
zont
ally
and
2 f
eet
apar
t
ve
rtic
ally
. The
y sh
ould
not
be
ve
rtic
ally
one
und
er t
he o
ther
.
• Fi
ll th
e so
il m
ater
ial i
n th
e op
enin
g be
twee
n th
e po
les
or
ba
mbo
os a
nd p
ress
with
out
leav
ing
any
void
s.
• Pu
t br
anch
es o
f sp
rout
ing
livin
g pl
ants
in t
he o
pen
spac
es
be
twee
n th
e po
les
or b
ambo
os in
suc
h a
way
tha
t no
t m
ore
than
¼
of
thei
r le
ngth
pro
trud
es.
• Re
peat
the
ste
ps u
ntil
the
desi
gned
hei
ght
is a
ttai
ned.
At
the
top,
pl
ace
the
horiz
onta
lly p
lace
d ba
mbo
o pl
oes
in s
uch
a w
ay t
hat
a
ba
mbo
o pe
g ca
n be
driv
en in
a s
pace
bet
wee
n ho
rizon
tally
pl
aced
bam
boo
one
belo
w a
nd a
bove
.
• Ti
ltin
g th
e w
all t
owar
ds t
he h
ill s
lope
incr
ease
s th
e st
abili
ty o
f th
e w
all a
nd it
s ef
fect
iven
ess.
Typ
ical
ly, w
alls
may
be
til
ted
by 6
to
10 d
egre
es.
• Fo
r gr
eate
r he
ight
ret
aini
ng w
alls
, ste
ppin
g is
rec
omm
ende
d to
incr
ease
the
ir s
tabi
lity.
• A
fter
the
con
stru
ctio
n, e
nsur
e th
at t
he s
lope
s ar
ound
the
str
uctu
re a
nd u
p-sl
ope
are
trea
ted
usin
g ap
prop
riat
e
bi
oeng
inee
ring
mea
sure
s. R
emov
e al
l sur
plus
deb
ris
to a
void
the
ero
sion
and
slu
mpi
ng.
• D
ry w
alls
co-
exis
t w
ith, a
nd a
re s
tren
gthe
ned
by p
lant
roo
ts. E
ncou
rage
or
plan
t ve
geta
tion.
Guideline on Landslide Treatment and Mitigation | 53
Mat
eria
l
Crib
wal
lLo
ose
ston
e re
tain
ing
wal
lG
abio
nM
ason
ry /
Con
cret
e
• Ba
mbo
o or
rou
nd /
squ
are
timbe
r /
log
(1
0 –
15 c
m in
dia
met
er)
• Li
ve c
uttin
g th
at r
oots
eas
ily, a
t le
ast
1 m
le
ngth
with
a la
rge
num
ber
of s
ide
br
anch
es
• Sp
rout
ing
woo
den
pole
s of
8 t
o 12
cm
di
amet
er o
r ba
mbo
o po
le a
bout
1 m
long
.
• G
ood
qual
ity s
tone
(St
rong
, big
, and
flat
st
ones
are
pre
ferr
ed)
• G
abio
n bo
x
• G
ood
qual
ity s
tone
(St
rong
, big
, and
flat
st
ones
are
pre
ferr
ed)
• Sp
ecifi
catio
n of
gab
ion
box:
• Ce
men
t
• Sa
nd
• G
ood
qual
ity s
tone
(St
rong
, big
and
flat
st
ones
are
pre
ferr
ed)
Cons
truc
tion
per
iod
Crib
wal
lLo
ose
ston
e re
tain
ing
wal
lG
abio
nM
ason
ry /
Con
cret
e
• D
urin
g D
orm
ant
seas
on if
the
site
is m
oist
.
• Ju
st b
efor
e ra
iny
seas
on if
the
site
is d
ry
• A
ny t
ime
of t
he y
ear
whe
n it
is c
onve
nien
t,
ho
wev
er d
ry p
erio
d is
pre
fera
ble.
• Pl
ant
cutt
ings
just
bef
ore
rain
y se
ason
if t
he
si
te is
dry
. Pla
nt c
uttin
gs d
urin
g th
e
do
rman
t se
ason
if t
he s
ite is
moi
st.
• A
ny t
ime
of t
he y
ear
whe
n it
is c
onve
nien
t,
ho
wev
er d
ry p
erio
d is
pre
fera
ble.
• Pl
ant
cutt
ings
just
bef
ore
rain
y se
ason
if t
he
si
te is
dry
. Pla
nt c
uttin
gs d
urin
g th
e
do
rman
t se
ason
if t
he s
ite is
moi
st.
• A
ny t
ime
of t
he y
ear
whe
n it
is c
onve
nien
t,
ho
wev
er t
he d
ry p
erio
d is
pre
fera
ble.
• Pl
ant
cutt
ings
just
bef
ore
rain
y se
ason
if t
he
si
te is
dry
. Pla
nt c
uttin
gs d
urin
g th
e
do
rman
t se
ason
if t
he s
ite is
moi
st.
Mai
nten
ance
Crib
wal
lLo
ose
ston
e re
tain
ing
wal
lG
abio
nM
ason
ry /
Con
cret
e
• In
spec
t th
e cr
ib w
all r
egul
arly
dur
ing
the
ra
iny
seas
on. R
epai
r an
y op
enin
g be
fore
it
ge
ts w
orse
.
• Re
plac
e th
e de
ad c
uttin
gs.
• So
me
thin
ning
of
cutt
ing
may
be
requ
ired
af
ter
few
yea
rs.
• Re
pair
any
dam
age
imm
edia
tely
.
• Pr
ovid
e th
e ad
equa
te d
rain
age
syst
em in
th
e do
wnw
ard
side
.
• Ca
rry
out
plan
tatio
n of
app
ropr
iate
spe
cies
in
upw
ard
side
.
• Re
pair
any
ope
ning
of
the
gabi
on b
ox
im
med
iate
ly.
• Pr
ovid
e th
e ad
equa
te d
rain
age
syst
em in
th
e do
wnw
ard
side
.
• Ca
rry
out
plan
tatio
n of
app
ropr
iate
spe
cies
in
upw
ard
side
.
• Pr
ovid
e th
e ad
equa
te d
rain
age
syst
em in
th
e do
wnw
ard
side
.
• Ca
rry
out
the
imm
edia
te r
epai
r of
any
da
mag
e.
• Ca
rry
out
plan
tatio
n of
app
ropr
iate
spe
cies
in
upw
ard
side
.
• Cl
ean
the
clog
ging
of
the
wee
p-ho
le.
Prec
auti
ons
/ P
ract
ical
con
side
rati
ons
Crib
wal
lLo
ose
ston
e re
tain
ing
wal
lG
abio
nM
ason
ry /
Con
cret
e
• M
ake
sure
cut
tings
are
not
allo
wed
to
dry
in
th
e su
n.
• A
void
spl
ittin
g of
the
sta
kes
by p
laci
ng a
pi
ece
of s
tron
g w
ood
on t
he t
op o
f th
e
st
ake
whe
n it
is b
eing
driv
en in
.
• A
void
usi
ng t
hese
tec
hniq
ues
in a
poo
rly
dr
aine
d ar
ea s
ubje
ct t
o m
ediu
m t
o la
rge
sc
ale
slum
ping
.
• D
ress
all
ston
e (i
f it
is r
ound
ed)
into
re
ctan
gula
r bl
ocks
.
• O
verl
ap a
ll jo
ints
. Mai
ntai
n th
e jo
ints
in a
st
agge
red
fash
ion
as in
the
bri
ck m
ason
ry.
• U
se s
tone
s as
larg
e (b
igge
r th
an 1
5 cm
) as
po
ssib
le. I
f m
ainl
y sm
all s
tone
s ar
e
av
aila
ble,
use
larg
e on
es a
t le
ast
ever
y on
e
m
eter
to
impr
ove
the
tyin
g.
• St
ones
sho
uld
be t
abul
ar a
nd a
ngul
ar.
• Pa
ck a
ll st
ones
car
eful
ly a
nd d
ense
ly.
• En
sure
tha
t th
e m
inim
um d
imen
sion
of
all
st
ones
is la
rger
tha
n th
e w
ire
mes
h si
ze.
• En
sure
the
qua
lity
of t
he g
alva
nize
d w
ire.
• En
sure
pro
per
seal
ing
of t
he b
ox u
sing
12
SW
G w
ire.
• Sa
me
as lo
ose
ston
e re
tain
ing
wal
l.
| Guideline on Landslide Treatment and Mitigation54
• Th
e pr
ojec
tion
of a
ny f
ootin
g co
urse
sho
uld
no
t ex
ceed
hal
f th
e de
pth
of t
he c
ours
e.
• U
se fl
atte
r st
ones
for
the
top
laye
r. C
over
th
e to
p of
the
ret
aini
ng w
all w
ith s
oil o
r
bu
ild a
bou
nd m
ason
ry b
and
alon
g th
e to
p
to
sto
p it
unra
velin
g.
U
se t
hese
dim
ensi
ons
for
dry
ston
e
re
tain
ing
wal
ls, d
epen
ding
on
slop
e an
gle.
Th
is t
able
pro
vide
s a
guid
e to
the
di
men
sion
s of
wal
ls o
n di
ffer
ent
slop
es.
• W
ire
all g
abio
n bo
xes
toge
ther
usi
ng 1
2
SW
G w
ire,
allo
win
g an
add
ition
al 5
% o
f
w
ire
for
bind
ing
and
tyin
g.
Slop
eW
all H
eigh
tB
ase
heig
htTo
p w
idth
30 –
35°
1.5
– 2.
0m1.
25 –
1.5
m0.
75m
35 –
40°
2.0
– 2.
5m1.
5 –
2.0m
0.75
– 1
.0m
40 –
45°
2.5
– 3.
0m2.
0 –
2.3m
1.0m
• U
se o
f th
e ab
ove
men
tione
d di
men
sion
s do
es n
ot n
eed
the
stab
ility
tes
t ag
ains
t
ov
ertu
rnin
g, c
olla
psin
g, a
nd s
lidin
g.
• Fo
r a
com
plic
ated
des
ign,
con
sult
exp
erts
.
Refe
renc
es: F
AO
, 198
5., S
CWM
C, 2
001.
, Sth
apit,
K. M
., 19
98, D
SCW
M 2
004.
Guideline on Landslide Treatment and Mitigation | 55
Titl
e: C
HEC
K D
AM
Wha
t is
it?
A s
mal
l, lo
w d
am c
onst
ruct
ed a
cros
s a
gully
or
any
othe
r w
ater
- co
urse
.
Func
tion
• M
inim
ize
the
chan
nel s
cour
ing
and
prev
ent
vert
ical
and
late
ral e
rosi
on b
y re
duci
ng t
he v
eloc
ity o
f w
ater
and
not
allo
win
g it
to r
un o
n
lo
ng s
lope
s.
• Co
nvey
the
run
off
safe
ly.
• Tr
ap t
he s
edim
ent
goin
g do
wns
trea
m.
• Ra
ises
the
bed
leve
l to
the
exte
nt t
hat
it ca
n su
ppor
t th
e un
stab
le s
ide
slop
es.
