Storage coefficient of merged subbasins

This study investigates the effect of the merging of subbasins on the storage coefficient of the entire basin with the concept of parallel and serial systems of linear reservoirs having different storage coefficients. Based on the linear reservoir theory, both the parallel and serial connections of two subbasins are analyzed and the storage coefficient is derived from the impulse response function of the merged subbasins. The storage coefficient of the entire basin could also be derived by merging subbasins one by one from upstream to downstream. The applicability of the proposed methodology is tested considering the subbasin arrangement of the Chungju Dam Basin in Korea. The findings are as follows: (1) the storage coefficient of a basin with parallel subbasins is represented as the weighted average by the subbasin areas, and that of a basin with serial subbasins is represented simply by the sum of storage coefficients; and (2) the storage coefficient of the Chungju Dam Basin is estimated to be approximately 30.53 h by considering the structure of 44 subbasins, i.e., the combination of parallel and serial subbasins.