Keynote Lecture by Martin Verlaan, Delft University of Technology & Deltares, The Netherlands at the joint Delft3D User Days and the OpenDA User Day, during Delft Software Days 2016 on Tuesday, 1 November 2016, Delft.

1. November 1st 2016
From global to local:
the latest
developments
Martin.verlaan@deltares.nl

2. Outline

Motivation – global to local

A Global Tide and Surge Model (GTSM): Delft3D FM

Initial model development

Calibration with OpenDA

Applications

Towards the next version

Regional storm surge models

Regional SAL effects

Innundation modelling (local)

Innundation risk in Mozambique

Xynthia flood

3. Impacts of storm December 6th
2013

4. Global effects of South pole ice
Present day ice line Weddell sea covered by ice

5. A Global Tide and Surge
Model

6. Grid in Delft3D FM (D-Flow FM module)
This D-Flow FM grid uses triangles and rectangles
for local grid refinement. Resolution is based on Courant number.
Unstructured approach - with grid refinement in shallow areas

7. July 5 2016

8. Computational performance

9. Calibration GTSM version 1

10. Model calibration
ModelpParameters ym Model output
yo Measurements
- CompareJ(p)Cost function

11. • Open source (LGPL) data-assimilation toolbox
• Library of data-assimilation algorithms:
– Simplex, conjugate gradient, LBFGS, DUD, ...
– EnKF, ENSR, steady-state, particle filter, ...
• Set of interfaces: models, observations, algorithms,...
• Platform for cooperation
• Association
11
www.openda.org
What is OpenDA?

12. Model connectors
 Hydrodynamics
• D-Flow FM (Delft3D FM Suite)
• Delft3D-FLOW
• EFDC
• Nemo
 Waves
• SWAN / Delft3D-WAVE
 Water quality
• DELWAQ* / Delft3D-WAQ
• HSPF
 Rainfall runoff
• HBV
• OpenStreams*
• Mike-SHE
• MCRM
• Sacramento
 Sewer systems
• SOBEK-FLOW (Delft3D FM Suite)
• WANDA
 Groundwater
• Modflow*
 CFD
• OpenFOAM*
 Oil-gas reservoirs
• Eclipse*
 Air quality
• Lotos-Euros
• Chimere

13. Calibration of the Model
FES2012
Altimeter observations:
- assimilated FES2012 gridded data
- very accurate on deep water
Calibration parameters:
- Depth & Friction
- 7 regions
Automated calibration:
- 21 parameters
- deep water series Jan2007
347 locations

14. Calibration results for deep water
Region Before After
Arctic 5.1 cm 3.2 cm
N. Atlantic 9.4 7.4
S. Atlantic 12.1 8.4
N. Pacific 8.1 6.2
S. Pacific 11.2 7.3
Indian Ocean 11.7 8.2
S. Ocean 12.4 10.2
Total 10.2 7.4

15. Reanalysis

16. July 5 2016
Highwater exceedance estimates
Reanalysis with ERA-interim meteo-forcing (1979-present)
Cooperation:
Sanne Muis

17. July 5 2016

18. Validation of return periods

19. July 5 2016
GTSM-ERA-interim
GTSM-spiderweb
Without coastal refinement
Dietrich et al 2009

20. GLOSSIS operational
forecasts
Hurricane Matthew

21. GLOSSIS operational forecasts: Hurricane Matthew

22. GLOSSIS operational forecasts: Hurricane Matthew

23. Storm Matthew Oct-07-2016 // FL, GA, SC
GLObal Storm Surge Information System
snapshot storm surge forecast
Max potential inundation level

24. Towards GTSM-v2

25. Grid refinement
Bathymetry gradient based refinement:

26. Sensitivity to resolution
2x finer in deep water
2x finer in shallow water

27. Tidal dissipation through
generation of internal tides (IT)

28. IT dissipation – Anisotropic phenomenon
Barotropic tidal dissipation sources:
• Bottom friction (dominant in shallow waters)
• Generation of internal waves when flowing over rough topography in
stratified oceans (dominant in deep waters)
 New anisotropic numerical implementation
Dissipation=f(Stratification, bathymetry
gradient, cross-slope flow)
• Mid-ocean ridges and trenches (e.g. Mid-
Atlantic Ridge)
• Continental shelves (e.g. Bay of Biscay)
• Island chains (e.g. Hawaiian Ridge)
Literature values: = 1TW (4TW total)
( )1
ITτ = CρNκ h u h-
Ñ Ñg

