Erosion is increasing in those areas being converted rapidly from vegetative cover to agricultural land. National level statistics were not obtained for this paper, however several examples of Districts undergoing rapid conversion are presented. For example, the land being converted in Mbeere district is marginal, and therefore of low productivity, and when the rains are irregular or absent, as they often are, farming families don’t produce enough to feed themselves. Land is not being left fallow for as long as it has been traditionally, leading to an increase in erosion. Additionally, more than half of all men in the area has left to find additional work, leaving women to manage the households. This rapid change has had negative social and economic impacts on the area. Whereas a poor household can often raise its economic standard over time, many farming households in Mbeere district are not able to increase their income levels. Poverty is therefore on the rise as the population grows (Olson/LUCID, 2000).
Erosion trends have been extensively studied for Machakos District, where soil conservation measures are widely practiced. Grazing areas in the district still suffer eroding soils on a serious level, however some terraced (cropped) areas do show less degradation than many agricultural areas in other parts of the district and of Kenya, according to researchers who have examined long-term trends in Machakos (Tiffen, Mortimore, and Gichuki 1994, p. 117). Erosion is a serious problem for Kenya’s arid areas as a whole, however, as noted by increasing sedimentation and declining crop productivity mentioned in other sections of this report.
5.4.5. Irrigation of agricultural areas.
Irrigation schemes extend over 40,700 ha in Kenya, encompassing 19 different projects in various parts of the country (FAO, 1993). Approximately 11,500 ha of these lands are under small-scale schemes, largely in ASALs (GOK, 1992). As noted in the section on threats to freshwater systems, large-scale dams developed for this purpose have caused a variety of environmental and social problems already in Kenya. The government's most recent policy for irrigation development in arid and semi arid lands notes that "there has been a long history of successful, low-cost, small-scale irrigation schemes in ASALs extending back to the pre-colonial era. However, in recent years, pre-occupation with the development of large-scale irrigation schemes in the country has caused these past achievements to be ignored. When new schemes are proposed for the ASAL areas, the basic approach will be to adapt accessible irrigation technology to the needs of smaller units." (GOK, 1992, p. 10). Environmentally sustainable approaches are favored in this policy.
The policy document notes that a number of irrigation experiences have been negative for reasons ranging from high costs to overestimation of impact to social costs of removing people from impacted areas. "Even small irrigation schemes on low-lying and seasonally damp land…can take away land that is necessary for the survival of pastoralists in dry years" (GOK, 1992, p. 46).
5.4.6. Relative severity of threat to land and soil resources.
The issue of land use change and threat to soil and land resources in Kenya merits an “extremely severe” ranking, due to the nature of its long-term impacts on all sectors of society, in economic development, ecosystem health, and human health. This is an area requiring drastic attention and action.
5.5. Energy resources
5.5.1. General statistics and trends.
Energy is not always perceived as a "natural resource," although most of the raw materials used to create it are; by the same token, energy is not always seen as directly related to environmental concerns. In Sub-Saharan Africa in particular, this is true, as the region's per capita consumption of "modern" energy resources is lower than any other part of the globe (Karekezi and Mackenzie
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