• St
ores
wat
er a
nd in
crea
ses
its in
filtr
atio
n /
perc
olat
ion
in t
he s
oil.
• Co
llect
s su
ffici
ent
soil
and
wat
er t
o pr
omot
e pl
ant
grow
th.
Type
Bru
shw
ood
Loos
e st
one
Bou
lder
Gab
ion
Mas
onry
/ C
oncr
ete
Gen
eral
char
acte
rist
ics
• M
ade
of w
oode
n po
les
an
d br
ush.
• Su
itabl
e fo
r sm
all
gu
llies
of
1 to
2 m
eter
s
in
wid
th a
nd d
epth
.
• Le
ast
perm
anen
t of
al
l typ
es, b
ut a
re
ch
eap
and
mad
e
w
ith lo
cally
ava
ilabl
e
m
ater
ials
.
• M
ade
of lo
ose
rock
s.
• St
abili
ty a
nd s
tren
gth
de
pend
s on
the
siz
e of
ro
cks
and
the
qual
ity o
f th
e
co
nstr
uctio
n.
• Co
mm
only
use
d in
the
gul
ly
co
ntro
l wor
ks in
sm
all t
o
m
ediu
m w
ater
cou
rse.
• Sa
me
as t
he lo
ose
ston
e
ch
eck
dam
s ex
cept
tha
t,
bi
g bo
ulde
rs a
re u
sed
in it
s’
co
nstr
uctio
n.
• M
ade
with
gab
ion
boxe
s
fil
led
with
sto
nes.
The
y ar
e
pr
efer
able
whe
re b
ig s
tone
s
ar
e no
t av
aila
ble.
• Co
mm
only
use
d in
the
gul
ly
co
ntro
l wor
ks in
med
ium
to
bi
g w
ater
cour
ses.
• M
ade
of c
emen
t m
orta
r
or
con
cret
e.
• Pe
rman
ent
stru
ctur
es.
• G
ener
ally
use
d to
pro
tect
im
port
ant
deve
lopm
ent
in
fras
truc
ture
, suc
h as
roa
ds,
bu
ildin
g.
Adv
anta
ges
• U
ses
loca
l mat
eria
ls, s
impl
e
an
d lo
w c
ost.
• O
nce
root
s an
d sh
oots
are
pu
t ou
t, it
for
ms
a lo
ng-t
erm
ba
rrie
r.
• U
ses
loca
l mat
eria
ls, s
impl
e
an
d lo
w c
ost
• U
ses
loca
l mat
eria
ls, s
impl
e
an
d lo
w c
ost.
• If
mad
e pr
oper
ly, a
lmos
t
a
perm
anen
t st
ruct
ure
lik
e ga
bion
s, m
ason
ry, a
nd
co
ncre
te s
truc
ture
s.
• Fl
exib
le, p
erm
eabl
e, a
nd
ec
onom
ical
com
pare
d to
ot
her
solid
str
uctu
res.
• Su
itabl
e, w
here
land
mas
s is
m
ovin
g.
• Pe
rman
ent
stru
ctur
e
• Lo
oks
good
Dis
adva
ntag
e•
Take
s tim
e to
est
ablis
h.•
Wea
k if
not
prop
erly
mad
e
an
d do
not
use
siz
eabl
e
st
ones
.
• Tr
ansp
ort
of t
he b
ig b
ould
ers
is
diffi
cult
if n
ot lo
cate
d
up
slop
e of
the
site
.
• La
rge
void
s in
the
dam
may
cr
eate
wat
er je
ts, w
hich
co
uld
be d
estr
uctiv
e if
di
rect
ed t
owar
ds b
anks
.
• Co
stly
• Co
st o
f th
e ga
bion
doe
s no
t
re
mai
n in
the
com
mun
ity.
• N
eeds
ski
lled
labo
r fo
r
co
nstr
uctio
n.
• Co
stly
• Co
st o
f th
e m
ater
ial
(c
emen
t, r
ods)
doe
s no
t
re
mai
n in
the
com
mun
ity.
• N
eeds
com
plic
ated
en
gine
erin
g de
sign
and
sk
illed
labo
r.
| Guideline on Landslide Treatment and Mitigation56
CHEC
K D
AM
Des
ign
spec
ifica
tion
Site
sel
ecti
onSe
lect
the
site
for
the
con
stru
ctio
n of
che
ck d
ams
taki
ng in
to a
ccou
nt t
he f
ollo
win
g co
nsid
erat
ions
:
• To
acc
omm
odat
e hi
gher
floo
d ru
n-of
f m
akes
it n
eces
sary
to
sele
ct a
pla
ce, w
hich
is w
ide
enou
gh t
o lim
it sp
ecifi
c ru
n-of
f (p
er m
eter
wid
th)
“q”
and
so t
he s
cour
de
pth.
The
spi
llway
has
to
be b
ig e
noug
h w
ith a
t le
ast
0.5m
fre
e bo
ard
to t
ake
flood
run
-off
, oth
erw
ise
the
side
fou
ndat
ion
of t
he c
heck
dam
s w
ill w
ash
out
and
th
e riv
er w
ill b
y-pa
ss t
he c
heck
dam
s an
d de
stro
y th
em.
• M
ake
chec
k da
ms
at a
str
aigh
t an
d fir
m s
trea
m b
ank.
Nev
er m
ake
chec
k da
ms
on t
he c
urve
, jun
ctio
n of
tw
o st
ream
s, o
r ju
st b
elow
it.
• Bu
ild t
he la
st c
heck
dam
on
good
fou
ndat
ion
of b
ase
rock
as
it af
fect
s th
e fo
unda
tion
of t
he r
est
of t
he c
heck
dam
s ab
ove.
• Th
e se
lect
ion
of t
he s
ite is
als
o re
stric
ted
by t
he h
eigh
t of
the
str
uctu
re. I
f th
e el
evat
ion
diff
eren
ce b
etw
een
two
succ
essi
ve s
ites
is t
oo h
igh,
one
or
mor
e si
tes
ha
ve t
o be
sel
ecte
d in
bet
wee
n so
tha
t th
e st
ruct
ure
heig
ht w
ill f
ulfil
l the
con
ditio
ns.
Spac
ing
Plac
e th
e ch
eck
dam
s so
tha
t th
e bo
ttom
of
the
uppe
r ch
eck
dam
and
the
top
of
the
low
er c
heck
dam
give
a g
radi
ent
that
for
the
kin
d of
soi
l in
the
stre
am g
ives
a n
on-e
rosi
ve v
eloc
ity o
f flo
w. T
his
is t
he
com
pens
atio
n gr
adie
nt.
For
the
gene
ral p
ract
ice,
the
com
pens
atio
n gr
adie
nt is
a 3
to
5% s
lope
. How
ever
, if
the
bed
mat
eria
ls
are
cour
se a
nd s
trea
m b
ed s
lope
is s
teep
, a s
teep
er c
ompe
nsat
ion
grad
ient
can
be
cons
ider
ed.
The
horiz
onta
l dis
tanc
e be
twee
n tw
o su
cces
sive
che
ck d
ams
is g
iven
by
the
rela
tion:
d
= h
* 10
0 /
(SÓ -
Se)
Whe
re,
d
= S
paci
ng b
etw
een
two
succ
essi
ve c
heck
dam
s (h
oriz
onta
l dis
tanc
e)
h
= H
eigh
t of
the
che
ck d
am (
up t
o no
tch)
S Ó
= E
xist
ing
slop
e of
bed
in %
S e
= St
abili
zing
slo
pe o
f be
d in
%. I
n ge
nera
l, it
is 3
- 5
%.
Exam
ple:
-
Giv
en:
h =
2m
S =
15%
Se =
5%
d =
h*10
0 /
(SÓ -
Se)
=2*
100/
(15-
5)=2
0m
Num
ber
of c
heck
dam
s is
cal
cula
ted
follo
win
g th
e fo
rmul
a: -
Num
ber
of C
heck
dam
s =
(a-b
)/ H
Whe
re,
a
= Th
e to
tal v
ertic
al d
ista
nce
betw
een
the
first
and
the
last
che
ck d
am in
tha
t po
rtio
n of
the
gu
lly o
r to
rren
t.
d=
The
hor
izon
tal d
ista
nce
betw
een
the
first
and
the
last
che
ck d
am in
tha
t po
rtio
n of
the
gully
or
torr
ent.
b
= Th
e to
tal v
ertic
al d
ista
nce
calc
ulat
ed a
ccor
ding
to
the
com
pens
atio
n gr
adie
nt f
or t
hat
port
ion
of t
he g
ully
.
H
= A
vera
ge h
eigh
t of
the
che
ck d
ams.
Giv
en:
a =
30m
Se =
5%
d =
200m
b =
Se*d
/10
0 =
10m
H =
2m
No
of C
heck
dam
=(a
-b)/
H =
(30-
10)/
2=10
Foun
dati
on•
The
dept
h of
fou
ndat
ion
mus
t be
bel
ow t
he s
cour
leve
l.
• In
ero
dibl
e st
rata
, if
D is
the
ant
icip
ated
max
imum
dep
th o
f sc
ouri
ng b
elow
the
des
igne
d hi
ghes
t flo
od le
vel,
incl
udin
g po
ssib
le c
once
ntra
tion
of fl
ow, t
he
m
inim
um d
epth
of
foun
datio
n be
low
the
hig
hest
floo
d le
vel s
houl
d be
tak
en a
s 1.
33 *
D.
• Th
e sc
our
dept
h is
not
tak
en f
rom
the
pre
sent
bed
leve
l but
fro
m o
ne t
o be
exp
ecte
d in
the
fut
ure
afte
r si
ltat
ion
of t
he lo
wer
che
ck d
am a
nd a
fter
the
es
tabl
ishm
ent
of n
ew b
ed g
radi
ent
due
to t
he r
educ
ed b
ed-l
oad
afte
r th
e er
osio
n co
ntro
l.
• Ta
ke a
min
imum
of
1.0
m f
ound
atio
n as
a r
ule
of t
hum
b.
Guideline on Landslide Treatment and Mitigation | 57
Chec
k da
m
Des
ign
spec
ifica
tion
Scou
r de
pth
Scou
r oc
curs
whe
n th
e be
d ve
loci
ty o
f th
e st
ream
exc
eeds
the
vel
ocity
it t
akes
to
mov
e pa
rtic
les
of t
he
bed
mat
eria
l. Ve
loci
ty v
arie
s w
ith t
he g
radi
ent,
the
hyd
raul
ic d
epth
, and
the
cha
ract
eris
tics
of t
he b
ed
and
bank
s. W
hen
the
velo
city
of
the
wat
er s
low
s, s
ilt s
ettl
es; w
hen
the
velo
city
incr
ease
s, t
he w
ater
pick
s up
and
mov
es s
ilt. S
cour
is w
orst
whe
n th
e w
ater
in t
he r
iver
is f
allin
g so
it d
epen
ds m
ore
on
the
dept
h of
wat
er t
han
on t
he g
radi
ent.
A r
iver
has
to
adju
st it
s ve
loci
ty t
o th
e fo
rces
tha
t its
bed
and
bank
s ca
n st
and
by c
hang
ing
its s
ectio
n.
