Each year around 3 830 cubic km - that's 3.8 billion tonnes - of freshwater is withdrawn for human use. The lion's share is taken by the agriculture sector, which accounts globally for about 70 percent of all water withdrawals.
"Agriculture has been highly successful in capturing the bulk of the world's freshwater resources," says an FAO report to COAG, "but with little accountability." That is changing rapidly, in the face of demographic growth and economic development that has placed unprecedented pressure on water supplies, particularly in arid regions.
As the global population - especially urban population - grows, more water will be required worldwide for domestic and industrial use. Already there is intense competition for water in peri-urban zones and urban hinterlands in developing countries. Beyond the "productive sectors", awareness is growing that part of the available surface water must be left to follow its natural course to safeguard aquatic ecosystems.
FAO says agriculture's role in generating water scarcity - and degrading high quality surface and groundwater for marginal output - is not disputed. "What is often ignored, however, is the potential of sound management of agricultural water use to open up more options for reallocation." The report makes the case for consolidating FAO's existing water-related activities under an explicit water programme designed to leverage all the multi-disciplinary capacities available within the Organization.
"The scope of FAO's involvement with water resource management is extremely wide, from the precise application of water to the root zone, to the development of livestock watering strategies and aquaculture," the report says. Among UN specialized agencies, "FAO has the highest comparative advantage in tackling water scarcity issues in agriculture", being able to deliver the full range of technical analysis and support required. This has already been recognized by the United Nations' coordinating mechanism, UN-Water, which has assigned FAO to lead its water scarcity initiative.
But water expertise is currently dispersed across the organization. A more coherent water programme would, therefore, enhance the delivery of technical and policy advice to member countries and regional groupings, particularly those having to reconcile water scarcity with agricultural development. The programme would implicate all FAO technical departments, and require a much sharper, systemic focus from the relevant units to be built into a substantive programmatic framework.
The proposed programme would aim at generating water use efficiencies and productivity increases in on-farm water management, and optimizing water allocations within agriculture and across all the other productive sectors.
The productivity derived from water management is contingent on many factors, such as soil fertility, cultivar selection and post-harvest controls up to the farm gate. That, the report says, "sets the systemic value added chain in which water use efficiency can be evaluated and the scope for on-farm systemic improvement analysed". Under conditions of limited water availability, management improvements - e.g. sprinkler, trickle and deficit irrigation - are imperative. Also recommended are integrated water conservation practices and economic incentives to influence the total level of water use and the pattern of use. Maximizing crop yield per unit of land helps maximize yield per unit of water use.
The use of irrigation drainage water and resources of marginal quality, such as treated wastewater and saline water, is increasing. Those "non-conventional" water resources have become essential for millions of smallholders, both for its water and nutrient value and for its reliability. To protect and sustain high quality water for drinking, irrigation management should increase the "safe use" of low quality water resources, selecting and investing in water treatment technology that takes into account health protection, pollution control, costs, the scale of operation, and the quality of water needed for specific purposes.
Water harvesting has the potential to contribute substantially to increased food production, in water-scarce regions with few technical options for water storage and control. FAO studies show that
The report says "agricultural agencies need to be in a much better position to negotiate reallocation of bulk water resources before access and control is simply withdrawn through compulsory reallocation". FAO advises agricultural agencies to provide clear information on agricultural water use, engage with other key players in the water sector, and establish transparent methods to negotiate allocations. Institutional shifts are also needed to enhance the economic mobility of water both within agriculture and across competing economic sectors. In irrigation, there must be a shift from a supply-driven approach to development strategies that are much more responsive to demand.
Read the full FAO report to COAG on Agriculture and water scarcity (PDF, 145K)
See also in Spotlight: Environment and agriculture, Reconciling livestock and environment, and Agribusiness boom
Get the full list of COAG documents
Published April 2007