World water productivity: current situation and future options.

Abstract

AbstractWater productivity is generally defined as crop yield per cubic metre of water consumption, including 'green' water (effective rainfall) for rainfed areas and both 'green' water and 'blue' water (diverted water from water systems) for irrigated areas. Water productivity defined as above varies from region to region and from field to field, depending on many factors, such as crop patterns and climate patterns (if rainfall fits crop growth), irrigation technology and field water management, land and infrastructure, and input, including labour, fertilizer and machinery. This study analyses water productivity at the global and regional levels through a holistic modelling framework, IMPACT-WATER, an integrated water and food model developed at the International Food Policy Research Institute. Scenario analysis was undertaken to explore the impact of technology and management improvement and investment on water productivity and to search for potentials in improving food security through enhancing water productivity. It is found that the water productivity of rice ranged from 0.15 to 0.60 kg m-3, while that of other cereals ranged from 0.2 to 2.4 kg m-3 in 1995. From 1995 to 2025, water productivity will increase. The global average water productivity of rice and other cereals will increase from 0.39 to 0.52 kg m-3 and from 0.67 to 1.01 kg m-3, respectively. Both the increase in crop yield and improvement in basin efficiency contribute to the increase in water productivity, but the major contribution comes from increase in the crop yield. Moreover, water productivity of irrigated crops, although higher than that of rainfed crops in developing countries, is lower in developed countries.