Geospatial Analysis of Urban Expansion and Its Impact on Vegetation Cover in Kaduna Metropolis, Nigeria

Abstract

Cities world-wide are experiencing rapid spatial growth and cities in the less developed countries are already accounting for more of this growth. If such rapid growth is unplanned and uncontrolled, it would have adverse effect on the environment and in most cases, vegetation is highly endangered. Such   removal of vegetation cover causes great harm to the ecosystem and contributes greatly to the global warming effect. The aim of this paper is to analyze urban expansion and its impact on vegetation cover in Kaduna metropolis, Nigeria using geospatial techniques. Landsat MSS imagery of 1973, Landsat TM image obtained in 1990, Landsat ETM+ data of 2001 and Nigerian Sat-1 image (2009) were used. Visual interpretation method was used to sort the various datasets into land use/cover classes. The built-up area and vegetation cover were extracted and the rates of change were ascertained for each of the landcover types. ILWIS 3.3 software was used for the analysis.  The results show that the built-up area increased from 14.3% in 1973 to 44.1% in 2009.  The city was growing at the rate of 5.72% per annum within the period studied. Within the same period, 81.8% of the vegetation cover was lost at an annual rate of 2.3%. The regression analysis revealed a strong positive correlation between increase in built-up land and vegetation loss at 0.175 significant level. The R value of 0.825 and R2 of 0.680 suggests that 68.0% of the vegetation loss in the area was accounted for by built-up. At this rate of vegetation loss and urban expansion, the city may be stripped bare of almost all her vegetation cover within the shortest possible time if no adequate control measure is put in place. This paper recommends: i) the application of geospatial techniques for proper planning and development of Kaduna and other cities ii) proper monitoring of the pattern of urban expansion proper decision making on the planning process.