Agricultural water supply in theOkanagan Basin – using climate changescenarios to inform dialogue and planning processes
Denise Neilsen, Scott SmithPacific Agri-Food Research Centre, Summerland, B.C.Stewart CohenEnvironment Canada, AIRG – Vancouver, B.C.
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Expanding the dialogue on water management & climate change in the Okanagan
• Mark Barton, Bill Taylor EC-PYR
• Jeff Carmichael, James Tansey SDRI/UBC
• Andrew Reeder RDOS
• Brian Symonds BCMWLAP
• Younes Alila, Wendy Merritt Forestry/UBCSupported by a grant from the Climate Change Action Fund(#A463/433), Natural Resources Canada, Ottawa.
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Water Management & Climate Change in the Okanagan – CCAF Project
• Climate change scenarios
• Hydrologic modeling (water supply)
• Agricultural modeling (water demand)
• Population Growth• Adaptation Options
• early adopters• costs• stakeholder dialogue
Supported by a grant from the Climate Change Action Fund(#A463/433), Natural Resources Canada, Ottawa.
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Okanagan water supply
‘The Okanagan Basin has the lowest, per capita availability of freshwater in Canada’Statistics Canada. 2003. Human activity and the environment. Annual Statistics 2003. Cat. No. 11-509x XPE
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Okanagan Basin – Snow melt watershed with semi-arid climate
April/04
Supply depends onstorage in
• upland reservoirs
• mainstem lakes
• ground water (limited)
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Water Purveyors
Fragmented water supply system
• 53 public
• 3 large private
• 1147 small private
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Agricultural land in the Okanagan basin
• created 1972
• protects agricultural land
• applications for removal to Agricultural Land Commission
• unirrigated – range
• irrigated – all crops
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Irrigated agriculture in the Okanagan Basin
• high value horticulture
• pasture/forage
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Range of water management practices
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Agricultural vulnerability: competition for water and land
• highly controlled• flood
• fish• water supply
• agriculture 70-80% of diverted water
• municipal
• recreation
• urban development
• trans-boundary requirements
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Winter Season (DJF) 2050, Lat=50o Lon=120o
0
5
10
15
20
25
0 1 2 3 4 5
Mean Temperature Change (oC)
Pre
cipi
tatio
n C
hang
e (%
)
Summer Season (JJA) 2050, Lat=50o Lon=120o
-40
-30
-20
-10
0
10
0 1 2 3 4 5Mean Temperature Change (oC)
Pre
cipi
tatio
n C
hang
e (%
)
Six climate change scenarios at three time slices (2020s, 2050s,
2080s)
CGCM2 A21
CGCM2 B21
CSIROMk2 A21
CSIROMk2 B21
HadCM3 A22
HadCM3 B22
Legend
Winter 2050s
Summer 2050s
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Climate change scenarios (18)
1. GCM-adjusted baseline• ∆T, ∆p – monthly differences between future projection and
baseline climate (1961-1990) - add ∆T, - % change for ∆p
2. Normals model• Apply to 1961-90 normals for station data or gridded data sets
(PRISM 1x1km): • Interpolate to daily temperatures using cubic spline (Morrison
(1998)
3. Inter-annual model• Apply to 1961-90 daily for station data:
• Temporal and spatial interpolation by cubic spline
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Hydrology model
UBC – watershed model (Quick, 1995)• Semi-distributed conceptual model• Meteorological data distributed to series of
elevation bands • Parameterization of ungauged tributaries
with data from gauged, unregulated tributaries
• Aggregates sub-watersheds
Source: Wendy Merritt & Younes Alila, 2004
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Impacts on Water Supply
Modeled SWE for Pearson Creek catchmentbased on Joe Rich Creek
0
100
200
300
400
500
600
700
1961 1971 1981 1991 2001 2011 2021 2031 2041 2051 2061 2071 2081 2091
SW
E (m
m)
BaseCGCM2 A2HadCM3 A2CSIRO A2
• Reduction in snow pack
Source: Wendy Merritt & Younes Alila, UBC – UBC Watershed Model
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Impacts on Water Supply
• More rain dominated hydrograph
• Change in volume of peak flows
• Earlier peak flows• Earlier recessionImplications for water
users –• less in-stream flow• earlier withdrawal from
storage
Source: Wendy Merritt & Younes Alila, UBC – UBC Watershed Model
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Data required for modeling crop water demand-using GIS
• Spatial distribution of climate data (griddeddatasets at fine scale 1x1 km)
• Derived relationships between evapotranspirationand actual crop water use for different crop types
• Derived relationships between climate data and estimates of potential evapotranspiration
• Length of growing season based on degree day accumulation (for indeterminate crop types)
• Spatial distribution of crops
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Model Structure
Prism grid 1 x 1km
Water purveyor boundary
Crop polygon
Accumulation of crop water use1. Crop polygon
• mm water use x polygon area (ha) = m3 x 102. Sub-watershed
• Sum of crop polygons3. Water Purveyor
• Sum of crop polygons4. Basin
• Sum of crop polygons
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Climate Normals Model: Basin crop water use in response to climate change
20
60
100
140
180
220
260
300
340
1961-03 2020s 2050s 2080s 2020s 2050s 2080s
m3 x
106
Historic CGCM2 CSIROMk2 HadCM3
B2A2
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Climate Normals Model: Water use in response to climate change – crop
(by crop)Grapes
CGCM2-A21
0
1
2
3
4
1 2 3 4 5 6 7 8 9 10 11 12
Months
m3
x 10
3
historic 2020s 2050s 2080s
AppleCGCM2-A21
0
1
2
3
4
1 2 3 4 5 6 7 8 9 10 11 12
Months
m3 x
103
historic 2020s 2050s 2080sPasture/Forage
CGCM2-A21
0
1
2
3
4
1 2 3 4 5 6 7 8 9 10 11 12
Months
m3 x
103
historic 2020s 2050s 2080s
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Climate Normals Model: Basin water supply/demand response to climate change
