Environmental Flow

Environmental flow is the quantity, timing, and quality of water flows and levels needed to sustain freshwater and estuarine ecosystems and the people who depend on them. The Brisbane Declaration of 2007, endorsed by more than 750 delegates from 50 nations and renewed in 2018, set the consensus definition. E-flows reproduce key features of the natural flow regime: seasonal pulses, floods, and low-flow periods that cue fish migration, floodplain renewal, and wetland regeneration. They are set through hydrological, hydraulic, habitat-simulation, or holistic methods and implemented as dam-release rules or abstraction limits. In estuaries, e-flows govern salinity gradients, sediment supply, and nutrient delivery to coastal waters.