Although global annual water availability is largely stable, with small increases as a result of accelerated water cycles under climate change (Oki and Kanae 2006), the demand on water resources has grown substantially over the past 50 years, due to population growth, agricultural and economic growth, and urbanization (WWAP 2016;Bates et al. 2008). This has led to increasing competition across water-using sectors and contributed to severe degradation of water and related ecosystems and biodiversity loss in parts of the globe and, in some cases, outmigration of humans. Higher temperatures, less certain precipitation patterns, as well as shorter, more concentrated rains together with prolonged dry seasons are putting further pressure on available water supplies (Bates et al. 2008;Fishman, Jain, and Kishore 2013; WWAP 2016). All of these developments have put access by farmers to water for food production at risk.Globally, most crops and livestock are produced using soil moisture that comes from precipitation (also known as rainfed agriculture) (FAO 2011). Rainfed agriculture accounts for approximately 95 percent of the harvested crop area in Africa south of the Sahara, 86 percent in Latin America, two-thirds in the Middle East and North Africa region, half in Asia, and 85 percent of the harvested crop area in high-income countries (Ringler 2017). Conversely, Asia features the world's largest irrigated areas, followed by the Middle East and North Africa regions, and there has been little investment in irrigation in Africa south of the Sahara until recently.While most crop area is rainfed, the contribution of irrigation to food security has been essential, generating 40 percent of global food production on less than a third of the world's harvested land. For this, irrigation requires large volumes of freshwater. This is reflected in the agriculture sector accounting for approximately 70 percent of global water withdrawals, largely for irrigation but also for livestock watering and aquaculture as well as for more than 80 percent of consumptive water use of withdrawn water (FAO AQUASTAT Chapter 20