A decade of rainfall, one risk map: GIS-based flood susceptibility mapping in a rapidly urbanizing coastal regency

Abstract

Flooding has become a major hydrometeorological hazard in rapidly developing urban areas, including Tangerang Regency, Banten Province, Indonesia. Increasing rainfall over recent years has intensified flood occurrences, highlighting the need for spatially informed flood-risk assessment. The study analyzed ten years (2015–2024) of rainfall observations obtained from the Budiarto Meteorological Station of the Indonesian Meteorological, Climatological, and Geophysical Agency (BMKG), complemented by Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) satellite rainfall data for GIS-based spatial analysis. Statistical analysis was applied to evaluate rainfall patterns and temporal variability, while GIS-based spatial analysis was employed to delineate flood-prone zones. The results indicate an increasing trend in rainfall during the observation period, with peak rainfall occurring in February and March and average monthly rainfall ranging from 70.86 to 249.90 mm. Spatial analysis identified Kresek, Gunung Kaler, Mekar Baru, Kronjo, Kemiri, Mauk, Sukadiri, Pakuhaji, Teluknaga, and Kosambi as areas with high flood susceptibility. Overall, approximately 34.48% of the study area was classified as as a zone with a high level of flood susceptibility. The integration of long-term rainfall analysis with GIS-based flood mapping provides a robust spatial framework for understanding flood susceptibility in Tangerang Regency. These findings provide a GIS-based framework that can support flood-risk assessment, disaster mitigation planning, and sustainable land-use management in flood-prone regions.