LONGITUDINAL ASSESSMENT OF HYDROPEAKING IMPACTS AND EVALUATION OF MITIGATION MEASURES

Hydropeaking is one of the main environmental impacts on running water ecosystems in Austria. Many affected rivers have a poor ecological status. Habitats for fish and invertebrates can be reduced, abundances can be diminished and organisms are affected by drift and stranding during the increase and decrease phases of peaks. To assess the ecological impact of hydro peaking, intensity thresholds according to different species and life stages can be applied. However, due to retention effects, the hydrological impact is not constant in a longitudinal view. A model to assess hydrological impacts considering distances to the power plant outlets is needed. For this purpose, we developed a model by detecting fluctuation intensities out of multiple hydrographs along the affected river reaches. This forms the basis for describing potential effects of hydro peaking by contrasting the varying hydrological impact intensity to threshold values of river organisms. Furthermore, mitigation scenarios can be evaluated, both ecologically and economically, by modelling modified hydro peaking intensities.