The
scou
ring
of t
he c
urre
nt is
not
uni
form
and
it is
all
alon
g th
e be
d w
idth
. Sco
urin
g is
dee
per
than
norm
al a
t ob
stru
ctio
ns a
nd a
t be
nds
in t
he r
iver
. The
refo
re, t
he m
axim
um d
epth
of
scou
ring
has
to
be
dete
rmin
ed.
Nor
mal
Sco
ur D
epth
:
i). S
choc
klit
ch’s
For
mul
a:
4.75
* h
0.2
* q0
.57
Scou
r D
epth
, Ds
= -
----
----
----
----
----
----
----
----
---
dm
0.35
Whe
re,
Ds =
Sco
ur d
epth
(in
met
er)
belo
w w
ater
leve
l
d m =
Gra
in d
iam
eter
(in
mm
) w
hich
div
ides
bed
mat
eria
l in
a w
ay t
hat
90 %
is s
mal
ler
than
dm
h =
Wat
er le
vel d
iffer
ence
(in
met
er)
abov
e an
d be
low
the
che
ck d
am
q =
Run-
off
(in
cubi
c m
eter
s /
met
er w
idth
) in
the
spi
llway
Exam
ple:
Giv
en: -
dm =
20cm
= 2
00m
m
h =
2m
q =
1.25
cum
ecs
/ m
eter
Ds
=(4
.75*
h 0.
2 *
q0.57
)/ d
m0.
35
=(4
.75*
2 0
.2 *
1.2
50.5
7)/
200
0.35
Ç7.
496/
6.39
Ç1.
17 m
Brea
dth
of S
cour
Hol
e =
Brea
dth
of S
cour
Hol
e=
1.5
* Le
ngth
of
the
Not
ch
Ç1.
5*4
= 6
met
ers
Leng
th o
f Sc
our
Hol
e =
Leng
th o
f Sc
our
Hol
e or
the
Apr
on
= 4*
(0.4
67 *
q 2/
3 )1.
5 *h0.
5
=4*
(0.4
67*1
.252/
3 )1.
5*20.
5
Ç4*
0.39
9*1.
42
Ç2.
26 m
.
Runo
ff e
stim
atio
nTh
e Ra
tion
al F
orm
ula
is:
Q
= C
* IT
c *
A /
360
Whe
re,
Q
= T
he r
ate
of r
un-o
ff in
cub
ic m
eter
per
sec
ond
i.e. c
umec
s =
IT
c =
The
inte
nsity
, tha
t is
the
rat
e of
rai
nfal
l in
mill
imet
ers
per
hour
for
des
igne
d fr
eque
ncy
f
or a
dur
atio
n eq
ual t
o th
e tim
e of
con
cent
ratio
n, T
c
A
= A
rea
of w
ater
shed
in h
ecta
res
C
= D
imen
sion
less
run
-off
coe
ffici
ent
Exam
ple:
Fact
orVa
lue
Rem
arks
I Tc =
240m
m/
hour
Valu
es a
re f
rom
cal
cula
tion
as c
arri
ed o
ut in
the
follo
win
g se
ctio
ns.
A
=22
.5 h
a
C =
0.33
5
Q =
(0.
335
* 24
0 *2
2.5)
/36
0 =
5 cu
mec
s
q =
1.25
cum
ecs/
met
er, i
f no
tch
leng
th =
4 m
eter
s
Proc
edur
e:
• M
easu
re t
he c
atch
men
t ar
ea “
A”
in h
ecta
res
by s
urve
ying
or
from
top
ogra
phic
al m
ap o
r ae
rial
ph
otog
raph
s.
Cult
ivat
ed la
nd A
1 =
10 h
a.
Past
ure
land
, A
2 =
7.5
ha
Fore
st la
nd,
A
3 =
5 h
a
Tota
l Are
a, A
= 2
2.5
ha.
| Guideline on Landslide Treatment and Mitigation58
• Ca
lcul
ate
the
Tim
e of
con
cent
ratio
n (i
.e. g
athe
ring
time)
by
usin
g th
e fo
rmul
a:
Tc
= L
1.15
/ 1
5 *
H 0.
38
Whe
re,
T c =
Tim
e of
con
cent
ratio
n (g
athe
ring
time)
in h
ours
L
= L
engt
h of
the
wat
ersh
ed a
long
the
mai
n st
ream
fro
m t
he o
utle
t to
the
mos
t di
stan
t ri
dge
in
kilo
met
ers,
and
H
= T
he d
iffer
ence
in e
leva
tion
betw
een
the
wat
ersh
ed o
utle
t an
d th
e m
ost
dist
ant
ridg
e in
kilo
met
ers
Exam
ple:
L =
700m
=
0.7
km
H =
50m
=
0.05
km
T c =
L 1.
15 /
15
* H
0.3
80.
7 1.
15 /
15
* 0.
05 0
.38
=0.
6635
/(1
5*0.
32)
0.13
8 ho
urs Ç
8m
inut
es
CHEC
K D
AM
Des
ign
spec
ifica
tion
Runo
ff e
stim
atio
n
cont
inue
d
Calc
ulat
e ra
infa
ll in
tens
ity f
or d
urat
ion
equa
l to
time
of c
once
ntra
tion.
Use
loca
l rai
nfal
l rec
ords
to
estim
ate
this
if p
ossi
ble.
Sin
ce, t
here
is n
o pu
blis
hed
reco
rds
of o
ne h
our
rain
fall
(mm
) fo
r N
epal
, for
thi
s pu
rpos
e, w
e ca
n dr
aw f
ollo
win
g in
form
atio
n fr
om t
he d
ata
prep
ared
for
Indi
a.
Freq
uenc
y an
d O
ne H
our
Rain
fall
in m
m.
Freq
uenc
y1
hour
rai
nfal
l (m
m)
10 Y
ears
fre
quen
cy
East
ern
and
Mid
dle
Zone
100
Wes
tern
and
Far
wes
tern
Zon
e80
25 Y
ears
fre
quen
cy
East
ern
and
Mid
dle
Zone
120
Wes
tern
and
Far
wes
tern
Zon
e10
0
50 Y
ears
fre
quen
cy
For
Who
le N
epal
120
Conv
ert
1- h
our
inte
nsity
to
inte
nsity
for
dur
atio
n eq
ual t
o ga
ther
ing
time
for
the
catc
hmen
t or
the
tim
e
of c
once
ntra
tion
i.e. I
Tc f
rom
the
figu
re t
o th
e le
ft.
Exam
ple:
Giv
en 2
5 ye
ars
freq
uenc
y, E
aste
rn Z
one:
-
I hr =
120
mm
T c =
8 m
inut
es
• M
ark
one-
hour
rai
nfal
l on
Y-ax
is.
• D
raw
a h
oriz
onta
l lin
e fr
om Y
-axi
s. W
e kn
ow t
hat
8 m
inut
es p
oint
lies
bet
wee
n 2
and
15
m
inut
es c
urve
. Mor
eove
r, 8
min
utes
poi
nt is
6 m
inut
es a
way
fro
m 2
min
utes
cur
ve t
owar
ds 1
5
m
inut
es c
urve
.
• Ex
trap
olat
e 8
min
utes
poi
nt o
n th
e ho
rizon
tal l
ine
draw
n fo
r 12
0 m
m/h
our
rain
fall
inte
nsity
.One hour rainfall intensity in mm / hour
Min
utes
96
0 48
0 24
0 12
0 60
30
15
2
180
160
140
120
100 80 60 40 20 10 0
0 40
80
12
0 16
0 20
0 24
0 28
0 32
0 36
0
Rain
fall
inte
nsity
for
dur
atio
n in
dica
ted
in m
m/
hour
Guideline on Landslide Treatment and Mitigation | 59
• D
raw
a v
ertic
al li
ne f
rom
the
poi
nt e
xtra
pola
ted
for
8 m
inut
es t
ime
of c
once
ntra
tion
• Re
ad t
he v
alue
in t
he X
axi
s fo
r th
e Ra
infa
ll in
tens
ity f
or t
he t
ime
of c
once
ntra
tion
I Tc Ç
240
mm
Rela
tion
of O
ne H
our
Rain
fall
Inte
nsiti
es t
o In
tens
ities
at
othe
r
Dur
atio
n (c
onve
rted
and
red
raw
n fr
om G
. A. H
ataw
ay, M
ilita
ry
Air
Fie
ld -
Des
ign
of d
rain
age
faci
litie
s, T
rans
. Am
. Soc
. Civ
il
Engi
neer
s 11
0: 7
00. 1
945.
Cite
d by
Gup
ta, e
t. a
l. 19
73)
CHEC
K D
AM
Des
ign
spec
ifica
tion
Runo
ff e
stim
atio
nCa
lcul
ate
the
cons
tant
“C”
as
a m
easu
re o
f th
e pr
opor
tion
of t
he r
ain,
whi
ch b
ecom
es r
unof
f. Fo
llow
ing
Tabl
e be
low
giv
es s
ome
valu
e of
C.
Valu
e of
C f
or U
se in
Rat
iona
l For
mul
aLa
nd u
se t
ype
Soil
Type
Cult
ivat
edPa
stur
eFo
rest
With
abo
ve a
vera
ge in
filtr
atio
n ra
te, u
sual
ly s
andy
or
grav
ely
0.29
0.15
0.10
With
ave
rage
infil
trat
ion
rate
no
clay
pan
s, lo
ams
and
sim
ilar
soil
0.40
0.35
0.30
With
bel
ow a
vera
ge in
filtr
atio
n ra
te, h
eavy
cla
y so
ils, o
r
soils
with
a c
lay
pan
near
the
sur
face
, sha
llow
soi
ls a
bove
impe
rvio
us r
ock
0.50
0.45
0.40
Com
pute
d w
eigh
ted
“C”
for
the
wat
ersh
ed:
C
= (A
1* C
1 +
A2*
C2
+……
……
An*
Cn
)/ (
A1
+ A
2 +…
……
… A
n)
Whe
re,
A
1 , A
2 ,…
……
… A
n ar
e ar
eas
in h
ecta
res
unde
r va
riou
s la
nd u
se a
nd s
oil t
ypes
hav
ing
co
rres
pond
ing
valu
es o
f
C 1,
C2
,……
……
Cn
resp
ectiv
ely;
and
A =
A1
+ A
2 +…
……
… A
n =
Tota
l are
a of
the
wat
ersh
ed.
Lim
itat
ion:
Thi
s m
etho
d is
usu
ally
sug
gest
ed f
or u
se f
or a
wat
ersh
ed o
f le
ss t
han
50 h
ecta
res.
Exam
ple:
Land
use
cat
egor
yA
rea
Run-
off
coef
fici
ent
Cult
ivat
edA
1 =
10ha
C1=
0.29
Past
ure
A2
=7.
5ha
C2=
0.35
Fore
stA
3 =
5ha
C3=
0.40
C =
(A1*
C1
+ A
2* C
2 +
A2*
C2)
/ (
A1
+ A
2+ A
3)
=
(10*
0.29
+ 7
.5*0
.35+
5*0.
