Soda-Mattress Riverbank Soda-Mattress Riverbank Protection MeasuresProtection Measures

Ministry of Public Works and TransportDepartment of Waterways

Lao, PDR

Mr. Houngla SENGMUANG Mr. Phaknakhone RATTANA

Ms. Vanh DILAPHANH Mr. Kazumitsu MURAOKA

5th World Water Forum, Istanbul, Turkey16 – 22 March 2009

Contents:Contents:

• 1) Introduction (Background of Lao PDR 1) Introduction (Background of Lao PDR and Mekong River) and Mekong River)

• 2) The Condition in the Activity Area2) The Condition in the Activity Area

• 3) Design of Riverbank Protection 3) Design of Riverbank Protection WorksWorks

• 4) Features and Installation of Soda 4) Features and Installation of Soda MattressMattress

• 5) Construction Cost5) Construction Cost

• 6) Conclusion6) Conclusion

Lao Peoples Democratic Lao Peoples Democratic RepublicRepublic

Area: Area: 236,800 sq km.236,800 sq km.

Population:Population: 5.6 million (2005).5.6 million (2005).

GNP or GDP:GNP or GDP: 491 US$ (2005)491 US$ (2005)

Capital city:Capital city: Vientiane.Vientiane.

Bordering:Bordering: China, Myanmar,China, Myanmar,

Thailand, Cambodia and Thailand, Cambodia and Vietnam. Vietnam.

Altitude:Altitude: 90 - 1500 m above 90 - 1500 m above MSL MSL

Climate: Climate: Tropical, monsoon.Tropical, monsoon.

Temperature: 15Temperature: 15C to 38C to 38C C

Mekong RiverMekong River The world’s twelfth longest river, The world’s twelfth longest river,

length of mainstream 4,825 km, runs length of mainstream 4,825 km, runs through the Lao territory with a through the Lao territory with a length of 1,865 km.length of 1,865 km.

The tenth largest in terms of annual The tenth largest in terms of annual flow with total drainage area flow with total drainage area 795,000 sq km.795,000 sq km.

Runs through six countries: China, Runs through six countries: China, Myanmar, Lao PDR, Thailand, Myanmar, Lao PDR, Thailand, Cambodia and Vietnam. Cambodia and Vietnam.

Monthly Average Water Level at KM4 in Vientiane (1992-2001)

158

159

160

161

162

163

164

165

166

167

168

169

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month

Wat

er L

evel

(m

, M

SL

) Max.

Mean

Min.

2002

2003

Water Level of Mekong Water Level of Mekong RiverRiver

Mechanism of bank erosionMechanism of bank erosion • Due to Due to scouring at foot of riverbedscouring at foot of riverbed

(Most of the eroded vertical riverbank cliffs are of this (Most of the eroded vertical riverbank cliffs are of this type)type)Due to lowering river water levelDue to lowering river water level

• Due to slope failureDue to slope failure

• Severely eroded riverbanks form Severely eroded riverbanks form Vertical CliffsVertical Cliffs mostly.mostly.

• Damage by the erosion extends to many facilities Damage by the erosion extends to many facilities (such as road, houses, oil bases, factories, (such as road, houses, oil bases, factories, electric cables).electric cables).

Design Philosophy of Design Philosophy of Riverbank Protection WorkRiverbank Protection Work

• Using Using local construction materiallocal construction material as as much as possible.much as possible.

• Using Using manpowermanpower of Lao P.D.R. as of Lao P.D.R. as much as possible.much as possible.

• Construction and maintenance Construction and maintenance work can be done by people of Lao work can be done by people of Lao P.D.R.P.D.R. as much as possible. as much as possible.

• To pay attention to To pay attention to keep riverine keep riverine environment environment

Japanese Traditional River Japanese Traditional River WorksWorks

• Japanese traditional method of river works Japanese traditional method of river works

are suitable for Mekong River around are suitable for Mekong River around

Vientiane City, those are ;Vientiane City, those are ;

– ““SODA” Mattress esp. for foot SODA” Mattress esp. for foot

protection worksprotection works

– Cobble-Stone with Willow Branches Cobble-Stone with Willow Branches

WorkWork

– Wooden Pile Dike Groyne WorkWooden Pile Dike Groyne Work

WHAT IS “SODA” ?WHAT IS “SODA” ?

• MAY TIOU NAM, MAY TIOU NAM,

MAY POHOU, MAY POHOU,

MAY PAO, MAY PAO,

MAY MOUK, MAY MOUK,

etc.etc.

