Analyzing Spatiotemporal Changes in Flood Risk Zones to Mitigate Flood Hazards in a Floodplain Area Using a GIS-Based AHP Technique

Storms with intense but brief downpours can cause flooding, a common natural danger, which can cause significant property damage, transit disruptions, and casualties. Comprehensive flood risk zone analysis is crucial for minimizing property and life losses. This study gives a flood risk zone analysis to aid in developing improved flood management and risk reduction measures using a GIS-based AHP technique applied to the selected area of the Teesta and Brahmaputra River floodplain in Gaibandha, Bangladesh. The spatial database was constructed with 30 m × 30 m grid cells using various flood conditioning factors: land use/land cover, altitude, surface slope, drainage density, soil texture, drainage system, topographic wetness index, and rainfall. The most efficient influencing components were identified using the Information Gain (IG) test, and the Weights of Evidence (WoE) technique establishes the relative importance of each element. In the research region, 114 flood spots were found. Of them, 80 (or 70%) were randomly chosen for training, while the remaining 34 (30%) were utilized for validation. The findings showed that all influencing components had a somewhat beneficial impact on the danger of flooding, with altitude and drainage density having the most significant effects. The results show that the very high-risk, high-risk, and medium-risk zones increased by 1.57%, 5.74%, and 9.28% from 2002 to 2022, respectively, and the low-risk zone decreased by 15.63%. The very high-risk and high-risk zones are located along the rivers. This finding may help local governments and researchers develop flood control plans and suggest that increasing the carrying capacity of the existing drainage system, improving science and technology, and the accuracy of weather forecasts may mitigate flood hazards.