Assessment of land use and land cover change in Makueni County for selected time periods

The surface of the earth is undergoing rapid land use and land cover changes (LULCC) due to various socio-economic activities and natural phenomena. The main aim of this study was to gain a quantitative understanding of LULCC in Makueni County between 2000 and 2016, and analyze the relationship between these changes and their possible underlying drivers in the County. ArcGIS 10.3.1 and ERDAS IMAGINE 2014 were used for the digital image processing and GIS analyses. Image pre-processing and enhancement were done to prepare the images for classification. Supervised classification technique was used to sort and define spectral signatures in the imagery for different land use and land cover (LULC) classes that were identified. Ground truthing was done so as to check the precision of the classified LULC maps. Change detection analysis was performed to assess the class- to- class conversions and change in areal coverage between identified LULC classes between time intervals under study. Accuracy assessment was performed to determine overall, producer’s and user’s classification accuracies. The study area was defined to have seven LULC categories, which were: Built up areas, water bodies, croplands, evergreen forests, bushlands, grasslands and barelands. The results revealed both increase and decrease in the areas of the LULC classes from 2000 through to 2016. Evergreen forest decreased from 3105.8 km2 in 2000 to 1373.0 km2 in 2016 while built up areas increased from 160.7 km2 in 2000 to 644.5 km2 in 2016. Possible drivers of the observed changes ranged from climatic factors such as rainfall and drought to socio-economic factors. Since the results reveal that LULCC has occurred in Makueni County, the study recommends that consistent LULC mapping should be carried out in order to establish trends that will enable resource managers to project realistic change scenarios helpful for natural resource management.