40)/
(10+
7.5+
5)
=
7.52
5/22
.5Ç
0.33
5
Not
ch d
esig
nO
nce
runo
ff is
cal
cula
ted,
des
ign
the
notc
h si
ze.
The
spill
way
has
to
acco
mm
odat
e pe
ak r
unof
f, w
hich
oth
erw
ise
will
was
h ou
t th
e si
de f
ound
atio
n of
the
chec
k da
m, a
nd d
estr
oy t
he c
heck
dam
. Des
ign
the
notc
h/w
eir
or s
pillw
ay u
sing
the
fol
low
ing
form
ula.
A. R
ecta
ngul
ar N
otch
:
Fran
cis’
s Fo
rmul
a:
Q =
1.8
4 *
Bsp
* H
sp 1.
5
Whe
re,
Q =
Pea
k ru
n-of
f, c
umec
s
B sp =
Len
gth
of N
otch
, in
met
ers
Hsp =
Hei
ght
of N
otch
, in
met
ers
For
trap
ezoi
dal n
otch
, cal
cula
te t
he le
ngth
of
the
notc
h as
the
ave
rage
of
top
and
bott
om w
idth
of
the
spill
way
/not
ch.
Exam
ple:
Calc
ulat
ed Q
= 5
cum
ecs
Case
1.
Case
2.
Fact
orVa
lue
Fact
orVa
lue
Hsp
=0.
75m
Hsp
=1m
Bsp
=3m
Bsp
=4m
Case
1.
Q =
1.8
4 *
Bsp
* H
sp 1.
5 =
1.84
* 3
*0.7
51.5
Ç1.
84 *
3*0
.65 Ç
3.5
cum
ecs
Sinc
e ca
lcul
ated
Q is
5 c
umec
s, t
he d
esig
n no
tch
cann
ot
acco
mm
odat
e th
e ru
noff
. The
refo
re, n
otch
siz
e ne
ed t
o be
incr
ease
d.
Case
2.
Q =
1.8
4 *
4*11.
5 Ç7.
36 c
umec
s >5
cum
ecs,
OK
q =
Q/
Bsp =
5/
4 =
1.25
cum
ecs
/ m
eter
| Guideline on Landslide Treatment and Mitigation60
Stru
ctur
al•
Stru
ctur
al d
esig
n in
volv
es t
he d
eter
min
atio
n of
the
dim
ensi
ons
of t
he v
ario
us c
ompo
nent
s of
the
che
ck d
am a
nd it
s st
reng
th a
nd s
tabi
lity.
• Sc
ourin
g en
dang
ers
the
safe
ty o
f th
e ch
eck
dam
s m
ost.
The
refo
re, t
he f
ound
atio
n de
pth
and
spill
way
siz
e an
d sh
ape
have
, the
refo
re, t
o be
sel
ecte
d ta
king
sc
ourin
g de
pth
into
con
side
ratio
n.
• Fo
r co
mpl
icat
ed d
esig
n, c
onsu
lt e
xper
ts.
CHEC
K D
AM
Gen
eral
spe
cific
atio
n (A
fter
Gey
ik, 1
986)
Type
of
chec
k da
mM
axim
um e
ffec
tive
Hei
ght
Min
imum
fou
ndat
ion
dept
h
Thic
knes
s of
dam
at
spill
way
leve
l
Slop
e of
dow
nstr
eam
face
of
the
dam
Slop
e of
ups
trea
m f
ace
of
the
dam
Thic
knes
s of
the
bas
e of
the
dam
Bru
shw
ood
Max
imum
hei
ght
is 1
m
from
gro
und
leve
l.
Woo
den
pole
s ar
e dr
iven
to
a de
pth
of a
bout
0.7
5-1
m.
Loos
e st
one
1.0
m0.
5 m
0.5
– 0.
7 m
20%
(1:
1/5
Ratio
)Ve
rtic
alCa
lcul
ated
acc
ordi
ngly
Bou
lder
2.0
mH
alf
of E
ffec
tive
Hei
ght
Pref
erab
ly 1
.0 m
30 %
(1
: 0.3
Rat
io)
Vert
ical
Calc
ulat
ed a
ccor
ding
ly
Gab
ion
May
var
y (R
ecom
men
ded
not
mor
e th
an 5
.0 m
)
Hal
f of
Eff
ectiv
e H
eigh
t>
1.0
m20
% S
lopp
ed, S
tepp
ed o
r
vert
ical
Step
ped
or v
ertic
alCa
lcul
ated
acc
ordi
ngly
Rem
arks
Use
of
the
dim
ensi
ons
abov
e do
es n
ot r
equi
re t
he s
tabi
lity
test
aga
inst
ove
rtur
ning
, col
laps
ing,
and
slid
ing.
How
ever
, the
siz
e of
the
spi
llway
nee
ds t
o be
com
pute
d
acco
rdin
g to
the
max
imum
dis
char
ge o
f th
e gu
lly c
atch
men
t ar
ea.
Cons
truc
tion
spe
cific
atio
n
Bru
shw
ood
Loos
e st
one
/ B
ould
erG
abio
n
• Cl
ear
the
site
and
mar
k th
e lin
e of
co
nstr
uctio
n us
ing
strin
g.
• D
ig a
tre
nch
of a
bout
15
cm d
eep
acro
ss t
he
gu
lly, d
rive
the
woo
den
pole
s in
to
a de
pth
of
ab
out
1/3
to ½
of
the
pole
leng
th, s
paci
ng
th
e po
les
30-5
0 cm
apa
rt.
• M
ake
the
tops
of
the
pole
s in
the
mid
dle
lo
wer
tha
n th
e si
des
to f
orm
a n
otch
of
the
re
quire
d si
ze t
o ac
com
mod
ate
the
max
imum
ru
noff
.
• W
eave
the
flex
ible
bra
nche
s of
tre
e (s
alix
,
po
plar
, vite
x, e
tc.)
and
shr
ub b
etw
een
w
oode
n po
les
driv
en in
to t
he g
roun
d un
til
th
e da
m is
the
req
uire
d he
ight
.
• Th
e en
ds o
f in
ter-
linke
d m
ater
ials
sho
uld
en
ter
at le
ast
30 c
m in
to t
he s
ides
of
the
gu
lly.
• Fi
ll th
e ba
ck o
f th
e br
ushw
ood
chec
k da
m
w
ith s
oil.
• Cl
ear
the
site
and
mar
k th
e lin
e of
con
stru
ctio
n us
ing
st
ring.
• Cu
t th
e si
des
of t
he g
ully
to
a sl
ope
of 1
:1. T
he
fo
unda
tion
of t
he w
ings
sho
uld
be m
ore
than
0.5
m
eter
s. E
nsur
e th
at t
he h
eigh
t of
the
win
g w
all i
s
le
vel w
ith t
he t
op o
f th
e ch
eck
dam
.
• Th
e fo
unda
tion
wid
th o
f th
e da
m h
as t
o be
mor
e
th
an t
he le
ngth
of
the
spill
way
.
• Fo
r la
rge
dam
s, c
onst
ruct
tw
o w
ing
wal
ls w
ith
ap
prop
riate
fou
ndat
ions
at
the
uppe
r si
de t
o di
rect
th
e flo
w in
to t
he s
pillw
ay o
r no
tch
and
prev
ent
it
fr
om d
amag
ing
the
bank
s.
• U
se la
rge
flat
ston
es o
n th
e no
tch
and
dow
nstr
eam
si
de o
f th
e sp
illw
ay. K
eep
the
cent
ral p
ortio
n lo
w f
or
th
e sp
illw
ay.
• W
hen
larg
e qu
antit
ies
of r
un-o
ff a
re e
xpec
ted,
it is
ad
visa
ble
to u
se s
ome
conc
rete
in t
he n
otch
and
the
cr
own
of t
he d
am, o
r to
cov
er e
very
thin
g w
ith a
w
ire n
ettin
g.
• Th
e st
ruct
ure
shou
ld e
nter
at
leas
t 0.
5 m
into
the
sid
e of
the
gul
ly a
nd b
e
pr
otec
ted
agai
nst
flash
wat
er b
y w
ing
wal
ls.
• Co
nstr
uct
the
win
g w
alls
with
app
ropr
iate
fou
ndat
ions
at
the
uppe
r si
de t
o gu
ide
th
e flo
w in
to t
he s
pillw
ay o
r no
tch
and
prev
ent
it fr
om d
amag
ing
the
bank
s. F
ill
th
e sp
ace
betw
een
the
dam
and
win
g th
e w
alls
with
soi
l.
• Th
e w
ing
wal
ls s
houl
d en
ter
at le
ast
0.5
m in
to t
he s
ide
of t
he g
ully
. The
hei
ght
of
th
e w
ing
wal
ls m
ust
leve
l with
the
top
of
the
chec
k da
m.
• Th
e fo
unda
tion
wid
th o
f th
e ch
eck
dam
has
to
be m
ore
than
the
leng
th o
f th
e
sp
illw
ay.
• Pu
t la
rge
flat
ston
es a
long
the
sid
es o
f th
e ga
bion
box
es, fi
ll sm
alle
r on
es in
the
m
iddl
e. T
he s
ize
of s
tone
s us
ed f
or t
he c
onst
ruct
ion
shou
ld b
e la
rger
tha
n th
e si
ze
of
the
wir
e m
esh.
• W
hen
debr
is is
exp
ecte
d, it
is a
dvis
able
to
prot
ect
the
spill
way
and
ste
ps in
the
fr
ont
part
of
the
dam
s by
a la
yer
of c
oncr
ete
to p
rote
ct t
he g
abio
n w
ire
from
cu
ttin
g by
the
fal
ling
debr
is.
• Co
mpu
te t
he s
pillw
ay d
imen
sion
s ac
cord
ing
to t
he m
axim
um d
isch
arge
est
imat
ed
fr
om t
he g
ully
cat
chm
ent.
• Be
low
the
dam
, an
apro
n ha
s to
be
cons
truc
ted.
• Fi
ll th
e ba
ck o
f th
e ch
eck
dam
s w
ith s
oil f
or g
reat
er s
tren
gth.
Guideline on Landslide Treatment and Mitigation | 61
• M
ake
a br
ushw
ood
apro
n of
abo
ut 1
.5 -
2
tim
es t
he h
eigh
t of
che
ck d
am t
o pr
otec
t th
e
ch
anne
l fro
m s
cour
ing.
It n
eeds
to
be
an
chor
ed w
ith g
alva
nize
d w
ire.
• Pr
ovid
e si
dew
alls
to
dire
ct t
he fl
ow t
o th
e
w
eir
(cen
ter)
.
• Co
rrec
t th
e sl
ope
of a
ste
ep g
ully
hea
d.
• Be
low
the
dam
an
apro
n ha
s to
be
cons
truc
ted
with
st
ones
.
• Pl
ace
the
larg
e st
ones
in t
he b
otto
m o
f th
e da
m a
nd
us
e st
ones
of
abou
t 50
cm
x 3
0 cm
thr
ough
out
the
bo
dy o
f th
e ch
eck
dam
.
