Irrigation Rehabilitation versus New Systems

In view of the disappointing performance of many irrigation schemes to date, most reviews of investment strategies recommend giving priority to rehabilitation of irrigation areas rather than development of new areas. As the FAO has put it:

A prime opportunity for irrigation advancement - and indeed for development in general - lies in the enormous potential of the 237 million ha already operating [world-wide].

46. D. Kone, Epuration des eaux usées para lagunage à microphytes et à macrophytes en Afrique de l'Ouest et du Centre-état des lieux, performances épuratoires et critères de dimensionnemente, PhD Thesis, Ecole Polytechnique Fédérale de Lausanne, No. 2653, Lausanne, Switzerland, 2002 (reference supplied by the International Network on Participatory Irrigation Management (INPIM)).

While the total value of irrigation investment in the development world today is about $1000 billion, the returns are well below the known potential. Many irrigation schemes need substantial investment to be completed, modernized or expanded. Although it is increasingly expensive, rehabilitation can yield high returns.48

However, the priority accorded to rehabilitation needs to be qualified in a number of respects. It may be more important to improve the institutional aspects of the system, or the policy environment, than to rehabilitate the physical structures, or those kinds of improvements may be a prerequisite for successful system rehabilitation. These concerns have been summarized by Moris and Thom, as follows:

Obviously, in those countries like Niger or Tanzania where the rate at which already developed irrigable land is going out of production exceeds the development of new irrigation, rehabilitation should take first priority. In recent years, this has indeed been the emphasis among most donors. However, experience with attempted rehabilitation shows the issue is not so clear-cut:

— Engineering considerations tend to predominate during rehabilitation, when in fact the greatest need may be for O & M modifications.

— The need for rehabilitation is usually linked to a lack of adequate maintenance procedures. Unless these can be instituted within the local system, physical reconstruction will effect only a temporary improvement.

— Where the main system has been allowed to badly deteriorate, the costs of reconstruction can be just as high as for the building of new schemes.

— The pyramiding of new loans on top of old ones creates a crushing financial burden beyond the support capacity of many schemes. .. .

Thus, while the balance of effort in Africa probably should be directed towards improvement of existing irrigation, it does not necessarily follow that physical reconstruction of these schemes under external loan financing is what is needed. A carefully done, case-by-case comparative analysis of O & M deficiencies which makes rehabilitation necessary within existing schemes would appear to be [a precondition] before effective remedial measures can be instituted.49

In cases in which physical rehabilitation would appear to have a role, it is important to evaluate the original engineering design and decide whether it functions sufficiently well to warrant rehabilitating it. Caution should be exercised in financing rehabilitation projects in which the design of the basic water delivery infrastructure is deficient. In this context, Willem Van Tuijl has effectively posed three options for decision makers: (i) changing the system's basic design - upgrading it, (ii) rehabilitating it according to the original design, and (iii) leaving it alone if the original design is seriously deficient and too costly to improve. He points out that:

Guidelines for determining when upgrading would be preferable to rehabilitation are difficult to provide. The decision would depend on local conditions, such as investment costs, anticipated on-farm irrigation technologies, the value of additional crop production, and the value of the water saved by applying improved technologies As part of project preparation for future rehabilitation and improvement projects, more diagnostic work (technical, agronomic and socio-economic) should be carried out to evaluate the existing systems and to determine the need for upgrading.50

50. Willem Van Tuijl, Improving Water Use in Agriculture: Experiences in the Middle East and North Africa, World Bank Technical Paper No. 201, The World Bank, Washington, DC, USA, 1993, pp. 21-22.

A common reason for deterioration of the production potential of irrigation systems is inadequate drainage systems and/or lack of corresponding monitoring measures. The marked deterioration of the drainage facilities in Turkmenistan was mentioned. The International Irrigation Management Institute has observed that:

In China, for example, more than 930000ha of irrigated farmland have become unproductive since 1980, an average loss of some 116000ha per year. ... It has been estimated that about 24 percent of the irrigated area worldwide is affected by salinization, though many observers regard this estimate as too high.51

Returning to the more general question, programs for rehabilitation generally should be based on a broad vision of the system's functioning, including its supporting policies, its management components and the role of farmers. While physical rehabilitation or upgrading often is needed, a new conception of how the system is managed and operated may also be required and may be more urgent. An early illustration of some components of this broader approach to irrigation rehabilitation was provided by World Bank proposals for Mexico:

There is vast potential for increasing productivity in the majority of the [Irrigation] Districts, and six areas of action are recommended in which the Government's efforts should be concentrated: (a) completion of structures and on-farm works in existing systems; (b) realization of water savings through more economical use of water resources; (c) better training and management of extension and research services to achieve more rapid yield gains; (d) less restrictive Government policies with regard to desired crops, leading to more diversified production patterns and a higher value crop mix; (e) provision of sufficient funds and resources for adequate maintenance through increased water charges as well as by more active farmer participation; and (f) raising farmgate prices to a point as close as possible to border price levels to stimulate production and enable farmers to pay for higher water charges and a share of investments to improve systems.52

The narrow objective of rehabilitation or upgrading, which appears to emphasize physical reconstruction, should be replaced with the more comprehensive objective of improvement of irrigation's overall efficiency and of water distribution. Efficiency can be decomposed into its constituents of on-farm efficiency and system efficiency, and both depend on institutional and economic factors as well as the physical aspect. According to Van Tuijl, the requirements for improving the efficiency of water distribution

Waterlogging and salinity are among the principal causes of decreasing production on many irrigated projects. Waterlogging is due to an excessive input of water into systems that have finite natural drainage capacities. After waterlogging has occurred, soil salinity increases because the irrigation water leaves dissolved solids in the soil. It is essential to monitor the water table levels from the beginning of a project in order to implement corrective measures before the soil damage has occurred. . . . in rainfedagriculture, surface drainage is required to prevent any temporary waterlogging andflooding of lowlands. In irrigated agriculture, artificial drainage is essential under most conditions. It is vital to minimize drainage requirements and costs by reducing the sources of excess water through improved system design and on-farm water practices. . . . (FAO, 1993, p. 287).

51. International Irrigation Management Institute, 1998.

52. Latin America and the Caribbean Regional Projects Department, The World Bank, Mexico: Irrigation Sub-sector Survey - First Stage, Improvement of Operating Efficiencies in Existing Irrigation Systems, Vol. I, Main Findings, Report No. 4516-ME, The World Bank, Washington, DC, USA, July 13, 1983, p. 7.

include improvements in policies for land tenure in the direction of providing greater security of land tenure rights, more appropriate levels of water charges and more realistic budget allocations for operation and maintenance (O & M), improvements in institutional aspects of management such as water users' associations and institutions for agricultural support services, and, where necessary, irrigation system rehabilitation and improvement.53

Improvements in the agricultural policy environment could be added to this list, in order to provide greater incentives for farmers to cultivate under irrigation and maintain the system.

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