Hart T raun Enns DRAU Catchment area Styria › files › Downloads... · and video monitoring as a...

HausmeningStaning

PichlernDeutenham

Buchleitenwehr

Gmunden

Stadl Paura

Hart

Loiblbach

Enns

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r

Ager

DrauDrau

Drau

Arriachbach

Gail

Gurk

Inn

Mur

Salzach

Salzach

Mur

Sulm

fualr

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Traun

Möll

Klagenfurt

Graz

Salzburg

N i e d e r ö s t e r r e i c h

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S a l z b u r g

C a r i n t h i a

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DRAU Catchment area

41

Measures in the Drau catchment area

River portrait of Drau catchment areaAfter the Save, Theiss and Inn, the Drau is the

fourth-longest tributary of the Danube. With

11,997 km2, the Drau has the third-largest catchment

area of all Austrian rivers after the Danube and the

Inn reaching a mean discharge of 670 m3/s. Until

it flows into the Danube coming from the south in

Croatia, the Drau travels a long 749 km course with

an elevation difference of 1,360 m. The Austrian

part of the course of the Drau counts for 261 km

while its source is on the other side of the Austrian-

Italian border at the Dobbiaco Saddle in South Tyrol

at a height above 1,450 m. After reaching Austrian

national territory, the Drau first crosses the East

Tyrolian Pustertal. The Isel flows into the Drau from

the northwest at Lienz, through which the Drau

HausmeningStaning

PichlernDeutenham

Buchleitenwehr

Gmunden

Stadl Paura

Hart

Lieserbrücke

Arriach

Schütt

Althofen

PasseringLaunsdorf

Gößnitz

LoiblbachGabl

PaternionKellerberg

Villach

Schwabeck

Rosegg-St.Jakob

Malta

Lavamünd

Weinzödl

GössendorfKalsdorfMellach

Gralla

RetzneiSpielfeld

Humpelmühle

Ybbs

Mürz

Mürz

Enns

Enns

Stey

r

Ager

DrauDrau

Drau

Arriachbach

Gail

Gurk

Inn

Mur

Salzach

Salzach

Mur

Sulm

fualr

E

Traun

Möll

Klagenfurt

Graz

Salzburg

N i e d e r ö s t e r r e i c h

I TA L YS L O W E N I E N

S a l z b u r g

C a r i n t h i a

S t y r i a

N

0 10 20 km

OESTERREICHS ENERGIE | HYDROPOWER 42

DRAINAGE BASIN DRAU

then reaches the border of Carinthia with twice the

amount of water.

After the inflow of the Isel, the next large tributary

of the Drau is the Möll that flows into the Drau at

Möllbrücke. This mountain river has its source 80

km northwest at the foot of the Grossglockner and

meanders from the Sonnblick and Reisseck groups

in the north to the Schober and Kreuzeck groups in

the south. The Möll drains a high Alpine catchment

area of 1,105 km2.

Starting at Spittal an der Drau, the energy of the

Drau is used to generate electricity in multiple large

reservoirs in an eastward direction down to the Aus-

trian-Slovenian border. Here, the course of the Drau

leads further to the east and bows increasingly to

the south. The confluence with the Gail, the largest

right tributary of the Drau, is located in the west

of Villach, followed by another right tributary, the

Loiblbach, coming from Rosental at Unterferlach.

After approx. 10 km, the Drau changes its direction

to the northeast and picks up the Gurk which is the

second-longest river in Carinthia at 157 km, near

Stein. The Drau leaves Austria east of the Lavamünd

power plant, crosses Slovenia and Croatia finally

flowing into the Danube in Osijek, Croatia.

Fish faunaIn contrast to the oxygen-rich, cold, and fast-flowing

upper reaches of the Drau in eastern Tyrol and

Upper Carinthia, the Drau moves much slower in

the large reservoir areas in Lower Carinthia east of

Spittal an der Drau. This also has an impact on the

fish habitats: The river sections of the lower Drau,

warming up more, mainly attract fish such as the

pikeperch and pike, brook trout and tench.

