Detection and Mapping of Flood Prone Areas of Jimeta, Adamawa State, Nigeria

Abstract

The detection and mapping of flood prone areas in Jimeta Metropolis using remotely sensed data and Geographic Information System (GIS) is aimed at identifying areas that are potentially susceptible to urban flooding. The objectives of the study include; analyzing the physical terrain attributes such as elevation, slopes, and drainages among others in relation to urban settlement under flood risk, to prepare Digital Terrain Model (DTM) and flood simulation model to serve as a tool for managing flood plains. The elevation data was obtained from Earth explorer (SRTM Dem) and Google earth (Landsat image). The satellite image from google earth software online has the advantage of taking points data with ease and was obtained at regular intervals. The study area was gridded into 400 grid squares that gave rise to 441 intersections of the grid lines which serve as the points whose X,-Y and Z coordinates were taken. Surfer 8 and ArcGIS 10.2 version were used to create Surface Elevation Model (SEM) and Digital Elevation Model (DEM) respectively. Other flood assessment maps such as detail contours and flood simulation models were created and analysed. The result reveals two extensive Benue floodplains at the northern and southern fringes of Jimeta metropolis. The factor that was responsible for serious flood hazards in Jimeta metropolis is the backflow of the runoffs due to insufficient carrying capacity of the River Benue and Lake Gerio which was filled with sediment deposits leaving very narrow channel and shallow reservoir respectively. The susceptible flood risk areas were identified and mapped using Buffer analysis for zone round the natural streams within Jimeta metropolis. Hence, it was recommended that, the people located at the river bank, be relocated and the area turn to green area. Secondly, there should be well-articulated sewer drains, in areas liable to flood, particularly in Doubeli and Damilu. Finally, there is need for dredging and expansion of both river Benue and Lake Gerio so as to accommodate as much as possible the runoffs that usually backflows. These will go a long way in mitigating the effects of flood in the mapped areas.