The Sustainable Coexistence of Wetlands and Rice Irrigation: A Case Study from Tanzania

Abstract

An existing United Kingdom–funded water project, located in the Usangu Plains of Tanzania, aims to understand the causes for dry season zero flows in the previously perennially flowing Great Ruaha River, which drains from the Usangu wetland. Studies reveal that the common explanation of competition for water between wetlands and irrigation alone is insufficient to explain reduced flows. Instead, complex biological and hydrological processes influence the allocation of water between wetlands and irrigation. This article outlines these processes and proposes some hypotheses: (a) Certain types of rice irrigation development may not be detrimental to the Usangu wetlands; (b) the sustainability of rice irrigation and wetlands can be supported by recognizing their dynamic nature; (c) the concept of efficiency of irrigation in areas with a semiarid climate should be treated with caution. The studies will assist in the sustainable management of water for both environmental and developmental needs.