Estimating impact of rainfall change on hydrological processes in Jianfengling rainforest watershed, China using BASINS-HSPF-CAT modeling system
Climate change over the past several decades has resulted in shifting rainfall pattern and modifying rain-fall intensity, which has exacerbated hydrological processes and added the uncertainty and instability tothese processes. This study ascertained impacts of potential future rainfall change on hydrological pro-cesses at the Jianfengling (JFL) tropical mountain rainforest watershed in Hainan Island, China usingthe BASINS (Better Assessment Science Integrating Point and Nonpoint Sources)-HSPF (HydrologicalSimulation Program-FORTRAN)-CAT (Climate Assessment Tool) modeling system. The HSPF model wascalibrated and validated with available measured data prior to its applications. Three simulation scenar-ios were then performed to gain a better understanding of the impacts of different rainfall rates and stormintensities on stream discharge, surface water runoff from forest land, and water outflow from the JFLwatershed outlet. Results showed that a 10% increase in rainfall rate could result in 1.3 times increase instream discharge, surface runoff, and water outflow. A potential future wet climate could have profoundimpacts on hydrological processes at the JFL watershed, whereas a potential future dry climate couldresult less impacts on stream discharge, surface runoff, and water outflow at the same watershed. Oursimulation further revealed that climate change driven by extreme rain storms had greater impacts onannual surface runoff than on annual stream discharge. The coupled CAT-HSPF model is a useful toolto modify historical rainfall data for projecting future rainfall variation impacts on forest hydrologicalprocesses due to climate change. This approach would be able to extend to other regions around theworld.