Spatial-Based Flood Susceptibility Mapping Using Analytical Hierarchy Process Techniques (Case Study: Gresik Regency)

Over the past four years, Gresik Regency has frequently been hit by floods. In 2019, there were 17 occurrences, followed by 13 occurrences in 2020, 19 occurrences in 2021, and a rise to 33 occurrences in 2022. To support the 11^th Sustainable Development Goals (SDGs) on sustainable cities and communities, especially in the mitigation of water-related disasters, research on flood-prone areas in Gresik Regency is needed. This study analyzes flood-prone areas in the Gresik Regency using the Analytical Hierarchy Process (AHP) and weighted overlay methods to provide information to the community and agencies to be used as a reference in disaster mitigation. The data utilized include the Digital Elevation Model, river network data, Sentinel image data, soil type data, rainfall data, and questionnaire results. The criteria used in this research are land elevation, slope, land cover, river distance, soil type, rainfall, and flood extent. Results show that rainfall criteria have the highest weight at 25%, followed by elevation at 17%, flood extent at 17%, land cover at 15%, river distance at 10%, slope at 9%, and soil type at 7%. The area of Gresik Regency classified as low vulnerability is 8.79 km² or 0.82% of the total area, the medium vulnerability category is 936.13 km² or 87.60% of the total area, and the high vulnerability category is 123.66 km² or 11.57% of the total area. The most flood-prone sub-districts are Driyorejo with 28.46 km² of highly vulnerable flood-prone area, followed by Wringinanom with 13.17 km², and Benjeng with 12.50 km².