Global Water Challenges
Rainfed versus Irrigated Agriculture
Globally, agriculture uses more than 70% of all freshwater resources. Some 19% of arable agricultural land is irrigated, producing almost 40% of all food. Water use in agriculture must become significantly more efficient if we hope to meet the food demands for nine billion people by 2050.
Since the demand for water for other uses is increasing it is unlikely that irrigation can be expanded significantly by 2050. The projected changes in irrigated areas show that in North America and Oceania irrigated areas are declining with small increases in the other regions. The projected changes in irrigated areas are provided in the graph below.
Depending on the country the amount of irrigation from groundwater sources is highly variable and managing groundwater in a sustainable manner is very challenging because this requires significant knowledge about the aquifer, the recharge and extraction rates, the age of the water, and internal movement of groundwater.
Asia has the highest amount of irrigated land, while North America, Asia and Europe rely the most on groundwater for irrigation. India has the largest irrigated agricultural area and relies most heavily on groundwater.
High income countries have generally more land suitable for rainfed agriculture and the arable land per person is highest in developed and middle income countries. These are also the countries with the highest annually renewable freshwater sources.
Available Renewable Water
Brazil, Russia, Canada and the USA have the highest annual renewable water supplies. If we consider the arable land and the renewable water then these four countries have the greatest potential to increase food exports.