Previous national and international studies on hydropeaking provide partially insufficient basic information to generate national river basin management plans with regard to the implementation of the WFD. For Austria, as alpine country, it is of special importance to fill these knowledge gaps in the context of hydropeaking related to variable river hydraulics and morphology. The present diploma thesis provides, based on 2D depth-averaged HN-models (hydro_AS-2d) and the integrative tool of habitat modelling (Habitat Evaluation Model HEM), basic information for the evaluation of hydropeaking reaches at the Carinthian Drau River. Understanding of hydropeaking processes in revitalization reaches like river widenings could be determined. The habitat changes in small-scale structures caused by short term fluctuations of water levels induced by hydropeaking were analysed for the juvenile brown trout (Salmo Trutta, 0+). Additionally, a water temperature monitoring was performed by temperature data loggers. The results indicate that similar restoration measures at the Drau River (river widenings) react differently to hydropeaking impacts. Too high and fast discharge fluctuations can possibly limit the suitable habitats within restoration sites. Base flow and the magnitude of hydropeaking discharge represent crucial factors for the extent of the habitat losses. Moreover, based on near-natural river reaches (increased roughness impact) considerable reductions of the dewatering rates could be documented and quantified.