Mitigation measures for the impact of hydrotechnical works in Răstoliţa River, Romania on Hucho hucho species

Abstract

Hucho hucho habitats in the Răstoliţa River, Romania are under the pressure of anthropic activities, the most significant impact coming from hydrotechnical works implemented in the river started in the ‘80s. In the context of further development of the hydropower system, mitigation measures must be taken in order to ensure the conservation of ichthyofauna habitats, especially for Hucho hucho, a critically endangered species in Romania. Based on available data regarding the fish specimens’ presence and specific local hydromorphological and hydrodynamic conditions, a scientific-based tailored impact mitigation measures set for the conservation of Hucho hucho habitats is proposed for the Răstoliţa dam downstream area. By using hydraulic modelling and hydrological statistics, 12 monthly discharge values ranging from 1.00 to 1.80 m3/s have been determined as echohydrograph minimum values to be spilled by the Răstoliţa dam, with an additional 0.5 m3/s to be provided for April and May in order to ensure the conditions for the spring-cleaning phenomena. The proposed set of measures aims to mitigate the negative impact of the planned hydrotechnical works on the conservation of species of community interest, especially Hucho hucho.