Planning dam portfolios for low sediment trapping shows limits for sustainable hydropower in the Mekong

Abstract

The transboundary Mekong Basin has been dubbed the “Battery of Southeast Asia” for its large hydropower potential. Development of hydropower dams in the six riparian countries proceeds without strategic analyses of dam impacts, e.g., reduced sediment delivery to the lower Mekong. This will impact some of the world’s largest freshwater fisheries and endangers the resilience of the delta, which supports 17 million livelihoods, against rising sea levels. To highlight alternatives, we contribute an optimization-based framework for strategic sequencing of dam development. We quantify lost opportunities from past development and identify remaining opportunities for better tradeoffs between sediment and hydropower. We find that limited opportunities remain for less impactful hydropower in the lower basin, where most development is currently planned, while better trade-offs could be reached with dams in the upper Mekong in China. Our results offer a strategic vision for hydropower in the Mekong, introduce a globally applicable framework to optimize dam sequences in space and time, and highlight the importance of strategic planning on multiple scales to minimize hydropower impacts on rivers.

Remotely sensed rivers in the Anthropocene: state of the art and prospects

“…For instance, the CAtchment Sediment Connectivity And DElivery (CASCADE) modelling framework enables a quantitative, spatially explicit analysis of network sediment connectivity with potential applications in both river science and management (Schmitt et al, 2016;Figure 12). In the Mekong delta, understanding the cumulative effects of constructed and planned dams helps identify new solutions addressing both economic and environmental objectives (Schmitt et al, 2018a(Schmitt et al, , 2018b(Schmitt et al, , 2019.…”

Hydropeaking Operations of Two Run-of-River Mega-Dams Alter Downstream Hydrology of the Largest Amazon Tributary

“…Uncoordinated construction of dams throughout the world has resulted in environmental impacts that could have been minimized through strategic basin-wide dam planning (Schmitt et al, 2018;Almeida et al, 2019b). New frameworks for watershed-wide, multiobjective optimization of dam planning have recently been proposed for major river basins of the world (Ziv et al, 2012;Schmitt et al, 2019), including the Amazon (Almeida et al, 2019b). It is imperative to consider potential hydrological effects along with other social and environmental impacts related to future Amazon dams.…”

What Is the Future of the Lower Mekong Basin Struggling against Human Activities? A Review

“…The different governments of the Mekong Basin chose large-scale hydro-power projects because the region was so far limited in term of dam development infrastructures [42]. Consequently, the development of massive water infrastructures is now booming [35,43]. The first dam directly built on the Lancang River (Chinese name of the Mekong) was the Manwan Dam, in 1986 and was fully operational in 1996 [44].…”

“…The reduction of sediment load in the delta clearly depends on the position and quantity of dams in the mainstream and tributaries and hence, on political decisions [43]. The construction of all planned dams would have consequences on sediment transportation (95% being trapped), leading to a reduction of the amount of sediment in the delta at 9Mt.yr.…”