Oct 2008

The future Ems System:

restored by the power of

‘nature’

or

‘engineers’ ?

Prof. Dr. Victor N. de Jonge DSc 1 & Dr. Henk Schuttelaars 2

1 IECS, University of Hull, United Kingdom2 TUD, Delft, The Netherlands

Sunrise or Sunset

for the Ems estuary ?

Starting point:

The Ems estuary between the

North Sea and the weir at Herbrum

is one undividable system

Challenge:

How we can restore it

STRUCTURE OF TALK

1. What happened to the Ems estuary and its river?

2. What were the resultant environmental changes to

the Ems river and Ems estuary?

3. Options on ‘how to proceed’

1.What happened to the river ?

Canalisations, deepenings & dredging

result: 10 times more suspended mud

1.What happened to the estuary ?

Varying but large scale channel dredging

result: 2.5 – 3 times more suspended mud

+

Ems estuary River Ems

110200

900

0

200

400

600

800

1000

1200

0 10 20 30 40 50 60 70 80 90 100

1975/ 76

0

200

400

600

800

1000

1200

0 10 20 30 40 50 60 70 80 90 100

2005/ 06

mean suspended matter concentration in the Ems estuary (near water surface)

0

200

400

600

800

1000

1200

0 10 20 30 40 50 60 70 80 90 100

distance from Herbrum (km)

mean SPM

(g.m-3

)

1954

Leer HGOEHEmdenRiver SeaP’burg

Zoom in

fit 28 - 100 km

1975-1976

y = 1181e-0.0403x

R2 = 0.9396

2005-2006

y = 8244.5e-0.0624x

R2 = 0.9722

1992-1993

y = 8528.5e-0.0628x

R2 = 0.8620

1954

y = 531.9e-0.0448x

R2 = 0.5333

0

200

400

600

800

1000

30 40 50 60 70 80 90 100

Km from weir Herbrum

SPM

(gm-3

)

BorkumEemshavenEmden

1954 ‘reference’ situation

1975-1976 provides effect of channel maintenance dredging (CMD)

1992-1993 combines effect of CMD + Ems canalisation and deepening

2005-2006 combines effect of CMD + Ems canalisation and deepening

Ems estuary

fit 28 - 100 km

1975-1976

y = 1181e-0.0403x

R2 = 0.9396

2005-2006

y = 8244.5e-0.0624x

R2 = 0.9722

1992-1993

y = 8528.5e-0.0628x

R2 = 0.8620

1954

y = 531.9e-0.0448x

R2 = 0.5333

0

25

50

75

100

70 75 80 85 90 95 100 105 110

Km from weir Herbrum

SPM

(gm-3

)

BorkumEemshaven

1. 1975-1976:

channel change

2. Steep slope

since 1992-1993

3. Effect

measurable until

Eemshaven

4. 2.5 to

3-fold increase

Why important ?

This is the area where the food is produced for the rest of the system

also the river !

2. The resultant environmental

changes to

the Ems river and Ems estuary

sea

Phosphate, Fe, Al, dissolved organic C concentration

salinity

Ems estuary

Van Beusekom & de Jonge 1998

- extremely high SPM (organic material included)

- extremely high BOD

- extreme fluctuation in phosphorous levels

- extremely low minimum oxygen in summer

- extreme environment to organisms with gills

Minimum oxygen concentration in ETM as function of temperature

y = 0.0056x3 - 0.223x2 + 2.0893x + 4.3071

R2 = 0.9934

0

2

4

6

8

10

12

0 5 10 15 20 25

Water temperature (oC)

Oxygen

(mg l-1)

ALGAL GROWTH

(tonnes organic C a-1)

LOWER

REACHES

MIDDLE

REACHESDOLLARD

TOTAL

ESTUARY

Reference conditions

(no dredging)160000 200000

Measured

(1975 - 1980)

35km estuarine dredging120000

estuarine dredging +

river improvements

(2005 - 2006)

75000

THE ULTIMATE PROBLEMS IN SUMMARY

fit 28 - 100 km

1975-1976

y = 1181e-0.0403x

R2 = 0.9396

2005-2006

y = 8244.5e-0.0624x

R2 = 0.9722

1992-1993

y = 8528.5e-0.0628x

R2 = 0.8620

1954

y = 531.9e-0.0448x

R2 = 0.5333

0

25

50

75

100

70 75 80 85 90 95 100 105 110

Km from weir Herbrum

SPM

(gm-3

)

ALGAL GROWTH

Primary production (%)

LOWER

REACHES

MIDDLE

REACHESDOLLARD TOTAL ESTUARY

Reference conditions

(no dredging)82 12 6 100 (%)

Measured

(1975 -1980)

35km estuarine dredging62

Estuarine dredging +

river improvements

(2005 – 2006)38

THE ULTIMATE PROBLEMS IN SUMMARY

Minimum oxygen concentration in ETM as function of temperature

y = 0.0056x3 - 0.223x2 + 2.0893x + 4.3071

R2 = 0.9934

0

2

4

6

8

10

12

0 5 10 15 20 25

Water temperature (oC)

Oxygen

(mg l-1)

3. How to proceed technically?

Knock

Emden Leer Herbrum

The ‘power of nature’ acting on the Ems has been amplified by the

‘power of the engineers’ changing the morphology of the river.

