Research

Hydrology and Water Resources: Current Research

Examining the Impacts of Climate Variability and Change on Water Use in the Snake River Basin

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Background and Research Goals

In comparison to the remainder of the Columbia basin, southern Idaho's Snake River basin is more highly developed in terms of water extractions (relative to mean streamflow) and at greater risk of experiencing the potential hydrologic effects of climate change.

Our intent with this research is to develop the understanding and capability to predict interactions among water management and climate variability and change in the Snake River basin.

Work is underway to construct a modeling framework that encompasses the complex interactions among climate, irrigation technology, aquifer recharge, and the interconnected groundwater and surface water systems in the Snake River basin. Previous efforts in modeling the trade-offs between power, fish, and irrigation in the Snake River basin have been limited by a variety of factors, including our ability to model groundwater, the detail of the models used for irrigation decisions, and the economic impacts on agriculture.

The model currently being developed, the Snake River Simulation Model (SnakeSim), is a monthly timestep surface and groundwater resources simulation model that incorporates the major projects and operational features of the Snake River basin and simulates the movement and storage of water within the basin given current operational policies. 91.5% (13.3 million acre-feet) of the total storage in the basin is modeled in SnakeSim. The system is shown in Figure 1.

The study uses five regional climate change scenarios for 2020 and 2040 developed (using the delta method) from the following global climate simulations:

HadCM2 (“hc”) and ECHAM4 (“mpi”), which characterize well the range of climate changes projected by the four scenarios, are illustrated in Figures 2-4 along with a “composite” scenario (comp), which is an average of the regional changes from all four models.

Ultimately the new Snake River model will be incorporated into the existing ColSim water resources operations model (see Hamlet and Lettenmaier 1999) to allow an integrated investigation of the role of the Snake in the context of the entire Columbia basin.

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map: Snake River system

Figure 1 Snake River system.

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chart: Naturalized runoff at Milner

Figure 2 Naturalized runoff at Milner.

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chart: Upper Snake River basin system storage under historical and predicted future climate change conditions.

Figure 3 Upper Snake River basin system storage under historical and predicted future climate change conditions.

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chart: Upper Snake River basin total hydropower production.

Figure 4 Upper Snake River basin total hydropower production.


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Selected References

For publications on climate impacts on Pacific Northwest (PNW) water resources, please see CIG Publications.