DSD-INT 2014 - Symposium 'Water Quality and Ecological modelling' - Optimisation of the Nutrient Reduction Strategy in the North Sea, Ronald van Dokkum, WVL and Tineke Troost, Deltares
Similaire à DSD-INT 2014 - Symposium 'Water Quality and Ecological modelling' - Optimisation of the Nutrient Reduction Strategy in the North Sea, Ronald van Dokkum, WVL and Tineke Troost, Deltares
Similaire à DSD-INT 2014 - Symposium 'Water Quality and Ecological modelling' - Optimisation of the Nutrient Reduction Strategy in the North Sea, Ronald van Dokkum, WVL and Tineke Troost, Deltares (20)
Raman spectroscopy.pptx M Pharm, M Sc, Advanced Spectral Analysis
DSD-INT 2014 - Symposium 'Water Quality and Ecological modelling' - Optimisation of the Nutrient Reduction Strategy in the North Sea, Ronald van Dokkum, WVL and Tineke Troost, Deltares
1. DSD-INT 2014: 3 November 2014
Optimisation of the nutrient reduction strategy for the North Sea
IenM/RWS WVL : Ronald van Dokkum Deltares: Tineke Troost , Hans Los, Jan v. Beek, Christophe Thiange, Marc Weeber, Joost v.d Roovaart, Sibren Loos
5. Nitrogen targets (winterconc DIN mg/l)
In case of overlapping targets the most strict of the two is considered
5
Offshore targets (OSPAR)
Coastal targets (WFD)
6. 6
Project objective
• Starting point: Several areas with present nutrient concentrations
• Desired end point: target nutrient concentrations
• Potential Measures: River load reductions
Objective: To find the optimal set of river load reductions to meet all targets
8. 8
Modeling approach
due to:
-Transboundary transport of nutrients
-Biogeochemical processes
-Limiting factors may vary (e.g. nitrate, phosphate, light)
Relative reduction (%) in chlorophyll concentration following 50% river loads reduction
Non-linear response of the ecosystem to reduced river loads
10. 10
biogeochemical processes: Delft3D-WAQ
•N, P, Si, plankton, detritus , O2
•4 functional groups: diatoms, flagellates, dinoflagelates, Phaeocystis
•3 phenotypes adapted to environmental conditions (light, N, P limitation)
•Nutrient uptake, respiration, mortality + ‘grazing’
•Decay in water & sediments, nitrification, denitrification: parameterised
•O2 production, consumption, reareation
•Light extinction (CDOM, SPM, algae, detritus)
(see e.g. Los & Wijsman, JMS, 2007)
AlgaePNCNNH4-NNO3-NPPO4-PDetritus PNCsettlingsettlingrespirationphotosynthesisNutrientmineralisationmineralisationmetabolismmortalityDOproductionconsumptionreaerationDetritus in SedimentC N P SiSiSiN2 denitrificationmineralisation& nitrificationautolysisSiconsumptionnitrificationGrazersgrazinggrazingoxygen consumptionbiodepositionAIPadsorptionMicrophytobenthosC N P SiAIP in sedimentsettlingmortalityphotosynthesis
11. How to determine required nutrient reductions
Traditional approach (source oriented)
•Change some forcings (river loads)
•Rerun several times (scenarios)
•Look at difference between scenarios and base case
11
?
Current situation
Desired end point
12. How to determine required nutrient reductions
12
Alternative approach (target oriented)
1. Labelling: follow fate and transport of all nutrients
2. Set up composition matrix
3. Apply optimization technique
Current situation
Desired end point
13. Step 1. Labelling nutrients
13
• Labeling the nutrients when they enter the system and following
them throughout time and space
FR
BE
NL2
NL1
GM
UK1
UK2
Atlantic
Channel
Atm
Dep
NH4
NH4r
flux
shadow flux
NH4r / NH4 x flux
16. Step 3: Optimisation (2 x 2 example)
Ems
Rhine
Reduction
goal
GC1
0.10 * f1
0.12 * f2
≥
0.08
NLC2
0.00 * f1
0.33 * f2
≥
0.13
1.00 * f1
0.00 * f2
≤
0.85
0.00 * f1
1.00 * f2
≤
0.85
16
Goal: Find set of reduction factors f1 and f2 which will achieve the targets and be as cheap as possible
Cost function
10 * f1
100 * f2
Optimal reduction f1 = 0.33, f2 = 0.4
18. Nitrogen targets (winterconc DIN mg/l)
In case of overlapping targets the most strict of the two is considered
18
Offshore targets (OSPAR)
Coastal targets (WFD)
19. Target concentrations
0
0.5
1
1.5
2
2.5
3
Current
Target
Winterconcentrations of DIN (mg/l)
• only the most strict targets per area are shown;
• the WFD-target for the Ems-Dollard estuary is 1.33 mg/l
19
30. Conclusions
Optimisation method is a quick and powerful tool to:
•optimise nutrient reductions
•check consistency and attainability of targets
•facilitate discussions between stakeholders
30