Comparative Analysis of Flood Risk Zoning and Susceptibility Assessment for the Western Corn Belt Plains using Geospatial Techniques

S M Samiul Islam , Ibrahim Demir

Flooding is among the most destructive natural hazards, causing severe socioeconomic and
environmental impacts. Accurate flood susceptibility assessment is critical for effective mitigation
and sustainable resource planning. This study integrates Geographic Information Systems (GIS),
Remote Sensing (RS), and multi-criteria decision-making (MCDM) methods to evaluate flood
vulnerability across four Iowa sub-basins: Middle Cedar, Lower Cedar, Middle Iowa, and Lower
Iowa. Three approaches—Analytic Hierarchy Process (AHP), Fuzzy AHP (FAHP), and Equal
Weighting (EW)—were applied to compare the influence of geophysical and socioeconomic
factors. Key parameters included elevation, slope, land use/land cover (LULC), soil type,
precipitation, river proximity, and low-income households. High-resolution (30-meter) datasets
from SRTM DEM, Landsat-8, and TRMM precipitation sources were processed to develop
composite flood susceptibility indices within a GIS framework. Results reveal significant spatial
variability, with high-risk zones concentrated in low-lying areas near major rivers and socioeconomically vulnerable urban regions. The Middle Cedar sub-basin exhibited the highest
susceptibility, while Lower Cedar and Middle Iowa showed lower risk levels. FAHP demonstrated
greater sensitivity in capturing risk variations compared to AHP and EW models. The findings
underscore the importance of integrating physical and socioeconomic factors into flood
assessments. They also highlight the need for targeted interventions, such as enhancing drainage
infrastructure, equitable resource distribution, and supporting vulnerable populations. This study
delivers a robust, scalable approach for flood susceptibility mapping, offering valuable insights for
policymakers, urban planners, and disaster management authorities to enhance community
resilience and guide flood mitigation strategies in Iowa and similarly flood-prone regions.