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Content short introduction to the model model outputs standard run

A 3D MODEL SIMULATING SEDIMENT TRANSPORT, EROSION AND DEPOSITION WITHIN A NETWORK OF CHANNEL BELTS AND AN ASSOCIATED FLOODPLAIN Derek Karssenberg 1 & John Bridge 2 1 Utrecht University, the Netherlands 2 Binghamton University, U.S.A. Content short introduction to the model

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Content short introduction to the model model outputs standard run

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  1. A 3D MODEL SIMULATING SEDIMENT TRANSPORT, EROSION AND DEPOSITION WITHIN A NETWORK OF CHANNEL BELTS AND AN ASSOCIATED FLOODPLAIN Derek Karssenberg1 & John Bridge2 1Utrecht University, the Netherlands 2Binghamton University, U.S.A.

  2. Content • short introduction to the model • model outputs standard run • model components and sensitivity analysis • conclusions

  3. Channel network • multiple channels • erosion and deposition from sediment continuity equation • bifurcations (incl. avulsions)

  4. Channel belts • width increases through time

  5. Overbank deposition • function of deposition at nearest by channel belt • decreases away from channel belts

  6. Hillslope erosion • occurs in area next to channel belts • function of stream power

  7. 3D architecture • compaction

  8. Standard run • parameters and boundary conditions comparable to Rhine-Meuse • cell size 200 m, modelling area 30 x 60 km • external forcing: base level change base level

  9. Standard run • video

  10. 3D volumes 0-13 KY 13-16.5 KY 16.5-20 KY

  11. 3D volumes

  12. Cross sections (Left-Right) 10 m 0 m

  13. Bifurcations

  14. Probability P(a) of a new bifurcation (in a year, for each cell) Ps probability of a bifurcation as function of the superelevation -> function of ratio of downstream slope and slope perpendicular to the channel belt Pd probability of a yearly flood discharge leading to an avulsion, given a very high superelevation of the channel belt

  15. Aggradation and degradation at a bifurcation point 56 m bifurcation 52 m 3500 yr 4500 yr

  16. Strong decrease in bifurcation probability after a bifurcation

  17. Bifurcation frequency, external and internal forcing

  18. Water flow routing • at a bifurcation, water discharge is distributed over the two distributaries according to with, q1, q2 water discharge (m3/year) for the two distributaries s1, s2 channel gradient of the two distributaries (directly downstream of the bifurcation)

  19. Channel network evolution • a channel disappears when with, at the bifurcation, qlow water discharge (m3/year) of the channel with the lowest discharge qhigh water discharge (m3/year) of the channel with the highest discharge

  20. Sensitivity to ucrit: ucrit = 0.4 (was 0.48)

  21. Sensitivity to ucrit ucrit = 0.4 ucrit = 0.48

  22. Overbank deposition

  23. Increase in channel-belt width Bank erodibility parameter defines rate of increase in width maximum width of channel belt (m), function of channel width width of channel belt (m) minimum width of channel belt (m), equals channel width age of channel belt (yr)

  24. Low bank erodibility High bank erodibility

  25. Sediment transport through the channels

  26. Diffusion qs sediment transport (m3/yr) qw discharge (m3/yr) a parameter h elevation of the bank of the channel (m) xc distance along the channel

  27. Changing the diffusion parameter and sediment input standard run diffusion x 5, sediment input /5 5 ky 10 ky 5 ky 10 ky

  28. Changing the diffusion parameter and sediment input standard run diffusion x 5, sediment input /5 15 ky 20 ky 15 ky 20 ky

  29. Effect on bifurcation location

  30. standard run diffusion x 5, sediment /5

  31. Cross sections (Left-Right) 10 m 0 m standard run 10 m 0 m high diffusion

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