Water is a critical input for agricultural production and plays an important role in food security. Irrigated agriculture represents 20% of the total cultivated land and contributes 40% of the total food produced worldwide. Irrigated agriculture is, on average, at least twice as productive per unit of land as rainfed agriculture, thereby allowing for more production intensification and crop diversification. Due to population growth, urbanization, and climate change, competition for water resources is expected to increase, with a particular impact on agriculture. Population is expected to increase to over 10 billion by 2050, and whether urban or rural, this population will need food and fiber to meet its basic needs. Combined with the increased consumption of calories and more complex foods, which accompanies income growth in the developing world, it is estimated that agricultural production will need to expand by approximately 70% by 2050. Currently, agriculture accounts (on average) for 70% of all freshwater withdrawals globally (and an even higher share of “consumptive water use” due to the evapotranspiration of crops).
Managing these waters, including runoff and reuse of excess agricultural wastewater during surface irrigation (as well as reclaiming municipal wastewater for agricultural use), is critical for ensuring food security.