• O
n th
e up
-str
eam
sid
e, t
he d
am h
as t
o ge
t an
ear
th
fil
l for
gre
ater
str
engt
h.
• Fi
nally
, sup
plem
ent
the
stru
ctur
e by
pla
ntin
g
se
edlin
gs a
nd c
uttin
gs o
f su
itabl
e sp
ecie
s w
ith a
de
nse
and
wid
e sp
read
roo
t sy
stem
.
• Fi
nally
, sup
plem
ent
the
stru
ctur
e by
pla
ntin
g se
edlin
gs a
nd c
uttin
gs o
f su
itabl
e
sp
ecie
s w
ith a
den
se a
nd w
ide
spre
ad r
oot
syst
em o
n th
e gu
lly s
ides
.
• Th
e ga
bion
box
es n
eed
to b
e la
ced
toge
ther
ver
y st
rong
ly w
ith t
he 8
gau
ge w
ires
.
Mai
nten
ance
Bru
shw
ood
Loos
e st
one
/ B
ould
erG
abio
n
• In
spec
t th
e gu
lly a
fter
eac
h st
orm
. Rep
air
any
sc
ourin
g of
pol
es b
efor
e it
gets
wor
se.
• Cl
ose
the
open
ing
in t
he ja
fri (
brus
h).
Chec
k da
m c
an c
olla
pse
if:
a) E
ven
one
ston
e of
the
spi
llway
sec
tion
is w
ashe
d ou
t.
b) T
he f
ound
atio
n of
the
che
ck d
am is
sco
ured
.
c) T
he w
ater
flow
s fr
om t
he s
ide
foun
datio
n of
the
ch
eck
dam
.
Ther
efor
e, c
ontin
uous
mon
itori
ng o
f th
ese
inci
denc
es
is e
ssen
tial a
nd if
any
dam
age
is s
een,
car
ry
out
mai
nten
ance
and
fur
ther
con
trol
mea
sure
s
imm
edia
tely
. Als
o, t
o re
duce
the
dam
age
to t
he c
heck
dam
s, r
emov
e bo
ulde
rs, t
rees
, bus
hes,
and
oth
er fl
ow
rest
rictio
ns t
hat
wou
ld r
esul
t in
the
ban
k cu
ttin
g or
over
topp
ing
of t
he c
hann
el.
Sam
e as
loos
e st
one
/ b
ould
er c
heck
dam
. Als
o ch
eck
the
gabi
on w
ires
are
inta
ct.
Repa
ir a
ny lo
ose
or b
roke
n w
ire
in t
ime.
Prec
auti
ons
• A
void
spl
ittin
g of
the
sta
kes
by p
laci
ng a
pie
ce
of
str
ong
woo
d on
the
top
of
the
stak
e w
hen
it
is b
eing
driv
en in
.
• A
fter
the
str
uctu
re is
bui
lt, t
ram
p ea
rth
solid
ly
be
hind
and
aro
und
it to
pre
vent
cra
ckin
g.
• Th
e w
ater
mus
t go
ove
r th
e st
ruct
ures
and
no
t go
aro
und
them
.
• Th
e w
ater
way
s sh
ould
not
be
used
as
path
s.
• St
reng
th o
f th
e ch
eck
dam
dep
ends
on
the
qual
ity
of
the
con
stru
ctio
n i.e
. lay
ing
of t
he s
tone
in t
he
st
ruct
ure.
Ens
ure
bond
ing
betw
een
the
ston
es w
ithin
th
e st
ruct
ure.
• Bi
g st
one
need
s to
be
plac
ed a
t th
e sp
ill w
ay a
nd a
t
th
e fo
unda
tion.
• A
ny f
all o
f th
e st
one
from
the
spi
llway
to
the
stru
ctur
e ea
sily
cut
the
gab
ion
wir
e.
Th
eref
ore,
pro
tect
the
gab
ion
wir
e of
the
fou
ndat
ion
from
the
fal
ling
debr
is b
y
co
veri
ng it
with
sto
ne.
• Se
al t
he g
abio
n bo
x pr
oper
ly. A
ny o
peni
ng in
the
gab
ion
box
easi
ly w
ashe
s ou
t
th
e st
ones
.
| Guideline on Landslide Treatment and Mitigation62
Cons
truc
tion
per
iod
Bru
shw
ood
Loos
e st
one
/ B
ould
erG
abio
n
• D
urin
g D
orm
ant
seas
on if
the
site
is m
oist
.
• Ju
st b
efor
e ra
iny
seas
on if
the
site
is d
ry
• A
ny t
ime
if no
n-sp
rout
ing
spec
ies
are
used
.
• A
ny t
ime
of t
he y
ear
whe
n it
is c
onve
nien
t, h
owev
er
dr
y pe
riod
is p
refe
rabl
e.
• A
ny t
ime
of t
he y
ear
whe
n it
is c
onve
nien
t, h
owev
er t
he d
ry p
erio
d is
pre
fera
ble.
Refe
renc
es: G
eyik
, M. P
., 19
86.,
Hill
er, B
. 197
9, G
upta
et.
al.,
197
3.. 1
979.
Sth
apit,
K. M
. and
L. C
. Ten
nyso
n, 1
991.
, Tau
tsch
er, O
tto.
, 197
8/79
, DSC
WM
200
4.
Guideline on Landslide Treatment and Mitigation | 63
Titl
e: W
ATE
R H
ARV
ESTI
NG
PON
D
Pond
(ne
w o
r ol
d) u
sed
for
stor
age
of r
un-o
ff w
ater
dur
ing
exce
ss r
ain
to r
educ
e er
osio
n an
d fo
r la
ter
use.
Func
tion:
Lim
itatio
n
• St
ore
surf
ace
runo
ff /
was
tew
ater
to
redu
ce s
oil e
rosi
on a
nd t
orre
nt•
If th
e so
urce
is n
ot p
eren
nial
suc
h as
rai
n, t
he p
ond
may
not
ha
ve w
ater
thr
ough
out
the
year
.•
Gra
dual
ly s
oaks
wat
er in
to g
roun
d im
prov
ing
soil
moi
stur
e.
• U
se o
f st
ored
wat
er f
or e
cono
mic
pro
duct
ion
(aah
ale,
irr
igat
ion,
fish
erie
s, e
nter
tain
men
t).
Type
by
linin
g
Eart
h lin
ing
Ston
e lin
ing
Cem
ent
linin
gPl
asti
c lin
ing
Rem
arks
Clay
lini
ng is
che
ap, m
aint
enan
ce is
easy
and
in lo
ng r
un m
ore
dura
ble.
Ston
e lin
ing
is c
ostl
y an
d du
rabl
e an
d
has
aest
hetic
val
ue.
Cem
ent
linin
g is
cos
tly
and
if cr
ack
deve
lops
, it
is d
ifficu
lt t
o m
aint
ain.
Plas
tic li
ning
look
s ex
otic
but
req
uire
s
regu
lar
repl
acem
ent.
Type
by
cons
truc
tion
Dug
out
pon
dRa
ised
pon
dCo
mbi
ned
pond
Rem
arks
This
is h
ow t
he p
onds
wer
e m
ade
in p
ast.
Alt
houg
h in
the
beg
inni
ng s
eepa
ge lo
ss
is m
ore,
with
tim
e se
epag
e lo
ss is
gre
atly
redu
ced.
With
ext
erna
l sup
port
man
y pr
ojec
ts m
ade
mas
onry
rai
sed
pond
s. H
owev
er, a
fter
cra
cks
deve
lope
d m
any
pond
s re
mai
n un
used
.
In h
ill t
opog
raph
y, d
ue t
o lo
w s
oil d
epth
mos
t
site
s ar
e su
itabl
e fo
r m
akin
g pa
rtly
dug
out
and
part
ly r
aise
d po
nd.
Adv
anta
geD
isad
vant
age
• Pr
ovid
es m
ultip
le b
enefi
ts if
des
igne
d m
ulti-
purp
ose.
• Ev
apor
atio
n lo
ss is
sig
nific
ant
in p
ond
with
big
sur
face
are
a.
| Guideline on Landslide Treatment and Mitigation64
Cons
truc
tion
ste
ps
Surv
ey s
teps
Map
ping
Mea
sure
men
tA
sses
smen
tEs
tim
atio
n
• Co
nstr
uctio
n si
te f
or p
ond
• Ca
tchm
ent
boun
dary
• D
iffer
ent
land
use
typ
es a
nd
dr
aina
ge li
nes
and
eros
ion
fe
atur
es (
mic
ro-g
ully
, rill
s, s
lope
fa
ilure
) re
quiri
ng d
iffer
ent
m
easu
res
in t
he c
atch
men
t
• A
lignm
ent
for
Inle
t an
d O
utle
t
• M
easu
re t
he c
ross
-sec
tions
at
X a
nd Y
dir
ectio
ns a
t ev
ery
3
m
eter
s in
terv
al c
over
ing
at le
ast
10
met
ers
mor
e on
eith
er s
ide
of
th
e co
nstr
uctio
n si
tes.
• Le
ngth
of
conv
eyan
ce s
yste
m
• A
vera
ge a
nd m
inim
um s
oil d
epth
at
the
con
stru
ctio
n si
te f
or
de
sign
ing
the
pond
and
es
timat
ing
quan
tity
of w
orks
• A
sses
s th
e so
il ty
pe o
f th
e
co
nstr
uctio
n si
te
• A
sses
s av
aila
bilit
y of
cla
y so
il an
d
co
nstr
uctio
n m
ater
ials
.
• D
iffer
ent
land
use
typ
es a
nd c
onse
rvat
ion
m
easu
res.
• Co
nser
vatio
n m
easu
res
requ
ired
on
eith
er s
ide
of
the
inle
t an
d ou
tlet
cha
nnel
s.
• Co
mm
and
area
if t
he p
ond
is f
or ir
riga
tion.
• Se
dim
ent
deliv
ery
from
the
cat
chm
ent:
-
o
5 -
10 c
u.m
./ha
./ye
ar f
rom
goo
d ca
tchm
ent,
o
10 -
15
cu.m
./ha
./ye
ar f
rom
mod
erat
e
catc
hmen
t
o
40 c
u.m
./ha
./ye
ar f
rom
poo
r ca
tchm
ent
Site
sel
ecti
on
For
harv
estin
g su
rfac
e ru
noff
,
loca
te a
t lo
wes
t la
nd a
rea,
so t
hat
the
larg
est
volu
me
of
wat
er c
an b
e st
ored
.
For
harv
estin
g st
ream
runo
ff, l
ocat
e th
e si
te s
o th
at
runo
ff f
rom
the
sou
rce
can
conv
enie
ntly
fed
to
the
pond
.
For
emba
nkm
ent
dam
, loc
ate
whe
re m
axim
um s
tora
ge
volu
me
is o
btai
ned
from
min
imum
siz
e of
dam
.
For
tapp
ing
wat
er f
rom
spri
ng a
nd w
ater
tap
, loc
ate
imm
edia
tely
bel
ow a
nd c
lose
to s
uch
sour
ce.
For
easy
wat
er u
se f
or
lives
tock
, loc
ate
clos
e to
the
trai
l and
abo
ve c
omm
and
area
for
irri
gatio
n.
