irrigation strategies for - unifrutp. s. 2008... · range of water management practices. ... drip...
TRANSCRIPT
![Page 1: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/1.jpg)
Irrigation strategies for
apple production.
Denise Neilsen and Gerry Neilsen
Agriculture and Agri-Food Canada
Summerland, B.C. Canada
International Apple Symposium
Cuauhtémoc, Mexico
November 12th, 2008
![Page 2: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/2.jpg)
Okanagan region of British Columbia,
Canada
April/04
Okanagan Basin
◼ Semi-arid climate
◼ Dependent on winter snow for water supply
◼ Increasing competition for water
![Page 3: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/3.jpg)
183
259
258
168
760
689
732
826
Mean
Precipitation
Okanagan Basin Climate April - October
Growing season
water deficits
◼ 430 to 658mm
◼ Irrigation
required
Mean
Evapotranspiration
![Page 4: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/4.jpg)
Irrigated agriculture in the Okanagan
Basin◼ high value horticultural crops
◼ high density apple production
◼ sweet cherries, peaches
◼ wine grapes
![Page 5: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/5.jpg)
Range of water management practices
![Page 6: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/6.jpg)
Irrigated agriculture
◼ Highly productive
Approximately 40% of the world’s food
comes from the 17% of the land that is
irrigated (Postel, 2000).
![Page 7: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/7.jpg)
Water managed for
• flood control
• power generation
• in stream requirements
• fish
• other ecological needs
• water supply
• agriculture 70-80% of
diverted water
• municipal
• recreation
• urban development
Agricultural vulnerability:
competition for water and land
![Page 8: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/8.jpg)
Widespread North American drought in
2003 (September map)
![Page 9: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/9.jpg)
Drought has moderated in the last 2-3
years (Sept 2008 map)
Precipitation
in interior BC
& Washington
below normal
Precipitation
in
Chihuahua
nearer
normal in
last 2 years
![Page 10: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/10.jpg)
Standardized precipitation index for
semi-arid regions of Chihuahua
Above
normal
rainfall
Below normal
rainfall
Drought is recurring
SP
I
![Page 11: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/11.jpg)
◼ Much of western N. America has
unreliable water supply for irrigation
◼ Conservative irrigation practices are
required to reduce the risk from drought
![Page 12: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/12.jpg)
Presentation structure
◼ Plant water requirements
◼ Water management of tree fruits
Strategies for managing water well
◼ Increasing planting density
◼ Conservative systems
◼ Irrigation scheduling
◼ Amendments
◼ Deficit irrigation
![Page 13: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/13.jpg)
Plant water requirements
![Page 14: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/14.jpg)
Water in plants ◼ Plant constituent (e.g. apple fruit ~ 80%
water)
◼ Transports nutrients
◼ Chemical reactant
◼ Maintains cell turgidity - important for growth
◼ Modifies micro-climate (cools through evaporation, increases humidity)
![Page 15: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/15.jpg)
Plant water requirements
◼ adequate supply for crops
prevent stress
maximise yield
improve fruit quality
![Page 16: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/16.jpg)
Plant water movement
Root
Stem
Leaf
Transpiration
AbsorptionSoil
Water
◼ Water moves from soil to the air through the plant
◼ increases with high temperature and wind
◼ decreases with low soil water content
![Page 17: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/17.jpg)
Soil Water Content
Rapidly drained
Water Available Water
Bound
Water
Sandy Loam Soil
Clay Soil
Sandy or Gravelly Soil
Gravitational
Water Available Water
Bound
Water
Courtesy Curt Rom
![Page 18: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/18.jpg)
Saturation
Rapid drainage stops
Time
So
il m
ois
ture
co
nte
nt
Plant stress
begins
Water applied
Completely dry
Readily
Available
Water
Plant dies
Changes in soil water content over time
![Page 19: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/19.jpg)
Water movement through the plant –
stomates
(100k – 350K/sq in)
Mainly on undersides of
leaves
