OECD

Challenges in the field of water resources management in agriculture Wulf E. Klohn and Bo G. Appelgren Food and Agriculture Organization of the United Nations

Summary

Growth in agricultural production has exceeded demographic growth during the last 30 years and the nutritional situation of the world has improved. There are however clear indications that the "green revolution" based on high-yield varieties, irrigation and high inputs in fertilizers and pesticides is stalling. Because of physical, economic and environmental constraints, irrigated agriculture cannot continue increasing its water appropriation as in the past, a fact already reflected in decreasing expansion of irrigation since de 1980s. While rainfed agriculture is still producing some 60% of the global food supply, sustainability limits in the pattern of water use for irrigation have been met and much improved management of water is needed in the future. In the competition for water, improved water conservation measures aiming at increased rainfall infiltration provide an opportunity for transferring food production upstream, where runoff is generated.

Subsidized water and high-input agriculture have resulted in wastage and pollution of water resources that are needed for domestic water supply. The fact that large amounts of water are appropriated for low efficiency uses brings into the foreground the need for improvement in the way water is allocated among social strata, sectors, activities and regions in order to achieve the most worthwhile overall use across sectors in society. As water subsidies are terminated, society is increasingly willing to equitably compensate the farmer for protecting the environment and preserving the landscape, wetlands and forests. It is clear that policy and management decisions cannot be taken in isolation and integrated river basin management is often the only viable management process.

New and better adapted policies and strategies are being applied progressively, as the political and economic situation makes interventions feasible. These interventions generally go in the sense of removing subsidies to water and agriculture, re-allocating water with overall efficiency criteria, ensuring sustainability and environmental protection and using market mechanisms to achieve efficiency. Equity considerations have room in this approach through direct support targeted at individuals and not at agricultural inputs and products. Enhanced education and public information should support the process of overcoming future water management hurdles.

1. Introduction

Among the many roles of agriculture, the basic one is to produce food. Where rainfall is insufficient or unreliable, addition of water to the root zone through irrigation improves crop productivity. For the success of the crop, it is indifferent whether the optimum level of soil moisture at the root level is achieved through natural rainfall or is added by irrigation.

Agriculture is called to increase the total quantity of food it produces as the number of people living on the globe grows. A first question could be, why is agriculture at present not producing enough food for everybody? The reply is that the main reason for food insecurity and malnutrition is poverty. The broad objective of ensuring satisfaction of food and other basic needs for all is therefore closely related to a subsidiary universal objective of ensuring adequate income to the population concerned. A second question frequently raised is: Will there be enough water to allow for universal food security of the future population of the globe? The reply can be foreshadowed: enough water is available but sustainability limits have been met in various places and much improved management of water is needed in the future to overcome the straits while population stabilizes.

During the 20th century the rate of water withdrawals in the world has increased much faster than population, owing mostly to irrigation and industrial development. On a rough average, 70% of global water abstraction is for irrigated agriculture. The figure may be above 90% in some arid countries and regions, while the percentage is less in countries that can produce food without irrigation and in countries with a strong industrial and urban water demand. Growth in agricultural production has exceeded demographic growth during the last 30 years and the nutritional situation of the world has improved. The "green revolution" made this possible. There are however clear indications that the green revolution is stalling and the rate of increase of irrigated land is leveling off.

While the renewable amount of water annually available is fairly fixed, the amount of water available per person and per year diminishes as population increases. At a time when industrial and municipal users are in competition with agriculture for water, the preservation of the aquatic environment and of valuable ecosystem services also requires that an appropriate amount of water is left and protected in rivers, lakes and wetlands.

While irrigation water is applied to improve productivity and to open for agriculture regions that do not have appropriate rainfall, rainfed agriculture, which is not in direct competition with other water uses, is still producing some 60% of the global food supply. Water extracted from rivers, lakes and aquifers cannot be substituted for such uses as human consumption, municipal use and some industrial processes; in contrast, water applied in irrigation represents only a secondary, albeit very important, facet of global agriculture. Moreover, the current debate about water scarcity should not overshadow the fact that agricultural production is also constrained by excess water and that drainage is a condition to improve productivity.

