Spatial Assessment of Flood Vulnerability in Aba Urban Using Geographic Information System Technology and Rainfall Information

Abstract

This study investigated the relationship between topographic information and trends in rainfall in Aba urban, South Eastern Nigeria. GIS data were applied to generate topographical information on runoff characteristics, the slope, the contour, the aspect and the digital elevation model. The Mann-Kendall Trend was applied to the rainfall data to show if a monotonic increase, decrease or stability trend exist for the rainfall data of Aba metropolis for the period 2000-2010. Results showed that virtually all parts of Aba were liable to floods expect Ogbor hill axis. The flood vulnerability map indicated that 71.65% of the study area was vulnerable to flood. Rainfall trend showed a decrease in six out of the ten year period. Since within this period, flood intensity had generally remained the same, we concluded that topography, poor drainage infrastructure and non-compliance with building, planning and environmental regulations rather than rainfall trend were the key cause of flood problem in the study area.