Presentation by Fedor Baart (Deltares) at the Data Science Symposium 2018, during Delft Software Days - Edition 2018. Thursday 15 November 2018, Delft.

1. Global shorelines
Arjen Luijendijk, Gerben Hagenaars,
Gennadii Donchyts, Fedor Baart,
Stefan Aarninkhof, Rosh Ranasinghe

2. Outline

4. The Netherlands

5. Safety against flooding
Amsterdam
The Hague
Rotterdam

6. NL below sea level

7. Nourishing the Dutch beaches
Beach nourishment Foreshore nourishment
‘Dike in sand’ solution Vegetated sandy foreshore

8. Photo from south
Show dimensions
Delfland coast in 2010
1 km
2 km
21 mln m3

9. Photo from south
Show dimensions
1 km
2 km
21 mln m3
Pilot Sand Motor in 2011

10. ‘Living lab’ for studying processes & species
Vegetation
Dune formation
Recreation
Swimmer safety
Beach ecology
Fresh water below dunes
Book integrating these findings
January 2019 - Free of charge

12. Evolution and volume changes
August 2011
January 2017
Observations Model predictions

13. Evolution and volume changes
August 2011
January 2017
But it lacks the evolution of the dry beach and dunes!!!
Observations Model predictions

14. Existing morpho models
Subaqueous morphology
Process-based model: Delft3D
Open source
Luijendijk et al. (2017)

15. Subaqueous morphology
Process-based model: Delft3D
Luijendijk et al. (2017)
Subaerial morphology
• Process-based model:
AeoLiS
• Hoonhout et al. (2017)
Existing morpho models

16. Model coupling
Marine Flow and
sediment transport
Delft3D FM
Aeolian Sediment
transport
AeoLis
BMI
coupler
BMI - Basic Model Interface
Waves
SWAN

17. Temporal coupling

18. Dune growth rates
Observed: ~15 m3/m/yr

19. subaqueous
subaerial
dune
growth
Storm erosion
vegetation
Integrated modelling framework

20. Integrated modelling framework

21. Hagenaars 2017
Shoreline detection from space

22. Shoreline detection from space

23. Shoreline detection technique
shorelinewater
land
NDWI
no.ofpixels
landwater
What is the accuracy of this shoreline?

24. Validation at Sand Motor, NL
Single satellite image (16-7-2015)
pixel resolution Sentinel (10 m)
offset[m]
Scheveningen
Hoek van Holland
average 1 m
standard deviation 5 m
Hagenaars et al.
2017

25. But can we also determine trends?
Show messy animatino

26. Image composition to overcome clouds, etc.
15
Composite images: moving time averaging
• Clouds, tidal stages, surge, waves, shadows, seasonal effects, etc.

27. Multi-year validation @ Sand Motor
2012 2013 2014 2015 2016
distancealongtransect[m]
Can we analyze the coastline dynamics
of all beaches in the world?

28. Literature on beaches worldwide
Percentage sandy beaches; literature says: 10 – 70 %
Bird (1985): 70% of sandy beaches are eroding
Questions:
1) Where are the world’s sandy beaches located?
2) How have these beaches changed over the last decades?

29. Earth Engine
Storage and Compute
Landsat Satellite Data
NASA Landsat and Google Earth Engine
1984 2018

30. 31
All free available
satellite images
(Landsat) since 1987
For Hue, Vietnam
Unfiltered images
After pixel-based
filtering of clouds,
shadows, a.o.

31. • Machine learning with OSM Data (Texel, NL)
[Manual]
“Buildings”
[Automatic]
OSM Sand
Accuracy 99.6%
Misclassification 0.4%
True Positive 99.9%
False Positive 1.8%
Precision 99.7%
Classified
Sand
Training Dataset Sand Classification
10m
Location of world’s sandy beaches

32. Detecting sandy beaches worldwide

33. From sandy maps to sandy coastline
Cloud-free composite
2015-2016

34. Validation at Narrabeen, AUS
R2 = 0.88
RMSE = 13.7 m

35. Shorelinemonitor.deltares.nl
Luijendijk et al. State of the World’s Beaches
Scientific Report at Nature.com

36. News item

38. Nu.nl

39. Der Standard

40. Where are the world’s sandy beaches located?
Hayes, 1967!!
31% of the world’s coastline is sandy
Global map on Sandy Beaches

41. Global hotspots of dynamic beaches
➢ 2 million satellite images
➢ ~ 50,000 beaches

42. Example: Mekong Delta

43. Example: Mekong Delta

44. Near Abidjan, Ivory Coast
1 m/yr erosion &
accelerating!

45. Pacifica, San Francisco,
USA
4 m/yr erosion
& steady erosion rate!

46. Mekong Delta, Vietnam
31 m/yr erosion
& continuing!

47. Aveiro, Portugal
Construction of jetties caused accretion of
the northern beach of 9 m/yr, while the
southern beaches are eroding with 4 – 8
m /yr

48. Fire Island,
New York, USA
Hurricane Sandy
Hurricane Sandy caused
erosion of the dunes at Fire
Island. The eroded sand was
deposited at the foreshore
resulting the widest beach in 15
years, but the waves and wind
bring back the sand to the
dunes. This results in a
reduction of the beach width in
the years after the hurricane.
This is a nice example on how
resilient our beaches can be as
long as time allows to recover.

49. Beach erosion & accretion
per country in m/yr
North America:
1. Bahamas -2,10
2. Grenada -0,67
3. Cuba -0,64
4. Mexico -0,26
5. Honduras -0,23
Asia:
1. Myanmar -1,90
2. Bangladesh -1,77
3. India -0,43
4. Pakistan -0,28
5. Yemen -0,28
Asia:
1. Bahrein 4,79
2. Singapore 4,25
3. China 3,25
4. Kazakhstan 2,94
5. Turkmenistan 2,51

50. Dutch coastline trends

51. Top 7 most accreting coasts

52. Future nourishment needs due to climate change
120 mln m3 /yr
12 mln m3/yr

53. Sea level - erosion correlation

54. Sea level rise previous scenario’s

55. Coast on a diet

56. Shorelinemonitor.deltares.nl
Luijendijk et al. State of the World’s Beaches
Scientific Report at Nature.com