Agricultural water management in water-starved countries: challenges and opportunities

Agriculture commands more water than any other activity on this planet. Although the total amount of water made available by the hydrologic cycle is enough to provide the world's current population with adequate freshwater, most of this water is concentrated in specific regions, leaving other areas water-deficient. Because of the uneven distribution of water resources and population densities worldwide, water demands already exceed supplies in nearly 80 countries with more than 40% population of the world. Consequent to future population increase in these countries, supplies of good-quality irrigation water will further decrease due to increased municipal-industrial-agricultural competition. These facts reveal that the time has come for the sustainable management of available water resources based on global, regional, and site-specific strategic options: (1) understanding the concept of 'virtual water' and potential use of this water as a global solution to regional deficits, i.e. the water-short countries may import a portion of food crops or other commodities that require more water and export those that need less water in production; (2) improvement in current efficiencies of agricultural water use and conservation, both in the rain-fed and irrigated agriculture, i.e. to produce more with the existing resources with minimum deterioration of land and water resources; (3) use of efficient, economic, and environmentally acceptable methods for the amelioration of polluted waters and degraded soils, and (4) re-use of saline and/or sodic drainage waters via cyclic, blended, or sequential strategies for crop production systems, wherever possible and practical. We believe that these strategies will serve as the four pillars of integrated agricultural water management and their suitable combinations will be the key to future agricultural and economic growth and social wealth, particularly in regions that are deficient in freshwater supplies and are expected to become more deficient in future. (C) 2003 Elsevier Science B.V. All rights reserved.