47th Agenda 

47th Session Issues

Irrigation

During the 1960s and 1970s, large-scale developments dominated efforts to bring new lands under irrigation. Often linked to flood control and hydropower generation, these schemes were developed with great enthusiasm and pride. The availability of water and land resources, favorable markets for agricultural products, the low cost of construction and relatively easily available external funds made those developments possible. Since the 1980s, however, many of these conditions have changed and this has resulted in a declining trend with respect to irrigation expansion.

During the past four decades, irrigated agriculture was responsible for a major part of the increase in production to meet population demands. By the mid-1990s, 36% of the total crop production is expected to come from less than 15% of the arable land that is irrigated. On a global basis, the average rate of expansion was about 1. 5% per year in the early 1960s, reaching a maximum of 2.3% per year in the period 1972-1975. The rate of expansion began to decrease in the mid-1970s and is currently about 1% per year.

FAO reports that one of the most common causes for the decline in the rate of expansion was the high cost of irrigation. Construction costs have risen steadily and world prices for major cereals have fallen sharply. Furthermore, as much of the suitable land for irrigation development and available water-supplies are already developed, progressively less favorable and therefore more expensive areas are left for further expansion.

FAO’s projection (World Agriculture Towards 2000) of the expansion of irrigated land to the year 2000, based on previous trends and modified by land, capital and inputs required to meet future needs, is 2.25 per cent per year from the period 1982-1984 to 2000. According to this study, between the period 1982-1984 and 2000 about two thirds of the increase in arable lands will be accounted for by expansion of irrigation. The projected rate for developing countries is 2.4% per year. The World Bank estimates that although it will take an average annual growth rate of 2 per cent in agriculture as a whole to feed a world population estimated to reach 6 billion by the year 2000, and 8 billion by the year 2025, the growth rate for irrigated agriculture will need to be 3% per year.

Specifically, China needs to increase its annual food production from 400 million to 500 million tons by the year 2000. This would require increasing the irrigated land area by 1.4 per cent annually; modernizing irrigated lands; reclaiming waterlogged lands; increasing water conservation; and increasing the reservoir fish-farming area. India’s irrigation potential has been increasing at a rate of about 2 million hectacres (ha) per annum and by the end of the seventh 5-year plan (1986-1990), the developed potential was in the order of 79 million ha. During that time, India was able to increase its food production from 50 million to 170.63 million tons. Turkey’s potential for irrigated agriculture is about 8.5 million ha. By 1990, 1.65 million ha were under irrigation, with a further 750,000 ha projected by 1994. Egypt projects a 2% increase (125,000 feddans) in irrigated land over a five-year period, and predicts a change in water use from 49.7 billion cubic meters in 1990 to 59.9 billion cubic meters in 2000. Mexico has 20 million ha of cultivated lands, of which 6 million ha are irrigated, contributing 50 per cent of total production, and had a projected increase in irrigated area of 1, 125,000 ha by 1994 (a 4.6% annual increase).

FAO’s recent studies indicate that it will be difficult to sustain a 2.4% annual growth in irrigation expansion in developing countries as predicted earlier. Clearly, a major portion of the needed increase in food production must come from existing irrigated and rain-fed lands through increasing yield per unit area and yield per unit of water consumed. Thus, FAO’s International Action Program on Water and Sustainable Agricultural Development puts emphasis on increasing water-use efficiency through modernization and improvement of existing irrigation schemes, rehabilitation of waterlogged and salinized irrigated lands and promotion of small-scale water programs aimed at supplementary irrigation, water harvesting and soil moisture conservation in rain-fed arable lands. At the same time, however, expansion should continue at a rate that can be justified in terms of meeting the goals of food security, increased farm income, improved rural development and conservation of the natural resource bases.

FAO’s recent projections for new irrigated lands up to year 2000, based on current trends and taking into account agro-climatic conditions and availability of suitable lands and water, are given in table 1. These increases are conservative, as compared with the expansion planned by several countries. They are the essential minimum rates that should be sustained if major starvation is to be avoided. Increases in production from these new lands will supplement a larger portion of food that is expected to be derived from existing irrigated lands through modernization and adoption of improved water management and crop husbandry practices; reclamation of waterlogged and salinized areas; and improved moisture management in rain-fed areas.

