Water for people.pdf - WHO Thailand Digital Repository

S E C U R I N G F O O D F O R A G R O W I N G W O R L D P O P U L A T I O N / 2 0 7Map 8.1: Area equipped for irrigation as percentage of cultivated land by country (1998)0 5 10 20 >40 no data(in %)Expansive irrigated areas can be seen in the Middle East and Asia compared to the significantly under-irrigated arid and semi-arid regions such as sub-Saharan Africa.Developed countries worldwide show a consistently heavy irrigated area.Source: Map produced for the World Water Assessment Programme (WWAP) by the Centre for Environmental Research, University of Kassel. Data source: FAOSTAT, 2002.be expensive and requires willingness, know-how and action atvarious levels. Table 8.4 shows current and expected water useefficiency for developing countries in 1998 and 2030, asestimated by FAO. The investment and management decisionsleading to higher irrigation efficiency involve irrigation systemmanagement and the system-dependent farmers. National waterpolicy may encourage water savings in water-scarce areas byproviding incentives and effectively enforcing penalties. Whenupstream managers cannot ensure conveyance efficiency, there maybe no incentives for downstream water users to make efficiency gains.With groundwater, this caveat may not apply since the incentive isgenerally internalized by the users, and in many cases groundwaterusers show much greater efficiency than those depending on surfaceresources. Box 8.3 provides an overview of different aspects ofpotential improvements in agricultural water use efficiency.Future water withdrawals for irrigationIrrigation water withdrawal in developing countries is expected to growby about 14 percent from the current 2,130 km 3 per year toFigure 8.6: Irrigation and water resources: actual (1999) and predicted(2030) withdrawalsLatin AmericaEast AsiaSouth AsiaSub-Saharan AfricaNear East &North AmericaRenewable water and water withdrawal (km 3 )0 2,000 4,000 6,000 8,000 10,000 12 000 14 000(40 > 53)(33 > 37)(44 > 49)In brackets: movement in irrigation efficiency from 1997-99 to 2030.(33 > 35)Renewable water resourcesWater withdrawal, 2030Water withdrawal, 1997-99(25 > 25)This figure shows the expected growth in water abstraction for irrigation for theperiod 1999 to 2030. There is a potential increase in all regions, most notably insouth Asia, whereas the sub-Saharan Africa region is predicted to maintain its verylow level of irrigation water withdrawals.Source: FAO data and projections.