| Using water efficiently - Technological options |
During the International Workshop on Comprehensive Water Management, held in June, 1991 in Washington D.C., participants from borrowing and donor countries repeatedly raised the issue of 'water use efficiency' (WUE). The promotion of WUE was identified as an important contribution eto the management strategy needed to address problems of water scarcity and costly new supplies. It was ranked high among the priority strategies that participants suggested the Bank should support.
As the concerns related to water scarcity, the high cost of new supplies, and pollution increase, 'increasing water use efficiency' has broadened in scope from the traditional irrigation sector to industrial, domestic and environmental areas.
Efficiency in water use can be measured in different ways. This paper focuses on technical efficiency --water required compared to water delivered. It will discuss the following questions:
• What are the current levels of WUE in the irrigation and urban sectors?
• What are the major causes of low WUE?
• What are some of the technological and managerial measures required to improve WUE? What are their cost implications? Are there limits to increases in efficiency?
• How should efficiency be considered from a river basin perspective? When is low efficiency appropriate? What are the economic and environmental implications of increasing efficiency at both project and basin levels?
• What are the policy changes required?
This paper starts with a brief examination of sectoral water allocation in various countries and regions. After clarifying definitions, the paper presents estimates of sectoral water use efficiencies (agriculture and urban), and illustrates findings with country examples. It highlights factors affecting WUE. The technological and managerial options to improve WUE are discussed next, followed by illustrative cost comparisons of alternatives. The paper also discusses the effectiveness of increasing water use efficiency from a river basin point of view. The last chapter concludes by making some policy recommendations.