An urban flood-risk assessment of South Jakarta, Indonesia: A methodological approach through frequency ratio, receiver operating curve and analytic hierarchy process.

The main objective of this research is to conduct an urban flood-risk assessment approach for South Jakarta, Indonesia. Flood susceptibility was modelled using the frequency ratio (FR) method and validated with the receiver operating characteristic-area under the curve (ROC-AUC). Vulnerability was assessed using the analytic hierarchy process (AHP) across four domains: physical, economic, environmental and social. We used high-resolution spatial data (1:25 000) and a historical flood inventory to produce rapid, urban-scale risk information where conventional datasets are limited. The susceptibility map shows three classes: low, medium and high; the combined risk map indicates that most of the study area is at medium risk (108.64 km Contribution: This study presents an innovative and practical framework for urban flood-risk assessment, combining FR, ROC-AUC and AHP to evaluate flood susceptibility and vulnerability in South Jakarta, Indonesia. Leveraging high-resolution geospatial data at a detailed 1:25 000 scale, it addresses critical data gaps and equips policymakers with actionable tools to integrate risk sensitive strategies into urban spatial planning for further mitigation. The findings, revealing 74.55% of the area at medium flood risk, set a benchmark for advancing disaster resilience and sustainable urban development, offering valuable applications for other rapidly urbanising, data-constrained regions globally.