The limiting physical parameter of Nakayasu synthetic unit hydrograph

Abstract

Hydro-logical approaches in the watershed systems have granted great contributions to the hydraulic structured planning. However, it is not too easy to understand the process of run off thoroughly. The important factor in the waterworks design is to know the flood which is happened and this value will determine the dimension of waterworks which is closely related with the risk and the economic value of waterworks design. The Synthetic Unit Hydrograph is a popular method that is used in many designs of waterworks mainly in analyzing the design flood of ungauged watershed. One of them that is usually used in Indonesia is the Nakayasu Synthetic Unit Hydrograph which is found based on the observation in Japan (1948). This model is depended on the corrected factor of α influential one on the ordinate and time base of unit hydrograph. This study intends to investigate the influential factors to the physical parameter of α on the Nakayasu Synthetic Unit hydrograph. The limiting physical parameters is predicted increasingly related to the morphometric factors of watershed.