Abstract
Recent studies show that climate change is occurring and may lead to significant changes in the environment. These changes may directly affect weather patterns and the intensities of storms experienced in California. With the State being heavily dependent on its flood control system, climate change’s effects on weather may increase risks of flooding. The State of California’s Department of Water Resources (DWR) has begun to focus on the potential increase in risks of flooding due to climate change and increasing the sustainability of the State’s flood control systems. The purpose of this study was to examine the effects of increased rainfall on peak runoff magnitudes on the Ulatis Creek Watershed located in California’s Central Valley. Analysis was completed using estimated changes in precipitation developed by Das et al. (2011) and a rainfall-runoff model developed for the Central Valley Hydrology Study (CVHS) by the United States Army Corps of Engineers (USACE). Das et al. (2011) used downscaled general circulation models (GCMs) to develop estimates to changes in precipitation. Rainfall runoff modeling was completed using the Hydrologic Modeling System developed by the USACE’s Hydrologic Engineering Center (HEC-HMS). Results of this study show that increased precipitation resulted in increased runoff peaks. Using the maximum precipitation estimates of an increase of 10.7 percent in early century epoch, and 3.0 percent in the late century, the resulting runoff increased approximately 13.5 percent and 3.7 percent respectively. Reduced precipitation estimates of -0.5 percent in the early century and -10.1 percent in late century estimates, yielded reduction in flow magnitudes of -0.64 and -12.5 percent, respectively. Further analysis would be needed in order to accurately predict the effects of climate change on peak runoff. With many uncertainties in climate change estimations and modeling assumptions, it is difficult for law makers to develop approaches to planning for future flood risks.