IWRA Proceedings

Abstract1.Purpose River connectivity is an important feature of the river system, which has four dimensional characteristics of longitudinal, horizontal, vertical and time. The longitudinal dimension (i.e. longitudinal connectivity) which refers to the transporting smoothness of matter and energy along the river (from source to estuary) is most disturbed and affected by human activities in the urbanization. With the acceleration of urbanization, the construction of a large number of hydropower stations has a great impact on the river connectivity and has caused many irreversible adverse effects on the water environment and ecology of the basin. 2.Problems solved: Taking the Nanshan River basin in Yunfu Guangdong as an example, the priority order of demolishing the hydropower stations built in the Nanshan River basin is suggested. Improving the river connectivity, the water environment and ecology of the Nanshan River basin, it also provides feasible experiences and conclusions for the management of small and medium-sized basin in China. 3.Methods Based on the concept, research mechanism and calculation method of the river longitudinal connectivity all over the world, the methods of Vertical Connectivity Index (VCI) method, barrier coefficient method, improved barrier coefficient method and Dendritic Connectivity Index (DCI) method are used to quantitatively evaluate the impact of hydropower station construction on the longitudinal connectivity of Nanshan River basin. 4.Results Firstly, iiin the process of urbanization, the construction of hydropower stations, especially that of the small and medium-sized ones which doesn’t have any fish migration facilities, will greatly reduce the connectivity of the river system and cause obviously negative effects on it. Secondly, keeping the advantages of simple and quick calculation of the traditional barrier coefficient method, the improved barrier coefficient method will fully consider the barrier influence of the quantity, the construction type and the location of hydropower stations. Thus it is more scientific to evaluate the river system connectivity. Lastly, more attention should be paid to the study of the river system connectivity in small and medium-sized basin, since the impact of hydropower station construction on the river system connectivity in small and medium-sized basin is more significant than that of large-scale basin.