Predicting Hydrologic Response to Climate Change in the Luohe River Basin Using the Swat Model

This article assesses the effect of potential future climate change on streamflow in the Luohe River basin. The predicted future climate change by two SRES (Special Report on Emissions Scenarios) climate change scenarios (A2 and B2) and two general circulation models (HadCM3 and CGCM2) were applied. SWAT (Soil and Water Assessment Tool), a physically based distributed hydrological model, was calibrated using daily streamflow records from 1992 to 1996 with a powerful shuffled complex evolution optimization algorithm (SCE-UA) and validated using daily streamflow records from 1997 to 2000. The calibration and validation results showed that the SWAT model was able to simulate the daily streamflow well, with a coefficient of determination and Nash-Sutcliffe efficiency greater than 0.7 and 0.5, respectively, for both the calibration and validation periods. Using the average streamflow from 1992 to 2000 as a baseline, the simulated annual average streamflow showed almost no change in the near future (around 2020) and increased by approximately 10% by 2050. Predicted seasonal average streamflow showed changes within ±20%. Monthly average streamflow showed changes within ±20% for all months except May, which showed predicted monthly streamflow increases of as much as 60%. Based on model results, the Luohe River basin will likely experience a small change in streamflow by the mid-21st century. However, the uncertainty associated with climate change scenarios and general circulation model outputs need to be carefully evaluated in regard to future water policies and strategies.