Evaluating SWAT Snowmelt Parameters and Simulating Spring Snowmelt Nonpoint Source Pollution in the Source Area of the Liao River

Snowmelt hydrology becomes an important component of the soil and water assessment tool (SWAT) when spring flows are dominated by melting snow. The objective of this study was to evaluate the performance of the SWAT model's snowmelt parameters by simulating nonpoint source pollution in the source area of the Liao River - a cold area in China. The seven snowmelt parameters for the simulation were adjusted. The exports rule of nonpoint source pollution for the spring snowmelt period was analyzed. The result show that SFTMP, SMTMP, SMFMX, SMFMN, and TIME' were sensitive parameters, while SNOCOVMX and SNO50COV were insensitive. In addition, two common statistics (Nash-Sutcliffe coefficient, and coefficient of determination) were used to evaluate the model. This evaluation indicated that the SWAT model had good performance simulating the seasonal nonpoint source pollution with large snowmelt. According to the analysis, rainfall and snowmelt is a main driver of nonpoint source pollution in the cold area, and that summer and spring are high-risk seasons. The study provides a new and suitable method of nonpoint source pollution simulation for the cold areas.