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DSD-INT 2018 Application of XBeach to a Low-elevation Dune System with Hurricane Forcing - Johnson

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Presentation by Cody Johnson, Louisiana State University, USA at the XBeach User Day 2018, during Delft Software Days - Edition 2018. Thursday, 15 November 2018, Delft.

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DSD-INT 2018 Application of XBeach to a Low-elevation Dune System with Hurricane Forcing - Johnson

  1. 1. Application of XBeach to a Low-elevation Dune System with Hurricane Forcing Cody Johnson (cjoh296@lsu.edu) Dr. Qin Chen (q.chen@northeastern.edu) September 15th, 2018
  2. 2. photo credit: Weeks Marine Overview ▪ Importance and objectives ▪ Project description ▪ Geomorphic context ▪ Modeling system ▪ Results and Analysis ▪ Conclusions ▪ Future work
  3. 3. ▪ Hurricane driven morphological change threatens coastal sustainability ▪ Low-elevation, low-energy sedimentary shorelines are primarily shaped by storm impacts* ▪ Louisiana’s fragile coastline protects valuable and strategic infrastructure Importance Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work Aug. 2007 Sept. 2008 *Stone et al. (2004). “The Importance of Extratropical and Tropical Cyclones on the Short-Term Evolution of Barrier Islands along the Northern Gulf of Mexico, USA.” Marine Geology
  4. 4. 1. Simulate the morphodynamics of hurricane Gustav’s (2008) impact to the low-elevation Caminada Headlands (CH), Louisiana 2. Investigate the processes at work in the relationship between extreme erosion and hurricane driven hydrodynamics at CH 3. Establish modeling framework to forecast future hurricane impacts at CH given its recent beach and dune restoration Research objectives Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work
  5. 5. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work
  6. 6. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work
  7. 7. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work
  8. 8. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work Delta Cycle Penland et al. (1988). “Transgressive Depositional Systems of the Mississippi Delta Plain: A Model for Barrier Shoreline and Shelf Sand Development.” Journal of Sedimentary Petrology.
  9. 9. ▪ Tier-1 of nested structure ▪ Delft3D 4 model ▪ Delft3D-FLOW and SWAN ▪ 50 km – 10 km resolution ▪ 17,688 computational elements ▪ Fast and efficient runs Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work Hu et al. (2015). “A Numerical Study of Vegetation Impact on Reducing Storm Surge by Wetlands in a Semi-Enclosed Estuary.” Coastal Engineering
  10. 10. ▪ Tier-2: nested in basin scale model ▪ 3 km – 60 m resolution Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work Liu et al. (2018). “Modeling Hurraicane-Induced Wetland-Bay and Bay-Shelf Sediment Fluxes.” Coastal Engineering. ▪ Coupled Delft3D-FLOW + SWAN ▪ 430,620 elements
  11. 11. ▪ Spatiotemporally variable boundary conditions ▪ Curvilinear grid ▪ 2 – 40 m resolution ▪ Inlets and back-barrier channels resolved ▪ Lidar, terrestrial RTK and single-beam bathymetric surveys ▪ 1,011,164 elements Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work
  12. 12. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work
  13. 13. Statistic Value RMSE (m) 0.279 Bias (m) -0.029 Skill 0.408 r2 0.121 𝑅𝑀𝑆𝐸 = 1 𝑁 ෍ 𝑖=1 𝑁 (𝑧𝑏 𝑚𝑜𝑑𝑒𝑙,𝑖 − 𝑧𝑏 𝑜𝑏𝑠𝑒𝑟𝑣𝑒𝑑,𝑖)2 𝐵𝑖𝑎𝑠 = 1 𝑁 ෍ 𝑖=1 𝑁 (𝑧𝑏 𝑚𝑜𝑑𝑒𝑙,𝑖 − 𝑧𝑏𝑓,𝑜𝑏𝑠𝑒𝑟𝑣𝑒𝑑) 𝑆𝑘𝑖𝑙𝑙 = 1 − σ𝑖=1 𝑁 (∆𝑧𝑏 𝑜𝑏𝑠𝑒𝑟𝑣𝑒𝑑,𝑖 − ∆𝑧𝑏 𝑚𝑜𝑑𝑒𝑙,𝑖)2 σ𝑖=1 𝑁 ( ∆𝑧𝑏 𝑜𝑏𝑠𝑒𝑟𝑣𝑒𝑑,𝑖)2 Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work
  14. 14. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work
  15. 15. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work ▪ Available products out of date ▪ Shoreline and wetland interface > 100 m out of place ▪ Significant effects on sediment transport
  16. 16. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work
  17. 17. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work
  18. 18. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work
  19. 19. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work marsh outcrop
  20. 20. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work marsh outcrop
  21. 21. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work
  22. 22. Statistic Value RMSE (m) 0.335 Bias (m) 0.044 Skill 0.144 r2 0.258 𝑅𝑀𝑆𝐸 = 1 𝑁 ෍ 𝑖=1 𝑁 (𝑧𝑏 𝑚𝑜𝑑𝑒𝑙,𝑖 − 𝑧𝑏 𝑜𝑏𝑠𝑒𝑟𝑣𝑒𝑑,𝑖)2 𝐵𝑖𝑎𝑠 = 1 𝑁 ෍ 𝑖=1 𝑁 (𝑧𝑏 𝑚𝑜𝑑𝑒𝑙,𝑖 − 𝑧𝑏𝑓,𝑜𝑏𝑠𝑒𝑟𝑣𝑒𝑑) 𝑆𝑘𝑖𝑙𝑙 = 1 − σ𝑖=1 𝑁 (∆𝑧𝑏 𝑜𝑏𝑠𝑒𝑟𝑣𝑒𝑑,𝑖 − ∆𝑧𝑏 𝑚𝑜𝑑𝑒𝑙,𝑖)2 σ𝑖=1 𝑁 ( ∆𝑧𝑏 𝑜𝑏𝑠𝑒𝑟𝑣𝑒𝑑,𝑖)2 Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work
  23. 23. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work ▪ Incorporating additional processes is important for low- elevation, sediment scarce barriers ▪ Barrier restoration design in Louisiana needs to consider backbarrier wetland environment’s effect on overwash penetration ▪ Shallow, sub-surface stratigraphy may also be import for restoration design, but more study is needed Tentative Conclusions
  24. 24. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work 1. Medium-term erosion related to marsh platform topography 2. Back-barrier accommodation space and reduced roughness for overwash fluxes?
  25. 25. A BC Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work C B A
  26. 26. Importance and Objectives Project Description Geomorphic Context Modeling System Results and Analysis Conclusions Future Work ▪ “Loosely” couple the XBeach and Delft3D’s model by means of disk I/O and externally processing results (Matlab) ▪ Allow us to examine the effects of barrier disintegration on wave fields in the adjacent coastal embayments ▪ Ultimately place multiple XBeach domains within Delft3D model ▪ Target Louisiana’s levee (dike) flood protection system with an XBeach domain ▪ Everything is in place, we will begin testing tomorrow
  27. 27. ▪ LA Board of Regents ▪ CPRA and LACOE ▪ Drs. Kelin Hu and Ke Liu ▪ Kees, Robert, and Ap ▪ Deltares Acknowledgements

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