1 / 15

Orientation of Outer Deltas

Orientation of Outer Deltas. Why are outer deltas formed? What determines the orientation (of the channels) of the outer delta + their dynamics?. ALW - 05/04/2002. Orientation of the Outer Delta :. Conceptual model:. Updrift: Downdrift: wave-dominated. Tide-dominated

kiona-spence
Download Presentation

Orientation of Outer Deltas

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Orientation of Outer Deltas • Why are outer deltas formed? • What determines the orientation (of the channels) of the outer delta + their dynamics? ALW - 05/04/2002

  2. Orientation of the Outer Delta: Conceptual model: • Updrift: • Downdrift: wave-dominated • Tide-dominated • Interaction shore parallel current • and current in the strait • Preferred sediment deposition • on downdrift side

  3. Sediment flux Hypothesis: • Asymmetry due to ‘external’ asymmetry only. • Hence the asymmetry in back-barrier area + alignment of islands not considered. Proposition: outer deltas are downdrift oriented w.r.t. the ‘large scale’ sediment flux

  4. From process-based models + observations M2 amplitude M2 phase

  5. M4 amplitude M4 phase M0 amplitude M0 amplitude

  6. Model Setup: Parameters varied: • M2 amplitude (default = 1 m) + phase • M4 amplitude (default = 0 m) + phase • M0 amplitude (default = 0 m) • initial bed profile (default = flat)

  7. M2 Amplitude Z2=1 Z2=1 Z2=-0.4 Z2=1 Z2=-1 Z2=1

  8. Df2 = 40 deg Z2=1 Z2=1 M2 Phase

  9. Z0=0 Z0=-0.1 Z0=0 Z0=0.1 Default: Z2_l = 0.9 Z2_r = 1.0 Df2 = 40 deg Influence of M0

  10. Influence of M4 phase (1) Z4=0.2 F4=290 Df4 = 60 deg Z4=0.2 F4=350 FD ED FD FD ED

  11. Influence of M4 phase (2) Z4=0.2 F4=110 Df4 = 60 deg Z4=0.2 F4=170 FD ED FD ED

  12. Z0=0 Z0=-0.1 Z0=0 Z0=0.1 Initial bed not flat

  13. M0 amplitude Comparison with data Relative phase UD DD UD UD DD+UD FD UD DD UD UD DD+UD ED : updrift (UD) FD: downdrift (DD) ED: updrift (UD) : downdrift (DD) However: M0 seems to be more ‘efficient’

  14. Conclusion • Orientation of outer deltas is downdrift with respect to sediment flux • Correlates well with the Wadden Sea embayments • Initial topography changes details, not overall picture

  15. Future work • Add waves • Influence of shape of embayment and width of throat

More Related