![Page 20: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/20.jpg)
Water movement through the plant –
stomates
Open
light
water vapour
lost
Carbon dioxide for
growth from the
air
X
Closed
Low light
Dry soil
water stress
No carbon dioxide
for growth
![Page 21: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/21.jpg)
Need to avoid detrimental stress
(Gala/M.9)
0
50
100
150
200
full irrigation
¼ irrigation
*
**
**
****
0
50
100
150
200
full irrigation
¼ irrigation
*
**
**
****
Stress started
Stress finished
June July August Sept
Fru
it W
eig
ht
(g)
![Page 22: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/22.jpg)
Water Management
![Page 23: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/23.jpg)
Increasing plant density - more water
management options
![Page 24: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/24.jpg)
• Conservative, well
engineered systems
• Applying water to meet plant
requirements
(irrigation scheduling)
Strategies for managing water well
• Reducing soil water
evaporation
![Page 25: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/25.jpg)
Conservative water management
options
Small radius (1.5-2ft)
micro sprinkler
Drip (pressure
compensating)
Irrigation systems that position water in the
root zone
Drip ( PC) -in line for
surface or sub-
surface installation
![Page 26: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/26.jpg)
Irrigation scheduling
◼ how long an irrigation system should run
◼ matches water supply to demand
◼ uses some measurement or estimate of demand
![Page 27: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/27.jpg)
Improving water management with
irrigation scheduling
![Page 28: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/28.jpg)
Irrigation scheduling techniques
1. Soil Moisture Monitoring
2. Climate Monitoring
![Page 29: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/29.jpg)
TDRTensiometer
Electrical Resistance Block
Watermark
Capacitance
probes (fully
automated)
Soil moisture monitoring
![Page 30: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/30.jpg)
0
10
20
30
40
50
60
70
80
0 5 10 15
Soil moisture tension (bars)
So
il w
ate
r co
nte
nt
(%)
Clay
Sandy loam
PWP
Loamy sand
Soil moisture tension is also called soil suction or soil matric
potential
SATURATIONSoil moisture tension
![Page 31: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/31.jpg)
Tensiometers measure soil moisture tension
between 0 and 1 bar (0 and 100 centibars)
• for saturated soils tension = 0
• for dry soils tension = 100
0
20
10
40
30
50
70
60
90
100
80
Tensiometer
Works best
in coarse
soils (sands-
sandy
loams)
![Page 32: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/32.jpg)
0
20
10
4030
50
7060
90
100
80
Scheduling micro-irrigation systems
◼ Operate on 1-3 day
cycle
◼ Maintain desired
moisture level by
adjusting run time or
increasing frequency
![Page 33: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/33.jpg)
Climate based methods for potential ET
Evap. pan
Weather station
Web service
Fully automated
atmometer scheduling
Provide
estimates
of
potential
ET
![Page 34: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/34.jpg)
Transpiration from leaf stomates
Evaporation from the leaf surface
Evaporation from the soil surface
Water Loss via Evapotranspiration (ET)
Solar radiation Wind
![Page 35: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/35.jpg)
Estimating tree water use
◼ Actual water use (mm) = K x ETo (mm )
◼ K is the crop coefficient and is related to
canopy size
◼ K is the mm water required per mm of ETo
![Page 36: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/36.jpg)
Cro
p c
oeff
icie
nt
(Kc)
mm
wate
r u
se/m
m
evap
ora
tio
n
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 5 10 15 20 25 30
Weeks after shoot leaf budburst
Apply 0.5 mm/mmET0
Apply 1.2 mm/mmET0
Change in the crop coefficient (Kc) over
the growing season
![Page 37: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/37.jpg)
Data logger or
computer
programmed
with crop
coefficients etc.
Irrigation
controller
Electronically measure
evaporation daily using an
ATMOMETER
Estimate amount of
water used
Replace water
used next day
Automating scheduling using an
electronic atmometer
![Page 38: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/38.jpg)
10
15
20
25
30
203 205 207 209 211
Day of the year
So
il m
ois
ture
(%
)
Drippers 15 cm from emitter
Microsprinklers 15 cm from emitter
How well can we do?
