Estimation of Streamflow using SWAT: A Case Study of Upper Lam Phra Phloeng River Basin

Abstract

SWAT is embedded with Geographic Information System or GIS. The parameter distributions of SWAT were monthly analyzed to estimate the mean monthly streamflow in the Upper Lam Phra Phloeng River Basin. The mean monthly streamflow was analyzed using rainfall data at return period 10 year 20 year 50 year and 100 year. Moreover, the input data of this model were consisted of the Digital Elevation Map (DEM), land use, soil characteristic, weather data, and hydrological data. The monthly calibration at M.171 station during 2004-2008 were consisted of a coefficient of determination (R2) = 0.84 and a Nash-Sutcliffe efficiency (NSE) = 0.84. Thereafter, the results of monthly validation during 2009-2010 were contained a coefficient of determination (R2) = 0.89 and a Nash-Sutcliffe efficiency (NSE) = 0.90. Then, SWAT is suitable for the mean monthly streamflow computation in the Upper Lam Phra Phloeng River Basin. The results presents that the mean annual streamflow to the Lam Phra Phloeng reservoir at return period 10 years, 20 years, 50 years and 100 years are 94.11 MCM, 104.94 MCM, 136.68 MCM, and 153.91 MCM, respectively. Therefore, the capacity of the Lam Phra Phloeng reservoir should be increased to serve the downstream area. In addition, the conservation forest, the small reservoirs, and dams should be considered in the upstream sub-basin. For the downstream sub-basin, the river should be dredged to drainage water into the Lam Phra Phloeng reservoir.