Water systems in snowmelt-dominated hydro-regions such as California’s Sierra Nevada mountains are sensitive to regional climate change, hydropower systems in particular. The authors developed a water resources management model for the upper west slope Sierra Nevada to understand the potential effects of regional climate warming on hydropower at the watershed scale, a scale that has been largely neglected but is important for hydro-regional planning.
The model is developed with the Water Evaluation And Planning system (WEAP) and includes most water management infrastructure in the study region. Hydropower is simulated assuming historical long term electricity demand and a spill minimization rule. The method is suitable for simulating generation for most of the main watersheds in the region for most watersheds. To assess potential effect of climate warming, the authors considered uniform air temperature increases of 0°C, 2°C, 4°C and 6°C, with no change in precipitation, to approximate regional warming through 2100.
The highly productive northern Sierra Nevada sees large reductions in hydropower generation due to decreases in annual runoff. The central watersheds see less reduction in annual runoff and can adapt better to changes in runoff timing. Generation in southern watersheds, which are less productive, decreases. Results from this study can help identify which watersheds might easily adapt to climate change, where hydropower is likely to conflict with other uses, and where more detailed operational studies are needed.
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