Event Title

Session D1: How to Investigate the Influence of Auxiliary Discharge on the Attraction of Fishways

Location

Groningen, The Netherlands

Event Website

http://fishpassage.umass.edu/

Start Date

22-6-2015 10:55 AM

End Date

22-6-2015 11:10 AM

Description

Abstract:

Adding auxiliary discharge to the outflow of the fishway extends the attraction flow further into the tailwater and serves to guide fish to the entrance. Due to conflicting interests between ecological demands and hydropower generation this additional discharge is subject to critical scrutiny. How much auxiliary water is needed for a certain effect?

Suggestions about the necessary discharge vary and only few studies have been conducted so far. The German Federal Institute of Hydrology and the German Federal Waterways Engineering and Research Institute will address this question at four pilot sites in German waterways as part of a research program on ecological continuity.

However, developing a study design is not an easy task: Which is the best explanatory variable to investigate - a certain amount of discharge (which is easier to control) or a distinct flow pattern in the tailwater (which is more likely what fish will notice)? Is the total number of fish that find the fishway a good response variable? Where and how should we count the fish? How do we deal with the multitude of environmental parameters that also influence the number of migrating fish? Which sample size will suffice and what level of probability can be considered adequate?

To deal with these questions we have worked out a study design that includes several statistical approaches (blocked design, baseline measurement, regression techniques). We have developed discharge scenarios on the basis of CFD and used 2012-2013 monitoring data from a Vaki-Counter at the River Moselle to simulate effects and necessary sample sizes. We also used this data to find out which environmental parameters influence the number of migrating fish and may thus influence our studies. We like to share and discuss our results and approaches with colleagues from different regions and professions.

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Jun 22nd, 10:55 AM Jun 22nd, 11:10 AM

Session D1: How to Investigate the Influence of Auxiliary Discharge on the Attraction of Fishways

Groningen, The Netherlands

Abstract:

Adding auxiliary discharge to the outflow of the fishway extends the attraction flow further into the tailwater and serves to guide fish to the entrance. Due to conflicting interests between ecological demands and hydropower generation this additional discharge is subject to critical scrutiny. How much auxiliary water is needed for a certain effect?

Suggestions about the necessary discharge vary and only few studies have been conducted so far. The German Federal Institute of Hydrology and the German Federal Waterways Engineering and Research Institute will address this question at four pilot sites in German waterways as part of a research program on ecological continuity.

However, developing a study design is not an easy task: Which is the best explanatory variable to investigate - a certain amount of discharge (which is easier to control) or a distinct flow pattern in the tailwater (which is more likely what fish will notice)? Is the total number of fish that find the fishway a good response variable? Where and how should we count the fish? How do we deal with the multitude of environmental parameters that also influence the number of migrating fish? Which sample size will suffice and what level of probability can be considered adequate?

To deal with these questions we have worked out a study design that includes several statistical approaches (blocked design, baseline measurement, regression techniques). We have developed discharge scenarios on the basis of CFD and used 2012-2013 monitoring data from a Vaki-Counter at the River Moselle to simulate effects and necessary sample sizes. We also used this data to find out which environmental parameters influence the number of migrating fish and may thus influence our studies. We like to share and discuss our results and approaches with colleagues from different regions and professions.

https://scholarworks.umass.edu/fishpassage_conference/2015/June22/9