Spatial modelling of inundation flood using remote sensing and geographic information system in Bogowonto Watershed, Purwodadi and Bagelen, Central Java

Abstract

Purwodadi and Bagelen sub-districts are areas that are frequently inundated by floods from the overflow of the Bogowonto River. These inundations can disrupt community activities and has an impact on material, social and economic damage. Therefore, it is necessary to have an effective and efficient flood potential in the Bogowonto watershed. The purpose of this study is to extract data of land use and river geometry using remote sensing data and geographic information systems for estimating flood discharges and constructing flood inundation spatial models using HEC-RAS and ArcGIS software in return periods 1, 2, 5, 10, 20, 50, and 100 years. Modeling is doing with integrating HEC-RAS and ArcGIS software. This study generally carried out hydrological and hydraulic modeling in the Bogowonto watershed. Hydrological modeling was carried out to convert rainfall data into flood discharge using the Nakayasu Synthetic Unit Hydrograph. The data used is the maximum daily rainfall for 2010-2022 from 10 rain stations in the Bogowonto watershed. Hydraulic modeling was carried out to simulate flood inundation using the HEC-RAS software with 2D unsteady flow simulation. The data required in this study are river geometry, design flood discharge, and Manning's values. River geometry data and Manning's values were obtained visual interpretation from remote sensing data in the form of DEMNAS and Sentinel-2A. The results of the modeling were analyzed and visualized using ArcGIS. This study shows that remote sensing data and geographic information systems can extract land use and river geometry data, which can then be used in flood modeling.