For
dug
out
pond
, a s
ite
havi
ng fl
at t
erra
in w
ith h
eavy
soil
is s
uita
ble.
Des
ign
cons
ider
atio
n: W
ater
har
vest
ing
pond
has
thr
ee c
ompo
nent
s na
mel
y: S
ourc
e, S
tora
ge a
nd s
ervi
ce a
rea
Sour
ce: i
t m
ay b
e a
catc
hmen
t ar
ea g
ener
atin
g ru
noff
or
sprin
g, s
trea
m, o
r pi
pe w
ater
Stor
age
area
: mai
nly
depr
essi
on a
rea
eith
er n
atur
al o
r
man
mad
e to
hol
d th
e w
ater
i.e.
pon
d,
Serv
ice
area
: whe
re h
arve
sted
wat
er is
use
d
Month
Average No of rainy days
Remarks 1 rainy day in days
Monthly Rainfall
Rainfall per Event Period in mm
Runoff coefficient
Runoff in cu. m per hectare per event period
Pond size cu.m. (H)
Catch area in ha to harvest runoff to fill given conservation pond size in
cu. m.
AB
C =
30/
BD
E=D
/BF
G=
E*F*
10H
I=H
/G
May
113
339
310.
1855
.530
05.
4
Month
Rainfall per Event Period in mm
Runoff coefficient
Runoff in cu. m per hectare per event period
Catch Area in ha (J)
Pond size in cu. m. required for given catch area in
hectare
AE
FG
= E*
F*10
JK
= J *
G
May
310.
1855
.52
111.
1
Month
Appropriate cumulative days for water harvest
Crop water requirement l/sec/ha
Crop water requirement in cu. m. / ha / day
Given Pond Size in cu. m.
Command area in ha (Q)
AL
= C
MK
Q=
May
32
172.
811
1.1
0.24
Guideline on Landslide Treatment and Mitigation | 65
Inle
t st
ruct
ure
for
wat
er c
olle
ctio
n
Cons
truc
t w
ater
way
s to
lead
wat
er f
rom
the
sou
rce
into
the
pon
d. F
or s
afe
wat
er r
egul
atio
n, a
flow
con
trol
mec
hani
sm m
ust
be s
et a
t
the
inle
t an
d ou
tlet
of
the
pond
.
Gra
ss w
ater
way
s ar
e re
com
men
ded
for
chan
nel s
lope
s up
to
8%. C
hann
el s
lope
s of
mor
e th
an 8
% s
houl
d be
sto
ne p
aved
or
lined
. The
shap
e of
the
gra
ss w
ater
way
s sh
ould
be
para
bolic
whe
re a
s a
trap
ezoi
dal s
hape
is p
refe
rabl
e fo
r st
one
pave
d w
ater
way
s.
Ove
rflow
spi
llway
/ C
hann
el
Prov
ide
an o
verfl
ow s
pillw
ay a
nd c
hann
el t
o di
spos
e sa
fely
of
exce
ss w
ater
. Ove
rflow
cha
nnel
hav
ing
the
sam
e w
idth
as
inflo
w c
hann
el
mus
t be
10
% h
ighe
r th
an in
flow
cha
nnel
.
In t
he p
onds
con
stru
cted
for
irri
gatio
n, p
rovi
de a
con
trol
labl
e ou
tlet
(m
ainl
y pi
ped
with
gat
e va
lve)
at
the
bott
om o
f th
e po
nd. T
here
shou
ld n
ot b
e an
y le
akag
e. T
here
fore
, ass
ure
a go
od c
onta
ct b
etw
een
such
a m
echa
nism
and
the
wal
l of
the
pond
, mos
t pr
efer
ably
by
cem
ent-
conc
rete
.
Maj
or p
robl
ems
Seep
age
loss
esEv
apor
atio
n lo
sses
Sedi
men
tati
on
• H
igh
seep
age
loss
–
Mor
e po
rous
the
soi
l
–
Mor
e cr
acks
in t
he r
ock
–
Fres
hly
cons
truc
ted
pond
s
•
Up
to 1
0 cm
/day
•
See
page
loss
var
ies
(0.2
6-16
cm/d
ay)
with
wat
er d
epth
• 5
cm /
day
are
cons
ider
ed t
o be
per
mis
sibl
e fo
r
th
e du
gout
pon
ds
• D
epen
ds o
n cl
imat
ic c
ondi
tions
– T
empe
ratu
re, h
umid
ity, w
ind
spee
d an
d ra
diat
ion
•
Lar
ger
the
surf
ace
area
hig
her
the
evap
orat
ion
•
Evap
orat
ion
loss
es m
ay b
e
– U
p to
50
% o
f to
tal s
tora
ge lo
sses
in o
pen
s
hallo
w r
eser
voir
and
Up
to 2
0 %
in d
eep
rese
rvoi
r
– 0
.4 –
0.6
cm
/ d
ay is
con
side
red
to b
e pe
rmis
sibl
e
• Re
duce
s ca
paci
ty
• M
ajor
pro
blem
in r
unof
f ha
rves
ting
pond
Reco
mm
ende
d m
easu
res
Seep
age
loss
esEv
apor
atio
n lo
sses
Sedi
men
tati
on
• Im
prov
e po
nd li
ning
-
Use
of
Clay
: Ste
p fo
r Cl
ay li
ning
-
Vert
ical
see
page
loss
m
Add
a f
oot
thic
k he
avy
clay
. Add
ition
of
cow
-dun
g an
d pu
ddlin
g by
the
live
stoc
k w
ill h
elp
the
seal
ing
of fl
oor.
Hig
her
the
dept
h of
pud
dlin
g le
ss t
he s
eepa
ge lo
ss
-
Hor
izon
tal s
eepa
ge lo
ss
m
30
cm w
ide
heav
y cl
ay c
ompa
cted
bet
wee
n th
e po
nd w
all a
nd t
he g
roun
d
m
If
ther
e is
hea
vy c
lay
arou
nd t
he c
onst
ruct
ion
site
, bef
ore
digg
ing,
suc
h cl
ay s
houl
d be
put
asi
de
-
Use
of
Low
Den
sity
Pol
ythe
ne: S
tep
for
plas
tic li
ning
m
Sha
pe t
he s
ide
slop
e of
the
pon
d to
less
tha
n 1:
1 (V
:H)
m
Rem
ove
all p
rotr
udin
g st
ones
, roo
ts e
tc. a
nd r
amm
ed t
o sm
ooth
en t
he s
urfa
ce.
m
Pla
ster
the
sid
es a
nd b
otto
m o
f th
e po
nd w
ith s
ieve
d cl
ay (
6) :
cow
-dun
g (1
)
m
Nea
tly
line
the
LDPE
with
out
any
fold
s ov
er t
he p
ond.
Kee
p ov
erla
p of
abo
ut 5
0 cm
at
the
join
t.
• N
o ef
fect
ive
solu
tion
to r
educ
e
ev
apor
atio
n lo
sses
, exc
ept
to
re
duce
the
exp
osed
are
a an
d
in
crea
se h
eigh
t to
ac
com
mod
ate
the
volu
me.
H
owev
er, t
here
is a
lim
it to
th
e he
ight
incr
ease
.
• U
nles
s it
is e
mba
nkm
ent
dam
,
pr
efer
able
hei
ght
is u
p to
2
m
eter
s.
• La
nd u
se t
reat
men
t in
the
ca
tchm
ent
• Pr
ovid
e a
sedi
men
t tr
ap b
efor
e
th
e po
nd.
• Pr
ovid
e a
sedi
men
t flu
shin
g
m
echa
nism
and
use
it
re
gula
rly
| Guideline on Landslide Treatment and Mitigation66
m F
old
the
over
lapp
ed s
ectio
n to
red
uce
the
leak
age.
m
To
prov
ide
good
anc
hora
ge, t
he s
tone
s an
d so
il sh
ould
em
bed
an a
dditi
onal
por
tion
of t
he p
last
ic a
t th
e to
p.
-
Use
of
Soil-
Cem
ent:
Ste
ps f
or s
oil-
cem
ent
plas
terin
g
m
Pre
pare
the
gro
und
as m
entio
ned
unde
r LD
PE li
ning
.
m
Lay
ers
of c
lay-
cem
ent
(7:1
pla
ster
) un
iform
ly li
ned
coat
aft
er c
oat
until
a t
hick
ness
of
3 cm
is a
ttai
ned
• LD
PE li
ning
and
Soi
l-Ce
men
t Pl
aste
r ar
e on
ly a
ppro
pria
te w
here
the
re is
no
tram
plin
g da
mag
e by
live
stoc
k an
d hu
man
Tool
sCo
nstr
ucti
on p
erio
d
• D
iggi
ng o
f th
e po
nd is
pr
efer
red
whe
n th
e so
il is
not
to
o dr
y an
d no
t to
o w
et f
or
ea
sy s
oil w
ork.
• St
one
wor
k an
y tim
e w
hen
la
bor
is a
vaila
ble.
Mai
nten
ance
Prec
auti
ons
Scop
e (S
ite
for
appl
icat
ion)
• Re
gula
rly
mai
ntai
n th
e lin
ing
in t
he c
hann
el a
nd
po
nd t
o re
duce
see
page
loss
.
• Re
gula
rly
rem
ove
sedi
men
t de
posi
ted
in t
he
ch
anne
ls a
nd p
ond.
Avo
id s
ites
:
• Le
ss t
han
50 m
ups
lope
fro
m a
hou
se
• W
here
the
re a
re s
lope
mov
emen
t, s
ubsi
denc
e, la
nd s
lidin
g or
gu
llyin
g (w
hich
may
aff
ect
if ex
tend
ed)
the
area
bel
ow;
• W
here
val
ley
side
is n
ot s
tabl
e to
hol
d st
andi
ng w
ater
;
• A
t th
e to
e of
the
slo
pe, w
here
inst
abili
ty o
f th
e sl
ope
may
in
crea
se;
• Cl
ose
to a
clif
f, w
here
slo
pe-f
ailu
re m
ay o
ccur
due
to
seep
age
or
w
ater
pre
ssur
e;
• Co
nstr
uctio
n of
new
pon
d or
impr
ovem
ent
of o
ld p
onds
• La
nd u
se im
prov
emen
t (c
onse
rvat
ion
plan
tatio
n, d
egra
ded
land
re
habi
litat
ion,
gra
ss p
lant
ing)
and
ero
sion
con
trol
mea
sure
s su
ch
as
mic
ro-g
ully
plu
ggin
g (f
asci
ne, p
alis
ades
, wat
tlin
g, b
rush
la
yeri
ng, b
rush
woo
d ch
eck
dam
) in
the
cat
ch a
rea.
• W
ater
har
vest
ing
• Co
nstr
uctio
n of
con
veya
nce
syst
em (
inle
ts a
nd o
utle
ts)
• Pr
otec
tion
of t
he p
ond
Refe
renc
es:-
DSC
, 199
2, F
AO
and
IIRR
, 199
5. S
thap
it, K
. M. a
nd S
hash
indr
a La
l, U
npub
lishe
d. S
CWM
C, 2
001,
DSC
WM
200
4.
