Predicting the ecological impacts of large‐dam removals on a river network based on habitat‐network structure and flow regimes
Predicting the ecological impacts of large‐dam removals on a river network based on habitat‐network structure and flow regimes
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DOI：
10.1111/cobi.13137
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发表时间：
2018-08
影响因子：
6.3
通讯作者：
Nobuo Ishiyama;M. Ryo;T. Kataoka;S. Nagayama;Masanao Sueyoshi;Akira Terui;Terutaka Mori;T. Akasaka;F. Nakamura
中科院分区：
文献类型：
--
作者：
Nobuo Ishiyama;M. Ryo;T. Kataoka;S. Nagayama;Masanao Sueyoshi;Akira Terui;Terutaka Mori;T. Akasaka;F. Nakamura
大型水坝为人类提供重要的保护和服务。然而，世界范围内越来越多的大型水坝已经老化并且无法正常运行。拆除大型水坝具有恢复栖息地连通性和水流状况的巨大潜力；因此，预测相关的生态后果是水资源和生态系统管理的新需求。然而，目前还没有可用于盆地尺度的此类预测的建模方法。我们设计了一个方案，将流态和栖息地网络结构的变化纳入大型水坝拆除的流域规模影响评估中，并将其应用于日本长良-伊比盆地。我们使用图论方法和水文模型，量化了多种去除情景下 11 种淡水鱼类在流域尺度上栖息地可用性的变化。我们将这些结果与使用传统方案预测的变化进行了比较，传统方案仅考虑由于大坝拆除而导致的栖息地网络变化。我们提出的方案表明，与大坝拆除相关的流量变化的增加对流域规模的栖息地可用性既有积极影响也有消极影响，具体取决于重点物种，濒危物种对大坝拆除有负面反应。相比之下，传统方法仅对所有物种产生积极影响。结果的这种差异表明，由于水流状况的变化，大坝拆除可能对流域恢复产生负面和正面影响。我们的结果还表明，拆除大型水坝的效果可能取决于水坝及其位置。我们的研究是预测与流域规模的河流景观大型水坝拆除相关的生态权衡的第一步，并为未来基于过程的流域恢复奠定了基础。
Large dams provide vital protection and services to humans. However, an increasing number of large dams worldwide are old and not operating properly. The removal of large dams has excellent potential to restore habitat connectivity and flow regimes; therefore, projecting the related ecological consequences is an emerging need for water resource and ecosystem management. However, no modeling methods are currently available for such projections at the basin scale. We devised a scheme that integrates changes in flow regimes and habitat network structure into a basin‐scale impact assessment of removal of large dams and applied it to the Nagara‐Ibi Basin, Japan. We used a graph‐theoretical approach and a hydrological model, to quantify changes in habitat availability for 11 freshwater fishes at the basin scale under multiple removal scenarios. We compared these results with the change predicted using a conventional scheme that considered only changes to the habitat network due to dam removal. Our proposed scheme revealed that an increase in flow variability associated with dam removal projected both positive and negative effects on basin‐scale habitat availability, depending on the focal species, endangered species had a negative response to dam removal. In contrast, the conventional approach projected only positive effects for all species. This difference in the outcomes indicates that large‐dam removal can have negative and positive effects on watershed restoration due to changes in flow regimes. Our results also suggest the effect of removal of large dams may depend on the dams and their locations. Our study is the first step in projecting ecological trade‐offs associated with the removal of large dams on riverscapes at the basin scale and provides a foundation for future process‐based watershed restoration.