2. Projecting the water supply/demand balance

Food production is by far the largest user of water. An assessment of how much water is needed to produce food for the future world population could be based on the dietary energy supply (DES) at the national level, as a proxy for future water demand. The DES varies between some 2,200 calories for poor countries (that harbor a large numbers of undernourished), to 3,500 calories for rich countries (where sometimes obesity is a public health problem). The national food supply situation is considered just satisfactory at the 2,700 calories level, when few people are undernourished.

An estimate of the amount of water, regardless of origin, taken up by the crop plant to produce a selection of basic crops is given in Table 1. The same table contains estimates of the amount of water required to produce chicken and beef. An estimate of the water needed to produce an average balanced annual diet for one person could be based on the figure, 2000 m³ per person per year. World diets richer in meat, particularly beef, would however project significantly higher water demand (Klohn and Wolter, 1997).

Table 1: Foodstuff Liters of water per kg:

                Potatoes          500
                Wheat:            900
                Sorghum:    1,100
                Maize:          1,400
                Rice:             1,900
                Soya:             2,000
                ---------------------------------------
                Chicken:      3,500
                Beef :          20,000 - 100,000
                ---------------------------------------

Feeding the current world population of 5.8 billion effectively requires 11,600 km³ of water stemming both from rainfall and irrigation. Furthermore, accepting that some 40% of food is currently produced under irrigated agriculture, and that irrigated agriculture on average takes 40% of water from irrigation, one may conclude that irrigation effectively uses some 1,850 km³ of water for food production while 9,750 km³ of water inputs to food production stem directly from rainfall. The 8.2 billion population projected for 2025 would then demand 16,400 km³ of water, or 15% of total global rainfall, to produce the required food.

On the global water supply side, runoff in rivers and lakes or underground amounts to some 40,000 km³ or 35% of total rainfall. About 12,500 km³, or 30% of total runoff, is considered to be annually accessible in the given economic context. Some 5,000 km³ of accessible runoff are already appropriated, much more than the water effectively used for food production. Technically, more water can be mobilized by harnessing remote rivers, capturing floods, melting polar ice or desalinating sea water, but at a steeply increased cost in terms of finance, energy and environment.

Within the conceptual limits of the given assumptions, this finding confirms other global indicators that point to unsustainability of the current global trend of water use. There is not much unused suitable land left for horizontal expansion of agriculture, and demographic growth as well as scarcity of funds is forcing policies and practices that result in better use of irrigation water and rainfall, supported by more productive cultivars in a more technified agricultural environment.

Ultimately, however, whatever cumulated and averaged realities the global statistics reflect, water policies and practices are devised and implemented at the national or local level were the situation may vary from dire water scarcity to pervading humidity and flooding.

3. Local use of rainfall versus generation of runoff.

Figure 1: Partitioning of rainfall as it reaches the ground (from Rockstroem and Tilander, 1997)

Figure 1 is a close-up that shows the partition of rainfall at the point it hits the ground. The surface runoff and deep percolation that collects in water bodies is sometimes called "blue water", while "green water" is the productive or non-productive water loss that joins the atmosphere. Farmers dissatisfied with the quantity and opportunity of natural rainfall invented irrigation, which is but a way to reclaim runoff, seen as unproductively sunk into the oceans, and lead it to the root system of the crop. There are still other ways of intervention possible at this level; for example, soil additives that increase water storage within the root zone.

In a market situation, irrigation tends to lose out against rainfed cropping because there is a cost to irrigation in pumping, storage, conveyance and system maintenance, while rainfall is free. For this reason, once irrigation water is not subsidized and confronted with the market, it tends to become confined to specialty niches such as high value products that benefit from the sunny arid climate and from production off the rainy season. In the competition for water, food production may be transferred upstream, where runoff is generated, through improved cropping and tilling practices and other water conservation measures aiming at increasing infiltration while decreasing runoff with consequent costs for e.g. lost energy production. Already in some situations, downstream water users have complained about larger numbers of farmers applying better farming practices in upper catchments.

While water scarcity is dominating the current debate, it should not be forgotten that, to improve farm productivity, the water management problem to be faced sometimes is drainage, that is, leading water away from the root zone. In such cases, downstream consequences may include undesired flooding and increased risks of environmental pollution.

