Impact of projected 21st century climate change on basin hydrology and runoff in the Delaware River Basin, USA

A gridded hydrologic model was developed to assess the impact of projected climate change on future Delaware River Basin (DRB) hydrology. The DRB serves as a water supply resource to over 15 million people. Model evaluation statistics for both water year and monthly runoff projections indicate that the model is able to capture well the hydrologic conditions of the DRB. Basinwide, annual temperature is projected to increase from 2.0 to 5.5 degrees C by 2080-2099. Correspondingly, potential and actual evapotranspiration, precipitation, rainfall, and runoff are all projected to increase, while snowfall, snow water storage, snowmelt, and subsurface moisture are all projected to decrease. By 2080-2099, basinwide summer subsurface moisture is projected to decrease 7-18% due to increased evapotranspiration, while winter runoff is projected to increase 15-43% due to increased precipitation and snowmelt and a conversion of snowfall to rainfall. Significant spatial variability in future changes to hydrologic parameters exists across the DRB. Changes in the timing and amount of future runoff and other hydrologic conditions need to be considered for future water resource management.