Large sections of the Drau and Möll belong to both,

the grayling region (hyporhithral) as well as the

barbel region (epipotamal). This results in the target

species and the accompanying fish species. For the

Drau, the target species are trout, grayling (Drau

grayling) and Danube salmon. Less common are

loach and spined loach. Depending on their indivi-

dual regions of the Möll, brown trout, rainbow trout

and grayling are the target species.

The target species on the Drau and Möll is the

Danube salmon with a length of 100 cm. All dimen-

sions of the fish passage facilities in these two rivers

are calculated according to the size and swimming

performance of this species.


DRAINAGE BASIN DRAU

Fish pass at the Gößnitz power plant

Construction phase of the fish lift by the Gößnitz power plant

Completed fish lift except for a few remaining work items


DRAINAGE BASIN DRAU

Company Water body Water body number River kilometre

Kelag – Kärntner Elektrizitäts AG

Möll 900790076 28.10–30.40

Aim of measure Type of measure

Creation of connectivity and morphological improvements

Construction of a fish pass as well as measures in the residual water section

Description of measure

In detail, the following measures will be implemented at the Gößnitz power plant:

• minimum residual flow of 600 l/s for the diverted reach to achieve the “fish passage” objective

• construction of a fish barrier in the downstream water canal of the Gößnitz power plant in order

to prevent the fish from swimming into the downstream water canal and thereby preventing a

dead end effect

• redesign of the eight transverse structures through the construction of meandering ramps

and rock ramps.

• construction of a fish pass in the form of a fish lift

The fish lift based on the “water host” system was completed. Implementation of other measures is to

follow in 2016.

Period of construction/implementation (without monitoring)

15.09.2015 to 30.06.2016 (planned)

Financial expenditures

Total investment in € € 599,000.-

▪ Of which UFG funding € 89,850.-

▪ State funding € 0.-

(Expected) monitoring expense in € € 20,000.-

(Expected) operating expense in €/year not yet foreseeable

Generation losses in MWh/year

Around 1,500 MWh/year


DRAINAGE BASIN DRAU

Structuring measures in the Malta downstream power plant reservoir

Construction of the guiding dam in the Rottau reservoir

Overview photograph of the guiding dam in the Rottau reservoir


DRAINAGE BASIN DRAU


VERBUND Hydro Power GmbH

Möll 900930002 5.82–6.35


Morphological improvement of the ecological conditions

Construction of a guiding dam in the Rottau reservoir


In the event of an increased water flow in the Möll, the water level in the Rottau reservoir is lowered

slowly and in a controlled manner using suitable settings for the Rottau dam system, and the reservoir

is emptied.

This emptying helps the flood protection of the system, silting up in the reservoir is prevented, and safe

discharge of the flooding is ensured. The effluent is completely discharged via a deep channel.

In the part of the reservoir on the orthographic right side of the bank in the area of the Auernigbach

confluence, there is a horizontal settling area on which fine sediment deposits of ca. 2 m have formed since

the construction of the reservoir in 1977. In depressions of this sediment deposit, water-filled puddles

remain temporarily in which a multitude of fish seek refuge during the emptying of the reservoir. The

water from these puddles seeps away resulting in fish traps.

To effectively prevent these fish traps, a guiding dam was constructed on this settlement area downstream

from the Auernigbach confluence. Part of the fine sediment that built up inside the guiding dam was remo-

ved during the course of implementing the measures.

The guiding dam was constructed by means of underwater injection. With the method, it was possible to

build the dam and maintain operation of the power plant without having to first of all remove and deposit

the fine sediment in the dam area. In the process, water was added to the material removed during the

course of dredging the pond after treatment (screening and partly crushing) and then transported via

pipeline to the installation point. During the injection work, entry of fine sediment and hence clouding

into the Möll was prevented by hanging in a fleece insert.

The material was injected using water from a floating pontoon. The layers of sediment deposits were

stirred up with nozzles and the dam construction material was placed. The dam was built up accordingly

by panning and raising the nozzles.

A seal was installed inside the dam to stabilise the dam after the first flooding event in 2013. A filtering

and drainage geotextile was installed on the reservoir side of the outside surface of the dam, as well as

a drainage/covering layer and protection against wave impact.


