World agriculture towards 2030/2050: the 2012 revision - Fao
World agriculture towards 2030/2050: the 2012 revision - Fao
World agriculture towards 2030/2050: the 2012 revision - Fao
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
PROOF COPY<br />
harvested irrigated area (from 326 million ha in 2005/07 to 365 million ha in <strong>2050</strong>; Table<br />
4.9). This difference is in part explained by <strong>the</strong> expected improvement in water use efficiency,<br />
leading to a reduction in irrigation water withdrawal per irrigated hectare, and in part due to<br />
changes in cropping patterns for some countries such as China, where a substantial shift in <strong>the</strong><br />
irrigated area from rice to maize production is expected. Due to its high water needs for<br />
flooding, <strong>the</strong> expected decline in <strong>the</strong> irrigated area allocated to rice, in particular in South and<br />
East Asia, is an important factor in limiting water demand. Globally it could fall from 94.3<br />
million ha in 2005/07 to 89.5 million ha in <strong>2050</strong>, which alone would account for over 10<br />
km3/yr decline in water withdrawals. Irrigated rice area declines are estimated as from 30.6 to<br />
24.0 million ha in South Asia and from 53.5 to 52.7 million ha in East Asia (after peaking at<br />
57.5 million ha in <strong>2030</strong>).<br />
Table 4.11 Annual renewable water resources and irrigation water withdrawal<br />
Renewable<br />
water<br />
resources*<br />
Water use<br />
efficiency ratio<br />
2005/<br />
2007<br />
<strong>2050</strong> 2005/<br />
2007<br />
Irrigation<br />
water<br />
withdrawal<br />
<strong>2050</strong> 2005/<br />
2007<br />
Pressure on water<br />
resources due to<br />
irrigation<br />
cubic km percent cubic km percent<br />
<strong>World</strong> 42 000 50 51 2 761 2 926 6.6 7.0<br />
Developed countries 14 000 41 42 550 560 3.9 4.0<br />
Developing countries 28 000 52 53 2 211 2 366 7.9 8.5<br />
Sub-Saharan Africa 3 500 25 30 96 133 2.7 3.8<br />
Latin America 13 500 42 42 183 214 1.4 1.6<br />
Near East/North Africa 600 56 65 311 325 51.8 54.1<br />
South Asia 2 300 58 58 913 896 39.7 38.9<br />
East Asia 8 600 49 50 708 799 8.2 9.3<br />
* includes at <strong>the</strong> regional level ‘incoming flows’.<br />
Irrigation water withdrawal in 2005/07 was estimated to account for only 6.6 percent of<br />
total renewable water resources in <strong>the</strong> world (Table 4.11). However, <strong>the</strong>re are wide variations<br />
between countries and regions, with <strong>the</strong> Near East/North Africa region using 52 percent of its<br />
renewable water resources in irrigation while Latin America barely uses 1.4 percent of its<br />
resources. At <strong>the</strong> country level, variations are even more pronounced. In <strong>the</strong> base year<br />
(2005/07), 13 countries used already more than 40 percent of <strong>the</strong>ir water resources for<br />
irrigation, a situation which can be considered critical. An additional 9 countries consumed<br />
more than 20 percent of <strong>the</strong>ir renewable water resources, a threshold sometimes used to<br />
indicate impending water scarcity. The situation would worsen over <strong>the</strong> period to <strong>2050</strong>, with<br />
two more countries crossing <strong>the</strong> 40 percent and ano<strong>the</strong>r country <strong>the</strong> 20 percent threshold. If<br />
one would add <strong>the</strong> expected additional water withdrawals needed for non-agricultural use, <strong>the</strong><br />
picture would not change much since <strong>agriculture</strong> represents <strong>the</strong> bulk of water withdrawal.<br />
Never<strong>the</strong>less, for several countries, relatively low national figures may give an overly<br />
optimistic impression of <strong>the</strong> level of water stress: China, for instance, is facing severe water<br />
shortage in <strong>the</strong> north while <strong>the</strong> south still has abundant water resources. Already in 2005/07,<br />
four countries (Libya, Saudi Arabia, Yemen and Egypt) used volumes of water for irrigation<br />
<strong>2050</strong><br />
124