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Impacts of human activities on the structural and functional connectivity of a river network in the Taihu Plain

Deng, Xiaojun, Xu, Youpeng, Han, Longfei
Land degradation & development 2018 v.29 no.8 pp. 2575-2588
gates, hydrology, migratory behavior, rivers
Human activities are expected to change the hydrological connectivity of river networks. Understanding the impacts of human activities on hydrological connectivity is crucial for river‐basin management. The present study investigated the impacts of river network change and water gate construction on the structural and functional connectivity in the Taihu Plain. We found that the network circuitry, edge‐node ratio, and network connectivity of the arterial river network increased by 8.82%, 3.59%, and 3.57%, respectively, during the 1960s–2010s. In Jiangyin, the indexes decreased by 46.40%, 15.43%, and 15.42%, respectively, throughout the river network during the 1960s–1980s. The indexes of the capillary river network decreased by 61.90%, 24.89%, and 24.88%, respectively, while those of the arterial river network increased by 6.58%, 4.73%, and 2.72%, respectively. We also found that the current longitudinal continuity of the river network was 8.15. In the Sangan River of Zhangjiagang, the migratory continuity of the river network was 0.27, but it was between 0.33 and 1.00 when the current water gates were considered separately, and the decreases of their maximum values under different combinations were greater than those of their minimum values. Moreover, we found that the various water levels of the river network all exhibited increasing trends, and their correlations with functional connectivity were significant and positive. Our study suggests that the negative effects of river network changes on structural connectivity were far greater than the positive effects, and the impacts of water gate construction on functional connectivity had gradient and cumulative effects.