Abstract
<title>Abstract</title> <p>Flooding poses a significant threat to urban areas in developing countries, with Adama City, Ethiopia, experiencing recurrent flash floods that severely affect livelihoods and infrastructure. Previous flood hazard assessments in the study area have predominately engaged Conventional Analytical hierarchy process (AHP) approaches, which rely on crisp pairwise comparisons that fail to capture the inherent uncertainty and vagueness in expert judgements. This study addresses this methodological gap by employing the Fuzzy Analytical Hierarchy Process (FAHP) integrated with Geographic Information System (GIS) to assess flood hazards in Adama City and its surrounding region. Twelve Comprehensive flood-conditioning factors covering meteorological, topographic, geomorphological, and hydrological subsystems were integrate within fuzzy decision-making framework. Chang’s extent analysis method was applied using triangular fuzzy numbers (TFNs) to handle expert judgement uncertainty, with consistency ratio verification (CR= 0.062 < 0.10) that confirming the logical coherent of expert assessments. Results identify rainfall (18%), flow accumulation (15%), and elevation (12%) as primary flood drivers, while aspect (3%) shows minimal influence. The resulting flood hazard map classifies 9.70%, 20.75%, and 32.63% of the study area as very high, high, and moderate hazard zones, respectively. Validation using AUC-ROC demonstrates excellent predictive capacity (AUC=0.834). FAHP substantially improved hazard classification compared to AHP, reclassifying approximately 36% of ambiguous zones into extreme categories. Sensitivity analysis showed the reliability and stability of the highest-ranked factors while at the same time indicating moderate sensitivity of intermediate ranked variables. These findings provide a scientifically robust foundation for evidence-based urban planning and flood mitigation strategies in Adama City.</p>