Énergie

Dam construction is mostly aimed for multiple functions, including irrigation water provision, hydropower, and some others that bring substantial social benefits. However, global warming impacts on the interaction of the positive outcomes of damming remain little known, particularly in terms of the sustainability of their co-benefits, whereby investigating the different impacts of global warming scenarios of 1.5 °C and 2 °C has been a hotspot in water resources and energy research worldwide. This study used an integrative analysis based on a hydrological, techno-economic and agricultural modeling framework to evaluate the effects of global warming scenarios of 1.5 °C and 2 °C on the co-benefits between hydropower and irrigation in the Mekong River basin. The results show the declined hydropower generation and irrigation water supply in the Mekong River basin under 1.5 °C and 2 °C warming scenarios. The co-benefits between the hydropower and the irrigation is more undermined by the global warming of 2 °C relative to 1.5 °C in the Mekong River basin. Moreover, the changes of co-benefits are sensitive to the consideration of the protected areas in the basin. With the consideration of the protected areas, the co-benefits would be enhanced by 2 °C global warming compared to 1.5 °C global warming. Therefore, it is critical for decision-makers to consider the tradeoffs between the environment and dam construction for ensuring energy and food security under global warming scenarios.

As the demand for hydroelectricity progresses worldwide, small hydropower operators are increasingly examining the feasibility of using existing infrastructure (e.g., settling basins) in run-of-the-river schemes for intermittent power production. Such flexible production causes short-term discharge fluctuations (hydropeaking) in downstream reaches with potential adverse effects for the sensitive fauna and flora in alpine streams. In an experimental field study on a previously unregulated section of the upper Rhone River (Switzerland), we measured density and composition of macroinvertebrate drift in two habitats (riffle, pool) following a 15-minute hydropeaking wave. The experimental hydropeaking was replicated five times over 14 days with decreasing recovery times between peaks (8, 3, 2 days, and 24 h), and drift measurements were compared with kick samples for the benthic community. Results from the kick sampling showed that benthic macroinvertebrate abundance and composition did not significantly change between the experimental peaks. There were habitat specific reactions in macroinvertebrate drift to hydropeaking, with the pool experiencing more pronounced drift abundances than the riffle. Overall, drift abundance was not significantly correlated with recovery time, but results indicate taxa-specific differences. This research advocates for the importance of completing more in-situ field experiments in order to better understand the ecological impact of flexible power production in small hydropower plants.