Mapping the Risk and Mitigation of Flood Occurrence in Calabar , Nigeria

Abstract

The paper focuses on mapping the risk and mitigation of flood occurrence in Calabar south local government area in Cross River state of Nigeria. GPS points were taken at 100m intervals; along the major drainage channel from the beginning of the channel to the end of the floodplain in Calabar south and the different other points were taken at different location of Calabar considering the terrain. The procedure was to ascertain the variations in the terrain of the area. The analysis of data was carried out using the ArcGIS version 9.3 to digitally map the positions of the major drainage channels other points on each of the map layer that was generated. Contour, Risk and mitigation maps were generated from the coordinates collected from the field as well as risk categorization and their areal extent in relation to the built environment. The result shows that the increase in depth in flood water is greater nearer the beach locations adjacent to the rivers and creeks and decreases towards the northern axis of the study area. This follows the configuration of the terrain. Very high risk areas are close to the rivers and the wetlands which include Anantigha, Henhsaw town and Fishing Camps.  More than 60 per cent of the built up area, are prone to flood. Also most built structures align the flood plain and the inland water channels. Retention pond and reconstruction of drainage facilities were modelled and recommended in suitable areas to avert flood disaster.

Key words: Mapping, Risk, Flood, Mitigation, Retention pond