140
180
220
260
300
340
500 600 700 800 900 1000
Okanagan L. inflow (m3 x 106)
Crop
wat
er d
eman
d (m
3 x 1
06 )
HistoricCGCM2CSIROMk2HadCM3
2080s
2050s
2020s
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Agricultural water demand in response to climate change-interannual study
Summerland Case study• integrated system• irrigation currently greater than domestic demand • Trout Creek, 2nd largest flow in basin• fish flow requirements
• 2003-04 municipality and DFO in court over fish flow • municipality facing $1million fine
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Variation in crop water demand and Trout Creek flows in response to climate change
Summerland Case study
HadCM3-A2
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2
4
6
8
10
12
14
0 50 100 150 200 250
Annual flow (m3 x 106)
Cro
p w
ater
dem
and
(m3 x
106 ) Historic
2020s2050s2080s
CGCM2-B2
0
2
4
6
8
10
12
14
0 50 100 150 200 250
Annual flow (m3 x 106)
Cro
p w
ater
dem
and
(m3 x
106 ) Historic
2020s2050s2080s
‘defined drought – 30% average annual flow’
‘max. allowable demand – 2002 use’
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Residential water demand in response to population growth and climate change
Penticton Case study• irrigation currently less than domestic demand • three population growth rates
• high = City of Penticton OCP projections• med = 50%• low = 25%
• relationships for indoor/outdoor use developed from 1998-2002 data
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Residential water demand in response to population growth and climate change
Average Annual Water Use
0
5000
10000
15000
20000
25000
30000
35000
40000
2001 None CC1 CC2 CC3 CC4 CC5 CC6
Climate Scenario
Aver
age
Annu
al W
ater
Use
(ML)
2001low population growth 2020smedium population growth 2020shigh population growth 2020slow population growth 2050smedium population growth 2050shigh population growth 2050s
PentictonCase study
max. demand irrigation adjusted for climate change
Source: Jeff Carmichael, Tina Neale, UBC – Population case study
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Adaptation costs
Adaptation option
% saved or gained
Cost/acre-foot
Who pays
Irrig. Sched. 10 $500 –835 Producer
Trickle Irrig. 30 $500-1666 Producer
Education 10 $835 Taxpayer
Metering 20-30 $1880-3400 Taxpayer
Mainstem pump.
0-100 $648-2700 Taxpayer
Storage limited $1500 Taxpayer
Source: Roger McNeil EC PYR and Bob Hrasko
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Adaptation issues – current/future
• Insufficient water supply
• Increased agricultural demand
• Increased population demand
• Fragmented water management responsibilities
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Stakeholder views on adaptation:(2003/4 Basin wide)
Engaging dialogue to identify opportunities and challenges for basin-wideimplementation of adaptation strategies to scenarios of streamflow reductions and increased demand in the Okanagan Basin need• integration with local growth strategies; • local ownership of solutions • sense of belonging to the basin• support for expanded role for OBWB • financial support needed from all levels of government
Institutional challenges?• clearly defined mandates to manage water quantity • integratation land use plans with long term water management needs
Scaling up from community to basin...
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Adaptation responses – supply side
• 2003 – in response to drought, number of W.P. applied for licences to withdraw from mainstem and groundwater
• consideration of increased upland storage
• separation domestic/irrigation delivery systems
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Adaptation responses (water purveyors) –demand side
• Water management advisors hired in several districts
• Bylaw enforcement including shutoff after number of violations
•Metering options - SEKID model being considered
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SEKID - Water management through education and metering
Difference between water required and used
Water us
e report
Source: Ted van der Gulik, Peter Parchomchuk, Toby Pike SEKID project
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Adaptation issues – NGO/institutional responses (2004-
• Okanagan Partnership – recently formed group of members of the business,academic and government communities to study and stimulate Okanagan economy
• Major issues identified• Need for integrated water and land use planning• Need to retain agriculture as the ‘backdrop’ of the community
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Water Purveyors
Consolidate fragmented water supply system
• 53 public
• 3 large private
• 1147 small private
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Local governments
Incorporate climate change information into planning process
Osoyoos
Oliver
PentictonSummerland
Kelowna
Vernon
Okanagan ValleyPARC GIS July 2004
Kamloops
Legend
Urban
First Nations
Okanagan Watershed
Urban – municipalities
Rural – regional districts
First Nations
Municpalities
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Adaptation by agriculture – demand side
• change crop profile to crop with lower demands • e.g. irrigated hay pasture ⇒ grapes, tree fruits
• more efficient irrigation practices• micro-irrigation • mulching• deficit irrigation • improved irrigation scheduling (e.g. fully automated)
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Concerns of agricultural water users
• water currently saved by agricultural conservation will be re-allocated for development and not ‘banked’ for future shortfalls
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Climate change: We are at risk
Report to the standing committee on Agriculture and Forestry, 2003
Seven recommendations were made• No. 3:
‘Research on water be made a national priority, with a special focus on “supply and demand” scenarios, water management and planning at the local level, and adaptation options including infrastructures’
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Thankyou
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