27.09.2011 to 07.04.2014





(Expected) operating expense in €/year € 0 .-


None


DRAINAGE BASIN DRAU

Fish pass at the Rottau damat the Malta downstream power plant

Aerial photograph of the fish pass – view from the residual water channel to the restored head pond canal

Photo of a 67 cm pike in the video monitoring


DRAINAGE BASIN DRAU



Möll 900930001, 900930002 5.50


Creation of ecological connectivity Construction of a fish pass


Building the fish pass created a connection that was passable for fish between the residual water channel

of the Möll in the area of the Rottau dam facility and the head pond canal of the Malta downstream power

plant. The enature® Fishpass on the right bank of the residual water channel has a total length of around

435 m and overcomes a maximum height difference of 15.5 m. The size of the individual pools are designed

around the Danube salmon as a fish used for calculating the dimensions, and they are 3.0 m long and

2.18 m wide.

The water level difference between the pools is 15 cm, the water depth is at least 1 m and the slot width is

35 cm. The maximum flow velocity is considerably less than that of conventional pool passes, and the ener-

gy conversion is very low at around 75 W/m3. The very low flow rates and the low energy conversion result

in considerably easier migration, especially for young fish and for weak-swimming fish species such as the

bullhead for example.

The functional capability of the fish pass was checked by comprehensive fish ecological monitoring of

the system. In the process, conventional monitoring was carried out in parallel by means of a box fish trap

and video monitoring as a prototype system (FishCam). Besides six species, which are to be considered as

natural species in accordance with the guideline, there were also brook trout, Alsatian char and rainbow

trout caught in the exit trap of the fish pass as non-native species and documented during the course of

the video monitoring. It was possible for all species that were caught during fishing in the downstream

water to pass through the enature® Fishpass. Hence, the ascent of 100% of the fish species potential in

the downstream water of the Rottau dam was established.

Monitoring by means of the FishCam during the course of the functional analysis of the fish pass at the

Rottau dam proved to be highly effective. Recording the migrating fish by means of video recording also

clearly showed, besides the benefits of contact-free and exact time recording of the fish pass, that monito-

ring by means of traps only records some of the individual fish that migrate through the fish pass.


01.10.2012 to 09.12.2013


Total investment in € € 1,464,334.-




(Expected) operating expense in €/year € 10,000.-


490 MWh/year


DRAINAGE BASIN DRAU

Structuring measures in the Malta downstream power plant reservoir

View from Rottau reservoir downstream in the direction of the restored Sachsenweg canal.

Installation of root membrane

Installation of geotextile and geogrid

Installation of the standing elements

Planting


DRAINAGE BASIN DRAU



Möll 900930001 0.14–2.20



Renaturation of the Sachsenweg canal


The head pond canal of the Malta downstream power plant, the so-called Sachsenweg canal, is designed

as a trapezoidal channel with asphalt surface seal with a relatively smooth surface in the bottom of the

canal as well as the canal banks. The canal is ca. 2.5 km long from the Rottau dam system to the intake

structure of the Sachsenweg tunnel. The entire Sachsenweg canal was secured with a 2 m high fence

before the renaturation for safety reasons, which interrupted the traditional migration corridor for wild

animals.

The objective of the renaturation was to design the canal banks so that a safe exit can be ensured for

people and animals without decisively affecting the functional capability of the power plant facility. For

the right side of the canal, the geotechnical conditions such as drainage of the water coming off the slopes

and the topographical conditions had to be taken into consideration in particular because of the cut into

the mountain slope. Through renaturation of the canal bank, space was created for typical local bank

vegetation, structuring, widening and shallow water zones.

The water and shallow water zones with their steep surfaces are an ecosystem that was created by

human hand that is used as a habitat for less common species whose population is threatened, especially

amphibians, reptiles and birds.

The very adaptable reed plants are typical for the shallow water zone. This includes above all reeds and

bulrushes in addition to several grasses and rushes.

The left side of the canal is almost completely formed by artificial dams. For the safety and protection

of the surrounding settlement areas, maintaining the dams and their leak tightness was decisive. The

objective was to minimise interventions in the existing sealing system. Therefore, a renaturation system

developed specifically for this was put on the existing seal in several work steps.


