1.1 The Role of Irrigated Agriculture in Global Food Security
1.2 Research Needs in Irrigated Agriculture
1.3 The Irrigation Research Community
According to the UN estimates, the current world population of 5.5 billion will increase to 10 billion by 2050. About 97% of that increase will occur in the developing countries, and two-thirds of this growth is expected to take place in the cities.
Parallel to this it is likely that the present worldwide economic growth will continue and result in rising incomes and standards of living, and hence in the demand for a meat-based diet. This will cause an increased demand for agricultural products, which will be added to the extra demand arising from population increase. It is estimated that total food demand in the developing countries will increase by approximately 150% by 2025. The continuing population increase will result in a decline of available cultivable land per capita worldwide from 0.3 ha in 1988 to 0.17 ha in 2050, with only 0.11 ha per capita in developing countries.
It is obvious that productivity in agriculture will have to grow rapidly to keep up with the demand for food. About 8% of the increase in food production in the last half century has come from the expansion of the cultivated area and 92% came from higher yields per ha. Over this period agricultural technology has produced remarkable responses, with doubling or tripling of yields in a number of crops. The main inputs have been new crop varieties, increased use of fertilizer and improved biocides, together with a large increase in the irrigated area, at a rate of about 3% per annum between 1950 and 1980. Since 1980 the annual rate of increase has declined to about 1%. The total world irrigated area has increased from 80 million ha in 1950 to 237 million ha in 1993.
The importance of irrigated agriculture at the present time can be best illustrated by the fact that the global irrigated area of 20% of the world's cultivated land produces US$ 104 billion worth of crops, or one-third of the world's food harvested, and that an estimated 46.5% of all grain is produced under irrigation. The irrigated sector in the developing countries, covering a total estimated area of 173 million ha, meets the basic food needs of billions of people, especially in Asia. In addition irrigated agriculture helps to alleviate poverty and unemployment, and maintains low food prices in rural areas and for the urban poor. Despite this excellent record, most irrigated areas in the developing world produce half or less of their potential yield which could be attained with the best management of water and other inputs.
In the developing countries, over the next 30 years another large increase in total food production of around 150% will have to be effected, or from 1.15 to 2.6 billion tons of grain in order to meet estimated food demand. Some of this need could be met by expanding the cultivated rainfed area, but the availability of good new land is now less, and its geographical location is not ideal; in particular, there is limited land available in Asia. The small contribution from increased land area to past yield increases argues that suitable land is not easy to find, and that increasing yield per ha on established fields is more cost-effective. The yield level on rainfed land may often be controlled by available water, which may be inadequate or irregular in supply. The benefits from additional bought inputs are therefore often low and farmers may be reluctant to invest in them. It is therefore uncertain how far yields on the rainfed lands of the developing world can be increased beyond the present level of 1 to 1.5 tons per ha of cereals.
When in the developed countries all current technologies of fertilizers, water supply, pest control and management are being used in full, the maximum yield for a single crop of cereals is about 10 tons per ha. This output level should be regarded as the limit of full intensification, and this is being quite closely approached in some industrialized countries. In practice the average yields over a large area will always be somewhat smaller than this, and the practical limit for full intensification under irrigated condition is about 8.5 tons per ha for a single crop. In the developing countries similar potential yield levels per year are achievable, from two crops per year and with well controlled growing conditions. However, due to the more difficult and adverse growing conditions in many of the developing countries it is more realistic to assume that at a regional scale on properly managed irrigated land yields of 6 tons per ha per year are obtainable. This level is currently obtained in some parts of the developing world, such as the Punjab and Egypt.
In this discussion we are assuming that the only technologies that will be available are basically those used at present, though clearly there will be improvements. These technologies all have their roots in the 19th century, though their full application has occurred in the 20th. The main discovery of the 20th century - biotechnology - still has to prove itself in practice, and its impact on crop yields may not be felt till well into the 21st century, so it seems unwise to rely upon immediate major breakthroughs.
We argue here that it is essential to move towards full intensification of agriculture in the developing world, taking all possible precautions against the environmental problems that could follow from this. It is only on the irrigated lands that the full potential for crop yield can regularly be approached. Some expansion of the irrigated area may occur (an estimated increase of 1% per year for the coming 30 years), but the rate of increase is declining, and economically viable new sites are becoming difficult to find. At present non-food crops occupy some 20% of the 173 million ha of irrigated land in the developing world. We therefore assume that the irrigated area for cereal production in the developing countries will rise to not more than 192 million ha by 2025.
Our fairly conservative assumption of a yield level of 6 tons per ha per year suggests that irrigated land in the developing countries could supply 1.15 billion tons of cereals by 2025. Adding to this the cereal output of the rainfed area, estimated as 0.65 billion tons, the developing countries will probably be able to produce in the year 2025 a total output of cereals of 1.8 billion tons. This indicates a net deficit of cereals in the developing world in 2025. We do not speculate on how this could be met: possibly average irrigated yields might be higher than this. We simply use this rough calculation to show that there is no room for complacency, but that the need for maximum production from irrigated agriculture at that time will be overwhelming. The same conclusion probably applies to most of the period between 2000 and 2025.
