Rainfall-runoff simulation for design flood estimation in small river catchments

Abstract

This paper presents development and application of the model aimed at simulating peak flood runoff from the small river basin Obnica in Serbia (having an area of 185 km2) with an aim to estimate design floods using different approaches. The model is developed using the HEC-HMS software (The United States Army Corps of Engineers (USACE) Hydrologic Centre?s Hydrologic Modelling System). The model is calibrated against eight events with observed hydrographs and corresponding rainfall, and verified with a separate set of events. Flood hydrographs are simulated with the constant intensity design storms of various durations and with the 24-hour design storm with design hyetograph determined using the alternating block method. All design floods obtained from the simulated hydrograph peaks are compared with the design floods estimated by statistical analysis of annual maximum flows. The results have shown that the temporally distributed 24-hour storms yield the design floods that are the closest to the statistically derived design flows, while the constant intensity storms cannot reproduce the statistically derived design flows.