Currently fresh water scarcity is an issue with huge socio-economic and environmental impacts. Transboundary river and lake basins are among the sources of fresh water facing this challenge. Previous studies measured blue water scarcity at different spatial and temporal resolutions. But there is no global water availability and footprint assessment done at country-basin mesh based spatial and monthly temporal resolutions. In this study we assessed water scarcity at these spatial and temporal resolutions. Our results showed that around 1.6 billion people living within the 328 country-basin units out of the 560 we assessed in this study endures severe water scarcity at least for a month within the year. In addition, 175 country-basin units goes through severe water scarcity for 3–12 months in the year. These sub-basins include nearly a billion people. Generally, the results of this study provide insights regarding the number of people and country-basin units experiencing low, moderate, significant and severe water scarcity at a monthly temporal resolution. These insights might help these basins’ sharing countries to design and implement sustainable water management and sharing schemes.

Ecological compensation standards and the allocation of compensation funds have always been the core issues of watershed ecological compensation. Due to the construction of the Eastern Route of the South-to-North Water Transfer Project (SNWTP), Jiangsu Province has paid a huge cost for the protection of water resources, and local economic development has been greatly affected. Therefore, this paper takes Jiangsu Province, the water source area of the Eastern Route of the SNWTP as an example, and combines a geographic information system (GIS) and remote sensing technology, using the ecosystem services value method to calculate the ecosystem services value of Jiangsu Province from 2005 to 2018. Then the change of this ecosystem services value in Jiangsu Province from 2015 to 2018 is taken as the basis for watershed ecological compensation standards of the Eastern Route. Through a compensation fund allocation model, watershed ecological compensation funds are allocated to four cities, Yangzhou, Huai’an, Suqian and Xuzhou, which are located along the Eastern Route of this SNWTP in Jiangsu Province. The results show that: (1) The ecosystem services value of Jiangsu Province has changed greatly. Urbanization and market environment of grain crops are the main reasons for this change; (2) the relationship between ecosystem services in Jiangsu Province is mainly synergistic; (3) Suqian receives US$24.73 million; Huai’an receives US$16.49 million; Yangzhou receives US$54.88 million and Xuzhou receives US$0.95 million in watershed ecological compensation, respectively. Watershed ecological compensation standards based upon the value of ecosystem services, and the allocation of compensation funds at the municipal level, are conducive to the improvement in efficiency of watershed ecological compensation in mainland China.

The Beijing–Tianji–Hebei region (BTHR) is economically developed and densely populated, but its water resources are extremely scarce. A clear understanding of the decoupling relationship between water footprint and economic growth is conducive to facilitating and realizing the coordinated development of water resources and economic growth in this region. This study calculated the water footprint and other related indicators of BTHR from 2004 to 2017, and objectively evaluated the utilization of water resources in the region. Then, logarithmic mean divisia index (LMDI) method was applied to study the driving factors that resulted in the change of water footprint and their respective effects. Finally, Tapio decoupling model was used to research the decoupling relationships between water footprint and economic growth, and between the driving factors of water footprint and economic growth. There are three main results in this research. (1) The water utilization efficiency in BTHR continues to improve, and the water footprint shows a gradually increasing trend during the research period, among which the agricultural water footprint accounts for a relatively high proportion. (2) The change of water footprint can be attributed to efficiency effect, economic effect, and population effect. Furthermore, efficiency effect is the decisive factor of water footprint reduction and economic effect is the main factor of water footprint increase, while population effect plays a weak role in promoting the increase in water footprint. (3) The decoupling status between water footprint and economic growth show a weak decoupling in most years, while the status between water footprint intensity and economic growth always remains strong decoupling. Moreover, population size and economic growth always show an expansive coupling state. In sum, it is advisable for policy makers to improve water utilization efficiency, especially agricultural irrigation efficiency, to raise residents’ awareness of water conservation, and increase the import of water-intensive products, so as to alleviate water shortage and realize the coordinated development of water resources and economic growth in BTHR.

Transboundary water pollution is a long-standing problem in China, although the Chinese government has been committed to the protection of water resources. Due to the different interests of multilevel governments and the regionalization of management, there is still no unified plan to solve the transboundary water pollution in China. Watershed ecological compensation as a holistic plan to deal with transboundary water pollution is being promoted currently. Taking the South-to-North Water Transfer Project’ eastern route as an example, this paper firstly analyses stakeholders’ strategies and establishes a tripartite game model based on evolutionary game theory. Secondly, by introducing Cobb Douglas production function creatively, the supervision level of the central government is refined into supervisory attitude and supervisory skills. Thirdly, the numerical simulation is used to analyze the sensitivity of influencing factors. The results show that: (1) whether the central government supervises the local governments mainly depends on the benefits of water environment improvement and supervision costs; (2) the initial negotiation plan of the stakeholders has a significant impact on their optimum strategies; (3) the fines imposed by the central government on the local governments have a small impact on the stable state of the system; (4) the higher the eco-compensation fee, the lower their likelihood of cooperation; (5) the central government’s supervisory attitude and supervisory skills have significant effect on the sustainability of the optimum arrangement, even when willingness of upstream and downstream governments to cooperate is low; (6) the initial ecological benefits of downstream governments have no effect on the optimum strategy. Therefore, considering these insights is helpful to improve the watershed ecological compensation mechanism in order to solve transboundary water pollution and achieve the sustainability of water resources.