Assessment of biophysical land degradation in Kerio river basin, Kenya.

Kerio River catchment is one of the catchments facing degradation. To determine the extent of biophysical land degradation, identify degradation hotspots and propose a policy framework for integrated management of degradation; a model was conceptualized from RUSLE soil erosion equation to determine the extent of land degradation. This considered five input data; vegetation index, rainfall erosivity, soil erodibility, slope length and population density. ERDAS IMAGINE 2013 and ArcGIS 10.4 was used for data processing and weighted ranking was done to determine the influence each data input on land degradation. The weights were obtained from pairwise ranking using Analytical Hierarchy Process (AHP) based on expert opinions. Degradation hotspots were then identified and SWOT analysis on institutional policy framework was carried out. Agriculture, bareland, bushland and forest coverage was 5.5%, 38.1%, 52% and 4.4% in 1990 and 21.4%, 24.7%, 52.7% and 1.2% in 2014 respectively. This showed an increase in agricultural land and decrease in forest coverage. Degradation index maps with indices ranging from very low to very high degradation showed that in 1990 agriculture based land was highly degraded whereas in 2014 it was the bushlands; these formed the hotspots areas. It is clear that degradation is taking place with main drivers being socio-economic activities. SWOT analysis showed that there are policies in place but there is need for proper management framework to enhance land degradation management at both national and county level of government.