Ecohydraulic investigations of hydropeaking: the role of river morphology (#69)
Hydropeaking is one of the major impacts on river ecology in the alpine region. It occurs predominantly downstream of storage hydropower plants, as a result of their “on-demand” energy production. Previous studies have established that that biocoenoses and particularly the early stages of fish are the most affected by the related rapid flow changes. Ecohydraulic modelling has been applied in several studies to describe and assess the impacts of different operational and morphological scenarios on river ecology. However, the type of morphological feature types beneficial for the mitigation of hydropeaking impacts remain to be throroughly investigated.
In the research project presented, instationary hydraulic models have been linked with habitat preference curved derived from a European database. Three morphologically distinct stretches of an alpine river have been assessed, comparing the effects of hydropeaking on juvenile fish. Different hydraulic and habitat indicators have been used to describe the intensity of negative impacts.
It can be shown that the total amoung areas with increased risk of stranding and drift is generally higher in a nature-like stretch with heterogeneous morphology than in more homogeneous stretches. However, because the total amount of suitable habitat is significantly higher, the overall habitat availability under hydropeaking conditions in such reaches is also better. Additionally, we show that areas with relatively stable habitat locations are more frequent and spatially related to specific morphological features. These features can be identified by their ”hydraulic stability” introduced as a novel hydropeaking indicator.