Low-Flow Variations in Source Water Supply for the Occoquan Reservoir System Based on a 100-Year Climate Forecast

The onset of climate and land-use change is forcing water managers to develop new techniques in response to the changing environment. This study uses established techniques to incorporate both projected climate change and projected land-use change into a hydrologic model of the Occoquan watershed, which encompasses an area of approximately in northern Virginia. The techniques used develop a future projection of weather that recreates the historic time series, including the drought of record, as influenced by climate change, thereby facilitating integration into existing water-management practices. Incorporating land use and using multiple metrics for analysis of low flow (drought) allows for the determination of variations between the historic and future model flows. This study revealed a likelihood of increased low-flow volumes for the Occoquan watershed from both climate and land-use change, the majority of which were produced from land-use change in combination with expanded reclaimed water supply. Also, the increases from climate change, although influencing measurable changes in flow patterns, were much less than those from land-use change. (C) 2013 American Society of Civil Engineers.