Namakhvani waterfall dam on the River Rion

Collection of international expertise projects at INRAE27 In 2017, the local branch of the Norwegian group Clean Energy Group, Georgia 1, planned to invest in Georgia in order to develop a hydroelectric cascade project at the Namakhvani dam, on the Rioni river, in the municipalities of Tskhaltubo and Tsageri. This project anticipated maintaining a minimum flow of 10% of the average annual flow, but without any prior scientific basis. Clean Energy Group therefore entered into an agreement with SRL Consulting (Grenoble) to fill this gap with additional studies on the environmental and social aspects of the project. For the studies on the impact of the project on fish habitat and fish populations, this consultancy firm itself chose to delegate and Hervé Capra from the Dynam laboratory (then the MALY unit) in Lyon was commissioned.

The fish species had been surveyed during a previous study in 2015: eight species were identified, some of which are endemic, and some of which are on the Georgian red list. However, the study did not take into account the likely impact of the existing dam downstream on fish populations, particularly migratory fish, due to the lack of a crossing device.

1. The aim of Hervé Capra’s study was therefore to :

• describe the river fish habitat affected by the presence and operation of the two dams/reservoirs;
• assess the effects of the 2 hydroelectric systems on the distribution of fish species in the river Rioni;
• justify the environmental flow defined downstream of the Namakhvani dam;
• propose measures to mitigate, compensate for or improve the management of hydropeaking flows.
• Enka, the new contractor, plans to commission the Namakhvani dam in 2018.