Impacts of Spatial Interpolation Methods on Daily Streamflow Predictions with SWAT

Precipitation is a significant input variable required in hydrological models such as the Soil & Water Assessment Tool (SWAT). The utilization of inaccurate precipitation data can result poor representation true hydrologic conditions catchment. SWAT utilizes conventional nearest neighbor method assigning weather parameters for each subbasin; representing spatial variations over large area, with sparse network gauging stations. Therefore, this study aims to improve variation daily streamflow simulation SWAT, even pre-model calibration. based on four interpolation methods, (default), inverse-distance-weight, radial-basis function, and ordinary kriging, were evaluated determine which best represents at Yongdam watershed. Based results study, application methods generally improved performance simulate In addition, no universal accurately represent long-term Instead, it was observed that optimal selection watershed dependent climatological It also certain meteorological watershed: cases when occurrence probability extreme high during wet moderately conditions; function number dry days high, wet, severely dry, extremely kriging or inverse-weight-distance conditions. methodology applied simulations watershed, calibration SWAT.