4. Issues in water management for agriculture

Agricultural policy and water management do not stand in isolation.

As agriculture is a heavy user and a potential polluter of water, water policy strongly depends on agricultural policy. In turn, agricultural policy is subordinated to national objectives, which may be served also by non-agricultural uses of water. Figure 2 shows possible relationships between overall and subsidiary objectives, decentralized means and government policy instruments. In this case, well-being of rural population is a main goal which depends on a subsidiary objective: real rural income, on decentralized means and on a policy instrument: social services available to rural people. Real rural income, a subsidiary objective, depends on real prices, a policy instrument subsidiary to tariffs and the exchange rate; on production, which is a decentralized decision variable, and on other policy instruments such as taxes, subsidies and direct income support. Agricultural production in turn depends on a number of direct and indirect policy instruments, such as infrastructure development. National water strategy and management cannot be isolated from national development goals, subject to subsidiary water objectives.

Environmental performance of agriculture.

At a time when global demography calls for intensification of food production, intensive, high-input agriculture in industrialized countries, often associated with highly subsidized water resulting in massive waste, is found to be environmentally non-sustainable and subject to significant policy changes. Water pollution stemming from inappropriated practices in the use of chemical fertilizer and pesticides, and from other intense forms of production such as livestock feedlots, has led to groundwater contamination that is highly damaging for domestic water supply. Similarly, over-use of groundwater has led to quality degradation by saline intrusion in heavily populated coastal zones. Alternative sources of water are often not available, treatment is beyond

Figure 2: Relations between objectives, decentralized decision variables and instruments in agricultural policy.

technical and economic reach and the recovery period of contaminated aquifers can be very long, in the hundreds of years. Thus, water pollution and over-exploitation leads to direct economic costs to society for water treatment and development of alternative supplies, while degradation of ecosystems and declining public health become important social and environmental externality costs and a threat to environmental sustainability and social security. In developing countries these effects, which are directly related to the increase in population density, normally get only a low level of attention. In the industrialized countries, however, the social and environmental externality costs for water pollution tend to be a main issue. No wonder therefore that societies take curtailing action on agricultural subsidies that have resulted in costly pollution. Moreover, in affluent countries the public reckons that a decreasing part of the family budget is used for food, and that the agricultural value in food is relatively low: more than 80% of the shelf cost of a food item may be caused by non-agricultural added value, such a conditioning, packaging, storing and promoting the brand. Thus, society becomes increasingly willing to compensate the farmer for protecting the environment and preserving the landscape. For example, it has been reported that Swiss mountain farmers income is based 30% on farm income and 70% on direct income subsidy, based on the nationally accepted need for preservation of the farming landscape. It can generally be stated that subsidies will continue for reasons of equity and services to the environment. but will focus on direct support rather than general input or product subsidies.

Ecosystem services, wetlands, forests and biodiversity

As the protection of the environment is becoming one of the major goals of civil society, awareness of the direct and indirect benefits of ecosystems services is increasing among the general public and at political levels and the protection of wetlands, forests and biodiversity is moving up on the agenda. Ecosystem products do have a significant value and can represent an important source of income for rural and urban communities. Wetlands, for example, which exhibit large diversity in size and shape, are complex, dynamic ecosystems that help and protect rivers and lakes by storing nutrients and reducing sediment loads. Considerable progress needs to be made in the science and art of wetlands development planning and management to conciliate production and conservation objectives Many developed countries have already drained and developed for agriculture a substantial part of their wetlands, while in developing countries, wetlands (valley bottoms, dambos) represent an important agricultural reserve prone to development as demographic pressure pushes the agricultural frontier. A number of governments have subscribed legally binding conventions or treaties that protect wetlands.

A sometimes overseen facet is that in a number of countries, the management of drained land is a major challenge for agricultural and water policy. The management objectives are twofold: restoring and maintaining drained systems to functioning conditions, and controlling agricultural pollution from drained land areas, two costly undertakings that require major infrastructure, with high social significance for rural welfare and environmental protection. In the restructuring of the agriculture sector, some of these lands may be used in intensive, high-input agriculture, while a part of the sector may turn to low intensity agriculture, landscape maintenance agriculture, runoff regulation and erosion control. Preservation of forests, landscape and traditional agricultural skills may tend to come under new lines of direct public support.

