Demand for water in the Usangu Basin is driven by a number of competing uses. These include domestic supplies, irrigated agriculture, livestock, fishing, maintenance of the Usangu wetland, a National Park and major hydroelectric system downstream. As a result of a number of driving forces including the growing population, the water resources of the basin are becoming increasingly stressed, and downstream flows have now reduced to zero during the dry season. The paper is based on recent work to study the situation and work with local stakeholders to develop a sustainable management plan for the basin.
Irrigated rice is by far the biggest user of water in the basin. The paper traces the successful development of irrigation there since the 1950s, based both on state-managed mechanised farms and on smallholder production. However, the expansion of irrigation has been a major factor in the change in water availability downstream, particularly as the cropping calendar expands into the dry season, when river flows are at their lowest.
A number of initiatives are under way to try to reduce the impact of irrigation on the basin's water resources. These include projects to increase irrigation efficiency in smallholder systems, and improvements to water management institutions and processes. The aim is to restore dry season flows for downstream users by the year 2010.
Irrigation and Drainage (2004) 53 (3) 277-286 [doi: 10.1002/ird.123]