FLOOD SUSCEPTIBILITY ASSESSMENT USING GEOSPATIAL ANALYSIS: A CASE STUDY OF NORTHERN ORANGE COUNTY IN CA

The likelihood of experiencing a megaflood in California has increased due to climate change. Southern California, in particular, is highly vulnerable to floods because of its topographic, hydrologic, and urban characteristics. The combination of varied terrain, intense seasonal precipitation, and urbanization creates significant challenges for flood management. Assessing flood susceptibility is therefore critical for identifying high-risk areas, enhancing community preparedness, and developing effective mitigation strategies. In this study, a flood susceptibility assessment was conducted for North Orange County (NOC) as a case study using geospatial analysis in the Geographic Information System (GIS) environment. Five key factors that influence flood occurrence were incorporated into the analysis, including precipitation, soil texture, drainage density, topographic elevation and slope. A weighted overlay analysis was performed to integrate these factors and classify the region into flood susceptibility zones, ranging from low to high risk. The resulting flood susceptibility map was then compared with the flood map provided by the Federal Emergency Management Agency (FEMA) for validation. The analysis revealed spatial variations in flood susceptibility across NOC. The results offer valuable insights for prioritizing flood-prone areas and can inform targeted flood mitigation strategies. Ultimately, this study provides a tool for integrating geospatial datasets and analytical approaches to support community resilience efforts and mitigate the adverse impacts of future flooding events.