1998 Volume 1998 Issue 193 Pages 61-67,a2
Knowledge of retention characteristics of watershed is essential for conducting proper watershed management. However, the methods for quantification of retention characteristics of watershed in long-term period have not been developed yet. This paper proposes a method using reservoir model for quantifying retention capacity of watershed as a retention capacity index. The method was applied to four catchment areas located in Tochigi and Ibaraki Prefecture. Simulations were carried out to analyze the effects of different rainfall pattern on retention capacity of watershed. If the same rainfall pattern was used as input to the model, the order of retention capacity indices among study areas were the same. That order were reasonably explained by general recognition on relation between physical and geomorphologic characteristics of watershed and retention capacity. For comparison of retention capacity among watersheds based on their retention capacity index values, standard rainfall to beused as input to the model has been decided through simulation with hypothetical rainfall.