The Development of Synthetic Unit Hydrograph Suitable to the Hydrologic Characteristics in Korea

Generally, the synthetic unit hydrograph method is presented to estimate the design flood in the ungaged watershed. However, due to the lack of rainfall-runoff data, the models developed in other countries such as U.S.A. and Japan have been widely used in Korea. Therefore, it may be essential to develope the rainfall-runoff model suitable for the hydrological char-acteristics in Korea. In this study, the representative unit hydrographs are derived from rainfall-runoff data at 19 basins in Selma-Cheon and 3-IHP experimental watersheds using ridge-regression method and Nash model. And a new synthetic unit hydrograph for Korea is suggested by integrating the described results and previous studies on unit hydrograph. The newly developed method is represented as two regression forms with three independent variables of watershed area, channel length, and channel slope by multiple regression analysis is carried out for each watershed, the coefficients of determination are not improved in all cases compared out for each watershed, the coefficients of determination are not improved n all cased the synthetic unit hydrograph for each watershed. Therefore, when the new method is applied to some watersheds, the result analyzed for all data has to be used.