Table 1
Projection of irrigation expansion in developing countries and related costs (1993-2000)

The cost of irrigation development varies from country to country and depends on the scale of development. Preliminary estimates by FAO indicate that the total cost for the development of 15.2 million ha in 130 countries from 1993 to 2000 would amount to US$ 6.5 billion per year. These estimates were made on a regional basis, using existing cost data and assuming that a majority of the future developments will be medium-scale.

In order to achieve these objectives, FAO suggests that the scale of a new irrigation development should be appropriate to its being sustainable, with focus on medium-scale and small-scale developments, while large-scale developments must be considered as components of multiple-purpose projects. Regardless of size, the project area’s basic water needs must be provided for, especially drinking-water and sanitation needs. All developments, however, must be subject to and must meet the stipulations of an environmental impact assessment at the planning stage before being pursued. In addition, during all phases of development, the relevant sectors of society should be involved and consulted, with especial importance being given to the involvement of women.

In most irrigation schemes, improvement to the physical system is important to increase water-use efficiency and to diversify cropping patterns.

The modernization of existing irrigation projects is vital to increase yield, save water, make the project economically viable and arrest environmental hazards. This may involve, inter alia, canal-lining, additional and improved hydraulic control structures, better land development, and new irrigation methods. Targets and cost of modernization in 130 developing countries are presented in Table 2. These estimates are based on the assumption that physical upgrading would amount to 10% of the total irrigated area over a 10-year period, and that the cost of upgrading would amount to 25% of the cost of new irrigation development.

Table 2
Estimated targets and costs for the modernization of existing irrigation schemes (1990-2000)

According to FAO, an estimated 20-30 million hectares, globally, are severely affected by salinity and an additional 60-80 million are affected to some extent. FAO suggests that reclamation should be pursued at a minimum rate of I million hectares per year between 1993 and the end of the century. The major cost of reclamation is to be found in the provision of artificial drainage, including farm drainage as well as main drains, and suitable disposal or reuse facilities. The estimated cost for the provision of such drainage facilities would amount to US$ 7 billion over the seven-year period.

Agricultural requirements in the years to come will require the intensification of production in high-potential rain-fed lands where intensification does not result in overexploitation of the natural resource base or in environmental degradation. Improvements in rain-fed lands are proposed by FAO in the context of soil moisture conservation and the enhancement of food production under traditional rain-fed farming conditions. A total area of about 10 million hectares would be improved within the period 1993-2000, constituting 2.5% of the total high-potential rain-fed lands, at an estimated cost of US$ 7 billion. FAO also estimates that approximately US$ 14 billion will be required over the same period for investments in aquaculture development.

The total cost of technical assistance required over this period, both from national and external sources, has been estimated at US$ 1,640 million, covering feasibility studies, the establishment or strengthening of databases and monitoring systems, adaptive research and technology transfer, institutional strengthening and human resources development, fisheries and aquaculture, environmental protection, and policy and strategy formulation.

Recognition is now emerging that conventional economic analysis methods, as applied to agricultural projects that do not take into account the degradation of the natural resource base, do not provide a suitable measure of long-term sustainability. Case-studies conducted by the World Resources Institute in India, Chile, the Philippines and the United States to the following general conclusions:

"First, economic analysis that fails to measure changes in the productivity of natural resources will make farming practices that degrade the resources base look more valuable than those that conserve it. Second, when changes in the natural resource base are included in calculating farm income, resource - conserving production practices can compete economically and financially with conventional ones. And finally, policies that encourage inappropriate natural resource use can cause significant economic and fiscal losses, as well as environmental ones."

As stated in the report on these case-studies, "erosion and salinization can have enormous impacts on the productivity of agricultural soils. Depletion and contamination can damage groundwater resources. The pollutants in agricultural run-off can severely reduce the productivity of ecosystems and drastically shorten a reservoir’s life." To the extent that no depreciation allowance is applied against current income for the loss of productivity, standard accounting practices provide an erroneous picture of the long-term economic and environmental sustainability of a given project.