Environmental Flow Requirements of Estuaries: Providing Resilience to Current and Future Climate and Direct Anthropogenic Changes

Estuaries host unique biodiversity and deliver a range of ecosystem services at the interface between catchment ocean. They are also among most degraded ecosystems on Earth. Freshwater flow regimes drive ecological processes contributing to their economic value, but have been modified extensively in many systems by upstream water use. Knowledge freshwater requirements for estuaries (environmental flows or E-flows) lags behind that rivers floodplains. Generalising estuarine E-flows is further complicated responses appear be specific each system. Here we critically review E-flow 1) identify key (hydrodynamics, salinity regulation, sediment dynamics, nutrient cycling trophic transfer, connectivity) modulated regimes, 2) drivers (rainfall, runoff, temperature, sea level rise direct anthropogenic) generate changes magnitude, quality timing flows, 3) propose mitigation strategies (e.g., modification dam operations habitat restoration) buffer against risks altered build resilience indirect anthropogenic disturbances. These support re-establishment natural characteristics which foundational healthy ecosystems.