The platform unifies societies and scientific bodies that are active in the field of geoscience. It acts as an interface between the various academic disciplines of geosciences as well as between research, practice, administration, politics and the public.more

Image: NASAmore

Sanierung Schwall - Sunk

Lorenzo Gorla (OFEV, Force hydraulique - assainissements) Diego Tonolla (ZHAW, Zurich University of Applied Sciences, Institute of Natural Resource Sciences)

Time

16:30 - 17:45

Im vierten Beitrag unserer virtuellen Vortragsreihe behandeln wir das Thema «Sanierung Schwall-Sunk». Lorenzo Gorla informiert über die rechtlichen Grundlagen und den Gesetzesvollzug bei der Sanierung der negativen Auswirkungen von Schwall und Sunk. Diego Tonolla referiert über den Einfluss des Schwall-Sunk Betriebs auf das Driftverhalten von Makroinvertebraten.

Éclusées 2
Image: Diego Tonolla, ZHAW

Contenue

Assainissement des éclusées en Suisse: une vue d’ensemble

Lorenzo Gorla (OFEV, Force hydraulique - assainissements)

La loi sur la protection des eaux (LEaux, 2011) contraint les détenteurs de centrales hydroélectriques à prendre des mesures pour empêcher ou éliminer les atteintes graves que des variations subites et artificielles du débit d’un cours d’eau (éclusées) portent à la faune et à la flore indigènes et à leurs biotopes. Les résultats de la planification stratégique cantonale (2011-2014) ont montré qu’environ 100 installations en Suisse provoquent une atteinte grave dans le domaine des éclusées et doivent faire l’objet d’un projet d’assainissement. Le délais pour la mise en œuvre des mesures d’assainissement est 2030.

En 2017 l’aide à l’exécution «éclusées – mesures d’assainissement» a été publiée par l’OFEV, dans le but d’aider et homogénéiser le processus d’assainissement. On y trouve une méthode et des instruments (indicateurs) spécifiques pour la mise en œuvre des obligations légales. Les premiers projets d’assainissement ont été réalisés et plusieurs sont en ce moment dans la phase d’étude.

Response of macroinvertebrate drift to hydropeaking simulations of flow and up-ramping rates in flume and field experiments

Diego Tonolla (ZHAW)
Lisa Schülting (University of Natural Resources and Life Science Vienna, Institute of Hydrobiology and Aquatic Ecosystem Management, Vienna)

High-head storage hydropower plants allow a quick response to peak electricity demand, but the storage operation causes frequent and severe unnatural fluctuations in discharge and water levels (i.e. hydropeaking) that negatively affect aquatic organisms in receiving waters. The unintentional, mechanical dislodgement from the substrate of macroinvertebrates not adapted to resulting harsh hydraulic conditions (i.e. passive drift), such as high shear stress, high flow velocities and up-ramping rates during hydropeaking events, is a well-known response. However, there is still a lack of quantification of macroinvertebrate drift and related key hydraulic forces. Here, we present results of flume and field experiments that combine different up-ramping velocities flow velocities. Specifically, we focus on taxa- and trait-specific drift response. Macroinvertebrate drift increased significantly during hydropeaking in comparison to low flow conditions and highest drift was found during the up-ramping phase and the first part of peak flow when corresponding hydraulic forces were at their maximum. Drift response strongly depends on benthic source populations and taxa classified as lentic showed the highest propensity to drift (i.e. drift intensity standardized by benthic density) in all hydropeaking rivers, whereas lotic and indifferent taxa showed comparable low drift propensities. Moreover, taxa dwelling at the river bottom generally showed higher propensity to drift than interstitial taxa. Additionally, the flume study and, to a lesser extent, the field study indicate that drift response patterns are strongly related to peak discharge and corresponding flow velocities and to a lesser extent to up-ramping rates. Both studies suggest that operative measures or constructive measures such as retention basins or caverns should aim to reduce peak discharge and up-ramping rates to mitigate detrimental effects on macroinvertebrate drift. Furthermore, morphological measure could improve resistance and resilience. Nevertheless, before defining specific hydraulic thresholds relevant towards implementation of mitigation measures, basic behavioral patterns of specific taxa should be emphasized in future studies.

Programme

16.30 - 16.35 - Bienvenue

16.35 - 17.05 - Présentation «Assainissement des éclusées en Suisse: une vue d’ensemble»

17.05 - 17.10 - Pause

17.10 - 17.45 - Présentation «Response of macroinvertebrate drift to hydropeaking simulations of flow and up-ramping rates in flume and field experiments»

Inscription

Categories

  • Hydrology
  • Limnology
Die Teilnahme am Referat ist kostenlos.
Der Vortrag findet virtuell via Zoom statt. Eine Anmeldung ist erwünscht.
Languages: English, French