02.09.2013 to 18.06.2014







None


DRAINAGE BASIN DRAU

Ecological measure in the Malta downstream power plant reservoir

Filling an incubator with fertilised eggs

Freshly hatched grayling larva


DRAINAGE BASIN DRAU


Fischereirevierverband Spittal/Drau / VERBUND Hydro Power GmbH / Kärntner Landes-regierung

Möll 900930001, 900930002 0.00–5.50


Ecological measure Grayling cocooning to support the grayling population


The lower course of the Möll between Kolbnitz and Möllbrücke is a highly changed river section

with a residual water channel flow and constant residual flow. In order to support a self-sustaining,

reproducible population of grayling in the Drau, grayling cocooning was carried out with subsequent

monitoring. To do this, the habitat conditions were improved with additional spawning grounds in

addition to the incubators.

Natural conditions were simulated with the cocooning. Fertilised eggs were put into the brood chambers,

which were filled with gravel and rock fractions, and they hatched under more or less natural conditions

after the cocoon was buried in the riverbed. Besides the pH value and oxygen content, the temperature of

the water was also essential above all.

The freshly hatched and hardly mobile larva move through the gaps of the substrate. As soon as the larva

are big enough and the yolk sack has been consumed in each case, the cocoons are dug out and opened

in order to determine the exact hatching and survival rates. Afterwards, the larva are released in the side

and protected gravel areas along the bank line and are able to completely develop there. With this method,

even new spawning grounds can be initiated, because the fish return to the place of birth after three to

four years.


2005 to 2015



▪ Of which UFG funding € 0.-

▪ State funding € 20,000.-


(Expected) operating expense in €/year € 0.-


None


DRAINAGE BASIN DRAU

Fish pass at the Lieserbrücke power plant

Construction phase of the Lieserbrücke fish pass

Covered vertical slot fish passes of the Lieserbrücke fish pass


DRAINAGE BASIN DRAU



Seebach bei Lieser No information No information


Creation of ecological connectivity Fish pass connected with residual water discharge


The fish pass located on the left bank at the Lieserbrücke power plant has a total length of ca. 34m.

It consists of a total of 15 pools that are 2.0 m long, 1.45 m wide and between 75 cm and 87 cm deep.

The slope is 5.66 %.

The fish pass and subsequent residual water section are fed with a water volume of 179 l/s.


16.06.2014 to 16.10.2014








Around 41 MWh/year


DRAINAGE BASIN DRAU

Fish pass at the Paternion power plant

Pool-type fish pass entrance area in the downstream water – construction phase March 2016

Exit structure and bypass channel – construction phase March 2016


DRAINAGE BASIN DRAU



Drau 900470003 543.07–545.74




The connectivity was restored at the Paternion power plant through the construction of a fish pass on

the orthographic right side of the Drau.

The 9.5 m height difference at the power plant is overcome by a combination of a near-natural pool-

type fish pass and a typical water body bypass channel with an exit structure. The connection in the

downstream water is based on a pool-type fish pass with 22 pools. To achieve the near-natural design,

the pool sizes are different. They have the minimum size of 2.6 m by 3.0 m called for in the guideline for

building fish passes. In the lower section on the left bank of the pool-type fish pass, a toe wall with bank

protection towards the Drau protects against log jams in the pool-type fish pass. An accompanying path

runs along the right bank of the pool-type fish pass, which simplifies the care and maintenance work.

Following the pool-type fish pass, the typical water body bypass channel begins with a length of almost

3 km. The existing drainage ditch at the foot of the dam was adapted for this, structured with individual

stones and dead wood, and minimum pothole depths of 110 cm were created as well as an average depth

of 88 cm in the migration corridor. The objectives of the structuring are the creation of a substitute habitat

along a substantially changed water body with initial formation of spawning grounds and hence the deve-

lopment of a “young fish room” with habitats and shallow water areas.

The water level fluctuations of 42 cm in the head pond are compensated for via the exit structure. The

intake canal to the exit structure is set back in the bank area of the Drau and is protected against log

jams with a groyne and scum board.

