State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China.
Chengdu Xingcheng Capital Management Co., Ltd., Chengdu 610000, China.
Int J Environ Res Public Health. 2022 Sep 17;19(18):11743. doi: 10.3390/ijerph191811743.
Dam removal is considered an effective measure to solve the adverse ecological effects caused by dam construction and has started to be considered in China. The sediment migration and habitat restoration of river ecosystems after dam removal have been extensively studied abroad but are still in the exploratory stage in China. However, there are few studies on the ecological response of fishes at different growth stages. Considering the different habitat preferences of () in the spawning and juvenile periods, this study coupled field survey data and a two-dimensional hydrodynamic model to explore the changes in river morphology at different scales and the impact of changes in hydrodynamic conditions on fish habitat suitability in the short term. The results show that after the dam is removed, in the upstream of the dam, the riverbed is eroded and cut down and the riverbed material coarsens. With the increase in flow velocity and the decrease in flow area, the weighted usable area (WUA) in the spawning and juvenile periods decreases by 5.52% and 16.36%, respectively. In the downstream of the dam, the riverbed is markedly silted and the bottom material becomes fine. With the increase in water depth and flow velocity, the WUA increases by 79.91% in the spawning period and decreases by 67.90% in the juvenile period, which is conducive to adult fish spawning but not to juvenile fish growth. The changes in physical habitat structure over a short time period caused by dam removal have different effects on different fish development periods, which are not all positive. The restoration of stream continuity increases adult fish spawning potential while limiting juvenile growth. Thus, although fish can spawn successfully, self-recruitment of fish stocks can still be affected if juvenile fish do not grow successfully. This study provides a research basis for habitat assessment after dam removal and a new perspective for the subsequent adaptive management strategy of the project.
拆除大坝被认为是解决大坝建设带来的不利生态影响的有效措施，已开始在中国被考虑。国外广泛研究了拆除大坝后河流生态系统的泥沙迁移和栖息地恢复问题，但在中国仍处于探索阶段。然而，对于不同生长阶段鱼类的生态响应研究较少。考虑到鱼类在繁殖期和幼鱼期的 () 具有不同的栖息地偏好，本研究结合野外调查数据和二维水动力模型，探讨了不同尺度的河型变化以及水动力条件变化对鱼类短期栖息地适宜性的影响。结果表明，大坝拆除后，在大坝上游，河床被侵蚀和切割，河床物质变粗。随着流速的增加和过水面积的减小，繁殖期和幼鱼期的加权可用面积（WUA）分别减少了 5.52%和 16.36%。在大坝下游，河床明显淤积，底部物质变细。随着水深和流速的增加，繁殖期的 WUA 增加了 79.91%，幼鱼期的 WUA 减少了 67.90%，有利于成鱼产卵，但不利于幼鱼生长。大坝拆除后短时间内物理栖息地结构的变化对不同鱼类发育阶段的影响不同，并非都是积极的。溪流连续性的恢复增加了成鱼的产卵潜力，同时限制了幼鱼的生长。因此，尽管鱼类可以成功产卵，但如果幼鱼不能成功生长，鱼类种群的自我补充仍可能受到影响。本研究为大坝拆除后的栖息地评估提供了研究基础，为项目后续的适应性管理策略提供了新的视角。
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