Assessment of the risk of rainstorm and flood hazards in Minna, Niger State, Nigeria

Abstract

Disaster occurrence in human settlement are engendered and driven by several underlying hazards and risk/actors which are preventable. The identification and assessment of hazard risks require empirical studies driven by research skills. This study examined and assessed both rainstorm and flood hazards in 23 neighborhoods of Minna. The main objective was to determine the potential risks of the existing hazards and to proffer measures for disaster risk reduction in the area. The data for the study were collected through direct field survey, using selected criteria for hazard recognition and documentation. Hazard risk assessment was done using the simple probability (likelihood) and severity rating\scoring method. A five point scale (5 to 1, indicating high to low) was adopted for both hazard probability and severity scoring based on the level of risk and potential impact. The cross tabulation function of the Statistical Package for Social Scientists (SPPSS) was used to capture the variations in the level of hazard risk across the neighbourhoods studied. Hazard mapping was done using ILWIS and ArcGIS 9. 3 software. Raster data from the street guide map and the Quick bird (3. 0 m resolution) image of Minna were used as inputs and map processing was done using the Geographic Information System (GIS). Amongst others, the research outcome shows that the neighbourhoods in Minna are exposed to the risks of rainstorm and flood hazards. The probability and severity of rainstorm occurrence was moderate in 70% (J 6 out of 23) of the neighbourhoods. However, high and extreme cases of flood hazards were recorded along the river banks and flood plain areas with an estimate of I, 657 buildings under the risk of flooding. Generally, the probability and severity of the two major hazards varied across the 23 neighbourhoods studied and the variation observed (X = 49.7328) is statistically significant at 0.460 alpha level and 49 degree of freedom. Based on the findings of the study, it was recommended that Niger State Government should formulate an action plan for disaster risk reduction. Some of the strategies recommended include massive construction and rehabilitation of drainages; removal of housing structures from the river banks and flood plains; massive trees planting and retrofitting of weak roofs in the study areas.