Abstract
Abstract. An integrated multi-objective method for environmental flow assessments was developed that considered variability of potential habitats as a critical factor in determining how ecosystems respond to hydrological alterations. Responses of habitat area, and the magnitude of those responses as influenced by salinity and water depth, were established and assessed according to fluctuations in river discharge and tidal currents. The requirements of typical migratory species during pivotal life-stage seasons (e.g., reproduction and juvenile growth) and natural flow variations were integrated into the flow-needs assessment. Critical environmental flows for a typical species were defined based on two primary objectives: (1) high level of habitat area and (2) low variability of habitat area. After integrating the water requirements for various species with the maximum acceptable discharge boundary, appropriate temporal limits of environmental flows for ecosystems were recommended. The method was applied in the Yellow River estuary in eastern Shandong province, China. Our results show that, while recommended environmental flows established with variability of potential habitats in mind may not necessarily benefit short-term survival of a typical resident organism on a limited temporal or spatial scale, they may encourage long-term, stable biodiversity and ecosystem health. Thus, short-term ecosystem losses may be compensated by significant long-term gains.
Highlights
The intense regulation of water resources, including major hydraulic engineering projects, has significantly altered the natural flow of rivers worldwide (Doll et al, 2009)
Because species vary in their water requirements and tolerance due to different and often conflicting life history strategies, we proposed an integrated multi-objective method to assess the impacts of changing environmental flows, utilizing a two-step process where environmental flow data were integrated for (1) one typical species and (2) a wider variety of representative taxa
Environmental flow assessments were evaluated based on an integrated multi-objective method which considered variability of potential habitats for various species in estuaries
Summary
The intense regulation of water resources, including major hydraulic engineering projects, has significantly altered the natural flow of rivers worldwide (Doll et al, 2009). Environmental flows, known as instream flows, describe the quantity, quality and timing of water flows required to sustain freshwater and estuarine ecosystems and the human populations that depend on them (The Brisbane Declaration, 2007). Environmental flow assessments have become an important tool for ecosystem restoration, water resource management and reservoir management (Arthington et al, 2006; Vogel et al, 2007; Poff et al, 2009; Yang, 2011; Archer et al, 2010). Hydrological alteration–ecological response relationships have been taken as one of the critical issues considered during environmental flow assessments (Acreman and Dunbar, 2004; Arthington et al, 2006; Poff et al, 2009; Fleenor et al, 2010).
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