Guideline on Landslide Treatment and Mitigation | 67
Annex 5. List of Commonly Used Species
Local Name Botanical Name Botanical Name Local Name
Amala Emblica officinalis Acacia arabica Babul
Amliso Thysanolaena maxima Acacia catechu Khair
Arare Acacia pennata Acacia pennata Arare
Assuro Adhatoda vasica Adhatoda vasica Assuro
Babiyo Eulaliopsis binata Agave Americana Ketuki
Babul Acacia arabica Albizia lebbeck Kalo siris
Badaam (ground nut) Arachis glabarata Albizia procera Siris
Badahar Artocarpus lakoocha Alnus nepalensis Utis
Bains Salix tetrasperma Alnus nepalensis Utis
Bakaino Melia azedarach Arachis glabarata Badaam (ground nut)
Bayer Zizyphus mauritiana Artocarpus lakoocha Badahar
Bedulo Zizyphus jujube Arundinaria intermedia Nigalo
Bhatwasi Flemingia macrophylla Arundo clonax Narkat
Bhimal Grewia oppositifolia Arunduella nepalensis Phurke
Bhimal Grewia optiva Bambusa balcooa (Dhanu) Dhanu bans
Bhuletro Butea minor Bambusa nutans / cupalata Mal bans
Bihaya / Saruwa Ipomoea fistulosa Bassia butyracea Chyuri
Casuarina Casuarina Bauhinia purpurea Tanki
Centipede grass Centipede grass Bauhinia veriegata Koiralo
Champ Michelia champaca Brassaiopisi hainla Chuletro
Chilaune Schima wallichii Butea minor Bhuletro
Chuletro Brassaiopisi hainla Cajanus cajan Rahar
Chyuri Bassia butyracea Casuarina Casuarina
Dabdabe Garuga pinnata Centipede grass Centipede grass
Desmodium Desmodium rensonii Chamaecrista rotundifolia
Dhaincha Sesbania grandiflora Choerospondias axillaris Lapsi
Dhanu bans Bambusa balcooa (Dhanu) Colquhounia coccinea Namdi phul
Dhonde Neyraudia reynaudiana Cymbopogon microtheca Khar
Dubo Cynodon dactylon Cynodon dactylon Dubo
Dudhilo Ficus nemoralis D. Hookeri (kalo) Kalo
Faledo / Phaledo Erythrina arborescenes Dalbergia sissoo Sisso
Ghangharu Pyracantha crenulata Dendrocalamus hamltonii Tama bans
Gideri Premna spp. Desmanthus virgatus
Gliricidia Gliricidia sepium Desmodium rensonii Desmodium
Gogan Saurauia napaulensis Dismanthus
Golainchi Plumeria acuminata Drepanostachyum intermedium Tite nigalo bans
Ipil ipil Leucaena leucocephala Duranta repens Nilkada
Ipil-Ipil Leucaena leucocephala Emblica officinalis Amala
Kabro Ficus lacor Erythrina arborescenes Faledo / Phaledo
Kalo D. Hookeri (kalo) Eulaliopsis binata Babiyo
Kalo siris Albizia lebbeck Euphorbia royleana Siuli
Kanda phul Lantana camara Ficus glaberrima Pakhuri
| Guideline on Landslide Treatment and Mitigation68
Local Name Botanical Name Botanical Name Local Name
Kans Saccharum spontaneum Ficus lacor Kabro
Katara khar Themeda species Ficus nemoralis Dudhilo
Ketuki Agave Americana Ficus religiosa Pipal
Khair Acacia catechu Ficus roxburghii Nimaro
Khanyu Ficus semicordata Ficus semicordata Khanyu
Khar Cymbopogon microtheca Flemingia macrophylla Bhatwasi
Khirro Sepium insegne Fraxinus floribunda Lankuri
Khus Vetiveria lawsoni Garuga pinnata Dabdabe
Kimbu Morus alba Gliricidia sepium Gliricidia
Koiralo Bauhinia veriegata Grewia oppositifolia Bhimal
Kutmiro Litsea monopetala Grewia optiva Bhimal
Lahare papal Populus deltoids Himalayacalamus hookerianus Padang bans
Laliguras Rhododendron arboreum Ipomoea fistulosa Bihaya / Saruwa
Lankuri Fraxinus floribunda Ipomoea fistulosa Saruwa/Bihaya
Lapsi Choerospondias axillaris Jatropha curcas Sajiwan
Mal bans Bambusa nutans / cupalata Lantana camara Kanda phul
Namdi phul Colquhounia coccinea Leucaena leucocephala Ipil ipil
Napier Pennisatum purpureum Leucaena leucocephala Ipil-Ipil
Narkat Arundo clonax Litsea monopetala Kutmiro
Nigalo Arundinaria intermedia Melia azedarach Bakaino
Nilkada Duranta repens Michelia champaca Champ
Nimaro Ficus roxburghii Morus alba Kimbu
Padang bans Himalayacalamus hookerianus Neyraudia arundinacea Sito
Painyu Prunus cerasoides Neyraudia reynaudiana Dhonde
Pakhuri Ficus glaberrima Paspalum Paspalum
Paspalum Paspalum Pennisatum purpureum Napier
Phurke Arunduella nepalensis Pinus roxburghii Sallo
Pipal Ficus religiosa Plumeria acuminata Golainchi
Rahar Cajanus cajan Populus deltoids Lahare papal
Sajiwan Jatropha curcas Premna spp. Gideri
Sallo Pinus roxburghii Prunus cerasoides Painyu
Saruwa/Bihaya Ipomoea fistulosa Pyracantha crenulata Ghangharu
Sesbania Sesbania Rhododendron arboreum Laliguras
Simali Vitex negundo Saccharum spontaneum Kans
Siris Albizia procera Salix tetrasperma Bains
Sisso Dalbergia sissoo Saurauia napaulensis Gogan
Sito Neyraudia arundinacea Schima wallichii Chilaune
Siuli Euphorbia royleana Sepium insegne Khirro
Stylo-184 Stylo-184 Sesbania Sesbania
Tama bans Dendrocalamus hamltonii Sesbania grandiflora Dhaincha
Tanki Bauhinia purpurea Stylo-184 Stylo-184
Tite nigalo bans Drepanostachyum intermedium Tephrosia candida Tephrosia
Utis Alnus nepalensis Themeda species Katara khar
Utis Alnus nepalensis Thysanolaena maxima Amliso
Source: DSCWM 2004.
Guideline on Landslide Treatment and Mitigation | 69
Annex 6. Proposed Training Module for Capacity Building in Landslide Treatment
Rationale Landslides are common in the mountainous landscape of Nepal, especially with heavy
monsoon rainfall. Landslides take lives and cause damage to livelihoods, settlements,
development infrastructure, agricultural fields, and forests. Landslide treatment is a major
task carried out every year to protect property and lives. Therefore, field professionals
need to understand the mechanisms of landslide and have skills in designing conservation
measures to treat landslides.
Objectives Enable participants to:
• Understand the concepts/mechanism/approaches of landslide treatment.
• Identify the problems and map the landslide based on the problems.
• Know about different techniques used to treat landslides
• Carry out surveying for landslide treatment
• Design different necessary conservation techniques to use to treat landslide.
By the end of the training
participants will be able to:
• Explain problems, causes, and mechanisms of the landslide.
• Carry out required mapping and surveying for landslide treatment.
• Explain different techniques applied for landslide treatment.
• Design necessary conservation measures for landslide treatment.
Target group All professionals designing and implementing landslide treatment
Prerequisites Trainees working or need to work in the field of soil conservation and watershed
management. Knowledge on mathematic and basic surveying would be beneficial.
Field/Lab work: 6 days of field and practical work in carrying out the survey, design, and presentation
Duration 2 weeks of working days
Venue/Responsibility The training is a residential training to focus on practical exercise after the mentioned
training period.
Remarks Training venue will be conveniently selected so that a real case can be surveyed and the
landslide treatment can be designed
Proposed training schedule is given below.
| Guideline on Landslide Treatment and Mitigation70
Day
08:3
0-09
:00
09:0
0-10
:30
10:3
0-10
:45
10:4
5-12
:15
12:1
5-13
:15
13:1
5-14
:45
14:4
5-15
:00
15:0
0-16
:30
1Re
gist
rati
onO
peni
ng, I
ntro
duct
ion
of
part
icip
ants
, exp
ecta
tion
colle
ctio
n, h
ighl
ight
the
tra
inin
g
mod
ule
and
logi
stic
brie
fing
Brea
k1.
Und
erst
andi
ng n
atur
e la
w in
Wat
er In
duce
d W
ater
Dis
aste
r
Man
agem
ent
Lunc
h2.
Intr
oduc
tion
to
Inte
grat
ed W
ater
shed
Man
agem
ent
and
Low
cost
soi
l con
serv
atio
n
tech
niqu
es
Brea
k3.
Intr
oduc
tion
to S
oil E
rosi
on
incl
udin
g la
ndsl
ide
and
its
mec
hani
sm
2Re
view
4. A
naly
sis
of u
rgen
cy a
nd
reco
mm
enda
tion
for
land
slid
e
trea
tmen
t
Brea
k4a
. Pra
ctic
al e
xerc
ise
on
Land
slid
e U
rgen
cy a
nd
Reco
mm
enda
tion
for
Trea
tmen
t A
naly
sis
Lunc
h5.
Und
erst
andi
ng
Geo
logy
with
res
pect
to
Land
slid
es
Brea
k5a
. Und
erst
andi
ng G
eolo
gy
with
res
pect
to
Land
slid
es
cont
inue
d.
3Re
view
6. C
onse
rvat
ion
tech
niqu
es: G
rass
and
Bam
boo
plan
ting
Brea
k7.
Con
serv
atio
n te
chni
ques
:
Cons
erva
tion
plan
tatio
n
Lunc
h8.
Con
serv
atio
n
tech
niqu
es: M
ulch
ing
and
Buff
er s
trip
Brea
k9.
Con
serv
atio
n te
chni
ques
:
Fasc
ine
and
Palis
ade
4Re
view
10. C
onse
rvat
ion
tech
niqu
es: B
rush
laye
ring
and
wat
tlin
g
Brea
k11
. Con
serv
atio
n te
chni
ques
:
Rip-
rap
and
wat
erw
ays
Lunc
h12
. Bas
ic S
urve
ying
and
Fam
iliar
izat
ion
with
Clin
o-co
mpa
ss
Brea
k12
a. F
ield
exe
rcis
e on
surv
eyin
g: P
rofil
e an
d cr
oss
sect
ion
5Re
view
13 C
onse
rvat
ion
tech
niqu
es:
Gab
ion
bols
ter
and
Reta
inin
g w
all
Brea
k13
Con
serv
atio
n te
chni
ques
:
Reta
inin
g w
all c
ontin
ued.
