Flood Discharge For Ungauged Catchment At Teriang River, Pahang By Using HEC-HMS

Abstract

Insufficiency of meteorological data during extreme rainfall events hinders simulation and forecasting analysis in flood mitigation systems. Hence, the existence of a reliable database in hydrology is crucial in flood modelling for ungauged catchments, especially for calibration and validation purposes. This paper focused on the generation of rainfall data by using Hydrological Procedure No. 1 (HP1) from the Department of Irrigation and Drainage (DID) Malaysia. Subsequently, analysis of flood hydrographs at Teriang River, Pahang, Malaysia, using HEC-HMS 4.8 for 50 and 100-year return periods was also obtained in this study. For validation purposes, the outcomes were compared to Hydrological Procedure No. 11 (HP11), designed for rural catchments. For precipitation data generation, the design rainfall was calculated based on generalised isopleth maps from HP1 for various rainfall durations ranging from 0.25 hours to 72 hours. Based on the results, the maximum peak discharge for 50 ARI was 354.7 m³/s, while for 100 ARI it was 410 m³/s before calibration. Comparing the results from the HEC-HMS model and the outputs from HP11, the analysis for 50-year and 100-year return periods in the Teriang River showed that the relative percentage differences for peak discharge were 19.99% and 17.64%, respectively. The calibration process managed to obtain a relative percentage difference of 2.94% for 50 ARI and 4.36% for 100 ARI. In conclusion, HEC-HMS can be used as a reliable tool to produce simulated streamflow for ungauged catchments with the help of the generated rainfall temporal patterns from HP1, which is a procedure that contains estimation of design rainfall intensity based on the rainfall intensity-during-frequency relationship (IDF relationship).