Gis-based multi-criteria decision-making for flood risk assessment and potential impacts in the upper tigris basin under global climate change

In this doctoral study, flood risks in the Upper Tigris Basin were comprehensively evaluated under the impacts of global climate change in both temporal and spatial dimensions. The originality of this research lies in integrating temporal trend analyses with spatial Multi-Criteria Decision-Making (MCDM) methods within a unified framework, and in demonstrating, through empirical data, the superiority of the Fuzzy Analytic Hierarchy Process (FAHP) over the conventional AHP in modeling uncertainty and improving decision accuracy. In the first phase, eight parameters representing the hydrological and geomorphological characteristics of the basin (precipitation, slope, elevation, geology, soil, land use, aspect, and distance to rivers) were analyzed within a Geographic Information System (GIS) environment. These criteria were weighted using both AHP and FAHP methods to produce spatial flood risk maps. The results revealed that FAHP provides more flexible, realistic, and consistent outputs for flood risk assessment. In the second phase, precipitation data from 13 meteorological stations covering the 2009–2023 period were analyzed using the Mann–Kendall, Sen's Slope, and Spearman Rho tests. The findings indicated statistically significant increasing trends at the Bismil and Çermik stations, while higher vulnerability levels were observed in Çüngüş, Lice, and Kulp. These trends suggest that climate change may increase the potential for flooding within the basin. Overall, the integrated assessment of climatic trends and spatial factors indicates that flood risk in the Upper Tigris Basin is likely to increase in the future. The results of this study are of critical importance for developing early warning systems, strengthening infrastructure planning, and implementing risk-based land use strategies within the framework of sustainable flood management.