The ecological sustainability of hydropower is one of the key aspects within Hydro4U. Lessons learned in Europe but also other parts of the world show that impacts of hydropower have caused a severe reduction of riverine fish in number and diversity. For instance, through hindering migration, changing the flow regime by lowering the base flows, generating fast artificial flow changes, or disturbing natural habitat structures.

At the demonstration site Shakimardan, Uzbekistan, the impacts of hydropower development on the river Koksu have been studied by SJE in cooperation with local experts such as the Central Asian partner TIIAME and European partners like BOKU and EVINBO. These results have been considered in the planning of the hydropower plant in collaboration with the project partners KJ Consult and TUM Munich.

A new cell phone-based mapping tool designed by SJE has been applied to collect habitat information along the affected, more than 3 km long section of the river Koksu and to integrate it into a GIS. Habitat information for the target species snow trout (Schizothorax eurystomus), has been jointly collected via E-Fishing by BOKU and TIIAME. This information has been used for simulations performed with the SJE-owned software CASiMiR (www.casimir-software.de) for various river flows to find a seasonally adapted E-Flow that protects the local fish population.

The existing diversion weir and intake structure are modernised and equipped with a state-of-the-art fish way respectively a bypass installation that enable up- and downstream migration for snow trout. A migration barrier within the diverted river section is made passable by building a fishway adapted to the local lack of space. Currently, a telemetry study is performed by TIIAME and EVINBO using fish tagging with passive integrated transponders and the mapping tool, to find out about the migration movements of snow trout. The gained insights will feed into the adaptive management of the future Hydro Power Plant.

Author: Matthias Schneider, SJE Ecohydraulic Engineering GmbH

Photos and figures by Matthias Schneider and Tobias Hägele, SJE GmbH