This project developed a total of 47 thematic maps using RS/GIS tools, of which 30 maps have been used in this report. Based on availability of RS data, the base year was set from 1990 and compared with conditions in 2010, thus giving a 20-year period for assessing trends. The results of land use mapping show that the predominant land use-land cover (LULC) type is the Savannah grasslands, combining a wide range of vegetation types, as it covers about 69.7% of the land area of Kenya. This is followed by agriculture, both rainfed and irrigated, covering 17.7% of the land area, while about 2.2% of the land area of Kenya was found to be bare lands. Spatial analysis of the LULC changes showed an overall deterioration of vegetation cover over the last 20 year period, meaning that land degradation is occurring in Kenya. This was identified through declining vegetation cover as depicted by NDVI, increasing bare lands, conversion of natural vegetation into agricultural lands and soil erosion. Generally, agricultural/cultivated areas increased by 7.3% and bare lands increased by 2.6%. The greatest losses of vegetation occurred in the period 1990 - 2000, when at national scales, 0.8% of forest was lost, and bare- land increased by 4%.
Soil erosion risk mapping revealed that almost all the counties in Kenya are at risk from one form of land degradation or other. The problem is serious because high land degradation is likely to occur on about 61.4% the total area of Kenya, while very high degradation affects 27.2% of the land. Land degradation affects especially the ASALs, where the soils are highly erodible and combined with high intensity storms, creates conditions for excessive runoff and soil erosion. The most affected counties include Samburu, Kitui, Garissa, Tana River, Mandera, Turkana, Marsabit, Baringo, West Pokot, Kajiado, Kilifi, Wajir and Makueni. Even some relatively wetter zones also have high propensity for soil erosion, especially on steep slopes of Mt. Kenya and the Aberdares, including parts of Muranga, Nyeri, Meru and Tharaka-Nithi. On the contrary, low degradation risks were found to be on protected areas and those with relatively flat terrains yet having adequate rainfall. These include the forest zones, national parks, tea- growing areas and plateaus e.g. Uasin Gishu, Trans Nzoia and parts of Lake Victoria basin.
Meanwhile, the causes of land degradation in Kenya are both natural and human induced. They include biophysical (natural) factors related to climatic conditions and extreme weather events such as droughts and floods, and catchment factors such as steep slopes and highly erodible soils. However, it is the human activities that pose greatest threat, and these include unsustainable land management practices (anthropogenic) factors such as destruction of natural vegetation, over-cultivation, overgrazing, poor land husbandry and excessive forest conversion.