Hydropower projects in China have caused ‘major flow changes’ to the Mekong River over the last six years, a study led by researchers from Aalto University in Finland has suggested.

The study, published in Journal of Hydrology in December 2016, suggests that the hydro operations have increased dry season flows and decreased wet season flows. This comes following an analysis of river flows in Northern Thailand.

The study says that river flow impacts were largest in 2014 after completion of the Nuozhadu dam, the largest hydropower project in the Mekong Basin, with impacts observable over 2000km downstream in Cambodia.

“The river flow changes are feared to affect the ecological productivity of the river and thus the livelihoods, economy and food security of the downstream people. In particular the impacts on fishing are a major concern because fish and other aquatic animals play a major role in the local and regional economy and food supply,” said researcher Timo Räsänen.

“However, the ecological and social consequences of the hydropower operations are not yet well understood and more research is needed. The downstream countries are also building hydropower stations and the cumulative impacts need further attention. Therefore the research highlights the importance of strong transboundary cooperation between upstream and downstream countries for understanding and mitigating the negative consequences.”