Field-level water savings in the Zhanghe Irrigation System and the impact at the system level
2002
Loeve, R. | Dong, B. | Molden, D.
The demand for freshwater from cities, industries, and environmental uses is growing rapidly throughout Asia. Less water will be available for agriculture and for rice in most places, yet more rice will be needed to feed a growing population. The per capita freshwater availability in China is among the lowest in Asia and it is becoming increasingly difficult to develop new freshwater sources. Much of the water will have to come from water savings - and rice, a water-intensive crop, is a major target for such savings. On-farm water-saving practices, such as alternate wet and dry irrigation (AWDI), have been developed to reduce irrigation application requirements and to improve growing conditions, thereby increasing yield. However, the question is, if these practices have led to "real" water savings, which can be transferred to other agricultural and nonagricultural uses? This paper explores water savings and water productivity on different scales to see if and how field-scale interventions scale up to subbasin-scale water savings in the Zhanghe Irrigation District (ZID) in Hubei Province, Central China. To study water savings and effects on different scales, the water-accounting procedure developed by IWMI was considered at four different spatial scales ranging from field to ZID. Results show that at the field level, the water productivity per unit of irrigation water was much higher under AWDI than under the traditional methods because of lower irrigation water input. Farmers Put much effort into making full use of irrigation water and rainfall. Moving up the scales, other land uses gain more importance. Apparently, a certain size of scale is needed to have an impact from reuse of water, which becomes evident only at the main canal command scale, where the water productivity per unit of irrigation increased dramatically and almost all water is used within the domain. It becomes clear that the ZID, with its possibilities of capturing rainfall and runoff in all the reservoirs with the system, is very effective in capturing and using water for productive use.
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Эту запись предоставил International Rice Research Institute