ABSTRACT

Chen, X.; Alizad, K.; Wang, D., and Hagen, S.C., 2014. Climate change impact on runoff and sediment loads to the Apalachicola River at seasonal and event scales.

In this study, potential climate change impacts on runoff and sediment load in Apalachicola River basin in Florida are assessed using Soil and Water Assessment Tool (SWAT), a semi-distributed hydrologic model. The observed streamflow and sediment load from 1984 to 1994 are used for the model calibration and validation. The streamflow Nash-Sutcliffe Coefficients (NSEs) for the simulation and validation periods (1984–1989 and 1990–1994 years) are 0.92 and 0.88, respectively. The sediment NSEs for the simulation and validation periods are calculated to be 0.46 and 0.36, respectively, with excellent description of trend variability. Rainfall data under climate change effects is applied as the calibrated SWAT model input to estimate the streamflow and sediment load change. The rainfall and temperature data is prepared using two regional climate models (RCM); HRM3-HADCM3, and RCM3-GFDL. Results show that the average daily level of streamflow and sediment load will not vary significantly, but the peak flow and peak sediment load will increase dramatically due to the more intense and less frequent rainfall events. The impact of climate change during an extreme rainfall event is also investigated. A storm event with 25-year return period and 24-hour duration in 1991 is taken as the baseline event. Based on the projection using RCM3-GFDL scenario, the streamflow and sediment load may increase by 50% and 89%, respectively.

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