Environmental flows in the Anthropocence: past progress and future prospects

Human modification of the global hydrologic cycle through the building and operation of hundreds of thousands of dams and diversions has significantly altered fluvial processes, leading to impairment of river ecosystem function and biodiversity loss worldwide. The concept of environmental flows (e-flows) emerged to mitigate the undesirable hydrological impacts of dams and water diversions, in order to strengthen ecologically informed water management. In this paper, we outline the scientific foundations and progressive development of the current e-flows framework over the last 25 years, identifying three discrete periods in its history: emergence and synthesis, consolidation and expansion, and globalization. We highlight the evolving challenges and audiences that e-flows engages, and discuss the challenges facing the framework during the current period of rapid global change. For e-flows to contribute most effectively to sustainable freshwater management on a global scale, it must, first, move from a focus on restoration to one of adaptation to climate and other environmental change stressors, second, expand its scale from single sites to whole river basins, and third, broaden its audience to embrace socialecological sustainability that balances freshwater conservation needs with human well-being in both developing and developed economies alike.