Future Water Budgets and Water Supply Stress under Climate Change and Urbanization in the Upper Neuse River Basin, North Carolina, USA

Urbanization and climate change are the two major threats to watersheds and the environment in the United States. It is imperative to understand the sensitivity of hydrologic responses to climate and urbanization across different physiographic regions in order to formulate sound watershed management strategies and policies. This study evaluated a watershed water balance model, Water Supply Stress Index (WaSSI), with measured historic streamflow data for the Upper Neuse River basin in central North Carolina. A user-friendly web version of the WaSSI model was applied to examine how climate change and potential urbanization over the next 50 years may affect streamflow (or water yield) of this river basin and water supply stress (water demand/water supply). Our simulation study suggested that urbanization could increase water yield (8%), while climate change could reduce (30%) water yield depending on future changes in precipitation and warming potential in the study basin. Climate change is likely to overwhelm the basin-wide impacts of urbanization in terms of its influences on water supply stress, but urbanization may aggravate the environmental problems by increasing stormflow and water quality degradation under a changing climate. Future climatic change models should reduce the uncertainty of climate projection in precipitation, a major control on watershed hydrology.