Water allocation efficiency and water use efficiency.

Wherever water is scarce, whether because of natural shortage or inadequate allocation, ways need to be found for its best possible use. In this respect, two different realms for exercising efficiency are recognized. One is allocation efficiency which addresses how water should be allocated among social strata, sector, activities and regions in order to achieve the most worthwhile overall use across sectors in society (Lundqvist and Gleick, 1997). Competing demands for water have various costs and benefits associated. If large volumes of water are allocated to a sector producing low value, the total amount of value generated in society will be low. For example, it has been reported that while 70% of water resources in Israel are devoted to agriculture, farming only generates 3 - 5 % of the GDP (Shuval, 1997). This is an interesting case because the Israeli agriculture uses water very efficiently in a technical sense. Allocation efficiency has been extensively discusses in the 1990s with a milestone set at the Dublin Conference: the fourth Dublin principle states that water has an economic value in all its competing uses and should be recognized as an economic good (ICWE, 1992). Opportunity costs are becoming increasingly important and need to be considered. Benefits from water need to be seen in a wide context and include such aspects as employment, production, poverty alleviation, public health and environmental values.

Another form of efficiency applies to performance in accomplishing a specific goal without using more water than necessary; for example, in efficient irrigation the water abstracted is applied to crop production and to preserving the salt balance in the soil, while non-productive evaporation, deep percolation and other losses are minimized. Modern irrigation technology provides a panoply of techniques and tools for accurate application of water to the roots according to the requirements of the crop. Such techniques do not need to be expensive or difficult to apply but they do require capable, diligent farming.

Farmer skills and public information

With increased financial and environmental responsibility in addition to technical skills, the farmers of the future are expected to exercise increased management capacities. The process will be supported by the advent of a new generation of farmers exposed to a more diversified education. This trend should be reflected in broadened curricula and enhanced thresholds in farmer training and managerial capacity. Attention is required to the fact that, as intensive production agriculture continues shifting from a system based on farmers to one based on agribusiness, land tenure tends to be separated from farming operations. This trend may result in decreased commitment to sustainable land use and practices. Not less important, public awareness is fundamental for future sustainable water use. There is consequently a need to further develop the quality of information on water issues and the level of understanding by the public of the multiple issues and facets involved in water management.

Water in agricultural trade.

At a time when an increasing number of countries slide away from food self-sufficiency, national food security becomes more dependent on trade. In this respect, some countries are self-reliant, meaning that they are able to generate sufficient foreign exchange to cover their food bill, but not self-sufficient, meaning that they do not have enough water, in the form of either rainfall or runoff, to produce domestically all the required food. The global market is somehow expected to take care of the transfer of food from the regions able to produce excedents to supply the countries in the deficit regions with agricultural products. For example, a recent FAO study estimated the net import of food for each country in the Near East region and transformed it into water equivalent (FAO, 1997). The results show that the food imports of the region represent a volume of water comparable to the flow of the Nile at Aswan. The policies of trading blocks and affluent countries have consequences in poor countries because of the potential for social disintegration and instability spilling over into large regions. In this aspect, there is a connection between water scarcity and national security (Appelgren and Klohn, 1997).

5. Conclusions

Past trends in the appropriation of water resources for human use, and in particular for irrigated agriculture, are not sustainable. The consequences of these trends, generally characterized by excessive water use owing to subsidies, have been perceived at various quarters in terms of water pollution, water scarcity and overdrawn aquifers. The process of adjustment and corrective action has already been initiated but the unsustainable water management question has as yet not been universally solved. New policies and strategies, better adapted to local water availability, climate and physical environment and to the priority needs of the population, are applied progressively, as the political and economic situation makes interventions feasible. These interventions generally go in the sense of removing subsidies to water and agriculture or replacing them with well-directed direct support, re-allocating water with overall efficiency criteria, ensuring productive sustainability and environmental protection and using market mechanisms to achieve use efficiency. Water policy and strategy is eminently a national matter; however, attention needs to be paid to the international implications that may ensue from the decisions of major trading blocks. As a consequence, a particular cause of concern in a global context are those countries that face serious water management issues but do not have the economic and technological resources to appropriately deal with the problem.

Bibliography

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