ABSRACT
Rivers and their floodplains have always served as physical limitation to the spatial growth of urban centres located along river course. The rapid growth and expansion of these urban centres have always resulted to encroachment of urban activities on floodplains with increase in vulnerability to flood disaster. Therefore the monitoring of urban growth and changes along these river floodplains are of concern to the physical planner and urban managers who must understand the urban growth dynamics and manage resources while providing service to these rapid changing environments. This research therefore analysed the spatial growth of urban built encroachment and management on river floodplains in Kaduna metropolis. In conducting the research, river floodplains as identified by the 1967 Max lock master plan of Kaduna were delineated and mapped out from digital elevation model (DEM) using ArcGIS 9.3. Satellite images of 1990, 2000, and 2012 time epoch were then used to establish the encroachment extent and pattern using the monitoring land use change technique (MOLAND) within the ArcGIS 9.3 tools. The analysis of floodplain encroachment due to spatial growth between 1967 and 2012 revealed that 25.8% of physical developments are on river floodplain. The analysis further revealed that 44.2% of the river floodplains banks reserved as urban green and agricultural floodplains areas have been encroached by urban built activities. The average rate of encroachment between the year 2000 and 2012 is estimated at 0.32 Km2 per year. Residential Land use constitutes 85.6% of urban built encroachment on floodplain. The pattern of residential encroachment revealed that 40.4% are low density, indicating sprawl while medium and high density constitute 24.5% and 35.1% respectively, reflecting continual infilling development on floodplains. These indicate high flood risk exposure and damage potential to the housing sector and infrastructural investment in the event of flood disaster. The study revealed that poor land management, ineffective zoning and development control have resulted to the continual urbanization of floodplains in Kaduna metropolis. Therefore effective institutional framework that will ensure integration of related policy, effective land use restructuring and development control were recommended.
Rivers and their floodplains have always served as physical limitation to the spatial growth of urban centres located along river course. The rapid growth and expansion of these urban centres have always resulted to encroachment of urban activities on floodplains with increase in vulnerability to flood disaster. Therefore the monitoring of urban growth and changes along these river floodplains are of concern to the physical planner and urban managers who must understand the urban growth dynamics and manage resources while providing service to these rapid changing environments. This research therefore analysed the spatial growth of urban built encroachment and management on river floodplains in Kaduna metropolis. In conducting the research, river floodplains as identified by the 1967 Max lock master plan of Kaduna were delineated and mapped out from digital elevation model (DEM) using ArcGIS 9.3. Satellite images of 1990, 2000, and 2012 time epoch were then used to establish the encroachment extent and pattern using the monitoring land use change technique (MOLAND) within the ArcGIS 9.3 tools. The analysis of floodplain encroachment due to spatial growth between 1967 and 2012 revealed that 25.8% of physical developments are on river floodplain. The analysis further revealed that 44.2% of the river floodplains banks reserved as urban green and agricultural floodplains areas have been encroached by urban built activities. The average rate of encroachment between the year 2000 and 2012 is estimated at 0.32 Km2 per year. Residential Land use constitutes 85.6% of urban built encroachment on floodplain. The pattern of residential encroachment revealed that 40.4% are low density, indicating sprawl while medium and high density constitute 24.5% and 35.1% respectively, reflecting continual infilling development on floodplains. These indicate high flood risk exposure and damage potential to the housing sector and infrastructural investment in the event of flood disaster. The study revealed that poor land management, ineffective zoning and development control have resulted to the continual urbanization of floodplains in Kaduna metropolis. Therefore effective institutional framework that will ensure integration of related policy, effective land use restructuring and development control were recommended.
