Evaluation of the environmental impacts of changing land use system from pastoralism to crop production: a case study of Katilu division, Turkana district.

Abstract

The focus of this study was to evaluate the long-term ecological impacts of irrigation farming in Katilu, along river Turkwel, in Turkana, Kenya. Before the introduction of irrigation farming, Turkwel riverine ecosystem was traditionally utilized as a dry season grazing and water resource. The objective of irrigation farming was to improve food security for destitute Turkana people after devastating effects of drought in 1960s. The study evaluated whether this has been achieved after three decades of irrigation farming in Katilu. The study further assessed its ecological impacts on the Turkwel riverine ecosystem and also on the traditional sorghum farming system, which was considered ecologically sustainable. The indigenous vegetation cover trends were also analysed. Both socio-economic and ecological indicators were used to explain the environmental changes observed in the area. The study used remotely sensed Landsat imageries for the years 1986 and 2000 to identify impact areas and establish trends of vegetation cover. Using Geographic Information System, land cover types of the area were produced. Descriptive statistical analysis was used to help identify proximate causes and driving forces. Field surveys were conducted to establish inter-relationships of various variables particularly land under livestock and crop production, migration to Katilu and food security. The study established that irrigation farming has had profound socio-economic and ecological impacts on the environment in Katilu. A number of people migrated to Katilu and the nomadic lifestyle changed to a sedentary one. Consequently, this resulted into a localized degradation of wood resources around the settlements. The most important tree species, that is Acacia woodland, has decreased while bushed-shrubland has increased. The climatic variability, human practices and insecurity seem to be the main causes of environmental degradation. Food security in the area has not improved, while the traditional form of farming has been modified by modem farming technologies. The number of people engaged in rainfed farming has increased but the farm sizes have remained fairly small. Consequently, the grazing area has been reduced as more land is being cleared for cultivation. In addition, indigenous management systems and drought coping strategies seem to have collapsed. Although introduction of irrigation farming was expected to improve food security in Katilu this has not been achieved. The traditional farming regimes, which were more ecologically friendly, have been modified. The reduction in acacia species is an indication of decline in range condition. The riverine ecosystem, which was a source of dry season pasture and water, is currently threatened by the extensive cultivation. This implies that Katilu community is now more vulnerable. It also appears that food security is not a factor of hostile environment as earlier thought but perhaps of socio-cultural management systems of the affected community. Based on the results, the study recommends that long-term environmental assessments need to be conducted before any more development of irrigation farming along river Turkwel. Furthermore, the study recommends that agro-silvo-pastoral land use system would be more appropriate along river Turkwel