Assessment of Urban Flood Risk in Nigeria, a case study of Lafia Zone

The aim of this research is to map flood vulnerability zones, as well as generating data on the nature of behavioral responses of the floodplain dwellers to the risk of flooding which will serve as a governmental guide in the... [ view full abstract ]

The aim of this research is to map flood vulnerability zones, as well as generating data on the nature of behavioral responses of the floodplain dwellers to the risk of flooding which will serve as a governmental guide in the control and management of flood in Lafia, Nigeria.

Rainfall data for a period of 30 years (1980-2010) was collected from the archive of the Nigerian Meteorological Agency in Lafia. The analytical techniques employed include regression, standardized rainfall anomally index, 5-year moving average and Gumbell Extreme probability theory. The flood risk map was done using the flood risk assessment of 9 environmental parameters of 16 flood-prone areas used in this study based on the rating procedure of Clarke’s principle (Clarke, 1951). 300 questionnaires were administered to the flood plain dwellers using systematic random sampling.

Results of analysis of annual rainfall trend shows that Lafia has upward trends of rainfall, which is statistically significant since P<0.5 (alpha level), an indication that the upward trends could be random and consequently, the possibility of flooding. Heavy rainfall of long durations and river overflow were identified as the most important causes of flooding in Lafia. Analysis of the behavioural responses of floodplain dwellers shows that there is greater stability in the population, as majority of them have stayed in the area for a period of 12 years and above. The population has knowledge of the hazard before moving to the area but due to their strong cultural attachment to land, majority of them considers the flood hazard either of little significant or sufficient enough to force them to consider alternative. The elements identified in the study for the control of flood risk include legislation, risk evaluation, land-use control and zoning, building codes as well as structural and non-structural measures of flood control.