Yedigol and Aksu Hydropower Projects

The power tunnels are designed as unlined.

Project Information

Client: Makyol-Ismil Joint Venture, Borusan - Enbw

Location: Ispir 

Status: Completed


Key Features

Diversion Type

Installed Capacity 52 MW

Cascade Projects

Unlined Power Tunnel




Yedigol and Aksu Hydropower Projects are cascade diversion type hydropower facilities over Aksu Stream. Yedigol Project has commenced to commercial activity in 2011 whereas Aksu Project in 2012.


Projects make use of the head between 1.598 m and 1.057 m of Aksu Stream for energy generation. The flows of Aksu Stream taken by tyrolean-type weirs are conveyed to powerhouses through energy tunnels. The tunnels are designed mostly without concrete lining except the parts where reinforced concrete lining is required. The total length of the tunnel for Yedigol is 4.800 m whose last 350 m is made up of steel penstock inside the tunnel, similarly the last 400 m of 6.400 m long Aksu energy tunnel is also made up of steel penstock. Both facilities have two equal capacity Pelton type units.

Since the powerhouse final design projects are prepared with poor soil investigations, the thick alluvial layer that is discovered during excavation of power plants necessitated the modification of the design of projects. In this respect, Prosem Engineering has relocated the Yedigöl powerhouse and compulsorily designed the Aksu powerhouse with pile foundation above alluvium. The architectural and final design projects of both powerhouse buildings together with the application projects of whole structures are prepared by Prosem and has been controlled and approved by the consultant firm HPI (Germany).