Presentation by Remi Caillibotte (Egis, France), Benjamin Jacob (Hereon, Germany) and Richard Marijnissen (Deltares, Netherlands) at the Delft3D User Days, during the Delft Software Days - Edition 2023 (DSD-INT 2023). Thursday, 16 November 2023, Delft.

1. This project receives funding from the European Union’s Horizon 2020 Research and Innovation action under grant agreement No 101037097.
RESTCOAST ecotope quantification
using D-Eco Impact
Richard Marijnissen (Deltares, Netherlands)
Remi Caillibotte (EGIS, France)
Benjamin Jacob (Hereon, Germany)
Delft 16/11/2023

2. REST-COAST
VISION:
Healthy and climate-resilient European coastal regions achieved through innovative large-scale
systemic restoration, enhance the delivery of ecosystem services and improve coastal biodiversity.
MISSION:
Demonstrate that upscaled coastal restoration can provide a low carbon footprint solution to climate
adaptation and disaster risk reduction for threatened coastal systems, combined with gains in their
biodiversity.
GOAL:
Overcome present hurdles to upscale coastal restoration interventions through new technical,
financial, management and transfer tools, aligned with the needs of coastal vulnerable regions and
society.

4. • EUNIS ecotopes as a
“common language”
between pilots
• Provides semi-
quantitative insight in
ecosystem services
• Combined with IUCN
redlist provides
qualitative insight in
biodiversity
Ecotopes
Ecotope map for the the Wadden Sea, Baptist et al. (2019)

5. Use in REST-COAST
2) Local ecotope classes
3) Conversion to EUNIS ecostopes
1) Model results of scenario or measure
4) [Changes in] biotopes as indicator of restoration
success
Consistent application of
ecological rules using
D-Eco Impact

6. Application
- Arcachon

7. • Between 1989 and 2012, a decrease of the
spatial extent of eelgrass beds has been
observed:
• -38% for Zostera noltii
• -85% for Zostera marina
• Impact on:
• Tourism activities: 137 000 inhabitants but
400 000 people in summer; economic benefits
estimated at 346M€; recreational (bathing,
sport, …) and cultural (museums, Dune of
Pyla = 1.5M visitors) activities
• Dredging of harbour entrances
• Oyster farming: 780 ha; from 8 to 10 000
tons per year; Growing of juvenile oysters; 40
M€ of revenue; 1 000 employments)
• Fishery: 2000 tons/yr
• Land use w.r.t. coastal flooding: Klaus in
2009; Xynthia in 2010
Restoration of eelgrass beds in the Arcachon Bay
Source: Cognat, 2019

8. Impacts at stake
Ecosystem services targeted:
● (1) Coastal flooding control
● (2) Coastal erosion control
● (3) Water quality improvement
● (4) Carbon sequestration
Impacts considered:
● (1) Coastal flooding at coastal sites inside
the Arcachon lagoon
● (2) Erosion of main channels and
sedimentation of harbor entrances
● (3) Turbidity, Water renewal (flushing time)
● (4) Specific/classic sediment dynamics and
distribution inside the lagoon
→ Link with WP1

9. General methodology
Environmental drivers:
Bathymetry
Meteorology (ERA5)
Large-scale tide conditions (FES2012)
Offshore conditions for waves (IOWAGA)
Sediment parameters
Vegetation parameters
Coupled model:
Waves
Hydrodynamics
Morphology
Vegetation
Modelling results:
Hydrodynamics / water levels
Sediment distribution and
morphological changes
Exposure / Uses
Vulnerability
→ KPIs
Risk
assessment
Restoration scenarios (WP1)
Climate change

10. D-Flow FM module
• 2D computation on a curvilinear grid
• Processes involved:
• Tide-driven flows
• Wind-driven flows
• Wave-driven flows (coupling with D-Waves)
D-Morphology module
• Bedload and suspended load transport
of cohesive and non-cohesive sediment
• Bed level update
• Morphological acceleration factor
Coastal eco-morphodynamic model Bathymetry
Flow
Boundary
conditions
Sediment
transport
Bed update
Hydro. time
Morpho. time
x13

11. Vegetation module
• Trachytopes (Baptist 2005; Baptist et al. 2007):
• Inputs:
• Fixed vegetation: cover corresponding to 2012
• Sensitivity analysis (e.g. regarding seasonality)
• Minor differences on water levels
• Max differences of 4 cm.s-1 for tidal currents
Cover
Height
(cm)
Density
(m-1)
Drag
coefficient
< 0.25 12 13.6
0.7
0.25 < . < 0.75 16 27.3
> 0.75 20 53.5

12. ● Non-neutral impact of the vegetation on sediment dynamics within the Arcachon Bay
● Restoration of vegetation could lead to:
• A decrease of sediment deposition on the bottom on the Bay
• An erosion of secondary channels (improving hydrodynamics)
● Risk assessment for coastal flooding and erosion risk
● New restoration scenarios to be integrated
Conclusions and perspectives on modelling works

13. ● Future changes in term of biotopes as indicators of restoration
success
● Application of the D-Eco Impact tool with conditions adapted to
Wadden sea pilot site → Proof of concept
→ Improvements for Arcachon Bay must be made and particularly on
seagrass and salt marshes classifications
Ecotopes mapping for Arcachon Bay

14. Application
- Wadden Sea

15. Model
Hereon
15
source:
http://ccrm.vims.edu/schismweb/
SCHISM
• 3D, RANS-Equations on unstructured grids
• Robust matrix solver following an efficient
semi-implicit time stepping schemes
• Includes Higher-order transport solver: TVD2
• Includes a variety of functional modules
WWM -III
• Wave Action balance Equation on an unstructured mesh.
• 3rd generation wave model
• ST4 physics Ardhuin et al. (2010)
SED3D
• 3D Sediment model for non-cohesive sediments
• Based on Community Sediment Transport Model (Warner et al., 2008).
• unstructured grid adaption (Pinto et al. (2012)
• Erosion/deposition/bedload of 8 Sediment Classes (0.06-2 mm)
German Bight ugrid downscaling configuration
Hydrodynamic (h)
B.C.
AMM15
WW3
Elements/Nodes
900000/480000
1.5 km - 50 m dx
21 vertical S-layers
90s dt
Wave
Spectra(h)

16. Hereon
16
• Present day scnerios,
• End of the century climate
projections
Seagrass as nature based solution
Physical
Parameters

17. D-Eco Impact – Preliminary results
Early stage work in progress …
• SCHISM output not yet ugrid conform
• Preprocessing scripts for conversion of
schism output (further work required)
Hereon
17

18. Hereon
18
#"MC521"
#"MB523"
D-Eco Impact – Preliminary results

19. Application
- Ems-Dollard

20. @RESTCOAST_H2020 rest-coast.eu RESTCOAST.H2020
This project receives funding from the European Union’s Horizon 2020 Research and Innovation action under grant agreement No 101037097.
Thank
you!