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close this bookBetter Health in Africa: Experience and Lessons Learned (World Bank, 1994, 236 pages)
close this folderChapter 17 - Technical and operational improvements in rehabilitation of irrigation projects
View the documentIntroduction
View the documentThe dam and reservoir
View the documentThe canal system
View the documentDrainage
View the documentIntroduction of high technology irrigation methods

Introduction

The meats of rehabilitation of existing irrigation systems versus construction of new projects have been debated for the last two decades. International financing agencies have increasingly favored rehabilitation. This is not an opinion which has always been shared by developing countries. In an earlier conference of the International commission on Irrigation and Drainage (ICID), there was a strong plea that priority be given to new construction, as "cultivators served by an existing project already have some supply of water, however deficient, while those in areas as yet unirrigated have none. The view was also expressed that rehabilitation was a slow and difficult task, and less likely to have a major impact on agricultural production than new projects. It was also not considered a vehicle for substantial aid inflows.

The increased recent emphasis on rehabilitation and improvement has been due to a number of factors, including the diminishing number of sites available for new projects and the greater recognition of ecological constraints on new work, particularly on reservoir construction. Projections of future demand for agricultural production can now no longer be matched by projections of area to come under irrigation from new projects. Increased productivity from existing irrigated areas is essential and that implies extensive rehabilitation.

Judged by crop production per unit of water used, there is certainly room for improvement in most South Asian schemes, and it is commonly asked to what extent could this situation be improved by adoption of the new technologies in water distribution and irrigation being practiced elsewhere. While there is indeed opportunity for injection of new technology, this would unfortunately address only part of the problem. The causes of the low productivity are to some extent inherent in the variable nature of the monsoonal climate and the limited possibilities for regulation by storage. The consequent uncertainty of irrigation supply has given rise to a number of social and management problems which do not have easy solutions.

One approach has been to attack the management problem first, making better use of the existing irrigation infrastructure. Notable increases in production have been achieved in some situations through such an approach and at low cost. However, a study of water management problems usually also discloses deficiencies in infrastructure either at the lower end of the system (the tertiary level) or further upstream. These must be remedied before improvements in management can be effective. Current World Bank practice (e.g the National Water Management Project in India) is to carry out a thorough review of the performance of a project including effectiveness of water use (selection of crops to be irrigated, seasonal use of stored water, etc), evaluate infrastructure and operational procedures, and analyze cultivator attitudes and problems before embarking upon any improvement program. Solutions developed are very much project-specific. However, there are a number of areas which can be discussed in general terms.