Hohensinner 2011: Importance of multi-dimensional morphodynamics for riverine habitat evolution

University of Natural Resources &

Life Sciences Vienna

Department of Water, Atmosphere & Environment I Institute of Hydrobiology & Aquatic Ecosystem Management I DI Dr. Severin Hohensinner 30.07.2013 1

Importance of multi-dimensional

morphodynamics for habitat evolution:

Austrian Danube River 1715 – 1821

Severin Hohensinner & Mathias Jungwirth

World‘s Large Rivers Conference

Vienna, 11th April 2011

Institute of Hydrobiology & Aquatic Ecosystem Management

Department of Water, Atmosphere, Environment

University of Natural Resources & Life Sciences Vienna (BOKU)




Focus and topics

Historical development of the Danube floodplain

in the Machland 1715 – 1812

Short-term morphodynamics 1812 – 1817

Consequences for floodplain habitats

(intensity of hydrological connectivity)

General considerations regarding

trajectories of habitat development

Conclusions




Danube

Austrian Danube River

80 % impounded

20 % free-flowing

National Park

Danube River in the

MACHLAND floodplain

Machland




Machland: current situation

2006 Inst. of Hydrobiology & Aquatic Ecosystem Mgmt.

Univ. of Natural Resources & Life Sciences Vienna




Inst. of Hydrobiology & Aquatic Ecosystem Mgmt.





Hütting

Franzenau











216

218

220

222

224

226

228

230

232

234

m

ü

A

River length - station (m)

Longitudinal profile 1812 - Northern main arm

bifurcation of main arms

conf luenceof main arms

river bottom

low water

mean waterca. 3-5-year flood

Longitudinal profile 1812

Northern main channel arm

backwater

effect














erosion:

15 Mio. m³

aggradation: 13 Mio. m³

cut-off

avulsion

Spatial morphological turnover

1812 – 1817 => changes in 35 % of the recent

river-floodplain system




Transect through river-floodplain system

1812 – 1817






avulsions

cut-off




Changes of water/groundwater level

1812 – 1817

total floodplain:

net change of water/

groundwater level

< 10 cm

=> short-term

„quasi-equilibrium“ ?

Hohensinner et al. (2008)

in CATENA

-40

-30

-20

-10

0

10

20

30

40

50

-1.1 - -1.0 -1.0 - -0.5 -0.5 - 0.0 0.0 - 0.5 0.5 - 1.0 1.0 - 1.1

Lowering/uplift of water/groundwater surface (m)

Are

a s

ha

res

of

ac

tive

zo

ne

(%

)

lowering

uplift



Department of Water, Atmosphere & Environment I Institute of Hydrobiology & Aquatic Ecosystem Management I DI Dr. Severin Hohensinner

0

10

20

30

40

50

60

70

80

90

100

Cu

mu

lati

ve

are

a s

ha

res

of

de

pth

s o

f th

e

gro

un

dw

ate

r le

ve

ls in

th

e f

loo

dp

lain

(%

)

Depth of groundwater table at MW (m)

Machland 1812

Machland 1817

Machland 1991

Vienna/Lobau 2003

30.07.2013 15

Hydrological subsurface connectivity

Depths of groundwater table in the floodplain

Hohensinner et al. (2008)

in CATENA




Inte

nsi

ty o

f h

ydro

log

ical

co

nn

ecti

vity

Time

high

low

terrestrialization

Trajectory of floodplain habitat development:

gradual change of hydrological connectivity

gradual main channel incision

gradual main channel aggradation




Inte

nsi

ty o

f h

ydro

log

ical

co

nn

ecti

vity

Time

high

low

terrestrialization of floodplain habitat

gradual main channel incision

gradual main channel aggradation

Avulsion

reduced connectivity due to avulsion


sudden change due to avulsion




Inte

nsi

ty o

f h

ydro

log

ical

co

nn

ecti

vity

Time

high

low

Avulsion



one habitat with avulsion




Inte

nsi

ty o

f h

ydro

log

ical

co

nn

ecti

vity

Time

high

low

Avulsion


intensified connectivity due to avulsion

intermediate connectivity


several habitats with avulsion




Shifting of navigable river arms 1700 – 1859




Inte

nsi

ty o

f h

ydro

log

ical

co

nn

ecti

vity

Time

high

low

Avulsion Avulsion


several habitats with several avulsions




Habitat dynamics

prior to chanelization 1812 – 1821 (main changes)

Eupotamon A

15 yrs

Eu B

6 yrs

Para A

5 yrs

Para B

5 yrs

Plesio

13 yrs

VABB

5 yrs

36 yrs

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85

In

tensity o

f hydro

logic

al surf

ace c

onnectivity

Median-age (50%-age) of the habitat type area (years)

min

max1.5 %

0.8 %1.4 %

2.1 %3.5

0.3 %2.8 %

2.6 %

5.7 %

7.4 %2.1 %

3.9 %

2.2 %

2.1 %

1.6 %

1.8 %

1.6 %

EFA - elevated floodplain area

30.07.2013 22




0

10

20

30

40

50

60

70

80

90

100

1715 - 1821natural

1829 - 1838initial channelization

1859 - 1991end of /af ter

channelization

Mean

devia

tio

n (

%)

1: total water body area at SMW (% of study site)

2: total habitat shares at SMW (% of study site)

3: aquatic habitat shares at SMW (% of total water bodies)

4: aquatic habitat shares at LW (% of total water bodies)

5: expansions of aquatic habitats LW - SMW (% of study site)

6: median habitat ages / 50%-ages in active zone (years)

7: Connectivity-Index of active zone (CI)

16

543

27

1

7

5

4

32

1

65432

599

699

248

315

6

7

30.07.2013 23

pre-channelization

pre-channelization

1715 - 1821:

variation of

most habitat

parameters < 10 %

=> long-term

„quasi-equilibrium“ ?

Variability of habitat characteristics of the

river-floodplain system 1715 – 1991 M

ea

n v

ari

ati

on

(%

)

















































Eupotamon A

157 yrs

Eu B

60 yrs

Para A

33 yrs

Para B

23 yrs

Plesio

26 yrs

VABB

125 yrs

elevated floodplain area

160 yrs

0 50 100 150 200 250 300 350 400 450 500 550 600

In

tensity o

f hydro

logic

al surf

ace c

onnectivity

Median-age (50%-age) of the habitat type area (years)

min

max

0.02 %0.01 %

0.03 %

0.76 %

0.54 %

0.53 %

0.42 %

0.66 %

0.31 %

0.72 %

0.56 %

0.14

%

0.17 %

0.15 %

0.25 %

0.05 %

0.04 %

0.14 %

30.07.2013 33

Habitat dynamics

after chanelization 1859 – 1991 (main changes)




on a broader spatial scale, morphodynamic processes can

effect counteracting habitat developments leading to a

„quasi“-stable habitat composition („shifting habitat mosaic“)

Conclusions

the spatio-temporal pattern of diverse morphodynamic

processes is reflected by a complex mosaic of differently

developed habitat patches

the development of riverine habitats

(besides hydrology) depends on gradually occurring

morphological changes (channel migration, terrestrialization)

and on sudden processes (avulsions, cut-offs)




Severin Hohensinner & Mathias Jungwirth

Institute of Hydrobiology & Aquatic Ecosystem Management

Department of Water, Atmosphere, Environment

University of Natural Resources &Life Sciences Vienna (BOKU)

Austrian Science Fund

Education

Hohensinner 2011: Importance of multi-dimensional morphodynamics for riverine habitat evolution