Assessing the impact of small hydropower stations on the connectivity of the Chishui River and restoration strategies
The Chishui River is an important component of the National Nature Reserve for rare and endemic fish species in the up-per Yangtze River.Its ecological connectivity is crucial for protecting endemic fish species in the upper Yangtze River.However,the widespread distribution of small hydropower stations in the Chishui River Basin has severely affected the connectivity of this re-gion.This study collected detailed information on the spatial location,construction year,and installed capacity of small hydropower stations in the Chishui River Basin.Four connectivity indices,namely the dendritic connectivity index(DC1),stream connectivity index(SCI),catchment area fragmentation index(CAFI),and the newly proposed modified catchment area fragmentation index(CAFIM),were used to assess the spatio-temporal changes in the connectivity of the Chishui River Basin due to small hydropower stations.The results showed that almost every river in the Chishui River Basin has small hydropower stations,mainly distributed in low-order streams.The DCI and SCI indices showed that as the number of stations increased,the connectivity of the Chishui River Basin significantly decreased.The connectivity in the middle and lower reaches was more severely deteriorated than that in the up-per reaches.The CAFI and CAFIM indices revealed similar trends,with the degree of river fragmentation continuously increasing,particularly in the Xishui River,Datong River,and Tongzi River Basins.The proposed CAFIM index incorporated the factor of in-stalled capacity of small hydropower stations,enabling a more comprehensive and accurate assessment of the impact of these sta-tions.Compared to traditional indicators,the CAFIM index is more sensitive to changes in installed capacity,and can effectively re-flect the impact of large-scale power stations.Based on the assessment results of the CAFIM and other indices,the study evaluated the priority of obstacles posed by each small hydropower station in the Chishui River Basin.The study demonstrated that priority should be given to rectifying stations with large installed capacities located at high-order streams to maximize the improvement of ba-sin connectivity.The study found that the location and installed capacity of the stations were the key factors determining the priority of their removal.The removal of stations located on high-order streams with large installed capacities(such as Jinyang and Yuan-manguan)had the most significant effect on improving basin connectivity.This study comprehensively evaluated the connectivity status of the Chishui River Basin,proposed strategies for optimizing the removal of small hydropower stations,and provided a deci-sion-making basis for ecological restoration in the basin.It is thus of great significance for protecting endemic fish species in the up-per Yangtze River.This research provided theoretical foundations and methodological support for assessing the impact of small hy-dropower stations on watershed river network connectivity and developing restoration strategies.
River connectivitysmall hydropower stationsmodified river fragmentation index CAFIMconnectivity indicesCh-ishui River Basin
万方数据
维普
