黑河下游额济纳三角洲生态用水效率变化与驱动机制研究

The ecological barrier function of the oasis at the lower reaches of the inland arid region is extremely important, while the contradiction between water use for ecological protection and economic development is increasing day by day. Therefore, rational transporting and distributing surface water, and improving ecological water use efficiency are becoming the key scientific issues and practical needs for the use and management of regional water resources. In this project, the Ejina Delta of the lower Heihe River is selected as the study area. Based on the database that includes hydrology and meteorology, vegetation and soil, and also aquifer systems in the study area, additional investigation such as observation of water vapor flux of the unsaturated zone and groundwater dynamic, measurement of river infiltration, and also field survey are supplemented. Remote sensing and GIS technology are used to classify regional landscape types and analyze changes in landscape patterns. Temporal and spatial changes of available water sources (e.g., river water, groundwater, precipitation, and soil water) and their cyclic transformation patterns will be analyzed. In addition, regional hydrological model is set to quantitatively reveal the hydrological relationship between various water sources and water use correlation between landscapes, and to estimate the monthly evapotranspiration from different landscapes since implementing the ecological water transport project. From the perspective of ecological conservation and improvement of the regional water use efficiency, this project aims to quantitatively expressing ecological water use efficiency, calculate monthly ecological water use efficiency since implementing the ecological water transport project, analyze its changing characteristics and driving factors and mechanisms. Further, suggestions for improving the efficiency of ecological water use are expected to put forward. This study can provide decision support for the efficient utilization of water resources and rational management of ecological water transport in the river basin.

干旱区内陆河下游绿洲的生态屏障作用极其重要，生态保护与经济发展的用水矛盾与日俱增，合理输配水、提高生态用水效率，是区域水资源利用与管理的核心科学问题与现实需求。本项目选择黑河下游额济纳三角洲为研究区，基于已有的水文气象、植被土壤、地下水系统等基础信息，补充部分包气带水汽通量、地下水动态观测、河水入渗观测、及实地查勘；利用遥感与GIS技术，划分区域景观类型并分析景观格局变化；分析地表自然景观可用水源（河水、地下水、降水、土壤水）的时空变化及其循环转化规律；构建区域水量转化模型，定量揭示区域各水源之间的水量转换关系和各景观之间用水关联性，并计算生态输水以来不同景观的月尺度生态耗水量；从生态保护目的和区域用水效率角度，定量表达生态用水效率，计算生态输水以来逐月生态用水效率，分析其变化特征及其驱动要素与机制，为生态输水的水资源配置与高效利用提供理论基础。

干旱区内陆河尾闾绿洲生态修复与维持的关键是水的供给，而干旱区水资源短缺，高效地进行生产、生活和生态用水成为区域可持续发展的必由之路。提高生态用水效益、提升生态输水效率成为水资源管理的难点与重要实践需求。本项目以黑河下游的额济纳绿洲为研究区，聚焦以提升黑河下游额济纳绿洲保护的生态用水效率的基础科学问题为核心，系统梳理了黑河下游生态输水以来地表水、地表景观、地下水位等观测资料，结合遥感监测与长期在研究区的研究结果数据信息，得到了可靠的长时间序列水文与生态数据；并基于所获得的数据，分析了绿洲地表生态保护景观（湖泊、植被）以及可用水源（径流与地下水为主）的时空变化及水循环转化规律；构建了考虑河道补给的额济纳绿洲地下水数值模型，定量了地表地下水转化关系；并在观测数据分析的基础上，构建了考虑植物根系依赖地下水变化的蒸散发计算模型，分析揭示了区域各水源之间的水量转换关系及景观用水的关联性；计算了生态输水以来不同景观（水域、河岸带植被、戈壁）的月尺度生态耗水量，并从生态保护目标角度，定量了生态用水效率，分析揭示了其变化特征及驱动机制。除规定任务之外，还对照研究了与项目区气候条件相似、但以地下水补给的敦煌湿地绿洲（额济纳绿洲是以地表水补给为主）水与湿地演变关系。研究成果为生态输水的水资源配置与高效利用提供了理论基础和管理依据。本项目研究发表了学术论文 10 篇，其中SCI论文 9 篇，中文核心论文 1 篇；另发表数据集一份；完成项目内容相关博士学位论文 3 篇，硕士学位论文 1 篇。项目完成了预期计划与目标，并进行了区域拓展研究，成果切实为生态输调水管理所用。