Journal of Korean Society of Agricultural Engineers ISSN:1738-3692(Print) 2093-7709(Online) 한국농공학회논문집

This study describes the estimation of upstream ungauged watershed streamflow using downstream discharge data. For downstream Dongchon (DC) and upstream Kumho (KH) water level stations in Kumho river basin (2,087.9 km²), three methods of Soil and Water Assessment Tool (SWAT) modeling, drainage-area ratio method and regional regression equation were evaluated. The SWAT was calibrated at DC with the determination coefficient (R²) of 0.70 and validated at KH with R² of 0.60. The drainage-area ratio method showed R² of 0.93. For the regional regression, the watershed area, average slope, and stream length were used as variables. Using the derived equation at DC, the KH could estimate the flow with maximum 41.2 % error for the observed streamflow.