Hogeboom Rick J, de Bruin Davey, Schyns Joep F, Krol Maarten S, Hoekstra Arjen Y
Twente Water Centre University of Twente Enschede Netherlands.
Water Footprint Network Enschede Netherlands.
Earths Future. 2020 Feb;8(2):e2019EF001363. doi: 10.1029/2019EF001363. Epub 2020 Feb 17.
Increased water demand and overexploitation of limited freshwater resources lead to water scarcity, economic downturn, and conflicts over water in many places around the world. A sensible policy measure to bridle humanity's water footprint, then, is to set local and time-specific water footprint caps, to ensure that water appropriation for human uses remains within ecological boundaries. This study estimates-for all river basins in the world-monthly blue water flows that can be allocated to human uses, while explicitly earmarking water for nature. Addressing some implications of temporal variability, we quantify trade-offs between potentially violating environmental flow requirements versus underutilizing available flow-a trade-off that is particularly pronounced in basins with a high seasonal and interannual variability. We discuss several limitations and challenges that need to be overcome if setting water footprint caps is to become a practically applicable policy instrument, including the need (for policy makers) to reach agreement on which specific capping procedure to follow. We conclude by relating local and time-specific water footprint caps to the planetary boundary for freshwater use.
对有限淡水资源的需求增加和过度开发导致了全球许多地方的水资源短缺、经济衰退以及水冲突。因此，一项控制人类水足迹的合理政策措施是设定特定地点和时间的水足迹上限，以确保人类用水的取水量保持在生态边界之内。本研究估算了世界上所有流域可分配给人类使用的月度蓝水流，同时明确为自然留出用水。考虑到时间变异性的一些影响，我们量化了潜在违反环境流量要求与未充分利用可用流量之间的权衡——这种权衡在季节性和年际变异性高的流域尤为明显。我们讨论了如果设定水足迹上限要成为一项切实可行的政策工具需要克服的几个限制和挑战，包括（政策制定者）需要就遵循哪种具体的上限设定程序达成一致。我们通过将特定地点和时间的水足迹上限与淡水使用的地球边界联系起来得出结论。
