Schutz der Fischpopulation, ein ganzheitliches Konzept für die Große Wasserkraft im Donaueinzugsgebiet

Aufsatz veröffentlicht in: "Wasserbau-Symposium 2021: Wasserbau in Zeiten von Energiewende, Gewässerschutz und Klimawandel, Zurich, Switzerland, September 15-17, 2021, Band 2" veröffentlicht unter: https://doi.org/10.3929/ethz-b-00049975

Session B1: Fish Passage in Large Rivers: Challenges and Solutions

Abstract Understanding and facilitating fish passage in large rivers is a major challenge. This challenge stems in part from the scarcity of surveys of large river, due the inherent difficulties associated with studying them. In addition large rivers host a great number of fish species differing in size, ecological requirements and swimming abilities. Notwithstanding the limited information regarding these topics, EU and national legislation require passage facilities for all species and size classes to reach the “good ecological status” till 2027. VERBUND, the largest power plant operator in Austria, is responsible to implement these measures on a variety of big rivers in Austria and Germany. First projects started in the mid-1980ies at the Power plant Greifenstein at the Danube followed by more than 15 fishways at a variety of large Rivers (Danube River, Inn River, Salzach River, Drau River, Möll River, Mur River). Most of the projects have been accompanied by a scientific monitoring program. In our contribution we present our experience and learnings gained with construction, operation and functionality of different types of fish ladders at big rivers including the “Hydrodynamic fishlift”, conventional vertical slot passes, and nature-like bypass channels. The projects show that the requirements formulated in the EU-WFD cannot be achieved by measures to improve fish passage alone. In order to achieve the objectives the improvement of habitat conditions is required. One of the key habitat types in large rivers are permanently connected side arms, which provide spawning grounds and shelter from ship-induced waves. A stepwise procedure using different types of fundings has proven successful so far to implement the environmentally and economically feasible in a reasonable time frame. It is also important to co-ordinate all actions with the different types of usage of the Danube (Energy, navigation, flood protection, ...) and the responsible stake holders

Numerische Untersuchungen des Turbinendurchganges von Fischen

Aufsatz veröffentlicht in: "Wasserbau-Symposium 2021: Wasserbau in Zeiten von Energiewende, Gewässerschutz und Klimawandel, Zurich, Switzerland, September 15-17, 2021, Band 2" veröffentlicht unter: https://doi.org/10.3929/ethz-b-00049975

Effect of sampling effort and sampling frequency on the composition of the planktonic crustacean assemblage: a case study of the river Danube

Although numerous studies have focused on the seasonal dynamics of riverine zooplankton, little is known about its short-term variation. In order to examine the effects of sampling frequency and sampling effort, microcrustacean samples were collected at daily intervals between 13 June and 21 July of 2007 in a parapotamal side arm of the river Danube, Hungary. Samples were also taken at biweekly intervals from November 2006 to May 2008. After presenting the community dynamics, the effect of sampling effort was evaluated with two different methods; the minimal sample size was also estimated. We introduced a single index (potential dynamic information loss; to determine the potential loss of information when sampling frequency is reduced. The formula was calculated for the total abundance, densities of the dominant taxa, adult/larva ratios of copepods and for two different diversity measures. Results suggest that abundances may experience notable fluctuations even within 1 week, as do diversities and adult/larva ratios

Biophysical landscape interactions: bridging disciplines and scale with connectivity

Landscape composition and land use impact the interactions between soil and vegetation. Differences in micro-behaviour, driven by the interplay of heterogeneous soil and vegetation dynamics, affect emergent characteristics across a landscape. Scaling approaches to understand the drivers of these emergent characteristics have been attempted, but the blueprint of interacting biophysical processes in landscapes is inherently messy and often still unknown. A complicating factor is single disciplinary focus in environmental sciences. Integrated knowledge is vital especially in view of future challenges posed by climate change, population growth, and soil threats. In this paper, we give examples of biophysical interactions that occur across various temporal and spatial scales and discuss how connectivity can be useful for bridging disciplines and scales to increase our understanding