29. Model sensitivity to grid resolution
Internal Tides dissipation (W/m2) distribution:
 Model is now
sensitive to user
defined parameters
for IT dissipation:
Tuning possible.
 RMSE reduction
with IT dissipation:
• Deep waters:~3 cm
• Coast: ~3.2 cm

30. Self Attraction and Loading
(SAL)

31. SAL – Implementation in GTSM
SAL is the sum of three effects:
Deformation of the seafloor under the weight of the column
of water (Earth is a elastic body)
Redistribution of Earth mass changes the gravitational field
Gravitational attraction induced by the mass of the ocean on
the ocean itself
LOADING
SELF
ATTRACTION
 Literature ~ 10% of astronomical tide Reality: Spatial and
temporal significant variability.
 SAL potential in spherical harmonics  Calculation of field at
every time step, analogous to Tide Generating Forces
 Reduction of errors in tidal representation of ~50 % in coastal
stations and ~60% in deep waters
 Minimal increase in computational times.

32. SAL tide spatial distribution
β approximation too simplistic
SAL tide Tide

33. Regional impact of SAL

34. Real-time data-assimilation

35. DCSM-v6 assimilation locations

36. Impact Kalman filter +6h
Computation for Vlissingen at Dec 5 19u

37. Results

38. Tide gages available through IOC/GLOSS

39. Satellite Data

40. JASON-3 Sealevel example

Todo

41. ASCAT Scatterometer winds

42. ASCAT Scatterometer winds

43. ASCAT Scatterometer winds

44. Data assimilation - future

45. Localization
“OpenDA-NEMO framework for Ocean Analysis and Predictions”,
N. Van Velzen, M. U. Altaf, M. Verlaan, and A.W. Heemink,
submitted to Ocean Dynamics
Sealevel
Observed Sealevel

46. Ensemble Kalman filter

47. Parallel scaling
Good scaling with standard OpenDA code
for up-to 16 nodes (each 8 cores)
SWAN wave model

48. Floodrisk Mozambique

49. Synthetic cyclone tracks

50. Regional model

51. Example TC track
Preliminary results

52. Example TC track and surge
Preliminary results

53. Synthetic cyclones
Maximum surge level
for 6 sample tracks out of more than 1000 cyclones that enter the area

54. Flooding example Mozambique

55. Xynthia storm

56. Xynthia storm surge
February 27 2010

57. Flooding computations
Grid 90m approx. 700x1000
Computation time (no MPI):
• Delft3D FM (10minutes)
• Lisflood-FP (18minutes)
Results sensitive to:
• DEM
• Boundary conditions
• Friction

58. Future plans
• Complete GTSM version 2 including calibration with OpenDA
• Incorporate real-time satellite observations in Delft-FEWS
• Develop real-time data-assimilation of satellite data
• Incorporate more accurate tropical cyclone estimates in global risk
estimates
• Incorporate wave effects for coastal flood risk
• Develop coastal inundation models
• Develop strategy for systematic validation of inundation models

59. Questions?

60. Thanks to …
Arthur van Dam
Dirk Eilander
Edward Melger
Firmijn Zijl
Herman Kernkamp
Hessel Winsemius
Joao Lima Rego
Kun Jan
Maialen Irazoqui Apecechea
Sander van der Pijl
Sanne Muis
Tony Minns
Albrecht Weerts
Alja Vrieling
Annette Zijderveld
Arno Kockx
Arjo Segers
Daniel Twigt
Julius Sumihar
Lora Buckman
Marieke Eleveld
Nils van Velzen
Sandra Gaytan Aguilar
Simone de Kleermaeker
Stef Hummel
…and others…