3510 65 km from Knock

1. Increasing the length of

the freshwater tidal river

2. Creating a ‘sill’ in the

lower tidal river between

Emden and Leer

Natural depth profile and ETM natural depth profile

ETM for natural depth profile but longer tidal river part upstream Herbrum weir

Knock Herbrum

Maximum near bottom concentrations of mud

Knock Emden Leer

Leer Herbrum

Sill option in river

Another convergence/ mud

accumulation area

upstream the sill

This is

upstream

Emden

- CHANGE EXTERNAL BOUNDARY CONDITIONS

1. Shipbuilding is partly done modulary.

Hull construction and heavy engines could be completed ‘upstream’

Completion (eg cabin mounting) above the engine-room could be

done near deep water

2. The present location of the weir is, given the present boundary

conditions, questionable. Upstream replacement is an option in

combination with restoring river meanders (lengthening the fresh

water tidal river.

3. The incoming tidal wave from the North Sea is very powerful. Seen

the upstream consequences of it, ‘shallows’ seaward from the tidal

inlet could reduce the tidal energy there instead of upstream

4. …. There are some more options

3. How to proceed technically?

Thank you

- TECHNICALLY: CHANGE BOUNDARY CONDITIONS

1. Shipbuilding is partly done modulary. Hull construction and heavy

engines could be completed in ‘upstream’ while completion (eg

cabins) above the engine-room could be done near deep water

2. The present location of the weir is, given the present boundary

conditions, questionable. Upstream replacement is an option in

combination with restoring river meanders (lengthening the fresh

water tidal river.

3. The incoming tidal wave from the North Sea is very powerful. Seen

the upstream consequences of it, ‘shallows’ seaward from the tidal

inlet could reduce the tidal energy there instead of upstream

4. Another option is a much longer new canal from circa Dörpen to

Pogum connecting the Ems estuary to the Dortmund-Ems Kanal

brings the water back where it was and provides big chances to

industry, area, river, ecology landscape and economy. Active river

undeepening may be necessary.

3. How to proceed ?

28 - 95 km

0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

0.0 20.0 40.0 60.0 80.0 100.0

1992/ 93

2005/ 06

BorkumEemshavenEmdenLeerPapenburg

Between 1980 and 1992 the system dynamics

significantly and structurally changed

Since then the system seems to be in another

‘steady state’

Fluid mud pool act

as a mud sink

Maximum dredging distance was

51.4 km in 1972 &

51.3 km in 1978

Curves calculated based on a statistical model and thus not predictive

Findings published internationally by de Jonge in 1983 and 2000

0

50

100

150

200

0 20 40 60 80 100

Distance (km)

SPM

(gm-3)

[35 km dredging]

[0 km dredging]

[50 km dredging]

Curves valid for 1954 (?), 1970 – 1979

(unchanged turbidity maximum, minimum mud disposal)

Natural situation

‘no dredging’

BorkumEemshEmdenHerbrum

(Fixed turbidity maximum)

Figure copied from Restoration Plan Ems and Dollard (Waddenvereniging 1999)

Publication in Dutch and German

Ongoing for already

30 years

Threshold for fish

No anticipation to these negative

environmental developments, which forms

a general problem in both countries.

- IN TERMS OF PROCEDURES:

1. Economic, ecological as well as social monitoring activities in the

estuary, on the river, along the Ems system and in the drainage basin

upstream should be carried out in co-operation between both countries

because there is a joint interest

2. An international restoration plan for the entire drainage basin should

be prepared and agreed upong at the highest possible level between

both countries (see advice by Wadden Sea Council)

3. A geographical restructuring of industrial, rural and leisure activities

required, in combination with other Belgian, Dutch, German regions

4. Giving ‘space to the power of nature’ should be practiced from both

an environmental and an economic perspective

4. How to proceed ?

Ecosystem Functions & Functioning

Ecosystem Services & Goods

Decision-making processes

Sustainable Management

Ecosystem Value

Ecosystem functions:

1. Regulation

2. Habitat

3. Production

4. Information

Ecosystem Services &

Goods

Ecological values

based on ecological sustainability

Economic values

based on efficiency and cost-effectiveness

Ecosystem Structure & Processes

Social-cultural values

based on equity and cultural perceptions

Total Value

Decision making process

After de Groot et al., 2002

Talking about the system values .......

this combination

represents the total

system value

ALGAL GROWTH

(tonnes organic C a-1)

LOWER

REACHES

MIDDLE

REACHESDOLLARD

TOTAL

ESTUARY

Reference conditions

(no dredging)160555 24316 11380 196251

Measured

(1975 - 1980)

35km estuarine dredging95895 15384 9721 121000

estuarine dredging +

river improvements

(2005 - 2006)

55757 9046 8892 73695

THE ULTIMATE PROBLEMS IN SUMMARY

ALGAL GROWTH

Primary production (%)

LOWER

REACHES

MIDDLE

REACHESDOLLARD TOTAL ESTUARY

Reference conditions

(no dredging)82 (100%) 12 (100%) 6 (100%) 100 (100%)

Measured

(1975 -1980)

35km estuarine dredging49 (60%) 8 (67%) 5 (83%) 62 (62%)

Estuarine dredging +

river improvements

(2005 – 2006)28 (34%) 5 (42%) 5 (83%) 38 (38%)

In terms of ‘compensation measures’ the value of this algal

growth to the functioning of the Ems system AND the UNESCO

World Heritage Wadden Sea needs to be calculated and

applied to come to future solutions in monetary units

- STARTING POINTS:

1. The Ems estuary is one undividable system

2. Do not exceed the limits of ‘evidence’

(Ian Townend, Wallingford, UK)

3. Get everybody involved

(also ‘locals’)

4. Think ‘out of the box’, ‘look over the fence’, being flexible ….

5. Create long term perspective …..

(not only economically ! Also ecologically, socially & culturally !)

3. How to proceed ?

Changes for the river in summary:

increased tidal range, lower low tides,

amplified flood currents, amplification of

gravitational circulation, higher SPM

(worsened light conditions) and related lower

algal growth and low oxygen values