Technical
background
document
Executive summary
FAO, 1996
Acnowledgements
Executive summary
2. WATER ISSUES AT GLOBAL LEVEL
Water: a limited resource
Water use for food production
Water situation by regions and countries
Managing water scarcity
Function of groundwater
Food security and water security
Water policy review and institutional changes
Transboundary waters
3. CONTRIBUTION OF WATER CONTROL TO FOOD SUPPLY
Water control and food production
Potential for irrigation
Droughts and water management
The situation in Africa
The situation in Asia
The situation in Latin America
4. STRATEGIES FOR TRANSFORMATION AND IMPROVEMENT
Water policy and legal prerequisites
Water pricing
Institutional development
Macroeconomic imbalances and water management
Social aspects of irrigation
Technological adaptation
Promoting private-sector initiatives
5. SUCCESSFUL APPROACHES TO WATER DEVELOPMENT
Low-volume, high-frequency irrigation
Water harvesting
Inland valley swamp development
Low-lift pump schemes
Peri-urban irrigation, a spontaneous development
Use of shallow aquifers
Conjunctive use of surface and groundwater
Rehabilitation of large schemes
6. BENEFITS AND COSTS OF WATER CONTROL
Investment trends
Water development costs
Possible ways to reduce water development costs
Economically justifiable investment in water control
Solving operational and maintenance problems
Without-irrigation scenarios
7. WATER DEVELOPMENT AND THE ENVIRONMENT
Instream water requirements
The crucial role of upper catchments
Water development and health
Preventing degradation of irrigated lands
8. PRIORITIES FOR ACTION
Assessment of resources and use
Policy
Research and technology transfer, capacity building and extension
Infrastructure and investment
Enabling environment
Preservation of natural resources
The preparation of the World Food Summit technical background documents has mobilized, in addition to FAO’s own staff contribution, a considerable amount of expertise in the international scientific community, drawn from international partner institutions and governmental or non-governmental circles. The process has been monitored at FAO by an internal Reading Committee to ensure that the whole collection meets appropriate quality and consistency criteria.
The present document has been prepared by FAO’s Hans Wolter, Arum Kandiah, Wulf Klohn and Simon Hocombe. Substantial contributions have been made by the late Ian Carruthers, and by Daniel Hillel, Mark Rosegrant, Joop Stoutjesdijk, Jean-Claude Legoupil and others. Much appreciated comments and advice were received from the Centre for World Food Studies (Amsterdam), the International Agricultural Centre (Wageningen), the International Irrigation Management Institute (IIMI) and the Union of Fertilizer Producers, the Netherlands; Ralph Cummings of the United States Agency for International Development (USAID), Washington, DC; Honorato L. Angeles of Central Luzon State University and Dominador Pascua of the National Irrigation Administration, the Philippines; the Southeast Asian NGO Liaison Committee on Food Security and Trade; and the governments of Australia, France, the Netherlands, Switzerland, Tunisia and the United Kingdom.
While grateful for the contributions received from all reviewers, the FAO Secretariat bears the responsibility for the content of the document.
The supply of easily accessible freshwater resources is globally limited. Taking into account that not all water can be abstracted but a part of surface waters must be left in the rivers to safeguard the environment, over one-half of accessible runoff is already committed. In arid and semi-arid regions, in densely populated countries and in most of the industrialized world, competition for scarce water resources has set in. In major food-producing regions, scarcity of irrigation water is spreading. In the light of demographic and economic projections, the freshwater resources not yet committed are a strategic asset for development, food security, the health of the aquatic environment and, in some cases, national security.
Water cannot be substituted for many of its functions: as drinking-water for human beings and animals; for hygiene, washing, sanitation and municipal use; for industrial processes; and for fish, aquatic life and the environment. Production of biomass, including food, is dependent on the availability of adequate moisture in the soil. The intensive agronomic technology that has allowed steady increases in world food production, based on high-yielding varieties, coupled with the application of fertilizers and effective means of pest control, is largely dependent on irrigation to secure and control soil moisture in the face of insufficient and unreliable rainfall. Yet irrigated agriculture is a highly water-intensive activity. It claims nearly 70 percent of world water abstraction: over 90 percent in agricultural economies in the arid and semi-arid tropics, but less than 40 percent in industrial economies in the humid temperate regions.
Irrigated agriculture, which is much more productive than rain-fed agriculture, contributes nearly 40 percent of world food production on 17 percent of cultivated land. Increased production to satisfy the food demand of the future must essentially come from intensification, not from expansion of agriculture. Both rain-fed and irrigated agriculture will need to be intensified, but the intensification potential of irrigated agriculture is much higher. Some authors indicate that 80 percent of additional food production will come from irrigated agriculture.
However, as food needs rise, it is becoming increasingly difficult to supply more water to farmers. Taking industrial and municipal use, water losses and instream flow requirements into account, overall water requirements by the year 2025 appear to overcommit all accessible runoff by some 5 percent. The figures underlying this analysis – the respective contributions of irrigated and rain-fed agriculture, the amount of water required to produce the food needed for human diets and instream flow requirements – may be subject to different interpretations. However, it is clear that human demands are about to collide with the ability of the hydrological cycle to supply water. Water is becoming globally scarce. The fundamental resource constraint will have an effect on the cost of food.
A worldwide overview of water supply and projected demand flags specific concern of the regions. Virtually all countries with a mainly arid territory, such as those in the Near East and North Africa, are already net food importers. The priority for water use in these countries will be to secure adequate water for cities and for a healthy economy in the industrial and services sectors, in order to earn the income required for food imports. Because of the scarcity value of water, these regions will not be able to harbour water-intensive industries. The agricultural sector in water-scarce arid countries is bound to rely more and more on waste water freed by cities and to specialize in producing crops that yield the highest revenue, such as fresh vegetables and fruits. Food security in these countries will be closely tied to the solidity of the trading position anchored in a context of regional stability and collective security.
