Assessment of Land Cover Changes in Lake Olbolosat Region of the Central Kenyan Highlands using Landsat Satellite Imagery Aided by Indigenous Knowledge
Ako, E. O.
Maingi, S. M.
Olang, L. O.
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The region around Lake Olbolosat in the central Kenyan highlands has witnessed significant land-use changes, which are believed to be major cause of the dwindling Lake volumes. Very few studies have been carried out in the region due to limited observed insitu data necessary for monitoring the land surface conditions. It is hence important that feasible, straightforward and cost-effective techniques are explored to asses the space and time variations with a view of providing the essential information for improved land and water management. This study investigated the land cover changes around Lake Olbolosat region using data obtained from Landsat satellite remote sensing. Five predominant land cover classes including farmland, floodplain, build-up area, forests and water body were selected for study. Two imageries for 1989 and 2010 when significant changes were witnessed in the area were subsequently selected. The Maximum-Likelihood function of the supervised classification scheme was applied to discern the space and time changes with the support of the indigenous knowledge of the area. From the results obtained, the size of Lake Olbolosat was noted to have significantly shrunk by 68% between the periods of study. Farmlands were noted to have increased by about 31% owing to the rapid rise in commercial and subsistence agriculture favored by the humid tropical climatic conditions of the highlands. The study revealed intense deforestation of the upstream area, which reduced the forested area by about 30% during the study period. The floodplains were also noted to have reduced by about 26%, with a majority of the area being gradually turned to farmland. Built-up area generally increased by about 33% consequent of the rising human population. In summary, the study revealed significant negative land cover changes in the area and hence a critical need for improved land-use planning to curtail further decline of Lake Olbolosat.