Author(s): Qian Li; Xin-Hua Zhang

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Abstract: Spur dikes can play an important role in improving aquatic habitats and ecological diversity in City Rivers, because its construction can lead to the changes of water and sediment structure and channel morphology near the spur dikes. The submerged and unsubmerged spur dikes have different impacts on aquatic habitats improvement, due to the different distributions of water depth, velocity and sediment under these two conditions. However, how to assess quantitatively the effect of the spur dikes still needs to be further studied. Based on the in-stream flow incremental methodology (IFIM), we developed a 2D habitat model, which is coupled with the flow, sediment transport, and bed variation to simulate the improvement conditions of weighted usable area (WUA) of habitats under different submergence conditions. The model was then applied to the Min-jiang River tributary of the Jin-jiang river through Hua-yang town of Chengdu city. Results of this study indicate that the submerged spur dikes can improve aquatic habitats more significantly with higher WUA values, compared with unsubmerged ones. In addition, to provide a suggestion or guidelines for ecological restoration of city rivers, we also investigated the best overtopping ratios of submerged groins on the basis of the maximum WUA value of aquatic habitats.

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Year: 2018