The unprecedented catastrophic flood that occurred in 2012 is described as the worst environmental disaster in Anambra state’s memorable history. The flood which was prolonged
than any known event, resulted in severe damage and untold sufferings to the inhabitants of the
state. Capturing the extent of flooding during an extreme event in an efficient manner is essential
for response, recovery, and mitigation activities.
This study exploits GIS and Remote Sensing Approach in flood management with the goal of
identifying and mapping areas vulnerable to flood hazard and identify the extent of damage
resulting from the 2012 flood disaster in Anambra state. It identifies spatial variations in flood
hazard levels, spatial and economic impact of the 2012 flood disaster and the population exposed
to different levels of risk in Anambra with a view of fostering the best approach for flood
management.
This study considered fiver factors as indexes of flood hazard identification and these included elevation, proximity to drainage, Land use, population density, flow accumulation and slope. These information were derived from SRTM, google earth imagery, and population data of the
study area. While the extent of inundation was mapped using MODIS remote sensing data
captured on 20th 0ctober 2010 before the flood and 13th October 2012 during the peak of the
event. To extract and map the flood-affected areas, the time series MODISdata and the google
earth imagery were entered into the ArcGIS 9.3 Version and projected to UTM coordinate system
for on-screen digitization. The true width of the river channel was extracted from the image
captured before the flood while the extent of inundation was captured on the image acquired
during the flood.
This study revealed that a total landed area of 1078Sq.kms was covered by flood excluding the
original extent of the river while property worth of twenty three billion naira was damaged. It
further revealed that area of land of 2106.78km2(43.40%), 55.392km2(19.68%),
835.054km2(17.20%), 555.48km2(11.44%), and 402.334km2(8.29%) are occupied by very high,
high, moderate, low and no hazard categories while total number of population of
1814733(43.40%), 822953(19.68%), 719298(17.20%), 478486(11.44%), and 346561(8.29%) are
residing at very high, high, moderately high, low, and no hazard zones.