Tingju Zhu,Claudia Ringler,Mark W. Rosegrant, International Food Policy Research Institute, , t.zhu@cgiar.org
Abstract
Agriculture is by far the largest consumer of water globally, accounting for approximately 70 percent of global water withdrawals and 90 percent of total water consumption. Irrigated agricultural land comprises less than 20 percent of total cropland but produces nearly 40 percent of the world's food. With growing population and income in the coming decades, additional demands for irrigation due to higher food demands as well as intensified inter-sectoral competition for water are expected for many places around the world. Climate change further complicates the situation as precipitation patterns and hydrological regimes are altered and potential evapotranspiration of crops will increase as a result of higher temperature. It is essential for water managers and policy makers to proactively address growing water challenges. To better understand future water demand and supply under global change, and especially for agriculture, the largest water user, we simulate sectoral water demand and supply out to 2050 for 281 water use units, which are intersections of large river basins and administrative units, using various climate scenarios. The analytical model used for the analysis is IMPACT, a global water and food projections model developed at the International Food Policy Research Institute, which includes a semi-distributed global hydrological module and a water management simulation module, in addition to the global agricultural trade module. Changes in water availability changes and irrigation water supply reliability are presented for the world’s regions.
Key words: Climate change, irrigation, consumptive use