Modeling the impacts of changing climatic extremes on streamflow and sediment yield in a northeastern US watershed

Abstract

Study region: We investigate the impacts of local temperature and precipitation trends on discharge and sediment loading by applying the model to a watershed in the northeastern US, where trends in increasing precipitation exceed those of other regions in North America. Study focus: In this study we simulate the response of watershed sediment loading to changing frequencies and magnitudes of extreme precipitation events using a coupled model that explicitly simulates streambank erosion and failure within a distributed watershed model. To drive the model, we use meteorological inputs from general circulation models (GCMs) as well as from a statistical weather generator (WG). New hydrological insights for the region: Changes in the timing and magnitude of snow melt and spring flows, as well as associated sediment mobilization, resulted from increases in temperature. Increases in discharge and sediment load resulted from increases in precipitation events exceeding the 95th percentile. In runs driven by WG weather data, positive trends were evident in peak (as well as annual) discharge and suspended sediment yields over the years modeled. No clear trends were seen in GCM-driven runs, which do not capture historically-observed trends in extreme precipitation. This work is consistent with other studies in that it shows important changes in discharge and sediment yields from a watershed resulting from ongoing changes in climate.

Keywords

• Extreme flows
• Suspended sediment
• Peak flows
• Changing precipitation
• Sediment modeling