Hydrologic Modeling System HEC-HMS Application for Direct Runoff Determination

The process of identifying the peak discharge using the rational method was introduced in the 1880s. This method is a simple procedure for determining the peak discharge derived from surface runoff flow. Therefore, this research modified a simple hydrological formulation (rational method) based on fieldwork and compared a numerical rainfall model to the relationship model by using the simulation parameters, namely rainfall, infiltration, land use, and stream for hydrological conditions. The novelty of this research is a modification of the theoretical formula (rational method) through the use of fieldwork factors to modify the run-off coefficient. The first scene-up was overlay mapping between land and land use shape files, while the scene-up sampling point was upstream and downstream. This was continued with the estimation curve number until a specific composite curve number was initiated. The rate of infiltration was determined using the Horton method to distinguish the soil type, while the Water Stage Data Logger Starter Kit 13" HOBO KIT-S-U20-04 was used to measure the water level, HEC HMS, and rating curve analysis. The relationships between the fieldwork data using hydrology analysis and modeling were then compared. The results showed that the maximum rainfall calculated and analyzed from the box-and-whisker plot was 140 mm in the year 2019. In addition, the infiltration rate at the upstream and downstream areas was 90 mm/hour and 26.4 mm/hour, or 30% out of the upstream area value. Finally, the estimations of the runoff coefficient were 0.60, 0.45, and 0.0133, while the discharges for the maximum rainfall intensity were observed at 405.7 m3/s, 304.3 m3/s, and 25 m3/s. The simulation using Hydrological Modelling HEC HMS 4.11 computed results of 0.1 m3/s and observed flow of 0.3 m3/s. Doi: 10.28991/HEF-2023-04-02-02 Full Text: PDF