1. DHI Water and Environment
THE 2002 OXYGEN DEFICIENCY UNDER DIFFERENT METEOROLOGICAL AND LOADING SCENARIOS
Ian Sehested Hansen
DHI Water and Environment

2. Agenda Modelling approach for oxygen assessments
Model description
2002 hydrodynamics
2002 oxygen conditions
Sensitivity to meteorological conditions
Sensitivity to load conditions

3. Model description
MIKE3 3D model
Bathymetry (9/3 nautical miles, 2 m)

4. Modules Hydrodynamic (HD)
Governing equations: continuity, momentum, turbulence, (S, T)
Forcing data:
Wind, pressure, precipitation, air temperature, cloudiness
Run-off
Tide and S/T on open boundaries
HD results:
water level
current
salinity
water temperature

5. Modules Advection-dispersion (AD) Eutrophication (EU) N mass budget
P mass budget
Oxygen mass budget
Carbon mass budget (open)

6. Modules Eutrophication (EU) 12(+) state variables Forcing data:
Light
Load (land and atmospheric)
Concentrations on open boundary
EU results:
Concentrations
Process rates (primary production, denitrification, etc.)
Mich. (Secchi depth, etc)

7. 2002 hydrodynamics
Surface salinity

8. Accumulated water flux Great Belt

9. Accumulated water flux The Sound

10. Validation by monitoring results from Great Belt

11. 2002 N-S transect of salinity and oxygen stratification
Kattegat  Great Belt FemerbæltDarss Arkona Basin

12. Oxygen in 2002
Oxygen concentration at bottom level

13. Oxygen in 2002
Oxygen depletion area within Kattegat to Darss (including Swedish and German areas)

14. Sensitivity to meteorology
Wind conditions 11 September to 20 October 2002
Wind conditions 11 September to 20 October 2000

15. Sensitivity to meteorology

16. Sensitivity to loading
Kattegat to Darss (year 2000): DK: ~ t TN S: ~ t TN GE: ~ t TN Atm: ~ t TN Total: ~ t TN
No Danish loading (45% reduction in local N load)

17. Sensitivity for annual mean of IN at surface level (year 2000)

18. Sensitivity for oxygen depletion area (year 2000)
Iltsvindaareal

19. Total area affected by oxygen depletion
km2
< 4 mg/l
<2 mg/l
<0.5 mg/l
Year 2000
Present
17100
8100
3500
No DK Loads
15700
7300
2800
(-8%)
(-10%)
(-18%)
Year 2002 (medio okt.)
Present
27200
16200
7800
Sep-oct 2000 meteo
24200
13200
5800
(-11%)
(-18%)
(-25%)

20. Sensitivity to loading
NMR project NOCOMMENTS:
Year 2000
-30% N run-off
-30% atm. N-load

21. Sensitivity to loading
Ongoing IMV project on VMP3 initatives with at further developed model setup:
actual 2000 conditions
reduction scenarios, including:
further Danish reductions
general reductions in North Sea/Baltic Sea catchment area ??