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DSD-INT 2018 Global Sandy Shoreline changes - Baart

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

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DSD-INT 2018 Global Sandy Shoreline changes - Baart

  1. 1. Global shorelines Arjen Luijendijk, Gerben Hagenaars, Gennadii Donchyts, Fedor Baart, Stefan Aarninkhof, Rosh Ranasinghe
  2. 2. Outline
  3. 3. The Netherlands
  4. 4. Safety against flooding Amsterdam The Hague Rotterdam
  5. 5. NL below sea level
  6. 6. Nourishing the Dutch beaches Beach nourishment Foreshore nourishment ‘Dike in sand’ solution Vegetated sandy foreshore
  7. 7. Photo from south Show dimensions Delfland coast in 2010 1 km 2 km 21 mln m3
  8. 8. Photo from south Show dimensions 1 km 2 km 21 mln m3 Pilot Sand Motor in 2011
  9. 9. ‘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
  10. 10. Evolution and volume changes August 2011 January 2017 Observations Model predictions
  11. 11. Evolution and volume changes August 2011 January 2017 But it lacks the evolution of the dry beach and dunes!!! Observations Model predictions
  12. 12. Existing morpho models Subaqueous morphology Process-based model: Delft3D Open source Luijendijk et al. (2017)
  13. 13. Subaqueous morphology Process-based model: Delft3D Luijendijk et al. (2017) Subaerial morphology • Process-based model: AeoLiS • Hoonhout et al. (2017) Existing morpho models
  14. 14. Model coupling Marine Flow and sediment transport Delft3D FM Aeolian Sediment transport AeoLis BMI coupler BMI - Basic Model Interface Waves SWAN
  15. 15. Temporal coupling
  16. 16. Dune growth rates Observed: ~15 m3/m/yr
  17. 17. subaqueous subaerial dune growth Storm erosion vegetation Integrated modelling framework
  18. 18. Integrated modelling framework
  19. 19. Hagenaars 2017 Shoreline detection from space
  20. 20. Shoreline detection from space
  21. 21. Shoreline detection technique shorelinewater land NDWI no.ofpixels landwater What is the accuracy of this shoreline?
  22. 22. 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
  23. 23. But can we also determine trends? Show messy animatino
  24. 24. Image composition to overcome clouds, etc. 15 Composite images: moving time averaging • Clouds, tidal stages, surge, waves, shadows, seasonal effects, etc.
  25. 25. Multi-year validation @ Sand Motor 2012 2013 2014 2015 2016 distancealongtransect[m] Can we analyze the coastline dynamics of all beaches in the world?
  26. 26. 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?
  27. 27. Earth Engine Storage and Compute Landsat Satellite Data NASA Landsat and Google Earth Engine 1984 2018
  28. 28. 31 All free available satellite images (Landsat) since 1987 For Hue, Vietnam Unfiltered images After pixel-based filtering of clouds, shadows, a.o.
  29. 29. • 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
  30. 30. Detecting sandy beaches worldwide
  31. 31. From sandy maps to sandy coastline Cloud-free composite 2015-2016
  32. 32. Validation at Narrabeen, AUS R2 = 0.88 RMSE = 13.7 m
  33. 33. Shorelinemonitor.deltares.nl Luijendijk et al. State of the World’s Beaches Scientific Report at Nature.com
  34. 34. News item
  35. 35. Nu.nl
  36. 36. Der Standard
  37. 37. Where are the world’s sandy beaches located? Hayes, 1967!! 31% of the world’s coastline is sandy Global map on Sandy Beaches
  38. 38. Global hotspots of dynamic beaches ➢ 2 million satellite images ➢ ~ 50,000 beaches
  39. 39. Example: Mekong Delta
  40. 40. Example: Mekong Delta
  41. 41. Near Abidjan, Ivory Coast 1 m/yr erosion & accelerating!
  42. 42. Pacifica, San Francisco, USA 4 m/yr erosion & steady erosion rate!
  43. 43. Mekong Delta, Vietnam 31 m/yr erosion & continuing!
  44. 44. 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
  45. 45. 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.
  46. 46. 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
  47. 47. Dutch coastline trends
  48. 48. Top 7 most accreting coasts
  49. 49. Future nourishment needs due to climate change 120 mln m3 /yr 12 mln m3/yr
  50. 50. Sea level - erosion correlation
  51. 51. Sea level rise previous scenario’s
  52. 52. Coast on a diet
  53. 53. Shorelinemonitor.deltares.nl Luijendijk et al. State of the World’s Beaches Scientific Report at Nature.com

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