FLOOD HAZARD ANALYSIS AND POLICY PRIORITIZATION USING INTERPRETATIVE STRUCTURAL MODELING IN PADANG CITY, INDONESIA

Abstract

Flooding in tropical coastal urban areas is increasingly influenced by a combination of intensified extreme events and increased spatial exposure resulting from uncontrolled land use. Therefore, this study aimed to analyze flood prone areas using spatial based hazard mapping validated with an Cyclone Senyar extreme event, so that the hazard classification accurately reflects actual flooding conditions. Furthermore, the resulting hazard and exposure patterns serve as an empirical basis for determining and prioritizing risk-reduction policies using Interpretative Structural Modeling (ISM). The analysis showed that 6 percent of the city's area fell within the low hazard class, 42 percent within the moderate class, 25 percent within the high class, and 27 percent within the very high class, with a dominant concentration in river corridors and coastal lowlands. Spatial overlay identified 186,621 buildings within the hazard zone, including 15,674 buildings located in the riverbank area, which was regulated as a protected zone. The extreme event on November 28, 2025, had significant impacts on residential areas and infrastructure, further strengthening the relationship between spatial exposure and loss magnitude. Furthermore, the ISM results showed that Enforcement of Spatial Utilization and Control Regulations, as well as Disaster Mitigation-Based Spatial Planning, were the policy elements with the highest driving force and served as the foundation for other interventions. Therefore, long-term flood risk reduction depended not only on structural mitigation but primarily on controlling exposure through consistent spatial governance, accompanied by effective regulatory oversight and enforcement mechanisms.