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Floods are the most common and costly disasters worldwide, while spatial flood risk assessment is still challenging due to fewer observations and method limitations. In this study, the flood risk zonation in the Nile districts of the Damietta branch, Egypt, is delineated and assessed by integrating remote sensing with a geographic information system, and an analytical hierarchy process (AHP). Twelve thematic layers (elevation, slope, normalized difference vegetation index, topographic wetness index, modified normalized difference water index, topographic positioning index, stream power index, modified Fournier index, drainage density, distance to the river, sediment transport index, and lithology) are used for producing flood susceptibility zonation (FSZ) and six parameters (total population, distance to hospital, land use/land cover, population density, road density, and distance to road) are utilized for producing flood vulnerability zonation. Multicollinearity analysis is applied to identify highly correlated independent variables. Sensitivity studies have been used to assess the effectiveness of the AHP model. The results indicate that the high and very high flood risk classes cover 21.40% and 8.26% of the area, respectively. In 14.07%, 27.01%, and 29.26% of the research area, respectively, flood risk zones classified as very low, low, and moderate are found. Finally, FSZ is validated using the receiver operating characteristics curve and area under curve (AUC) analysis. A higher AUC value (0.741) in the validation findings demonstrated the validity of this AHP approach. The results of this study will help planners, hydrologists, and managers of water resources manage areas that are susceptible to flooding and reduce potential harm. [ABSTRACT FROM AUTHOR]

The Himalayan region is the most sensitive due to its fragility, especially in soil erosion; therefore, it is a growing concern for environmentalists and natural resource planners. The study river basin Mandakini is situated in the central part of the Garhwal Himalayan region (Uttarakhand, India), which is highly prone to soil erosion due to various hydro-geomorphological factors. The factors include precipitous slope, geology, rugged terrain, land use and drainage pattern. Therefore, to identify the erosion-prone areas of the study basin, employed watershed prioritization technique using geographical information system and remote sensing integrated with weighted sum analysis (WSA), sediment production rate (SPR) and Technique of Order Preference Similarity to the Ideal Solution with Analytical Hierarchical Process (AHP-TOPSIS) models. It is calculated by taking different parameters indicating linear, landscape, and shape parameters. All the sub-watersheds (SW) of the basin were prioritized in different categories for all models with model performance for the Mandakini river basin in the central Himalaya. The results are showing almost similar results except for high erosion-prone regions. The results of the SPR model indicate that vary large areas (43.47%) of the basin suffering from severe erosion limited in the north-central (WS11, WS12, WS21), eastern (WS2), and southern (WS22 and WS23) parts of the basin among 23 sub-watersheds. The result of model evaluation indicates AHP-TOPSIS is the efficient model in assessing soil erodibility. The study can help to undertake the precise decisions to propose an effective framework for soil erosion control measures and encourage soil conservation priorities of the region. The findings have implications for defining sustainable land resource management and conservation, which are critical to attaining the United Nations' 2030 Agenda for Sustainable Development's societal goals. [ABSTRACT FROM AUTHOR]