How does the system work?

(1)

Ana Colina Alonso Albert Oost

Bas van Maren

Towards a Mud Balance for the Trilateral Wadden Sea Area

How does the system work?

N al

(2)

Mud Matters

2

(3)

Mud Matters

What we want to know:

• Where does mud matter?

• How much does it matter?

(4)

The Wadden Sea: a sand-mud system

Where does mud matter?

(5)

Mud system used to be about half of the Wadden Sea

800 AD

Dark green: mudflats and tidal marshes

(6)

sandy muddy

Very sandy or very muddy: bimodality

6

Herman, et al, 2018 Colina Alonso, 2020

(7)

Different behaviour in time and space

Sediment Atlas Wadden Sea

(8)

Different behaviour in time and space

8 AUFMOD

Sediment Composition Data

Sediment Atlas Wadden Sea

(9)

Different behaviour in time and space

AUFMOD Sediment Composition Data

Mud content versus distance from the gorge (Nieuwenhuis, 2001).

(10)

Sediment budgets

How much does mud matter?

(11)

Contribution of mud to the budget

Colina Alonso et al (in prep.)

(12)

Contribution of mud to the budget: 30%

12

Colina Alonso et al (in prep.)

(13)

• Literature study

• Existing data (NL, DE, DK)

• Bed level evolution & sediment composition

• Sediment budget: identify main sources and sinks

What is the contribution of mud to the sediment

budget of the Trilateral Wadden Sea?

(14)

14

Sources

(15)

Sources

(16)

16

Sources

Sinks

(17)

Sources of mud

Suspended sediment is brought to the Wadden Sea via:

1) North Sea Continental Flow 10-14.4*10⁶ ton/year

2) Rivers 1.6*10⁶ ton/year

3) Local production and eolian dust

0,5*10⁶ ton/year

Subtotal: 12.1-16.5*10⁶ ton/year

4) East Anglia Plume

Does this reach the Wadden system?

10 – 14.3*10⁶ ton/year 2*10⁶ ton/year?

(After Pietrzak et al., 2011)

(18)

Sources of mud

18

(Putzar & Malcherek, 2015)

?

2 *10⁶

(19)

Sinks

(20)

20

Sinks

(21)

Sinks

(22)

22

Sinks

Pedersen & Bartholdy, 2006)

(23)

Total sinks

Net import [10

⁶

ton/year]

Extraction [10

⁶

ton/year]

(24)

Mud balance

(ongoing work)

24

Sources [10

⁶

ton/year]

Net import [10

⁶

ton/year]

Extraction [10

⁶

ton/year]

(25)

A mud balance (ongoing work)

Sedimentation in 10⁶ton/yr

Area Period Net mud sedimentation

(= sedimentation + extraction)

Extraction Sources

Dutch Wadden Sea basins

1927-2015 1.2 - (only redistribution)

Ems Estuary 1990-2011 1.9 - 2.4 0.8

Lower Saxony 2000-2010 0.5

Jade Bay 2000-2010 0.9 ?

Weser Estuary 1998-2016 1.45 0.2

Elbe Estuary 1999-2016 1.3 0.8

Meldorf Bight 2000-2010 0.1

Schleswig Holstein 2000-2010 1.5

Danish Wadden Sea basins

Mainly: 1980–

2003

0.2 - (only redistribution)

Tidal marshes 1.7-1.8 -

Total Trilateral

Wadden Sea 10.9 – 11.5 12.1-16.5

(26)

Preliminary conclusions

26

• Separate “mud world” & separate “sand world” with interactions

• Mud matters: Sedimentation 11-11.5*10⁶ ton/yr of which 1.8*10⁶ ton/yr retrieval

• Mud not unlimited: Source 12.1-16.5*10⁶ ton/year → wise use of mud needed!

• Mud deposition depends also on mud availability → abundant mud supply in the West, but the East could be sediment starved, especially in combination with SLR

• We need mud to keep up with SLR, but note that SLR will also influence mud

• Uncertainties:

− Measuring inaccuracies of the data

− Temporal fluctuations

− Dependency on analysed period

(27)

Ana Colina Alonso Albert Oost

Bas van Maren

Towards a Mud Balance for the Trilateral Wadden Sea Area

How does the system work?

N aC