5. Water, Food and Environmental Security

Water scarcity has emerged as one of the key issues for food and environmental sustainability in the twenty-first century. Agriculture is far and away the largest consumer of water in the world, and irrigated agriculture accounts for 70 % of all freshwater withdrawals globally. An increasing portion of this is coming from groundwater, which is favored by farmers. However, shortages are emerging in many places and these are expected to result in curtailed supplies of irrigation water to farming. While irrigated area accounts for less than 20 % of all cropland, it accounts for about 40 % of production, and attempts to reduce this dependence will require significant expansion of rainfed area to make up for the resulting production losses. Fortunately, there is considerable scope for increasing the efficiency of water use in agriculture, through improved delivery to the plants, as well as through increased water use efficiency by the plants themselves. This chapter explores the role of water in agriculture in some detail as well as offering a series of simulation results, based on SIMPLE, to highlight the interplay between restrictions on irrigated agriculture and global land use change.