TREES WITH TREES WITH STRENGTH AND STRENGTH AND TENACITYTENACITY

FOR HURDLE WORK:FOR HURDLE WORK:

FLEXISIBILITYFLEXISIBILITY

““SODA” IS BRANCHES OF BRUSH WOOD CUT FROM SODA” IS BRANCHES OF BRUSH WOOD CUT FROM MISCELLANEOUS SMALL TREES IN FIELDS AND FORESTSMISCELLANEOUS SMALL TREES IN FIELDS AND FORESTS

STRUCTURE OF SODA MATTRESSSTRUCTURE OF SODA MATTRESS

1) Preparation of Soda bundles

2) Making ‘Rensai’ (connection beam made of fascine)

3) Fixing node of Rensai lattice

Foot Protection WorkFoot Protection Work- Assembling and installation of Soda Mattress- Assembling and installation of Soda Mattress

4) Flooring ‘Siki-Soda’ work

5) Piling short wooden piles to combine upper and lower lattice structures and for hurdling work

6) Placing floating Soda mattress at the planned position by boat

7) Connecting Soda mattresses by manpower 8) Row of connected mattresses

Danxi Laksamsip

Nongpen

Kao Liao

Ban Dongphosi

Ban Sakai(50 km from city center)

Nong Teng

Donloun

: Quarry site

: Fascine material site: Stockyard

2 km

Location of Material Collection Sites

2 km

Xiangkhouan

: Borrow site of sand, gravel and laterite

Wat Chom Cheng

Sibounheuang

Riverbank Protection Works Riverbank Protection Works ActivitiesActivities

Features of SODA Features of SODA MattressMattress• Flexible and Durable in waterFlexible and Durable in water

• Porous for good habitat of aquatic lifePorous for good habitat of aquatic life

• Suitable to sandy riverbed as foot Suitable to sandy riverbed as foot protectionprotection

• Effective against sand suctionEffective against sand suction

• Mainly adaptable to mild slope river of Mainly adaptable to mild slope river of less than 1/2000.less than 1/2000.

• Setting condition: Below low water Setting condition: Below low water levellevel

Typical Cross SectionTypical Cross Section

PlanPlan

Foundation Work Foundation Work (Log Hurdle work)(Log Hurdle work)

Foot Protection Work Foot Protection Work (Soda mattress work:(Soda mattress work:

23 sheets)23 sheets)

Slope Protection Work Slope Protection Work (Cobble stone with willow branch (Cobble stone with willow branch

work)work)

Total Length=156 Total Length=156 mm

Average Construction CostAverage Construction Cost

Construction MethodConstruction MethodAverage CostAverage Cost(US$/meter)(US$/meter)

1.1. Conventional Gabion Works implemented around Vientiane CityConventional Gabion Works implemented around Vientiane City 2,0002,000

2.2. Work Types proposed in the Master PlanWork Types proposed in the Master Plan

(1)(1) Riprap groyne work (L=50m, interval=150m)Riprap groyne work (L=50m, interval=150m) 190 190

(2)(2) 1) Cobble stone with willow branch work covering whole bank,1) Cobble stone with willow branch work covering whole bank,2) stone foundation and 3) soda mattress 2) stone foundation and 3) soda mattress

1,3001,300

(3)(3) 1) Cobble stone with willow branch work covering lower bank, 2) 1) Cobble stone with willow branch work covering lower bank, 2) log hurdle work and 3) soda mattresslog hurdle work and 3) soda mattress

700700

3.3. JICA Pilot Works (Reference)JICA Pilot Works (Reference)

(1)(1) Ban Dongphosi SiteBan Dongphosi Site 1,6901,690

(2)(2) Wat Chom Cheng SiteWat Chom Cheng Site 200200

(3)(3) Sibounheuang SiteSibounheuang Site 810810

Before construction (Oct. 2002)Before construction (Oct. 2002)January 2004January 2004

June 2005June 2005March 2005March 2005

Pilot Work at Ban Dongphosi (completed in May 2003)Pilot Work at Ban Dongphosi (completed in May 2003)

Continuous MonitoringContinuous Monitoring• The Climate in Laos is very much different from that in The Climate in Laos is very much different from that in

Japan (especially very long dry season in Laos).Japan (especially very long dry season in Laos).

• It is essential to monitor the completed works at least 5 It is essential to monitor the completed works at least 5 yearsyears– to verify the appropriateness of Japanese method such as the to verify the appropriateness of Japanese method such as the

effect of protection, growth of vegetation, sedimentationeffect of protection, growth of vegetation, sedimentation– to find the issues to be improved for localization. to find the issues to be improved for localization.

ConclusionConclusion

- Importance of a appropriate technology, the project - Importance of a appropriate technology, the project has introduced the Japanese traditional methods on has introduced the Japanese traditional methods on the riverbank protection (particularly Soda Mattress the riverbank protection (particularly Soda Mattress Method) instead of high technology.Method) instead of high technology.

- One of the characteristics of the method is low cost, - One of the characteristics of the method is low cost, it is easy to maintain by local people and can use of it is easy to maintain by local people and can use of existing material, it is suitable for developing existing material, it is suitable for developing country like Lao PDR. country like Lao PDR.

- Therefore, the appropriate techniques is very - Therefore, the appropriate techniques is very effective to make counterpart agencies to aware effective to make counterpart agencies to aware and strengthen partnership with relevant and strengthen partnership with relevant organization and local people to take the organization and local people to take the ownership.ownership.