THE EFFECT OF RIVER SILNING ON FLOOD POTENTIALS USING HEC-HMS AND HEC-RAS MODEL (CASE STUDY: CITARIK SUB-WATERSHED)

• Main Author: Firdaus, Miftah
• Format: Theses
• Language: Indonesia
• Subjects: Teknik saniter dan perkotaan; teknik perlindungan lingkungan
• Online Access: https://digilib.itb.ac.id/gdl/view/79103
• Institution: Institut Teknologi Bandung

The Citarik sub-watershed is one of the priority sub-watersheds in the upper Citarum watershed. The sustainability of this sub-watershed has an important role in maintaining the preservation of the Citarum watershed, but this sub-watershed has experienced a lot of hydrological function degradation. Increasing population and economic activity have resulted in massive changes in land use which are the main issues of this problem. Indications of damage are felt by the increasing extreme discharge, as well as the increasing value of the coefficient of water runoff, giving rise to the phenomenon of flooding in the rainy season, this phenomenon is exacerbated by sedimentation and silting of rivers, which from year to year this flood phenomenon is getting worse and causing a lot of economic losses. Therefore we need a hydrological and hydraulics modeling of the Citarik Sub-watershed which aims to predict sedimentation, river siltation, and their effect on flood potential using the HEC-HMS (Hydrologic Engineering Center Hydrologic Modeling System) and HEC-RAS (Hydrologic Engineering Center River Analysis) models. system). The model development begins with the data management stage using Microsoft Excel and QGIS (Quantum Geographic Information System), the processed data is then used as the basis for the development of the model structure and parameterization which is supported by the literature. The last setting is done by calibration testing with historical data, if the results of the calibration test are satisfactory then the model can be tested with actual conditions (Validation). Validation was carried out by direct sampling at 8 sampling points related to discharge data, bottom sediment gradations and drift sediments according to SNI. The HEC-HMS discharge model was produced with an NSE of 0.505 and the HECHMS sediment model with an error of 5.433%, while the HEC-RAS had an error in the flood model below 10% and the sediment model was 8.5%. Based on the HECHMS and HEC-RAS running models in the 2022-2025 range with changing rainfall and land use data, it was found that there was a phenomenon of silting of the river due to sedimentation of 107,549.9 m3 which was spread at several points, especially the middle and downstream areas, this phenomenon was also impact on the flooding that occurs which will increase the volume of flooding by 0.92% and an increase in flood height of 12.02%.