Derivation of flood hydrographs using SCS synthetic unit hydrograph technique for Housha catchment area

Abstract

Abstract SCS (Soil Conservation Service) synthetic unit hydrograph technique was used to estimate the storm runoff overflows entering the Housha tunnel. The flood hydrographs were derived under different storm event durations for the ungauged Husha Catchment area. Geomorphological and hydrological parameters of the watershed were extracted using GIS measurement tools. The data identified various parameters (time to peak, time of base, and peak flow) of the synthetic unit hydrograph. The peak discharge (Qp in m3 s−1 cm−1) of rainfall excess for different time durations (5, 10, 20, 30, 60, 120, 180, 360, and 720 minutes) was estimated. The results revealed that the peak discharge (Qp) decreased with the increase in time of rainfall excess. The maximum peak discharge (27.5 in m3 s−1 cm−1) was reached 84 minutes after the beginning of the rainfall storm for 5 minutes of rainfall excess whereas the minimum peak discharge (5.2 in m3 s−1 cm−1) was reached after 7 hours and 22 minutes for 12 hours of rainfall excess. Geographic information system (GIS) data-based SCS synthetic unit hydrograph model was verified by comparing the simulated runoff with the estimated runoff from measured rainfall data of the watershed.