Analyzing the impact of environmental flow indices on protecting the biodiversity of macroinvertebrates

This study evaluates the impact of environmental flow regimes in the river habitats on the biodiversity index of macroinvertebrates. A multiple linear regression model was developed to simulate the biodiversity index of macroinvertebrates in which two combined indicators were considered as the inputs. A combined water quality index that can integrate the impacts of all key water quality parameters as well as a combined physical flow index were considered as the inputs of the biodiversity model. Based on the case study results, some hydrological indices of environmental flows such as 10% of mean annual flow would remarkably weaken the biodiversity of macroinvertebrates. By contrast, some environmental flow indices such as the physical habitat index can mitigate the impacts of changing flow regimes by minimizing the differences between the biodiversity index in the natural flow and environmental flow regimes. Furthermore, some hydrological indicators such as 60% of mean annual flow performed similarly to physical habitat methods. However, the results demonstrated that the degradation of water quality due to human activities has considerably weakened the biodiversity even in the natural flow regime, which means implementing an environmental flow regime without water quality improvement might worsen biodiversity. This study highlights that environmental flow studies should be incorporated within the biodiversity modeling of macroinvertebrates.