生态用水及其核算方法

生态用水研究是近年来国内外关注的热点。在综合分析国内外生态用水研究进展情况的基础上，针对河流、植被、湿地以及城市4种生态用水类型，对其核算方法进行了分析，比较了不同方法的优缺点及适用范围。提出目前生态用水研究还存在如下问题：(1)生态用水核算中采用的不同方法都有其各自的局限性，但又都是针对具体的研究区域、特定的生态系统的较实用方法。因此在生态用水的核算方法上关键是方法的选择和结合具体案例对核算方法在深度、精度上的进一步探讨；(2)生态用水的机理研究不够深入。以往研究直接以植被生长用水量、鱼类等需保护动物用水量等作为替代生态用水量，难以反映生态系统需水的真实状况；(3)在研究尺度上往往都显得过于宽泛，对研究区域的基本情况、生态条件及水资源现状很难有详细明确的认识，因此数据的真实性及结果的可应用性也必然降低。文章最后认为，今后生态用水研究应点面结合，加强机理研究，增强研究结果的实践意义。

Ecological water use and the estimate method

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.