Flood Mitigation of Upper Citarum Base on HEC-HMS Model

Mitigasi Banjir DAS Citarum Hulu Berbasis Model HEC-HMS

Abstract

Floods that occur almost every year in the Upper Citarum River Watershed cause these watersheds to be in the spotlight of various parties. Hydrological modeling is one of the flood mitigation techniques for predicting flood discharge in a watershed. The HEC-HMS model can be used for prediction flood discharge base for analysis of a catchment system, particularly for calculating the unmeasured rainfall-runoff. HEC-HMS consists of rainfall and catchment characteristics as input and flow discharge and runoff volume as output. The objectives of this research are: (i) to the overview performance of the HEC-HMS model to predict peak discharge in Upper Citarum Watershed; (ii) to analyst of flood discharge using simulation HEC-HMS model; (iii) to recommend flood mitigation scenario to reduce peak discharge in Upper Citarum Watershed. Primary preparation of HEC-HMS model parameter input calculated by HEC-GeoHMS with the SCS method. Flood discharge calculated in the HEC-HMS model by SCS- Unit Hydrograph method for transform component, recession method for baseflow component, and lag method for routing component. The result showed that the HEC-HMS model has good performance in predicting flood discharge with R² and NSE value in the calibration process by 0.81-0.96 and 0.56-0.87. The validation process in predicting flood discharge produced R² and NSE value by 0.81-0.94 and 0.45-0.76 respectively. 4th scenario is best practice management that can be implemented in reduced peak discharge up to 61.96%, to increase time to peak by 3.75 hours and reduce volume discharge up to 49.58%.