Environmentally sound irrigation projects

Abstract

Upstream deforestation inaeasedfloodflows and silt loads, destroying these irrigation canals in Tanzania. IRRIGATION IS PRACTISED in many very different environments, some of which have been stable for hundreds of years. It has enabled a vital expansion in the production of foodstuffs that has helped to support greatly increased populations, and has reduced the likelihood of famine in many countries as well as supporting production for industry and export. Yet in issues of resource allocation and environmental impact, few development initiatives raise more debate and controversy than irrigation. In the race to increase output from irrigated production, technologies have often been taken up without a full appreciation of the political, social and economic structures that can provide environmental stability. Thus in irrigation development, whether intensifying traditional schemes or constructing new projects, the scale of potential improvements in production, employment and welfare can often be counteracted by risks of environmental degradation. What have irrigation practitioners learned from the past to help design and achieve environmentally sound irrigation schemes in the 1990s, and what dilemmas do we still face? What new challenges are facing us from new technologies, increasing water scarcity in some areas, and the tough financial climate of the late twentieth century? The 1980s was an important decade for understanding the links between environmental management and development issues. We came to understand that we not only needed to prevent the degradation and loss of land and water resources, but we also needed agricultural systems with reduced dependence on non-renewable