The fish pass is fed with a maximum of 640 l/s via the exit structure. In case of flooding and in the event

of a very high level of suspended solids in the Drau, there is the possibility to reduce the residual flow

for that time at the distribution structure of the exit structure and use water from a nearby groundwater

pond for the ecological flow for the fish pass. That way, the amount of suspended solids carried into the

bypass channel is to be reduced to a minimum.


07.10.2015 to 01.08.2016 (planned)








406 MWh/year


DRAINAGE BASIN DRAU

Fish pass at the Kellerberg power plant

Near-natural pool-type fish pass in the downstream water of the Kellerberg power plant

Structured bypass channel below the Kellerberg bridge

Entrance to the fish pass on the downstream water side


DRAINAGE BASIN DRAU



Drau 900470003 533.00–536.40




The connectivity was restored at the Kellerberg power plant through the construction of a fish pass on the

orthographic left side of the Drau.

The bypass of the power plant is channelled via the existing side arm, the so-called Kellerberg Loop. The

Kellerberg Loop, the former riverbed of the Drau before construction of the power plant facility, is an side

arm that is connected to the Drau on the downstream water side via a pool-type fish pass. The Kellerberg

Loop is fed via the groundwater and the Kellerberger Bach, which is directed into the side arm by means

of culverts under the Drau.

The objective of the measures was for it to once again be possible for all existing aquatic living organisms

in the Drau to ascend via the bypass channel or use the newly created migration corridor as an ecologi-

cally valuable habitat and spawning habitat.

The measures essentially address three sections with a total length of around 4 km in order to overcome

the height difference of a total of 9.5 m:

• Pool-type fish pass in the head pond: Connection of the bypass channel via a pool-type fish pass at the

end of the water body located upstream. In the process, a height difference of ca. 5 m has to be over-

come. Through the additional residual flow of 490 l/s to 560 l/s, connectivity is to be ensured both for

the biggest occurring fish species, the Danube salmon, as well as for weak-swimming species.

• Kellerberg Loop habitat: The pessimal locations (those areas that do not yet comply with the require-

ments of the Quality Objective Ordinance) were redesigned. The specifications in connection with the

required minimum water depths were achieved here via riverbed and bank structuring. Furthermore,

suitable spawning grounds for gravel spawn, such as grayling and trout for example, were introduced

in these areas.

• Pool-type fish pass in the downstream water: The pool-type fish pass already constructed in the

downstream water in the 1980s was adapted to the state of the art and technology.


01.03.2014 to 31.12.2015








348 MWh/year


DRAINAGE BASIN DRAU

Fish pass at the Villach power plant

Biotop Windstoß vor und nach den Vorschüttungen

Attraction flow pumps in the downstream water

Near-natural pool-type fish pass as fish habitat Aichholzgrabenbach

Outlet area of the vertical slot fish pass in the Aichholzgrabenbach


DRAINAGE BASIN DRAU


VERBUND Hydro Power

GmbH

Drau 900470057, 900470003 523.00




The ecological condition of the Villach power plant facility was improved considerably by the construction

of the fish pass. The fish pass on the orthographic left side of the Drau overcomes a head of ca. 9 m. Its top

section consists of a vertical slot pass with precast concrete elements and connected to the Aichholzgra-

benbach, which was partly redesigned as a rough channel pool-type fish pass on the downstream water

side. The fish can ascend in 54 pools made of precast concrete elements via slots that are 32 cm wide.

The design discharge is 250 l/s. An additional 120 l/s is channelled via a bypass line from the head pond

directly to the junction area of the Aichholzgrabenbach without the fish pass being hydraulically overloa-

ded by the additional outflow. The small, very energy-rich supplemental residual water volume from the

head pond is used to drive seven attraction flow pumps in the downstream water. In the process, the water

is transported through seven nozzles in seven pump structures at the end of the attraction flow line. The

jet from the nozzles carries along the surrounding water in front of the pump structures, therefore the

flow of the attraction flow comes mainly from the downstream water and is pumped by the attraction flow

pumps into the discharge of the fish pass.

