Existing measures & options for the future in large river ...€¦ · Existing measures & options for the future in large river impoundments Clemens Ratschan, Wolfgang Lauber, Martin

Compensatory habitats | 10. Sept. 2018 | FIThydro, Augsburg 1 / 29

Compensatory habitats

Existing measures & options for the future

in large river impoundments

Clemens Ratschan,

Wolfgang Lauber, Martin Mühlbauer, Gerald Zauner


Compensation for loss of habitat due to

• (River Regulation)

• (Navigation)

• (Hydropeaking, Residual flow, ..)

• Hydropower - Impoundments

Traun, 48°N 14°E Koppi, 48°N 140°E

figu

re: V

erb

un

d


Main effect for indicator „fish“

Loss of key habitats for rheophilic fish- spawning habitats

- habitats for early life stages

embryo, larva, juveniles (0+, 1+)

Small fish biomass ≈ small populations

free flowing free flowing head of imp. impoundment

Fis

h b

iom

ass [

kg /

100 m

]

0

1

2

3

4

5

6

7

8

K.O. Fish Index Austria

1985-87 2007-2014

n=115

n=49

n=213

n=111


Options for compensatory habitats

Figure: Boku Wien, IHG

head of

impoundment

impoundment


Measures at the head of an impoundment

Danube downstream HPP Ottensheim-Wilhering

side arm (800 m)

further measures planned and being built





Inn downstream HPP Ering-Frauenstein

widening, island / side arm, backwater

(picture: under construction)


Measures in the impoundment

• many examples

• limited longevity

• effect mainly for ubiquitary species

• limited contribution for

„good ecological potential“

Danube impoundment

Jochenstein


Measures between impoundments = fishways

What is a „NATURE-LIKE FISHWAY“?


Key factors for functional habitats

• Slope

• Morphology

• Dynamic flow

• Sediment dynamics

• Factor time (longevity, maintainance)

± state of the art in

„nature-like fishways“

poorly implemented

hardly implemented


Section nature-like bypass channel (Inn)

pot. spawning habitat


habitats for juveniles

Section nature-like bypass channel (Inn)


MNQ MQ QA bordvoll

Standard Standard Standard Standard

Gefälle %o 1,10 1,10 1,10 1,10

Sohlbreite m 2 2 2 2

Böschung Flachufer 1:… 8 8 8 8

Breite Wasserspiegel m 8,8 8,8 16,0 19,1

Wassertiefe (Tiefenrinne) m 0,80 1,30 1,60 2,80

Fläche m² 4,6 10,4 15,1 36,6

benetzter Umfang m 9,8 14,6 17,4 20,8

hydraulischer Radius m 0,47 0,71 0,87 1,76

mittl. Fließgeschw. m/s 0,50 0,66 0,75 1,21

Abfluss m³/s 2,3 6,9 11,4 44

mittl. Schleppspannung N/m² 5,1 7,7 9,4 19,0

Schleppspannung erhöhtes MW (Bereich Böschungsknick) 12,9

Innwasserstand

Profil bzw. Gefälle

"Hohe Laichplatzqualität" & "mittlere bis hohe

Qualität" als Jungfischlebensraum

Qmax to maintain key habitats at the shore

Maintainance of high quality

spawning habitats and

medium-high juvenile habitats:

Flushing with ≥ 40 m3/s needed

(sections with low valley slope)


Sedimentation of habitats at the shore


Sedimentation of habitats at the shore

Tau 40-35-30-25m³/s

40

35

30

25


Measures parallel to an impoundment

• Very high restoration potential in impounded river basins

(if area is available)

Slope

Morphology

Spacial dimension

Flow dynamics

Sediment dynamics

• Dynamic dotation from the impoundment + sediment management

and / or

• Integration of tributaries (space, base flow, flow dynamics, sediments)



Inn HPP Ering-Frauenstein

Dynamic bypass channel, 2,6 km

Dynamic dotation 2-10 m3/s

Sediment management

(picture: under construction)



