ANALISIS KERAWANAN BANJIR DAN IMPLIKASINYA MENGGUNAKAN METODE WEIGHTED OVERLAY PADA SUB-DAS OGAN, KABUPATEN OGAN KOMERING ULU, PROVINSI SUMATERA SELATAN

WULANDARI, ZHALSA and Setiawan, Budhi (2024) ANALISIS KERAWANAN BANJIR DAN IMPLIKASINYA MENGGUNAKAN METODE WEIGHTED OVERLAY PADA SUB-DAS OGAN, KABUPATEN OGAN KOMERING ULU, PROVINSI SUMATERA SELATAN. Undergraduate thesis, Sriwijaya University.

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Abstract

Floods can be caused by several factors, generally due to high rainfall levels, resulting in the river body being unable to accommodate the water discharge that falls to the surface, causing the water to overflow. The research area is the Ogan Sub-Das, administratively located in Sosoh Buah Rayap District, Ogan Komering Ulu, South Sumatra. This study aimed to identify potential flood-prone areas based on several parameters and simulate flood runoff in the study area using HEC-RAS. The primary and secondary data are used. Primary data in the form of lithology-type data to support the results of the flood potential analysis in the study area. Secondary data in the form of satellite imagery data, namely Sentinel-2, DEMNas data, and RBI SHP data. The rainfall analysis in this study was taken based on rainfall station data from BBWS and processed using a probability distribution using the following five methods: Normal Distribution, Log-Normal, Log Pearson III, Pearson III and Gumbel. Among the five distributions, the most suitable one is the Log Pearson III distribution which shows the highest rainfall intensity and can be used for further calculations, namely the calculation of the planned discharge. Through the probability distribution analysis approach using the Log Pearson III method, the highest rainfall value for a 100-year return period reached 258.05 mm. This figure confirms the potential for high-intensity rainfall over a more extended period. This study used several supporting parameters, including slope gradient, soil type, flow density, rainfall, and land cover. These parameters are made in the form of a map and a weighting score (Weighted Overlay) is carried out to obtain a flood vulnerability map in the study area. The overlay results of the five parameters show that most of the study area is classified as Moderately Vulnerable to flooding, which covers around 46.80% or 87.53 km2 of the total study area. Meanwhile, a small part of the other areas, especially those with gentler slopes or denser forest cover, are classified as Not Vulnerable or Somewhat Vulnerable. However, areas with worse soil conditions, especially those experiencing pressure from human activities such as irrigated agriculture, have a high potential for flooding, with several areas falling into the category of Vulnerable or Very Vulnerable to flooding. Areas with high flood potential include Pajar Bulan, Bumi Kawa, and Tanjung Lengkayap. This correlation illustrates that the flood risk in the research area is greatly influenced by the interaction between geological conditions, land use, and hydrological factors depicted in the overlay parameters. The results of the HEC-RAS modeling show that the flood simulation in the research area depicts the river flow that enlarges almost partially in the 100-year return period, the highest inundated area compared to other return periods, with an inundation area reaching 66.65 km2. It can provide an overview of the research area affected by flood runoff.

Item Type:	Thesis (Undergraduate)
Uncontrolled Keywords:	HEC-RAS, Curah Hujan, Kawasan Rawan Banjir, Sub-Das Ogan
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA703-712 Engineering geology. Rock mechanics. Soil mechanics.Underground construction
Divisions:	03-Faculty of Engineering > 34201-Geological Engineering (S1)
Depositing User:	Zhalsa Wulandari
Date Deposited:	13 Jan 2025 07:44
Last Modified:	13 Jan 2025 07:44
URI:	http://repository.unsri.ac.id/id/eprint/164385

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