Long-Term Simulation of Daily Streamflow Using Radar Rainfall and the SWAT Model: A Case Study of the Gamcheon Basin of the Nakdong River, Korea

In recent years, with the increasing need for improving the accuracy of hydrometeorological data, interests in rain-radar are also increasing. Accordingly, with high spatiotemporal resolution of rain-radar rainfall data and increasing accumulated data, the application scope of rain-radar rainfall data into hydrological fields is expanding. To evaluate the hydrological applicability of rain-radar rainfall data depending on the characteristics of hydrological model, this study applied R-gauge and R-radar to a SWAT model in the Gamcheon stream basin of the Nakdong River and analyzed the effect of rainfall data on daily streamflow simulation. The daily rainfall data for R-gauge, R-Z, and R-KDP were utilized as input data for the SWAT model. As a result of the daily runoff simulation for analysis periods using R-Z(P) and R-KDP(P), the simulation which utilized R-gauge reflected the rainfall-runoff characteristics better than the simulations which applied R-Z(P) or R-KDP(P). However, in the rainy or wet season, the simulations which utilized R-Z(P) or R-KDP(P) were similar to or better than the simulation that applied R-gauge. This study reveals that analysis results and degree of accuracy depend significantly on rainfall characteristics (rainy season and dry season) and QPE algorithms when conducting a runoff simulation with radar.