A Framework for Assessing Flash Flood Risks in Urban Geological Settings

Thesis Abstract

Urban areas worldwide increasingly face the threat of flash floods, driven by rapid urbanization, inadequate drainage infrastructure, and complex geological conditions that influence runoff patterns. This study addresses the critical need for a comprehensive framework to assess flash flood risks within urban geological settings, where heterogeneity in subsurface materials and land use significantly affect flood dynamics. The primary aim is to develop an integrative model that combines geological, hydrological, and infrastructural variables to improve predictive accuracy and inform urban flood risk management. Specific objectives include identifying key geological factors influencing flash flood susceptibility, evaluating existing risk assessment methods, and designing a multi-criteria framework for urban flood hazard evaluation. Employing a mixed-method research design, the study synthesizes quantitative and qualitative approaches to ensure robustness and contextual relevance. The population comprises urban districts within a metropolitan city characterized by diverse geological formations and recorded flash flood events over the last decade, with a total of 15 districts selected for detailed analysis. A sample of 300 households, obtained through stratified random sampling, provides insight into local awareness and exposure, while geotechnical and hydrological data are collected from 50 boreholes and rainfall stations across the districts. Primary data are gathered using structured questionnaires, geological mapping, geotechnical testing, and remote sensing imagery. Secondary data sources include municipal flood records, geological surveys, and hydrological models. Data analysis integrates Geographic Information System (GIS) spatial analysis, statistical techniques such as multiple regression analysis to identify predictors of flood occurrence, and the Analytical Hierarchy Process (AHP) for weight assignment of risk factors. The study further applies thematic analysis to qualitative interview data to understand community perceptions and adaptive capacities. The developed framework incorporates geological heterogeneity, surface runoff potential, infrastructure resilience, and socio-economic vulnerability, structured according to principles from the Pressure and Release (PAR) model and the Flood Risk Management Theory. Expected findings include a statistically significant correlation between geological factors (e.g., soil permeability, bedrock type), land use patterns, and flash flood incidence. The research anticipates that the integrated model will outperform existing single-variable approaches by providing a nuanced spatial risk map, essential for targeted intervention. The framework aims to identify high-risk zones and prioritize areas for intervention, infrastructure reinforcement, and community awareness campaigns. This research contributes to the growing body of knowledge by offering a tailored, scientifically validated tool for urban flood risk assessment that incorporates geological complexity. It advances theoretical understanding of flood risk dynamics in heterogeneous urban environments and demonstrates a practical application of multi-criteria decision-making in urban resilience planning. Policymakers, urban planners, and disaster management agencies can utilize this framework to develop evidence-based strategies for flood preparedness, mitigation, and response. In conclusion, the study underscores the necessity of integrating geological insights into urban flood risk assessments. It recommends adopting the proposed framework within municipal planning to enhance urban resilience against flash floods and encourages further research into real-time data integration and climate change impacts on flood risk dynamics. The findings advocate for interdisciplinary collaboration among geologists, hydrologists, urban planners, and community stakeholders to develop sustainable and adaptive urban infrastructure capable of withstanding flash flood hazards.