Description
Assessment of encroachment on floodplain along river Kubanni Zaria, Kaduna state.
Abstract
Floodplain management is a major world concern considering the rising trends in urban flooding. This research therefore analyses the physical development challenges and encroachments along the river Kubanni floodplain in Zaria. The study employed GIS technique, from the DEM the boundary of the floodplain was delineated by digitizing polygonizing shape files using ArcGIS software. Encroachment extents by the various communities along the floodplain were analyzed by overlaying the floodplain layers over already fragmented sub-centers built-up layers of Landsat maps (Landsat 4-5TM, 1987,1997, 2007 and 2016) and clip out, convert to polygons and spatial measurement of areas were performed using ArcGIS tool. The analysis of floodplain encroachment due to spatial growth revealed an increasing trend from 8.2Ha (6.0%) in 1987 to 71.9Ha (52.9%) in 2016, more than half of the floodplain has been encroached upon by built-up. The fastest encroachment was observed in the 1997 till date which corresponds with the rapid urbanization in the study area. The rate of urban built encroachment floodplain at Magume dropped after reaching its peak during the period of 1997 to 2007, The fall in the encroachment change rates was attributed to the reduction in sprawling development and physical limit challenges to physical development by river Kubanni. This study established that the consequences of the encroachment of built-up into the floodplains has implications including, flooding and its associated consequences and threat to the quality of aquatic and human life. Physical planning proposals such as flood protection embankment, plantation of economic trees within the 60-meter buffer, resettlement proposal and Recommendations were made to avert the effect of physical development on the floodplain and to preclude the future scenario effects in the study area.
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