The amount of fresh water currently available per person per year in major Asian countries (e.g. China, 2 300 m3; India, 2 000 m3) is fairly close to the amount of water needed to produce the food requirement per person per year (2 000 m3 for a balanced diet with meat). As population and the diversity of the Asian diet increase and the scope for irrigation expansion and water development narrows and intersectoral competition increases, some major irrigation-using countries in Asia may even become net food importers. Given that 60 percent of the world population lives in Asia, this evolution has the potential to stress global food markets in a serious way. The economic strength of a number of countries in Asia is widely recognized, but it should not be overlooked that large poverty pockets remain, particularly in South Asia.
Africa, with the exception of the central Congo-Zaire basin, is the driest continent (apart from Australia) and suffers from the most unstable rainfall regime. Each year more people are at risk from the effects of inevitable droughts of greater or lesser severity. Furthermore, Africa’s water resources are relatively less developed than those of other regions. Agricultural productivity per caput in sub-Saharan Africa has not kept pace with population increase, and the region is now in a worse position nutritionally than it was 30 years ago: food production has achieved a growth of about 2.5 percent per year, while population has risen at the rate of over 3 percent per year. Moreover, Africa’s ability to earn from exports in order to buy food has not improved. In the past, additional food in Africa came from increases in the area cultivated, but as good land becomes less available, the region will be forced to intensify production systems to increase yields. Water development in its various forms, from water harvesting to modern piped irrigation, is destined to make a major contribution to transforming the efficiency and security of the African food supply.
As a continent, Latin America is well endowed with water, although there are substantial intraregional differences. Water problems in Latin America are mainly related to low water-use efficiency, resource management, environmental degradation and pollution control.
Intensified demand for water will stimulate efforts to develop new water supplies and to use existing supplies in a more efficient way. Increasing water supply is technically feasible but expensive – the most attractive projects have already been done. It is believed that the next generation of storage reservoirs and water conveyance infrastructure, with a closer management of the “externalities” of the past such as equitable treatment of people, accounting of environmental damage and full recovery of investment, will cost several times more than the past generation of water development structures. The technology for desalting sea water has made tremendous advances, but wheat produced with desalinated water will still cost five times as much as the average world market prices. Various proven methods for rainwater harvesting are available and have promise for expanding supplies at low cost. Rehabilitation and protection of upper catchments, necessary for many reasons, also yield a more balanced hydrological regime and fewer sediments trapped in reservoirs.
Existing water supplies can be used more effectively by suppressing unproductive evaporation and preventing water pollution and salinization. A number of measures are available and are expected to yield increased food production with unchanged, or even diminished, water available for agriculture. At the level of the river basin, integrated (conjunctive) water management, both structural and non-structural, can reduce water losses from evaporation, pollution and salinization. At the irrigation scheme and farm level, irrigation efficiency, sometimes as low as 30 percent, can be substantially increased.
Population growth, migration and urbanization will continue to have a significant impact on all aspects of development. These changes will lead to improved infrastructure and marketing systems reaching out to underdeveloped rural areas. Enlarged and more reliable local food production, generated close to where it is consumed, is more than an insurance against the risk of rising prices. An increasingly efficient agriculture contributes to overall development. Ways must be found to overcome the evident opportunity costs and hardship generated by a growing gap between food needs and local production.
How can the necessary water development take place in the face of the general perception that water investments, particularly those of irrigation, are ineffective, inefficient and a threat to the environment? Such views are ill-informed. Prospects for water harvesting and for small- and large-scale irrigation need fresh appraisal. Many important lessons have been learned, and the mistakes of the past need not be repeated. In fact, small- and large-scale irrigation investments (avoiding the costly approaches of the last 25 years) can yield returns that are higher than those of other agricultural projects and close to those of non-agricultural investments. Existing infrastructure can be rehabilitated and modernized, and water management improved. The positive linkages to the economy can be greater in the case of water development than for other projects; indeed, irrigation generates employment and in doing so attracts settlers from the more fragile hilly and arid areas that are prone to environmental degradation. Where appropriate, farmers should be assisted in assuming ownership rights and management responsibilities for assets developed by the public sector. Without such developments there will be much reduced scope for farmers (and consumers) to benefit from the array of existing agricultural technologies.
The world is currently undergoing an era of rapid change. Irrigation requires an equitable macroeconomic environment, and there has been considerable progress in this regard. Water policy that led to past misallocation and wastage has been reviewed and its implementation supported by an enabling environment, with adequate and properly enforced laws. The importance of including the intended beneficiaries in the design and implementation of new projects is now recognized, as is the need for realistic, uncomplicated project designs. The institutional capacity of governments, non-governmental organizations (NGOs) and the private sector to work together is rapidly improving. A wide array of water development technologies is now available, but private and public investment funds are needed for their implementation. The major challenge, however, is to build capacity at all levels in order to achieve the efficient, highly productive management of water needed to secure sustainable, sufficient and low-priced food for the projected population.
An insufficient and unstable food supply has a high social and financial cost to society, accumulated year after year. An adequate and stable food supply for food security depends on a number of complementary measures. Among these, water control enables realization of the production benefits deriving from high-yielding varieties and improved cultural practices. Water control also tends to shield agricultural production from the vagaries of climate, ensuring a more stable food supply. Water development for food production thus constitutes an important element for increasing food security.
