Land Degradation in the Semi-Arid Catchment of Lake Baringo, Kenya - a minor field study of physical causes with- a socioeconimic aspect.

Abstract

Growing population in vulnerable semi-arid areas has led to exerted pressure on the land, which often has resulted in severe degraded land, soil erosion and sedimentation of open water bodies. The Lake Baringo region, in mid-west Kenya, exemplifies most of the problems of those marginal areas. The lake is situated in a semi-arid area but its catchment is characterized by large topographic gradients giving rise to considerable climatic and ecological differences. This Minor Field Study (MFS) focus on the environmental degradation in the catchment of Lake Baringo and on the physical causes and consequences of the factors contributing to the constant shrinkage of the lake, as altered hydrological conditions, climatic change, land cover changes and soil erosion. Also social and cultural aspects have been taken into account. Several methods have been used in this study, including field work, remote sensing, data analysis and interviews. During the last decades both the depth and the area of Lake Baringo has decreased dramatically. The study show that the shrinkage of the lake is due to both siltation and inadequate water volumes flowing to the lake resulting in a negative water balance. The increased erosion and sediment transport to the lake and changed hydrologic pattern is primarily caused by altered landcover, as deforestation, in the catchment area, but amplified by changed rainfall conditions. The rainfall data show a slight decreasing trend, but the year-to-year variability of the precipitation is very large so the uncertainty is high. However, our data clearly indicate a significant decrease in the frequency of rainy days. This could mean enlarged rainfall intensity, since the rainfall amount per rainy day is increasing. Even a small increase of intensity could have large effect on the soil erosion since the rains often fall on poorly protected soil with extreme erodibility and very high runoff yield. The soil erosion has a large impact on the arable land, water availability, etc. The bare land is increasing mainly a result of extensive overgrazing, which leads to a constantly decreasing vegetation cover. The changed landcover is in many respects an effect of the increased population combined with the large social importance of livestock. The interviews show that a key factor to solve the overgrazing problems could be to privatise the land.