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Riparian areas are ecosystem zones of transition between the terrestrial and aquatic ecosystem. There are usually in close proximity to lakes, rivers and streams and have dynamic and well-defined vegetation and soil characteristics. These important ecosystems have been under serious threat both globally and also at the regional and country level. In Kenya particularly the increasing population and urbanization has resulted to encroachment and compromise of the water quality since riparian zones act as protective shield against effluents directed into the water bodies. This study focused on delineation of the varying riparian width based on the their dynamic topographic, hydrologic and soil characteristics through use of RBDM also, it involved characterization of riparian land cover trends of the year 1989,1995.2001.2007,2013 and 2019. Lastly prediction of the land cover for the year 2030. The study area was the Lower River Nzoia covering Kakamega County, Southern part of Bungoma and the Northern part of Siaya County in Kenya.The datasets used include DEM, raster soil data and Landsat Imagery of the six epochs. Riparian ecotones were derived and also the maps of the riparian land cover. The riparian width was observed to vary along the river with the highest distance at 17kilometres stretch from the river’s mouth which was approximately 1.3 kilometres on either side of the river.the width decreased upstream to about 500metres on the main river and 350 metres on the tributaries. The riparian vegetation and forest cover were observed to decrease while cultivated land increased from 5526 to 2168, 2388 to 997 and 2803 to 7175 hectares respectively from the year 1989 to year 2019. |
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