For the irrigated sector to achieve this goal, irrigated agriculture has to become more efficient. All the evidence shows that the main impediment to this is in poor management of the irrigation system, and that the necessary inputs will largely be wasted until this is corrected. This task is IIMI's duty and opportunity, and it is the main reason for its existence. The Panel points to several other areas of legitimate interest for irrigation management in this report, but the most critical issue is our future food security, at a time when that future is so uncertain.
There are considerable global benefits in concentrating agricultural activity as far as possible within the irrigated area and using this area to its maximum capacity. If all cultivable land on the globe were to be taken into use, it would almost certainly be possible to feed the maximum expected population of the world. However, this would entail the development of areas now in forest or other wild vegetation, with the loss of ecosystems, biodiversity and biogeochemical cycles, which can be more usefully saved for future generations. Sustainability is an issue that should not be looked at in a purely local sense.
The other question is that of the rate of increase in food demand and in food output, which must be kept in approximate balance. It must in principle be easier and quicker to exploit existing facilities fully rather than create new ones. All these arguments thus converge on the conclusion that the improvement of the management of irrigated agriculture is a priority task.
This must happen at the same time that environmental impacts related to irrigation become more serious. Attempts to use larger fractions of available water will increase the danger of salinization. Intensification increases the danger of fertilizer elements and biocides in groundwater. Population pressure on the catchments from which water is drawn will lead to deforestation, poor land use and erosion, with siltation into irrigation systems. The total task facing irrigation research is truly formidable, and this is developed further in the next section.
Evaluations of irrigation projects have emphasized that many perform very poorly, and that most projects are operating well below the potential output used to justify the original investment. There has consequently been a decrease in the rate of expansion of the total irrigated area, due to the overall low economic return on investments in this sector. This is even more so because of the relatively high and rising capital costs for the construction of new irrigation capacity (about US$ 2,400 per ha in Asia to US$ 7,200 in Africa for medium-sized systems), and the low market prices of cereals. There is a serious shortage of well-sited, low cost opportunities for expansion of the irrigated area. Work on maximizing cost effectiveness of new systems by innovative irrigation technology is therefore important.
Many of the irrigation schemes which were constructed at the beginning of this century badly need rehabilitation in order to become economically viable again. The main reasons for their present low performance are insufficient funding for recurrent expenditure, and lack of systematic plans for maintenance and management practices. Most governments and donors have recognized that poor maintenance is a major obstacle to improving water use efficiency and output. The total annual investment in irrigation needed today for infrastructure maintenance is estimated at US$ 10 to 12 billion. This estimate does not include major costs for important rehabilitation works. Any improved lower-cost methods for maintenance would be extremely valuable, and rehabilitation should be carried out in ways that would minimize subsequent maintenance.
In addition to the poor maintenance, leading to crumbling and leaking canals, ineffective sluice gates, choked and untended watercourses, and inequitable distribution of water, the performance of irrigation systems is also damaged by more general institutional problems. One such problem, especially in large-scale irrigation schemes, is the lack of cooperation between the managers and operators of the water systems and the water users. The management style in most systems is supply-oriented, making water available on fixed schedules, rather than demand-oriented and responsive to the users needs.
The impact of the operation of an irrigation system on the farmers and their families within it is pervasive. A direct consequence of the inefficient and inequitable water distribution in many irrigation schemes is increased social tensions in the farming communities that they serve. Other socioeconomic concerns include the effects of water management on income distribution and tenure, the resettlement of those who are dispossessed by the construction of reservoirs and other irrigation infrastructure, and the effect of the operation of irrigated agriculture on the lives and behaviour of the water users, especially women. A major area of research is to find effective ways in which the water users can be given a much greater influence over the way in which water is distributed and the system is run, as this both increases efficiency and defuses the tensions mentioned above.
Another problem of increasing significance for the irrigation sector is the scarcity of water and the growing demand for water by other sectors of economic activity. In the developing countries irrigation uses 70% of available fresh water, and a large fraction of this water is lost before it is used, either as drainage water in the water courses draining the catchment area of the irrigation system or seeping into the underground and recharging the aquifer system. Overall, it has been estimated that these countries use twice as much water per hectare as the developed countries to achieve crop yields that are only one-third as high. What appears as a water scarcity crisis in many instances is largely a water management crisis. The mismanagement of water has multiple causes and requires a variety of interventions to correct it; these have to be designed by appropriate multidisciplinary research. The very large gap between optimal and current use opens the attractive possibility of simultaneously reducing water use by agriculture and making more of it available to other sectors of the economy, while at the same time increasing the effectiveness of irrigated agriculture as a whole, and thereby improving incomes, equity and sustainability. Understanding these causes of mismanagement and devising solutions to them is IIMI's fundamental mandate.
