Assessing the cumulative environmental impact of hydropower construction on river systems based on energy network model

Hydropower is the major renewable energy source for many nations and regions. Dam construction caused direct or indirect detrimental impacts on river systems by altering the water flow pattern and reshaping natural habitats. The dam-induced environmental impact assessment is critical in balancing the human demand for more accessible energy and the ecosystem conservation. In this paper, we proposed information network analysis for assessing environmental impact of hydropower construction based on energy network model of the river system. The framework is capable of evaluating multiple post-dam environmental stressors and tracking energy flows within the disturbed river system. By considering both direct and indirect interactions between system components in the network model, the environmental impacts of sedimentation, discharge change and heavy metal pollution are explicitly evaluated. Dam construction on the upper Mekong River was presented as a case study. The results suggested that the initial dam-induced impact only contributed less than 30% of the cumulative value and that the impact ranking among species, from a network perspective, significantly differed from the traditional toxicological/physiological estimation. Mollusca, benthic-feeding fish and zooplanktivorous fish in the middle trophic levels were most affected by damming, whereas the impact on species at the bottom of the food chain became less prominent in a cumulative way. The most valued species in fishery were found notably impacted and might become endangered because of dam construction. Ad-hoc management actions should be taken to enhance ecosystem conservation and sustainable hydroelectric development in China. By introducing the network approach to the cumulative environmental impact assessment, this study provided insights into a more sustainable path of hydropower construction.