Assessing Rainfall Contribution to Storm Flow on a Small Forested Catchment in Republic of Korea

The TOPMODEL was employed to analyze rainfall contribution to runoff generation in a 58.3-ha Myeong- seong catchment in Korea. The parameters of the model were calibrated using Monte Carlo simulation by comparing the observed and simulated runoff volume across nine recorded storm events. Parameter estimations gave the model an efficiency of 0.93 for the entire event set. Mean fraction of rainfall to storm flow was 23.1 %, ranging from 5.6 to 48.3 %. Variations were also observed in rainfall contribution related mainly to antecedent moisture conditions and other hydrological properties of the catchment. Quick response flow that was estimated from the saturated overland flow in the model comprised 41.9 -75.9 % of the total runoff for nine storm events, while base flow accounted for 41.7 % of streamflow for all events. No significant relationship between rainfall amount and quick response flow was found. This study introduced a modeling approach to identify the source of streamflow on a forested catchment. Difficulties in predicting accurately the runoff were encountered. In general, immense and high quality data are required to over- come the complexity of hydrologic processes that occur in forested catchments. Key words: Hydrology, runoff, storm, streamflow, TOPMODEL