"The discharge rate of a resource, expressed in volume during a certain period of time." (Lenntech, 2019)
The term environmental flow (eflow) has recently become increasingly popular as concerns about the destruction of freshwater ecosystems and the impacts of development activities (i.e., urban development and energy production) on river have intensified. Eflow is defined as "the quantity, timing, and quality of water flows required to sustain freshwater and estuarine ecosystems, and the human livelihoods and well-being that depend on these ecosystems" (Brisbane Declaration 2007). Alternatively, eflow is described as the foundation of water security for achieving sustainable development. Managing eflow is relevant to meet the most targets of SDG 6, but especially SDG 6.4 on water use efficiency (6.4.2 level of water stress) and SDG target 6.6 on the protection of water-dependent ecosystems.