Ecological water use and the estimate method
生态用水及其核算方法

Great attentions have been paid on ecological water use in recent years,but a lots of questions are still unsolved, such as confusion in definition of ecological water use. At first we redefined ecological water use as water resources demand for maintaining the special structure, process and services of ecosystems. Estimating methods of ecological water use were reviewed for four ecosystems whose ecosystem functions are closely pertain to water available: such as river, vegetation, wetland and urban etc. After comprehensively analyzing the studies on ecological water use published so far, three problems has been realized as follows: (1) It is difficult to find a universal methods satisfying to all regions and conditions. Previous studies have showed that different methods employed to estimate ecological water use have some limitations, but they are practicable methods for special area and ecosystem. So improving estimation of ecological water use should develop more accurate and comprehensive methods for specific region and target. (2) Mechanism of ecological water use is not well understood, including many processes that controlling water balance and cycles of ecosystems. Previous researches generally replace ecological water use with vegetation grown water use and fishes and other animals' protection water, which is hard to represent the actual status of ecosystem water requirements. (3) The spatial scale considered is too large to be difficult to having a detailed and accurate understanding of the basic situation, ecological condition and water resource of the studied area. So the accuracy of data and the adaptability of result are inevitably degraded. In conclusion, future studies should integrate point monitoring with area investigation simultaneously, and focus mechanism study so as to increase practicability of ecosystem water use for protecting eco environment.