Derivation of Flood Hydrographs for Ungauged Upstream Subwatersheds Using a Main Outlet Hydrograph

Abstract

Understanding watershed systems is a necessary prerequisite for comprehensive management of the overall basin. Applying simple hydrologic techniques, for which fundamental information is available, is a feasible solution for determination of subwatershed contributions to the generation of total runoff. In this study, an attempt was made to develop an analytical procedure through which the outflow hydrographs could be determined for each subwatershed/area. The technique was based on reverse application of the Muskingum hydrologic routing model and the Area-CN role factor. The technique introduced was then tested to determine if it could solve flood routing problems associated with data for which the input hydrographs were known. A high degree of affinity (i.e., relative error below 32%) was observed between the estimated hydrographs and the recorded data, which verified the satisfactory applicability of the developed approach for estimation of the runoff generated by each subwatershed/area.