The flow conditions at the attraction flow pump were measured as 1:11. This results in a supplemental

residual water flow rate of 1,320 l/s. Together with the 250 l/s from the fish pass and the outflow from the

Aichholzgrabenbach, there are ca. 1,600 l/s available for the generation of a suitable attraction flow.


01.03.2006 to 01.09.2007





▪ Miscellaneous € 150,000.-




256 MWh/year


DRAINAGE BASIN DRAU

Fish pass at the Arriach power plant

Panorama of Arriach fish pass


Near-natural bypass channel

Vertical slot pass


DRAINAGE BASIN DRAU



Arriachbach 901910021 2.60


Creation of ecological connectivity Construction of a fish pass combined with residual water discharge


The Arriach power plant in the inner Einöde in Gegendtal was put into operation in the year 1925. The

ecological connectivity at the power plant was created in the years 2014/15 with the construction of a

25 m long fish pass. It was designed as a vertical slot pass with 11 pools on the right bank of the dam

system. The dimensions of each of the pools are 2.3 m x 1.5 m x 0.5 m. The fish pass is fed dynamically

depending on the season with a water volume of 87 l/s to 116 l/s. To ensure connectivity of the subsequent

residual water section, the same amount of residual water is required there as in the fish pass.


17.11.2014 to 29.01.2015








Around 790 MWh/year


DRAINAGE BASIN DRAU

Fish pass at the Schütt power plant


Cross-sections of the different areas of the fish pass

Excerpt of a longitudinal section of the fish pass at the Schütt power plant

Site plan of the pool-type fish pass at the Schütt power plant


DRAINAGE BASIN DRAU



Gail 901870015 13.00–17.50


Creation of ecological connectivity Adaptation of the existing fish pass connected with residual water discharge


At the Schütt power plant, the currently implemented fish pass will be adapted in the form of a near-

natural pool-type fish pass by the end of 2018 in order to comply with the changed requirements.

Hence, a near-natural fish pass with 41 pools is to be developed over a total length of 91 m. The pools

will be dimensioned with a width of around 2.9 m, a length of around 4.8 m as well as a water level

difference of 15 cm.

The necessary residual flow in the fish pass is currently estimated to be 500 l/s. In addition, 1,000 l/s will

be input as an attraction flow via a pipe from the head pond.

There has been an ecological flow in the residual water section totalling 1,500 l/s since December 2015.


2017 to 2018 (planned)



▪ Of which UFG funding €1 35,000.-





Around 2,000 MWh/year


DRAINAGE BASIN DRAU

Structuring measures in the Rosegg-St. Jakob reservoir

Site overview plan

Aerial photograph of the Föderlach I and Föderlach II biotopes


DRAINAGE BASIN DRAU



Drau 900470057 507.8–509.46



Construction of a shallow water biotope for improvement of structural diversity


The reservoir of the Rosegg-St. Jakob power plant has been in a silting up condition since the beginning of

the 1990s. For maintenance of the flood protection for the neighbouring communities, extensive sediment

dredging (suction dredging) was carried out from 2006 to 2009. The dredged material was used in the area

of St. Niklas for a landscaping design.

As a residual measure for the loss of habitats that was caused by backfilling of the St. Niklas landscape,

a replacement biotope Föderlach II was created on an area of 10.4 ha directly following the existing

Föderlach I biotope. Already existing mud flats as well as a siltation zone were preserved. The newly

created deep channel close to the bank ends with a ford as an overflow. The existing silt sandbank was

expanded or alternatively shaped with the material obtained from the deep channel.


1. Quarter 2008






None


DRAINAGE BASIN DRAU

Fish pass at the St. Martin damat the Rosegg-St. Jakob power plant

Aerial photograph of the fish pass with a view from the residual water channel to the head pond canal

Detailed photo of the enature® Fishpass


DRAINAGE BASIN DRAU



Drau 900470057 505.90


Creation of ecological connectivity Construction of a technical fish pass


Building the fish pass created a connection that was passable for fish between the residual water channel

of the Drau in the area of the St. Martin dam facility and the head pond canal of the Rosegg power plant.

