Evaluation of the impact of urban river bends on the enhancement of aquatic habitats using a two-dimensional habitat suitability model

The complex hydro-morphology of river bends plays an important role for creating and maintaining diverse habitat conditions for aquatic organisms. In this study, a dedicated standalone piece of software for benthic habitat simulation, which couples a two-dimensional (2D) depth-averaged water-sediment mathematical model with an instream flow incremental methodology, was devised to quantitatively evaluate the impact of channel bends on enhancing aquatic habitats. The multi-species integrated suitability index (CSI) curves based on three ecological variables were obtained. The test site was a 1.7-km-long stretch of the Jin Jiang River, which is a tributary of the Min Jiang River that flows through Huayang Town in Chengdu City, China. The potential value of aquatic habitats was quantitatively evaluated using the weighted usable area (WUA). The predicted WUA in the bend reach was 10.2%-16.6% greater than that in the straight reach. Moreover, the mean WUA decline rate was -7.2% in the straight reach and -5.6% in the bend reach. With increase in discharge, the WUA decreased more slowly in the bend reach compared to the straight reach. Our study indicates that for improving the aquatic habitats in urban rivers, the channel bends are beneficial. Compared with straight reaches, they not only could improve the availability of aquatic habitats but could also reduce the negative impact of the changes of discharge on the habitat. To summarize, this study provides a specific reference for ecological restoration.

Automated summary

This study quantitatively evaluated the impact of river bends on enhancing aquatic habitats using a dedicated software, finding that bend reaches have larger weighted usable areas and slower decline rates compared to straight reaches, which could be beneficial for improving urban river habitats.