Lunc
h13
a. F
ield
sur
veyi
ng f
or r
etai
ning
wal
l
6Re
view
14 R
unof
f ca
lcul
atio
nBr
eak
14a
Prac
tical
exe
rcis
e on
run
off
calc
ulat
ion
Lunc
h13
b Pr
actic
al e
xerc
ise
on d
esig
ning
ret
aini
ng w
all
7D
ay O
ff
8Re
view
13c
Pres
enta
tion
of t
he r
etai
ning
wal
l des
ign
Brea
k15
Intr
oduc
tion
to C
heck
dam
Lunc
h15
a Fi
eld
surv
eyin
g fo
r ch
eck
dam
9Re
view
16 W
ater
Har
vest
ing
Pond
Brea
k15
b Pr
actic
al e
xerc
ise
on c
heck
dam
10Re
view
15c
Pres
enta
tion
of t
he c
heck
dam
desi
gn
Brea
k16
a Pr
actic
al e
xerc
ise
on t
he w
ater
har
vest
ing
pond
Brea
k16
b Pr
esen
tatio
n on
Cons
erva
tion
Pond
11Re
view
17 4
Ste
ps in
Des
igni
ng L
ands
lide
Trea
tmen
t an
d M
itiga
tion
Mea
sure
s
Brea
k17
a Fi
eld
surv
eyin
g fo
r La
ndsl
ide
trea
tmen
t (R
eal C
ase
Stud
y)
12Re
view
Fiel
d su
rvey
ing
for
Land
slid
e tr
eatm
ent
if re
quire
d or
Pra
ctic
al e
xerc
ise
on
desi
gnin
g la
ndsl
ide
trea
tmen
t (R
eal C
ase
Stud
y)
Lunc
hPr
actic
al e
xerc
ise
on d
esig
ning
land
slid
e tr
eatm
ent
(Rea
l Cas
e St
udy-
4
Step
s)
13Re
view
Pres
enta
tion
on la
ndsl
ide
desi
gnTr
aini
ng E
valu
atio
nCl
osin
g an
d Ce
rtifi
cate
Dis
trib
utio
n
Clas
s ro
om
Fi
eld
wor
k
Prac
tical
Pr
esen
tatio
n
Trai
ning
eva
luat
ion,
ope
ning
, and
clo
sing
Off
Prop
osed
Ten
tati
ve T
rain
ing
Sche
dule
Guideline on Landslide Treatment and Mitigation | 71
Annex 7. Landslide Inventory
Landslide is a general term used to describe a mass of
material that has slipped downhill under the influence
of gravity, frequently occurring when the material is
saturated with water . Landslides do not occur randomly or
by chance. A landslide is a dynamic process. Its occurrence
and stability is the result of the interplay of physical
processes, and mechanical laws controlling the stability or
failure of a slope .
The Gorkha Earthquake 2015 either enlarged old landslides
or triggered new landslides, leading to massive destruction
in districts affected by the earthquake. Immediately
after the Gorkha Earthquake, the Department of Soil
Conservation and Watershed Management (DSCWM) began
initiatives to protect affected communities by developing
infrastructure to mitigate the earthquake induced or
enlarged landslide hazards, and to prevent further
destruction as much as possible.
In consultation with other related Government
organizations and with the support of Nepal’s
development partners, DSCWM organized a consultation
workshop on September 28th – 29th, 2015 on the
inventory, hazard assessment, and treatment and
mitigation of landslides. The DSCWM led the consultation
workshop with support from ICIMOD, UNEP, UNDP, IUCN,
FAO, and WWF.
Objectives
Landslide inventory sheet is designed to collect
information on landslides essential for policy formulation,
strategy guidance, precautionary measures and treatment
of landslides in order to minimize the adverse effects and
impacts of landslides on lives and property.
Key features of the inventory: -
• Simple to use by practitioners especially agencies
engaged in landslide treatment and mitigation,
such as the Department of Soil Conservation and
Watershed Management and Department of Water
Induced Disaster Prevention. The inventory should be
compatible with easily accessible digital tools such as
Google Earth.
• The information used to analyze the urgency and
degree of recommendation for landslide treatment
should be consistent.
Key information included in the inventory fact sheet includes: -
• Where did the landslide occurred? Give the location of
and major land use associated with landslide
• How big is the landslide? Give the area of the
landslide.
• What type of landslide occured?
• What are the main causes? Specify the major factors
triggering or enlarging landslide.
• How often will it occur in the future? What is the
probability of its occurrence again?
• What will it damage? Where? What are the
elements at risk (Settlements, national heritage,
roads, irrigation, drinking water supply schemes,
hydropower, land use).
• What is the scale of damage? Quantify the degree of
damage to the element at risk.
• How easily it can be treated? What is the
recommendation for the landslide’s treatment? What
is the type of landslide in term of its treatability.
• What is the potential of the landslide blocking the
river?
The proposed fact sheet for landslide inventory is given in
Annex 7 Table 1.
10 Soil Conservation Society of America-1982, Resource Conservation Glossary Third edition.
11 Guzzetti, F., Mondini, A. C., Cardinali, M., Fiorucci, F., Santangelo, M. and Chang K.-T. 2012. Landslide inventory maps: New tools for an
old problem. Earth-Science Reviews, 112: 42–66.
| Guideline on Landslide Treatment and Mitigation72
Annex 7. Table 1. Landslide Inventory Fact Sheet
Landslide Index No: District Code + VDC Code + Landslide Code (All are 2 digit code)
BASIC INFORMATIONLocation (District/VDC/Ward): ………………………………………….….
Coordinate at the bottom of the landslide:
Coordinate:
Bounding Max:
Bounding Min:
Major Land use associated with landslide:
Forest Agriculture
Grazing Settlement
Approximate Area (sq. m.): .........................
Aspect: ………………
Elevation: Max. …….m. Min. ………in m.
History: When it was initiated?
Type of Landslides classification by Cruden and Varnes (1996).(Tick in appropriate box)
Movement type
Slide Flow
Mat
eria
l inv
olve
d Ea
rth Earth
Translational Slide Earth Flow
Rotational Slide
Complex Slide
Earth
Translational Slide Channelized flow
Rotational Slide Open slope debris flow
Complex Slide
Rock
Translational Slide
Rotational Slide
Complex Slide
Shallow seated: Deep seated:
Major Factors Triggering / Enlarging Landslide (Tick in Appropriate type):
Toe cutting, Heavy rain, Steep slope
Lack of water management, Heavy rain, Steep slope
Cracked rocks, Heavy rain, Steep slope, Earthquake
Probability of Occurrence Quantification of damage to the element at risk
High Medium Low High Medium Low
Geology:
Type of Landslide in term of Treatability (Tick in Appropriate type):
Easily Treatable Moderately Treatable Difficultly Treatable
Element at Risk
Settlement / National Heritage / Lives
Village Name: ………………………………………. National Heritage Name: ……………………………………….
No of House affected No of People displaced No. of People killed
Road
Road Type (Tick in Appropriate type)
Dirt road Gravel road Asphalt road
Length of Road affected in meters
Irrigation
Irrigation Type (Tick in Appropriate type) Command area in ha.
Community Multi community Multi VDC Affected Length in meters
Drinking water supply scheme
Drinking water supply Type (Tick in Appropriate type) No. of User Households
Community Multi community Multi VDC Length in meters
Hydropower (Tick in Appropriate type)
Intake: Dam: Tunnel Station: Stilling basin:
Land use
Agriculture National Forests Community Forests Pasture lands / Shrub / Grass
Landslides Blocking Stream / River (Tick Appropriate type)
Name Designation Signature Date
None (no signs of blockage of rivers)
Partially (partially blocked the river)
Complete (completely blocked the river, and still blocking)
Complete and broken through (blocked the river but later broken through)
Guideline on Landslide Treatment and Mitigation | 73
Brief description of type of movement
Type of Movement Description
Slides
Rotational
Translational
Slope movement caused by shear failure of distinct surface.
Movement is approximately on circular surface of failure. It may be single or multiple rotational
failure surface.
Movement is approximately on planar surface failure.
Flows Rapid movements of vicious fluid. Slip surfaces are almost absent.
Complex Combination of two or more principal types of movement.
Earth Flow Rapid movements earth materials as vicious fluid.
Channelized debris flow Rapid movement of debris as vicious fluid in channel.
Open slope debris flow Rapid movement of debris as vicious fluid in slope without confined channel.
Debris: Mixture of loose soil, rock, and organic matter. Debris
consists of <50% fine materials.
Earth: Mixture of loose soil, stones, and organic matter. Earth
consists of > 50% fine materials.
Type of landslide:
Not considered for treatment: Mass movement, such as
raiser failure in the agriculture land that farmers will likely
rehabilitate as a part of cultivation, will not be considered for
treatment. Landslide not affecting livelihoods or settlements
including educational centers and livelihood based property
such as agricultural fields, trail and roads, irrigation canals,
will not be considered for treatment. Such landslides are left
for nature to treat.
Landslide is divided into shallow seated and deep seated.
Shallow seated: Movement of earth mass disturbing up
to C horizons. This type of landslide is treatable with the
bioengineering techniques and with reasonable resources
and time frame and affecting livelihood based namely
agriculture, forest and grazing land and settlement. No
bedrock are disturbed or moved.
Deep seated: Movement has occurred resulting cracks in
bedrock and bedrock movement. Treatment of such landslide
requires big structures, especially reinforced concrete
structures and grouting, at the cost of huge resources
and time. Such landslides are treated if they are affecting
nationally important structures, such as highways, hydro-
power, and large settlements.
Shallow seated: A, B, and C Horizons Disturbed. Treatable
within reasonable timeframe and the scope of bio-
engineering techniques and resources.
Deep seated: Geological failure (Crack and slides bed
rocks) Required big structures (Concrete) and huge
resources, affecting nationally important structures.
Treatability Status Criteria
Easily Treatable with bio-engineering measures within 2 years
Moderately Treatable with some engineering structures and bio-engineering measures within 5 years
Difficultly Requiring many big engineering structures and requiring more than 5 years
| Guideline on Landslide Treatment and Mitigation74
Annex 8. Format for Documentation of the Lessons Learned
Documentation of lesson learned start with filling the landslide inventory fact sheet given in Annex 7, Table 1.
Analysis for urgency and recommendation for treatment will be carried out and documented in as per Annex 8, and Tables
1 and 2 of the main document.
List the techniques applied.
S.N. Name of the
techniques
Specify the
key problems
the technique
is applied for
Steps in
applying the
techniques
Change in steps
if the techniques
is to be applied
again
Does the techniques
help in addressing
key problem (Rank
the status: Very Good,
Good, Moderate, Low,
Very Low )
Specify
adverse effect
the techniques
if any
Document the pictures of each technique (With time series if possible until the landslide is no longer threatening)
Technique applied:
Before After
Overall picture of the landslide
Before After
Recommended Survey/Design/Practical Tips or Considerations: -
Department of Soil Conservation and Watershed ManagementKathmandu, June 2016
(Asar 2073)
Guideline on Landslide Treatment and Mitigation
Department of Soil Conservation and Watershed ManagementG.P.O. BOX 4719, Babar Mahal, Kathmandu, NepalT: 977-1-4220828/4220857 | F: 977-1-4221067
E: dscwm2031@yahoo.com/info@dscwm.gov.npW: www.dscwm.gov.np
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