The connectivity was restored at the St. Martin dam through the construction of a pool-type fish pass on

the right bank of the residual water channel. The enature® Fishpass is designed for the spectrum of fish

species in the Drau and is characterised by very low flow velocities in the individual pools.

The total length of the fish pass is around 500 m, and the maximum height difference to be overcome is

16.9 m. The individual prefabricated pools are designed for the Danube salmon as a fish used for calcu-

lating the dimensions, which are 3.0 m long and 2.18 m wide. The water depth in the pools is at least 1 m

and the slot width between the individual pools is 35 cm, which is also designed for the Danube salmon.

The water level difference between the pools is 13 cm. The maximum flow velocity is considerably less

than that of conventional pool passes, and the energy conversion is very low at around 60 W/m3.

The very low flow velocities and the low energy conversion result in a considerably easier migration,

especially for young fish and for weak-swimming fish species such as the bullhead, for example.

The functional capability of the fish pass was checked by comprehensive fish ecological monitoring.

During the course of the research project of VERBUND Hydro Power GmbH, there was the development of

a prototype system to record the individuals migrating through the enature® Fishpass by means of video

monitoring. The seamless recording of the fish migration ran extremely satisfactorily in the time period

from autumn 2014 to spring 2016. Both small and young fish as well as adult specimens were recorded

mostly in excellent picture quality. Altogether, the ascent of 24 fish species and thousands of individuals

was demonstrated. All predominant and typical companion species that were caught during basic fishing

in the downstream water were able to find and pass through the enature® Fishpass. Parallel to video

monitoring, there was also conventional monitoring by means of box fish traps, and the advantages

and disadvantages of the two monitoring methods were evaluated.


01.01.2013 to 31.12.2014








625 MWh/year


DRAINAGE BASIN DRAU

Fish pass at the Gabl power plant

Fish pass

Vertical-slot-passage of the fish pass


DRAINAGE BASIN DRAU



Loiblbach 903200003 6.10


Creation of ecological connectivity Construction of a fish pass combined with residual water discharge


A fish pass was constructed at the Gabl power plant. This 31 m long fish pass was designed as a vertical

slot pass with 12 pools on the right bank of the dam system. The dimensions of the pools are 2.3m x 1.5 m

x 0.5 m.

The fish pass and subsequent residual water section are fed with a water volume of 137 l/s.


07.07.2014 to 25.08.2014








Around 860 MWh/year


DRAINAGE BASIN DRAU

Fish pass at the Althofen power plant

Panorama of the fish pass with the dam system

Pool-type fish pass MABA System


DRAINAGE BASIN DRAU



Gurk 903760023 69.20




A MABM fish pass (enature® fish pass) was implemented by the Althofen power plant with 20 pools on

the orthographic right side of the Gurk. The total length of the fish pass is ca. 70 m, whereby a water level

difference of 3 m is overcome. The pools were built with a length of 3 m and a width of 2.18 m. The slot

width between the individual pools was designed to be 30 cm.

Residual water is released into the fish pass at 237 l/s. The monitoring and functional check of the fish

pass has already been carried out successfully.


04.11.2013 to 27.02.2014








Around 30 MWh/year


DRAINAGE BASIN DRAU

Fish pass at the Passering power plant

Construction phase of the vertical slot pass

Construction phase of the exit of the fish pass in the head pond


DRAINAGE BASIN DRAU



Gurk 903760031 52.60




A fish pass with a total length of ca. 173 m was constructed in the area of the power house of the Pas-

sering power plant. The fish pass was designed as a technical vertical slot pass on the orthographic left

bank of the Gurk due to the tight spatial conditions.

The entrance area of the fish pass is located ca. 6 m below the turbine outlet in order to use the resulting

attraction flow to ensure that it is easy to find the fish pass. In addition, the fish pass is provided dynami-

cally with 320 l/s to 350 l/s. The height difference between the head pond and downstream water is 7.5 m.

The fish pass consists of 50 pools with a water level difference of 15 cm each.