It is generally recognized that poorly designed, operated or managed irrigation systems lead to major environmental problems, and the importance that is assigned to these is rapidly increasing. The most significant environmental problem is the degradation of the natural resource base, the soil, because this may destroy the whole irrigation system. The most frequent problem of this type is an increase in waterlogging and soil salinity. Part of the reason for this is the inadequacy and/or the complete absence of a drainage network. Most plans for irrigation works now include some protection against these forms of soil degradation. This adds more than 10% to the cost of new irrigation systems, and thereby makes investments in irrigation projects less attractive when they are appraised using conventional cost-benefit analyses. Where soil salinity has appeared or is threatened there is an urgent need for site-specific research to determine the best way of controlling it.
There are also major problems that are located outside the irrigation system itself, and that greatly widen the scope of irrigation-related research. Careless land use activities in the catchment area of the irrigation system, induced by population pressure and resulting in deforestation, overgrazing, and poor tillage practices, cause soil erosion which can eventually render large areas almost sterile. The eroded soil adds to the silt in dams and canals, and thereby reduces the efficiency and shortens the effective life of the irrigation system. The main 'downstream' concern is on water quality. Saline soils naturally produce saline drainage water, and the increasing use of agrochemicals means that they also will find their way into the drainage unless used with care and expertise.
These effects can damage the quality of water used both for irrigation and for drinking. The long-term impact on water supplies becomes more serious when the agrochemicals seep into the aquifers that provide drinking water for downstream users, because corrective measures are then very difficult. The presence of either salt or agrochemicals can damage ecosystems and biodiversity, especially in fragile wetlands. These problems show that research on production systems has to work together with that on irrigation operation and management, and shows the wisdom of IIMI's new mandate on 'irrigated agriculture'. Further, irrigation can lead to increased health hazards to people living in irrigated areas through the propagation of vector-borne diseases.
Research in irrigation must address all the key problems listed above. Such a broad agenda and such a huge area require the work of many researchers. IIMI needs to identify what subjects and opportunities it can most fruitfully deal with itself, and then put concentrated efforts into building up collaborative teams with high-quality partners to deal with broad issues. The structure, progress and future of IIMI's research is described in Chapter 3; below we discuss the research community within which IIMI must find its partners.
There is a great variety of institutions which contribute to research that promotes improvement of irrigated agriculture. Some carry out research and others fund or coordinate it. They do not presently constitute an integrated community by any means, and there are many interfaces with related communities of parallel disciplines. This subject is developed further in Chapters 7 and 8.
Countries where the irrigated area is relatively limited in extent do not usually have separate irrigation research institutes but rather carry out such research within agricultural research institutes. When there is no separate organization there is a risk that irrigation-related research will receive low priority and be limited to agronomic aspects. Establishing regional facilities is one means of overcoming such problems, as in the case of CIEH (Comité Interafricain d'Etudes Hydrauliques, based in Burkina Faso). On the other hand, research in countries where there is a separate national irrigation authority is often likely to take a narrow disciplinary view, emphasizing technical and engineering factors more than management ones. The desirable interaction between irrigation and agriculture departments is often absent. Parallel to specialized institutes or departments, some irrigation research may also be carried out by national universities.
In addition to national capacities, numerous international organizations have been engaged with the advancement of irrigated agriculture through research and/or dissemination of information. Some are more focused on irrigation technology issues, such as the International Commission on Irrigation and Drainage (ICID) and the International Programme for Technology Research on Irrigation and Drainage (IPTRID). Their primary concern is to improve the technical performance of irrigation systems. Others touch on specific aspects associated with it, such as the World Health Organization (WHO) concerning health impacts and the United Nations Environment Programme (UNEP) on environmental consequences. Some of the other CGIAR Centres, in particular the International Rice Research Institute (IRRI), the West Africa Rice Development Association (WARDA), the Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT) and the International Food Policy Research Institute (IFPRI) are also working on problems of irrigated agriculture.
The main UN interest in irrigation research and technical assistance comes from FAO, in which the Land and Water Development Division deals with irrigation and drainage, and various other division are concerned directly or incidentally with irrigated agriculture. The Water Resources and Management Service of the Division prepares guidelines on irrigation and drainage technology.
Another important set of research contributors includes the universities and research institutions in the developed countries, that provide training and conduct fundamental and applied research on technological, socioeconomic, operational, managerial and environmental aspects of both rainfed and irrigated agriculture. In these institutions, training and research tend to follow disciplinary lines, with some institutions having now adopted a more multidisciplinary approach.
Given the enormous size of the financial resources invested in the establishment of the irrigation infrastructure, and the large amounts which are annually needed to keep the irrigation schemes operational, the world is not investing sufficiently in irrigation research. Total annual expenditure on irrigation and drainage research probably does not exceed US$ 130 million a year. This is slightly more than 1% of the annual investment in irrigation and drainage, and probably less than 0.1% of the total value of produce grown each year on irrigated land in developing countries. The total expenditure on irrigation and drainage research in the developing countries amounts to only US$ 80 million per year, and the actual expenditure ranges from US$ 0.1 to 1.5 per irrigated ha. It is difficult to justify this low level of activity in the light of the needs outlined here.