Danube HPP Ottensheim-Wilhering

Bypass channel: 14,2 km

MQ = 3,4 m3/s, MJHQ > 20 m3/s




Bypass including tributary Aschach

MQ = 6 m3/s, MJHQ =140 m3/s




Bypass including tributary Innbach

MQ = 17 m3/s, MJHQ 235 m3/s


Combination of measures – habitat network

restoration &

protection

of fish

population

spawning

Danube

HPP Ottensheim-Wilhering

+ backwater

+ further

tributaries


Combination of measures – habitat network

spawning & juvenile habitats (phytophilic species)

spawning juvenile habitats

(rheophilic species) (rheophilic species)

Inn HPP Ering-Frauenstein


Compensatory habitats,

migrations and fish protection

• Goal: Restoration of fish populations in series of impoundments

• Presently: Massive habitat deficits

• Danube catchment / Austria:

Populations of long-distance migrating fish species extinct

-> lower need for very highly efficient upstream passage

• Technical or nature-like approach?


impooundm

ent

impooundm

ent

impoundm

ent

impoundm

ent

A

technical fishway+protectionB

fishway+compensatory habitats

Hypothetical ScenariosRestoration of fish populations

in medium-sized / large rivers

intensive

migration

non-intensive

migration

key habitat

upstream

key habitat

downstream

turbine passage

mortalityx


fishw

ay

fishw

ay

fishw

ay

byp

ass c

hannel

byp

ass c

hannel

fishw

ay

Instr

eam

habitat

Instr

eam

habitat

rack+

bypass

rack+

bypass

rack+

bypass

A



intensive

migration

non-intensive

migration

key habitat

upstream

key habitat

downstream

turbine passage

mortalityx




Sta

u

migrations

upstream

migrations

downstream

xx

x

migrations

downstream

xxx x

xxx

migrations

upstream

A



intensive

migration

non-intensive

migration

key habitat

upstream

key habitat

downstream

turbine passage

mortalityx



20-40 km


FA

H

FA

H

fishw

ay

Sta

uS

tau

Sta

u

Rechen+

FAB

Rechen+

FAB

rack+

bypass

migrations

upstream

migrations

downstream

xx

x

migrations

downstream

xxx x

xxx

migrations

upstream

A



intensive

migration

non-intensive

migration

key habitat

upstream

key habitat

downstream

turbine passage

mortalityx

migration distances: lower

mortality adults: low

mortality juveniles: low

key habitats: high

recruitment: high

population size: high

risks: lower

investment: lower

energy loss: lower

[QFAH]



migration distances: high

mortality adults: (low)

mortality juveniles: higher

key habitats: low

recruitment: low

population size: low

risks: higher

investment: higher

energy loss: higher

[QFAH+QFAbH]

Huge positive effects for other biota

(incl. humans)


Rechen+

FAB

Rechen+

FAB

migrations

upstream

migrations

downstream

xx

x

migrations

downstream

xxx x

xxx

migrations

upstream

A



intensive

migration

non-intensive

migration

key habitat

upstream

key habitat

downstream

turbine passage

mortalityx

(Maximum) Variant B+

fishway + compensatory habitats

+ technical fish protection

still possible later

if feasible

& neccessary

with lower risk/higher knowledge




Conclusions

• Compensatory habitats in impoundments can be

feasible and very effective, especially at the

head of impoundments or parallel to

impoundments

• In nature-like fishways and bypass-channels,

sedimentology & dynamic hydraulics need

more attention

• In series of impoundments, creation of

compensatory habitats may restore fish

populations much more effectively than

technical solutions for fish passage and fish

protection


Thanks

All photos in this presentation: ezb-TB Zauner

For your attention!

The , which implemented many of the

measures shown in this presentation!

Existing measures & options for the future in large river ...€¦ · Existing measures & options for the future in large river impoundments Clemens Ratschan, Wolfgang Lauber, Martin

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