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 5Figure 8.3: Yields and water requirements of irrigated and non-irrigated agricultureCereal production (kg/ha)8,0007,0006,0005,0004,0003,0002,000Irrigated crops,high-yieldingvarieties, highinputsIrrigated crops,low inputsRainfed crops,optimal inputsRainfed crops,low inputs1,00001,000 2,000 3,000 4,000 5,000 6,000 7,000Water consumption (m 3 /ha)The graph shows the yield response and water requirements in irrigated and non-irrigated agriculture. Irrigated crops produce better than rainfed crops with high waterconsumption, even if those rainfed crops get optimal inputs. The graphs for rainfed agriculture stop at a certain point (5,500 m 3 /ha) as it is impossible for ‘typical’ rainfedcrops to consume more water without irrigation.Source: Smith et al., 2001.Figure 8.4: Competing uses of water in the Zhanghe irrigation district, China1,000900800Annual irrigation water suppliedWater supplied for irrigation - 5 year moving averagesOther uses - 5 year moving averagesWater (m 3 )70060050040030020010001963 1968 1973 1978 1983 1988 1993 1998YearsThis figure illustrates that increasing competition and demand from the industrial and domestic sectors result in the decrease of irrigation’s share of water use.Source: Molden, unpublished.