COASTAL FLOOD MAPPING OF EASTERN OBOLO AND IBENO LGAs OF AKWA IBOM STATE, USING SRTM AND SATELLITE IMAGERIES

Abstract

Coastal flooding is one of the devastating noticeable hazards of coastal environments. The hazard can originate from incidence such as rise in sea level, increase in precipitation, poor drainage network and anthropogenic activities. The coastal areas of Akwa Ibom state are vulnerable to these hazards as they directly border the Atlantic Ocean. The area has experienced a number of coastal flood issues in recent time necessitating the need to produce coastal flood map to show the risk zones necessary for making informed decision in case of emergency. Apart from the incessant coastal flooding, other environmental problems associated with the flooding includes waste deposits after flood, inundation of people's houses, covering of the surrounding areas with debris from water, rendering of agricultural lands unusable and alteration of the coastal ecosystem. To provide basic information that will help tackle these problems, this study mapped the coastal flooding of the area, using SRTM and satellite imageries. The primary objective was to determine the extent at which the area was at risk of coastal flooding, and to produce coastal flood map of the area. Areas within the zones that are highly vulnerable to coastal flooding were accurately mapped. SRTM and satellite imagery (Landsat8 OLI 2017) were used to classify the area into coastal flood risk zones based on factors such as elevation and slope. Landcover/Landuse classification into Built-up area, Vegetation, Mangrove and Water bodies was achieved. The classification results of Eastern Obolo and Ibeno local govt. areas in 2017 indicate that Vegetation respectively accounts for 46.49% and 50.04%, covering an areas of 4672.53 and 10615.77 hectares. Built up area had 30.09% and 31.71% with covering areas of 3024.9 and 6726.96 hectares respectively. Mangrove had 11.84% and 9.78%, covering an area of 1189.62 and 2074.5 hectares respectively. Lastly water bodies had 11.58% and 8.47%, covering an area of 1164.42 and 1797.75 hectares respectively. Also, 60% and 47.12% of the land masses are at risk of coastal flooding in Eastern Obolo and Ibeno LGAs respectively. Based on these results, there is need for further study to determine the effect of coastal flood, and the extent of rise in water level during coastal flooding.

Keywords: Coastal Flooding, Environment, Imageries, Mapping, Remote Sensing, Risk.