Abstract
Climate change is projected to have significant impacts on patterns of weather variables all around the world. To study the impacts of climate change on rainfall, different global climate models (GCMs) and climate scenarios are used to build projections for probable future patterns of rainfall. Using the rainfall projections, the change in runoff peaks and volumes can be projected. In this paper, a climate change impact study is presentedto investigate the effect of future uncertain rainfall patterns on urban runoff in the Bronx River watershed in New York City, USA. For the purpose of this study, the U.S. Environmental Protection Agency Storm Water Management Model (EPA SWMM) is developed for the study watershed and driven by precipitation data from the IPCC CMIP5 (Coupled Model Intercomparison Project Phase 5). Three scenarios of maximum, average, and minimum rainfall are defined to cover all the probable thresholds of future rainfall for a time horizon of 30 years. A change factor-based methodology is developed and employed to temporally disaggregate daily rainfall to an hourly basis. Flow-duration curves for climate change scenarios and the simulated runoff using the historical rainfall are compared. The results show climate change impacts to increase flow exceedances, runoff volume, and annual maxima peak discharges.