Geo-spatial Mapping and Multi-criteria Analysis of the Downstream Flood Risk Settlements of Usman Dam Abuja-Nigeria

Terwase YOUNGU, Samuel AZUA, Yahaya ALIYU, Aliyu ABUBAKAR, Adamu BALA, AbdulAzeez ALIYU and Moses JOEL, Nigeria

Flooding is a worrisome phenomenon especially in recent decades due to its effect on human life and man’s environment. This study thus mapped and analysed flood risk settlements in the downstream of Usman dam in Abuja, Nigeria, using geospatial techniques. Spatial data were captured which included positional coordinates, Landsat 7 (ETM+), soil map and the shuttle radar topographic mission (SRTM). The factors of flooding and their effect on the area under study were identified. The study results revealed that criteria weights slope (0.24) and elevation (0.24) were the most important factors contributing to flooding in the study area. Other ranking factors identified include drainage proximity (0.16), land use land cover (0.12) and soil (0.08) respectively. The results also showed that, the built-up area, farmland, forest, grassland, rock outcrop and water body covered about 278.0 km2, 306.9 km2, 1406.6 km2, 1635.8 km2, 387.5 km2 and 386.9 km2, respectively of the study area. Moreover, it was found out that 6.41% of the settlements were located in the highly vulnerable areas, while 64.02% were located within the areas moderately vulnerable to flooding. However, the remaining 29.57% were located in low vulnerable areas. It was suggested based on the results of the study that settlements close to the river course and dam reservoir, and along the flood plains should be relocated to the low vulnerable areas (east of the study area) in order to limit the impact of future flood hazard.

Event: FIG Working Week 2020 – CANCELLED – Smart Surveyors for Land and Water Management

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Document type:Geo-spatial Mapping and Multi-criteria Analysis of the Downstream Flood Risk Settlements of Usman Dam Abuja-Nigeria (822 kB - pdf)