Transcript Climate Change Impacts on Water Supply and Irrigation Water

Climate change impacts on water supply and irrigation water demand in the Columbia River Basin
Jennifer Adam1, Kiran Chinnayakanahalli1, Claudio Stockle2, and Michael Barber1
1Civil
and Environmental Engineering, Washington State University, PO Box 642910,Pullman, WA 99164-2910.
2Biological Systems Engineering, Washington State University, PO Box 646120, Pullman, WA 99164-6120.
1. Introduction
Rising temperature and changes in the frequency and magnitude of precipitation due to climate
change (IPCC-AR4 report) events are anticipated to affect crop production, water availability and
quality, and flood risk in the PNW (Stockle et al 2009, Elsner et al 2009, Hamlet and Lettenmaier
2007).
 Agriculture is a vital part of the economy in the Pacific Northwest (PNW). In 2008, wheat
production accounted for $1.7 billion, the third largest value in the United States (NASS, 2009) .
The eastern side of the Cascade Mountains, which receives only 5-25” of rain annually, is
particularly vulnerable to drought. In the last decade, there have been 10-20% yield losses during
severe drought years, with an average of $90 million/year (NASS, 2009).
The challenge is to anticipate the probable effects of climate change on the hydrological cycle and
make sound land use, water use, and agricultural management decisions that will best serve the
needs of agricultural production while protecting our freshwater resources.
 A system of models (see Boxes 2 and 3) are applied to assess the impacts of projected climate
change on hydrology, water resources, and agricultural productivity. Here we describe the
preliminary model integration work.
2. Methods and Tools
Four groups of socioeconomic scenarios
allow a range of future
greenhouse gas
emissions.
The greenhouse gas
scenarios are used to
drive coupled
Atmosphere-Ocean
General Circulation
Models (AOGCMs) to
simulate future
climate. Output from
17 AOGCMs are
archived with the
IPCC.
3. Modeling
OBJECTIVE: To apply a coupled hydrology
and cropping systems model to project and
compare future water supply and irrigation
water demand over the Washington State
portion of the Columbia River Basin for
improved water resources management.
VICCropSyst
Integration
Strategy
T
IP
T, IP
I
Q
Q01
updated
Soil moisture
Redistribute I,
Q01 and Q12 to
CropSyst layers
Q12
ET0 ,I, Q01, Q12
CropSyst
Impact models and other tools are
used to explore the impacts of
climate and hydrologic change on
agriculture and water resources
management.
The
downscaled
climate data
are used to
drive land
surface
hydrology
models to
simulate the
UW/Princeton
hydrologic
Variable Infiltration
cycle in an
Capacity (VIC)
altered
Model
climate.
Qb
VIC-CropSyst Integration Variables:
T – Transpiration, IP – Interception capacity, I – Infiltration, Q – Runoff, Qb – Baseflow, Q01 –
Drainage from 0 to 1, Q02 – Drainage from 0 to 2, ET0 – Penman Monteith Pot. Evap.
VIC
• We are applying a system of linked models, including VIC
hydrology model (Liang et al. 1994), a dynamic crop systems
model (CropSyst: Stockle et al. 2003), and ColSim
• Funding for this project is being provided by the
Washington State Department of Ecology
Physical System of Dams and
Reservoirs
crop
4. Conclusions
The future climate data from the
AOGCMs need to be bias-corrected
and spatially and temporally
downscaled before they can be
applied to regional basins. One
method is called Bias Correction
Statistical Downscaling (BCSD; Wood
et al. 2004).
LAND COVER
USA- USDA crop land data layer
Canada – derived from National
Ecological Framework for
Canada
*Not all land cover types shown in
the legend*
Columbia River Basin reservoir
operations model –ColSim
(Hamlet et al. 1999)
 Application of down-scaled and bias-corrected AOGCM climate data to drive hydrologic models has the potential to
improve our understanding of the impacts of climate and hydrologic change on agriculture and water resources
management. For example, the framework developed here can be used to study the impact of climate change on
crop dynamics.
 The major challenge to both of this project is the simplistic treatment of crops and agricultural practices in the
hydrologic models. Therefore, we are expanding the capabilities of the modeling framework by coupling VIC to a
dynamic crop growth model, CropSyst. The expanded capabilities of the coupled models will enable further
investigations into the linkages and feedbacks between climate, hydrology, and agriculture.