AN ASSESSMENT OF FLOOD VULNERABILITY IN SELECTED URBAN CATCHMENT: A CASE STUDY OF PORT HARCOURT METROPOLIS, NIGERIA

Abstract

Flooding occurs due to increase in global temperatures high rate of precipitation and increase rate of runoff and increase rate of urban flooding. The aim of study is to determine the flood risk assessment of selected urban catchment in Port Harcourt, Nigeria. The study adopted correlational research design where secondary data was generated from Landsat Imageries of the study area. The digital elevation model of the area was used to determine the water shed pattern, land use / land cover and inundation level using supervised classification of land use in the area. The study also adopted Geographic Information System (GIS) aided computer simulation of the storm water been generated through enhanced DEM to determine storm water level and inundation based on land use/land cover change. Data generated was analyzed using hydrological models and techniques which include storm water generation assessment, inundation modeling, assessment of land cover and level of inundation and evaluation of flash flood vulnerability using modeled inundation. Findings showed that Port Harcourt has a number of streams of different flow lengths which was higher in Port Harcourt ‘The study also revealed that Port Harcourt has about 654 sub basins. The total runoff in Port Harcourt was higher (0.74) inches ,Also the rate of change of catchment behaviour like the catchment precipitation, node flooding and runoff in both study areas continued to increase with time of the day, and the rate of change of volume of runoff varied slightly in Port Harcourt,. The width of hydrograph in Port Harcourt was wider as the areas prone to moderate and high flood in Port Harcourt was higher (95.03%) Based on these findings, the study recommends that better planning of the cities is required to regulate the effect of flooding in the study area. The area liable to moderate and high flood vulnerability should be well monitored and guarded to minimize the destruction of lives and properties.