Service Contract No 2007 / 147-446 Strategic ... - Swaziland

Although irrigation water is a scarce and valuable resource, it is currently available to userswithout charge. This was rational in the past when there was enough water for all who hadthe desire and capacity to irrigate. However, this is no longer the case.In the production of sugar cane, efficient furrow irrigation uses almost 30% more water perhectare than drip irrigation and, because per-hectare yields are higher under drip irrigation,furrow irrigation uses almost 60 percent more water per kg of sucrose output (Table 9). Thussubstantial quantities of water could be saved by shifting from furrow to sprinkler irrigationand especially to drip irrigation. If cane growers were to switch to drip in all areas where suchirrigation is feasible, there would be a substantial saving of water that could then be utilisedon other crops.Figure 14:Sprinkler and drip irrigation systems in SwazilandIn broad terms, irrigation efficiency increases from furrow, through dragline/sprinkler, centrepivot and drip. The capital cost of each system is higher but the operating costs areproportionately lower. Which system is used depends largely upon soil type and crop. To putthis into perspective, a 10% increase in water efficiency could bring another 7,000 ha of landinto irrigated production by 2020. Growing a crop with a lower physiological waterrequirement could also release water for irrigation and increase the irrigated area. Whilstspreading water over a larger area may not generate the maximum return per hectare, it mayspread the benefits more widely amongst the rural population.Table 9:The water efficiency of sugar production analysed by method ofirrigationType of Efficiency Water Usage Sucrose Yield Water Use per Tonne of Sucroseirrigation (%) (m 3 /ha) (t/ha) (m 3 )Drip 90 11.11 16.82 0.66Sprinkler 80 12.50 14.02 0.89Furrow 70 14.29 13.60 1.05Source: IWRM Survey and Status Report: Swaziland, 2009.RDMU (Strategic Environmental Assessment of the National Adaptation Strategy) - Page 44