Impact of climate change on hydropower production in Sacramento River hydrologic region

California has the most extensive water supply systems in the country. California reservoirs, more than 1000 reservoirs, play a major role in meeting the state’s water demand (ACWA, 2013). These reservoirs require careful planning and management in order to achieve the optimal balance between different demand sectors. Some of these reservoirs contribute to the state’s power supply through different hydropower plants. Beside some hydraulic and design parameters, the amount of produced hydropower is determined by amount of released water and the available storage. The amount of released water from any reservoir is a function of many factors, such as: climate, precipitation and inflows, demands and environmental requirements downstream. This study examines the implication of Climate Change and Warming on Hydropower production in Sacramento River hydrological region. A simulation model of the study area is built using Water Elevation and Planning System (WEAP). Three main reservoirs for hydropower generation in the study area were included: Shasta Reservoir, Oroville Reservoir, and Folsom Reservoir. Snowpack in west upper slope of the Sierra Nevada Mountains plays a major role in the hydrology of Sacramento River basin. Studies, (Franco et al. 2011) and (Rheinheimer et al. 2014), have shown a possible increase in the California’s air temperature from 1.5 oC to 6 oC, with an expected greater impact on the upper Sierra Nevada Mountains. To assess the impact of such possible increase in air temperature, three warming scenarios were developed. The historical climate data (1964-2014) was collected for each catchment. Then for future projections (2014-2064), three air temperature increase scenarios were developed. The scenarios are 0 oC (no change, for comparison), 2 oC, 4 oC and 6 oC. Air temperature was the only parameter changed, other parameters such as precipitation remained unchanged. The result obtained from the model shows that the increase in air temperature can yield a considerable change in hydropower production. Under 6 oC increase scenario, the reduction in the total hydropower supply over the 50 years (2015-2064) was 9.43% for Shasta, 6.76% Oroville, and 6.44% for Folsom reservoir.