Impacts of Dams on Downstream Riparian Ecosystems’ Health and Community Livelihoods: A Case of the Lesotho Highlands Water Project

Abstract

Environmental and social impact assessments and reviews for the Lesotho Highlands Water Project (LHWP) dams were completed and approved, thus providing rationale for the construction of the dams. However, little is known about the downstream effects of the dams on river flow regulations and riparian ecosystems’ health and subsequent impact on river-dependent communities’ livelihoods. This study assessed the impacts of Phase 1 LHWP on downstream river flow regulation and riparian ecosystems’ health and their subsequent impacts on river-dependent community livelihoods. The methodology included a review of secondary data and primary data derived from a questionnaire administered to a case study community. Data sets included in-stream flow requirements (IFR), riparian vegetation and responses of river-dependent communities on the impact of dams on their livelihoods. Construction of LHWP dams resulted in modification of the flow pattern of downstream rivers and overall condition of the riparian ecosystems. Excessive livestock grazing also caused extensive riparian zone degradation and soil erosion, thereby threatening people’s livelihoods. The riparian zone was characterized by loss of bushes and grass and invasion of the channel sloughs by woody vegetation. Community members downstream of LHWP dams reported experiencing reduction in fish populations in rivers, grass for thatching and crafts making, wild fruits, livestock grazing pastures, food sources, medicinal plants and timber. Livestock overgrazing was, however, also identified as significantly contributing to riparian ecosystems’ degradation long before the construction of the LHWP. The study concluded that reduced flows downstream of dams represent an escalating problem on riparian ecosystems’ health, threatening livelihood sources of river-dependent communities. This review is relevant in understanding of the linkages between dams, downstream river flow and its effects on riparian ecosystems’ health and subsequent impact on river-dependent community livelihoods. The paper concludes with recommendations for improving the integration of environmental flow considerations into riparian ecosystems’ management to sustain livelihoods of local communities.