Evaluation de la qualité physique de la rivière coşuştea (bassin de jiu) par la méthode téléos

The assessment of the rivers’ physical quality is one of the Water Framework Directive (WFD CE/ 60/2000) requirements and, as a result, there have been a number of methods developed by member-states that are tested and continually improved. Téléos (developed in 1998–1999 under the LIFE Environment WALPHY Project) is one of these methods targeted for analyzing the physical state of rivers in order to meet the demands of hosting and preserving the fish habitat and other biological components. In our study, three sectors of the Coşuştea River (SW Romania, 77 km long) were used to apply the Téléos method, in order to identify the river reaches characterized by a poor ecological and geomorphological condition that could be later restored. Descriptive elements of the Coşuştea River’s morphological state, as required by WFD, make up the four Téléos indicators of aquatic habitat: Heterogeneity, attractiveness, connectivity and bed stability (Téléos, 2010). The scores calculated for each sector of the Coşuştea River, as well as the general physical quality grade (QP), allowed for their inclusion in one of the five functionality classes (ranging from a good to a bad state). Two of the sectors fell into the C class (medium-quality), while in one of the sectors, the final score was D (poor quality). The analysis showed that, within the studied reaches, the Coşuştea River was found to be rather unattractive to fish, because of low heterogeneity and limited lateral and longitudinal connectivity. These weaknesses counterbalance the good overall geomorphological condition, with riverbanks seldom affected by mismanagement after morphogenetic flood events. According to the summarized results, we can conclude that the Téléos method brought a new perspective on the physical environment of the Coşuştea River. It can nevertheless represent an important phase in evaluating the physical quality of a river, in terms of its capacity to accommodate a diverse flora and fauna. Consequently, the Téléos method can serve as a decision-making tool for the management and restoration of rivers projects.