从水循环的角度分析，全球尺度上总降水的65%通过森林、草地、湿地和雨养农田的蒸散返回到大气中，成为绿水流（绿水），仅有35%的降水储存于河流、湖泊以及含水层中，成为蓝水。目前的水资源评价多集中于可见的、可以被人类直接利用的蓝水资源，忽略了绿水资源的评价和管理。绿水最初被定义为蒸散流，是流向大气圈的水汽流，后来被定义为具体的资源，即绿水是源于降水、存储于土壤并通过植被蒸散发消耗掉的水资源，尤其在雨养农业区是重要的水资源。介绍了绿水的概念，绿水在陆地生态系统中的作用，综述了绿水评价研究的进展、影响绿水流的因素、全球绿水资源状况和水安全等，展望了未来绿水研究，指出应将绿水资源纳入水资源评价之中，开展绿水管理、绿水和蓝水综合利用研究，自然生态系统与粮食生产绿水均衡利用研究。

At global level, about 65% of water received as precipitation returns to the atmosphere as green water flow (i.e. transpiration from forest, grassland, wetland and rainfed farmland). Still, water management and governance to date has almost exclusively focused on the visible blue water flow (i.e. runoff flow in rivers, aquifers and lakes). Green water is defined as water flow returned to atmosphere in the original document. Only in the past few years has it become recognized as resources of production of plant biomass that first remain in the soil in the form of humidity, are then stored in plants during their growth, and are finally released back into the atmosphere through evaporation. This paper presented the evolution of the green water concept, the effects affect green water flow, and the roles of green water played in the terrestrial ecosystems, and reviewed the advances in green water evaluation and the current status of global green water resources and green water security. It is pointed out that green water resources should be included in the water resources evaluation system, green water related researches such as green water management, comprehensive usage of blue water and green water resources, and balancing water for humans and nature should be deployed in the future.

绿水通过蒸散发、大气水输送和陆地降水过程形成陆地内循环，是连接水圈、大气圈、生物圈、人类圈等地球圈层的重要环节。对绿水陆地内循环的有限认知将低估人类活动对水和生态的影响。本文研究中国范围内绿水陆地内循环的格局以及自然和人类生态系统对其的作用。结果表明，2000—2018年中国绿水陆地内循环具有内循环率高（50.4%）和内循环量大（2.75万亿m³/a）的总体特点，存在由南向北、由西南向东北、西部以内循环为主的“三线”输送格局。其中，以草地为主的青藏高原为中国绿水陆地内循环提供了最多的水量（约8000亿m³/a）；以森林为主的东南丘陵和云贵川地区是辐射范围最广的绿水供应区；以耕地为主的长江中下游平原和以草地为主的黄土高原分别是绿水由南向北、由西南向东北输送的枢纽。中国绿水陆地内循环格局由生态系统、大气环流等大尺度地理系统决定，充分认识绿水循环的战略意义在于：① 绿水陆地内循环是中国水循环的“国内大循环”，是构建治水“全国一盘棋”新局面的着力点；② 绿水陆地内循环是水循环与“山水林田湖草沙”的紧密纽带，是践行“山水林田湖草沙”系统治理的重要抓手；③ 绿水陆地内循环与跨流域调水和虚拟水转移构成中国跨流域水转移的主要过程，三者的科学统筹与协调是实现中国水资源与经济发展“空间均衡”的新方案。

Terrestrial recycling of green water, which is created through a continuous cycle of evapotranspiration, atmospheric transport, and terrestrial precipitation, serves as bridges connecting hydrosphere, atmosphere, biosphere, and anthroposphere. Limited knowledge of terrestrial recycling may underestimate the impact of human activities on water and ecology. This study focuses on the structure of China's green water recycling (CGWR) and quantifies the contributions of natural and human ecosystems. Results indicate a high green water recycling ratio (50.4%) and a large recycled amount (2.75 trillion m³/a) over China, with significant south-to-north transport structures over eastern China, southwest-to-northeast transport structures from southwestern China to northern China, and high self-recycling structures in western China. The grassland-dominated Qinghai-Tibet Plateau provides the largest amount of green water (about 800 billion m³/a) and serves as the most critical region for CGWR. The forest-dominated southern hilly region and Yunnan-Guizhou-Sichuan region play a crucial role in supplying green water to a wide area of China. The cropland-dominated Middle-Lower Yangtze Plain and the grassland-dominated Loess Plateau are the key hubs for south-to-north and southwest-to-northeast transport of green water. The structure of CGWR is driven by large-scale geosystems such as ecosystems and atmospheric circulation systems, and has strategic implications in the following three aspects. First, CGWR serves as the "domestic cycle" of water, based on which a general domestic-level water governance framework can be established. Second, CGWR is a representative picture of the water-related processes in the Mountain-River-Forest-Farmland-Lake-Grassland-Desert (MRFFLGD) system and serves as a critical pivot to actualize the conservation and improvement of the MRFFLGD system. Finally, CGWR, together with inter-basin water resources transfer and virtual water transfer, forms a complete picture of China's inter-basin water transfer. The scientific coordination and integration of the three processes present a new approach for achieving spatial equilibrium between China's water resources and economic development.

