Fish habitat assessment model considering the spatial pattern and connectivity of habitat patches

Although the rational use of water resources through damming rivers can improve economic benefits, it inevitably changes the connectivity of rivers and the hydraulic characteristics of water reduced river reaches, posing a threat to fish habitats. Habitat assessment can provide a reference for assessing the ecological impact of hydropower development and the effectiveness of habitat restoration. However, previous evaluation methods only considered the number of habitats, which may mislead the evaluation results. In this article, we proposed a novel fish habitat assessment model based on the landscape pattern index method and circuit theory, which additionally considers the spatial pattern and connectivity of habitat patches. This model is applied to the Anshunchang reach of the Dadu River, and the target fish is Schizothorax prenanti. We obtained a suitable ecological discharge range for this river reach from 163.0 m3/s to 217.4 m3/s. To improve the suitability of fish habitats, we have also attempted multiple restoration measures. Comparing different habitat restoration measures, it was ultimately found that the river dredging scenario had the best ecological improvement effect, with a maximum improvement rate of 9.87 %. The habitat assessment model in this article can help reservoir managers evaluate fish habitats and formulate habitat restoration plans.