Floodplain Mapping and Risks Assessment of the Orashi River Using Remote Sensing and GIS in the Niger Delta Region, Nigeria

Abstract

Residents along the shoreline of the Orashi River have yearly been displaced and recorded loss of lives, farmland, and infrastructures. The Government’s approach has been the provision of relief materials to the victims instead of implementing adequate control measures. This research employs Shuttle Radar Topographic Mission and Google Earth imagery in developing a 3D floodplain map in ArcGIS 10.4. The result indicates the drainage system in the study area is observe to be dendritic with catchment of 79 subbasin with 76 pour point indicating the area is floodplain including 3D slope > 8 contain 1.15% and < 8 has 98.85% indicating floodplain area, aspect indicate west-facing slope are dark blue,3D hillshade indicate yellow is very low area and high area is pink and also the buffer analysis result reveals waterbodies reflecting blue with estimated area of 1.88 km^2, yellow indicate 0.79 km² of the shoreline, red indicate 0.81 km² of the minor floodplain and pink contain 0.82 km2 with length of 32.82km. The result from google earth image in 2007 indicate absent of settlement ,2013 indicate minimal settlement and 2020 indicate major settlement in the study area when correlated with 3D Floodplain mapping before and during the flood in other to analyze and manage flooding for further purpose and majority of the area are under seize with flood like in 2020. Therefore, Remote Sensing and GIS techniques is useful for Floodplain mapping, risk analysis for control measures for better flood management.