从绿水的概念、意义、绿水的组成和发生机理、绿水资源的研究历史和评价方法、各种评价方法的适用时间和空间尺度，遥感和模型技术在绿水资源评价中的应用等方面总结了相关领域的进展和未来的发展方向，以期为陆地生态系统绿水资源的有效利用提供参考和依据。

In this paper, the definiation, roles, and components of green water were introduced firstly. Then the machenism involved and its research history were discussed. Finally, various methods for green water flux accessement were introduced and their applicability under different temperal and special scales was discussed.

The ratio of plant transpiration to total terrestrial evapotranspiration (T/ET) captures the role of vegetation in surface-atmosphere interactions. However, several studies have documented a large variability in T/ET. In this paper, we present a new T/ET dataset (also including transpiration, evapotranspiration data) for China from 1981 to 2015 with spatial and temporal resolutions of 0.05° and 8 days, respectively. The T/ET dataset is based on a model-data fusion method that integrates the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model with multivariate observational datasets (transpiration and evapotranspiration). The dataset is driven by satellite-based leaf area index (LAI) data from GLASS and GLOBMAP, and climate data from the Chinese Ecosystem Research Network (CERN). Observational annual T/ET were used to validate the model, with R and RMSE values were 0.73 and 0.07 (12.41%), respectively. The dataset provides significant insight into T/ET and its changes over the Chinese terrestrial ecosystem and will be beneficial for understanding the hydrological cycle and energy budgets between the land and the atmosphere.

水分利用效率（WUE）是灌区生态环境保护和重建的重要依据。综合采用非线性最小二乘法、变异系数、相关系数、Mann-Kendall检验、Morlet小波分析和启发式分割算法等方法，研究了1985-2015年宁夏青铜峡灌区的WUE特征。结果表明：①灌区年均WUE为0.96 g/kg，WUE空间分布呈现出较强的空间异质性，总体呈现西高东低的特征；存在波动逐年上升趋势，WUE年际变化与ET有明显的负相关性，与TMP有明显的正相关性。②灌区WUE年内变化与ET、NPP、TMP和PRE均呈现正相关性，其中TMP的正相关系数更高。③总体来说，因为大量的生态恢复和重建工程，宁夏青铜峡灌区的生态系统的生产力有所提高，在一定程度上改善了灌区的生态状况，未来灌区生态系统的WUE会持续上升。

Water use efficiency （ WUE） is an important basis for ecological environment protection and reconstruction in irrigated areas. In this paper， nonlinear least squares， coefficient of variation， correlation coefficient， Mann-Kendall test， Morlet wavelet analysis and heuristic segmentation algorithm are used to study the characteristics of WUE in Qingtongxia Irrigation District of Ningxia from 1985 to 2015. The results are as follows： ① The average annual WUE in the irrigated area is 0.96 g/kg， and the spatial distribution of WUE show strong spatial heterogeneity， with the characteristics of high in the west and low in the east. There is an increasing trend of fluctuation year by year， and the interannual variation of WUE has an obvious negative correlation with ET， and a significant positive correlation with TMP. ② The annual variation of WUE in the irrigation area is positively correlated with ET， NPP， TMP and PRE， and the positive correlation coefficient of TMP is higher. ③ In general， due to a large number of ecological restoration and reconstruction projects in Qingtongxia Irrigated Area of Ningxia， the productivity of the ecosystem in the irrigated area has been improved， and the ecological status of the irrigated area has been improved to some extent. In the future， the WUE of the ecosystem in the irrigated area will continue to rise.

基于GLDAS-Noah水文模型,模拟长江流域蓝绿水资源量,并揭示其时空变化特征。结果表明:2000—2019年长江流域多年平均蓝水资源和绿水资源分别为420.24 mm和686.95 mm,绿水资源约是蓝水资源的1.62倍。近20 a来长江流域蓝水资源、绿水资源和绿水系数呈不显著增加趋势,2000—2019年蓝水资源与绿水资源变化速率分别为3.26 mm/a 和2.27 mm/a。从年内分配上看,蓝绿水资源在7—8月份较多,占全年的29%~32%;在1 —2月份较少,占全年的5%~6%。从空间分布来看,蓝水资源呈现东南高西北低的分布格局,绿水资源呈现东高西低的分布格局,而绿水系数呈现西北高东南低的分布格局。科学全面评价蓝绿水资源可以为优化水资源利用模式、提高水资源利用效率提供科学依据。

The blue and green water resources in the Yangtze River basin (YRB) were simulated by using the GLDAS (Global Land Data Assignment System) Noah hydrological model,and then the distribution of blue and green water resources and their temporal and spatial changes were revealed. Results demonstrate that from 2000 to 2019,the multi-year average blue water resource and green water resource in YRB was 420.24 mm and 686.95 mm,respectively,and the latter was about 1.62 times of the former. Over the past two decades,the blue water resource,green water resource and green water coefficient in the YRB showed insignificant increasing trends,and in particular,the change rate of blue water resource and green water resource was 3.26 mm/a and 2.27 mm/a during 2000-2019,respectively. On monthly scale,the blue and green water resources expanded in July and August,accounting for 29%-32% of the whole year,while shrank in January and February,accounting for 5%-6% of the whole year. On spatial scale,blue water resource distributed in a pattern of higher in the southeast and lower in the northwest,while green water resource higher in the east and lower in the west,and green water coefficient higher in the northwest and lower in the southeast. Scientific and comprehensive evaluation of blue and green water resources can provide scientific basis for optimizing water resources utilization mode and improving water resources utilization efficiency.