Soil moisture under scheduled micro-
irrigation
![Page 39: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/39.jpg)
Wate
r lo
ss (
L/t
ree)
May June July Aug. Sept. Oct.-May May
Scheduled to meet evaporative demand
Unscheduled (fixed rate)
1998 1999
*
*
**
0
100
200
Water added
(L/tree/season)
Scheduled 646
Unscheduled 1304
Water use and loss of water beneath the
root zone with irrigation scheduling
![Page 40: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/40.jpg)
Other conservation methods - to be
covered in the later talk
Geotextile mulchesOrganic mulches
Paper mulches
![Page 41: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/41.jpg)
0
500
1000
1500
2000
2500
3000
0 20 40 60
Mulch
No mulch
L H
2O
used
(3/0
5 t
o 2
7/0
9)
Trunk Diameter (mm)
Water use of apple trees under mulch
Water use
under mulch
~ 50%
![Page 42: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/42.jpg)
Preparing for and managing drought -
deficit irrigation
◼ High density planting: 3333 trees/ha
◼ Conservative irrigation system: pressure compensating drip
◼ Scheduled irrigation:100%; 50%; 33% (ET)
◼ Managed crop load: 3; 6; 10 fruit/cm2 TCSA
◼ 100% irrigation applied to herbicide strip = 480 mm/ha in 2008
Ambrosia/M.9
![Page 43: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/43.jpg)
Deficit irrigation
Ambrosia/M.9
0
10
20
30
40
50
60
70
80
Low Standard High
Yie
ld (
T/h
a)
100% I50% I (both sides)50% I (one side)33% I (2day accumulation)
IxCL *Standard crop loads
Yield maintained at 50% irrigation
Low crop loads
Yield maintained at 33% irrigation
![Page 44: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/44.jpg)
Deficit irrigation
Ambrosia/M.9
Irrigation effect
0
1
2
3
4
5
6
7
Sta
rch
In
de
x
b b b
a
100%
both
sides
50%
both
sides
50%
one
side
33%
alternate days
Crop load effect
0
1
2
3
4
5
6
7S
tarc
h Index
b ab a
Low Standard High
Irrigation effect
Water stressed fruit mature earlier
Crop load effect
Fruit mature earlier at higher crop loads
![Page 45: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/45.jpg)
Deficit irrigation Irrigation effect
0
50
100
150
200
250
Fru
it s
ize
(g
)
100%
both
sides
50%
both
sides
50%
one
side
33%
alternate days
b
aaa
Crop load effect
0
50
100
150
200
250
300F
ruit s
ize (
g)
Low Standard High
c
b
a
Ambrosia/M.9
Irrigation effect
Fruit size maintained at 50% irrigation
- 200g at 50% irrigation
Crop load effects
Fruit size decreased as crop
load increased
![Page 46: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/46.jpg)
Increase
planting
density
Design
conservative
irrigation
systems
Apply
irrigation
scheduling
Make use of
soil
amendments
Improving water management
Deficit
irrigation
![Page 47: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/47.jpg)
◼ International Dwarf Fruit Tree Association
◼ Washington Tree Fruit Research Commission
◼ Okanagan Kootenay Cherry Fruit Growers Association
◼ Agriculture and Agri-food Canada Matching Investment Initiative MII
Financial support
![Page 48: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/48.jpg)
Thank you
![Page 49: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/49.jpg)
Water supply is unreliable – winter
snow
May 15th Snowpack
0
100
200
300
400
500
600
1960 1970 1980 1990 2000 2010
Sn
ow
wa
ter
eq
uiv
ale
nt
(mm
)
![Page 50: Irrigation strategies for - UNIFRUTP. S. 2008... · Range of water management practices. ... Drip (pressure compensating) Irrigation systems that position water in the root zone Drip](https://reader033.vdocument.in/reader033/viewer/2022042312/5edad52f09ac2c67fa686109/html5/thumbnails/50.jpg)
Mote P.W.,Hamlet A.F., Clark M.P., Lettenmaier D.P.,
2005, Declining mountain snowpack in western North
America, BAMS, 86 (1): 39-49
Trends in Snow pack – W. North America
Many areas:
◼ Higher winter and springtime temperatures
◼ Reduction in precipitation that falls as snow
◼ Earlier snow melt and runoff
◼ Recharge to aquifers reduced