Thirsty Crops: Agricultural Water Use and River Basin Conservation
Adapted from Water Use for Agriculture in Priority River Basins, a study prepared for WWF by Rob de Nooy.
Water is indispensable for farming. Farming in turn uses the vast majority of all water withdrawn for human use, and food production needs to increase in the coming decades to support a growing world population. The potential for political conflicts within and between countries over water are intensified by the increasing scarcity of freshwater resources. It seems clear that if human needs are to be met, while at the same time conserving biodiversity and maintaining vital ecosystem services, a new approach is required that makes the best use of the limited water that is available.
With this in mind, WWF's Living Waters Programme has selected about 40 river basins in different parts of the world in which to concentrate its efforts to conserve and restore healthy freshwater ecosystems for people and nature. This report summarizes a study carried out by WWF on the major irrigated crops and their respective water consumption in nine of these river basins.
The main aim of the study was to support WWF's Living Waters Programme by identifying a limited number of global agricultural commodities that have probable impacts on priority freshwater ecosystems through their overall use of fresh water.
This report provides an overview of the findings on water use by agriculture in priority river basins. To evaluate the probable future water situation in the countries covered by the nine river basins, results from the International Water Management Institute's (IWMI) Working Paper No.32 Water for Rural Development were used as a basis. The IWMI data are based on each country s potential utilizable water resources and expected population growth.
Calculations were made to quantify future water needs and the outcome was set against current water use and available water supplies. The IWMI working paper then made forecasts of the required level of cereal production to feed the expected populations in each country in 2025, as well as the corresponding increases in irrigated and rain-fed cropland.
Against this background, the WWF study looked first at the countries sharing each of the nine basins and assessed the impact of each country on the river s flow. Countries covering a large portion of the river basin (generally over 25%) were then selected for further study. In each case, data on water resources, irrigation and agriculture were collected, in large part from the Food and Agriculture Organisation (FAO) website.
Calculations were then made to establish the total water requirement per crop in each river basin. This enabled the most thirsty crops to be identified and ranked, on the basis of their total water consumption in each river basin, as well as across the nine basins studied.
The study also describes various options for increasing the efficiency of irrigation water used in growing the highest-ranked crops, bearing in mind the constraints on future availability of water for agriculture in each of these river basins in the coming decades.