31.08.2015 to 30.11.2015








129 MWh/year


DRAINAGE BASIN DRAU

Structuring measures at the Launsdorf power plant

Overview of the measures at the Launsdorf power plant


DRAINAGE BASIN DRAU



Gurk 903760019 44.00–45.70



Construction of groynes as well as structural measures in the residual water section


To ensure the connectivity from the downstream water of the Launsdorf power plant to the fish pass,

the residual water section as well as the reservoir were adapted structurally section by section. That way

it was possible to reduce the flow velocity through the creation of deep channels, dump stone riprap and

small groynes and that way considerably improve the habitat situation for fish. To ensure that the fish

pass can be found, the residual water section has a total water flow of 300 l/s of which 200 l/s is dischar-

ged via the fish pass itself and 100 l/s via the dam system.

Two micro groynes were constructed on the orthographic right side of the Gurk to prevent silting-up of the

exit of the fish pass in the reservoir as well for the exit of the fish pass on the left bank, which was built in

the year 2000.


18.02.2015 to 25.02.2015








None


DRAINAGE BASIN DRAU

Fish pass at the Schwabeck power plant

Downstream water side area of the fish pass at the Schwabeck power plant

Downstream water side area of the fish pass looking towards the power plant and control room


DRAINAGE BASIN DRAU



Drau 900470058 419.10




The connectivity was restored at the Schwabeck power plant through the construction of a technical fish

pass on the orthographic left side of the Drau. This system overcomes a height difference between the head

pond and downstream water of more than 20 m for the first time, and is currently considered to be the

highest fish pass in Europe.

An important point was passing under the existing connection between the power plant and control room.

The fish pass had to “submerge” suitably far in the severely limited space between the head pond and dis-

tribution structure up to the crossing of the barrier.

An enature® multi-structure slot pool-type fish pass was built consisting of 158 pools with 21 additional

resting pools. The entrance into the system on the downstream water side is directly from the migration

corridor on the left bank of the Drau downstream of the stilling basin of the dam system and downstream

of the turbulence zone of the works water return directly below the end of the existing bank wall on the left

bank.

With a total length of around 635 m, the system overcomes a height difference of 20.54 m. The fish pass

has a dynamic ecological flow with 375 l/s to 415 l/s. Through the installation of double slots, the water

movement is kept calm constantly and the current is directed in an omega shape, which corresponds to

the resistance behaviour of natural water bodies. The ecological improvement here comes from the re-

duction of flow, the flow velocities and the turbulence in the double slot. The very low flow rates velocities

make it possible in particular for young fish and weaker swimming fish species such as the bullhead to

pass through easily.


01.03.2014 to 31.12.2015








572 MWh/year


DRAINAGE BASIN DRAU

Fish pass at the Lavamünd power plant

Downstream water side area of the fish pass before and during construction

Head pond area of the fish pass at the beginning of construction and after completion


DRAINAGE BASIN DRAU



Drau 903770000 41.11




The connectivity was restored at the Lavamünd power plant through the construction of a technical fish

pass on the orthographic left side of the Drau. Due to the extremely tight spatial conditions, the fish pass

in the left side wall of the dam was used for the route, which was partly from the construction time of

the power plant (1941 to 1949). Regardless, the entire downstream water side section of the fish pass is

located in the immediate flood water run-off area and therefore had to have a solid design and be secured.

An enature® multi-structure slot pool-type fish pass was built consisting of 74 pools with 14 additional

resting pools. The downstream water side entrance to the system was directly from the migration corridor

of the Drau on the left bank. The entrance is situated on the existing rock spur at the end of the concreted

bank protection. The flow in from the works water of the Lavamünd power plant is optimal.

A height difference of 9.6 m is overcome with this system with a total length of ca. 300 m. The fish pass

has a dynamic ecological flow of 375 l/s to 415 l/s. Through the installation of double slots, the water

movement is kept calm constantly and the current is directed in an omega shape, which corresponds

to the resistance behaviour of natural water bodies. The ecological improvement here comes from the

reduction of flow, the flow velocities and the turbulence in the double slot. The very slow flow velocities

make it possible in particular for young fish and weekly swimming fish species such as the bullhead to

pass through easily.


01.03.2014 to 31.12.2015








215 MWh/year


DRAINAGE BASIN DRAU

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