Agriculture, food and water - FAO.org

AGRICULTURE, FOOD AND WATER
25
Future water withdrawals for irrigation
Irrigation water withdrawal in developing countries is expected to grow by about 14 percent from
the current 2 130 km 3 per year to 2 420 km 3 in 2030. This finding is consistent with the one given
in Box 1 earlier but it is based specifically on individual assessments for each developing country.
Harvested irrigated area (the cumulated area of all crops during a year) is expected to increase by
33 percent from 257 million ha in 1998 to 341 million ha in 2030. The disproportionate increase
in harvested area is explained by expected improvements in irrigation efficiency, which will result
in a reduction in gross irrigation water abstraction per ha of crop. A small part of the reduction is
due to changes in cropping patterns in China, where consumer preference is causing a shift from
rice to wheat production.
While some countries have reached extreme levels of water use for agriculture, irrigation still
represents a relatively small part of total water resources of the developing countries. The
projected increase in water withdrawal will not significantly alter the overall picture. At the local
level, however, there are already severe water shortages, in particular in the Near East / North
Africa region and in large parts of Asia.
Of the ninety-three developing countries surveyed by FAO, ten are already using more than 40
percent of their renewable water resources for irrigation, a threshold used to flag the level at which
countries are usually forced to make difficult choices between their agricultural and urban water
supply sectors. Another eight countries were using more than 20 percent, a threshold that can be
used to indicate impending water scarcity. By 2030 South Asia will have reached the 40 percent
level, and the Near East and North Africa not less than 58 percent. However, the proportion of
renewable water resources allocated to irrigation in sub-Saharan Africa, Latin America and East
Asia in 2030 is likely to remain far below the critical threshold.
The special role of groundwater
Water contained in shallow underground aquifers has played a significant role in developing
and diversifying agricultural production. This is understandable from a resource management
perspective: when groundwater is accessible it offers a primary buffer against the vagaries of
climate and surface water delivery. But its advantages are also quite subtle. Access to groundwater
can occasion a large degree of distributive equity, and for many farmers, groundwater has
proved to be a perfect delivery system. Because groundwater is on demand and just-in-time,
farmers have sometimes made private investments in groundwater technology as a substitute for
unreliable or inequitable surface irrigation services. In many senses, groundwater has been used
by farmers to break out of conventional command and control irrigation administration. Some
of the management challenges posed by large surface irrigation schemes are avoided, but the