CROSMOR 2004 model: modelling of cross-shore transport and morphology

This model is a very advanced cross-shore profile model (Fortran code) which computes the cross-shore distribution of (see Plot below):

1) wave height,
2) longshore and cross-shore flow velocity,
3) peak orbital velocities (including asymmetry effects),
4) bed load and suspended load transport (using a single-fraction or multi-fraction method),
5) morphological changes (including dune erosion).

The CROSMOR profile model is a probabilistic model (wave by wave model) which simulates the propagation, transformation (shoaling) and breaking of individual waves along a cross-shore profile, which is assumed to be uniform in longshore direction. Statistical parameters are computed from the results of the individual waves. The individual waves shoal until an empirical criterion for breaking is satisfied. Wave height decay due to bottom friction and breaking is modelled by using an energy dissipation method. Wave-induced set-up and set-down and breaking-associated longshore and cross-shore currents are also modelled. The near-bed orbital velocities of the high-frequency waves (low-frequency effects are neglected) are described by the method of Isobe and Horikawa to account for wave asymmetry effects in the nearshore zone (forward peak orbital velocity is larger then backward peak orbital velocity). The depth-averaged return current (U_R) under the wave trough of each individual wave (summation over wave classes) is derived from linear mass transport and the water depth (h_t) under the trough. Streaming in the wave boundary layer due to viscous and turbulent diffusion of fluid momentum is taken into account. The streaming (u_b) in the wave boundary layer is of the order of  5% of the peak orbital velocity and generally onshore-directed in deeper water (symmetric waves).
The sediment transport rate of the model is determined for each wave (or wave class), based on the computed wave height, depth-averaged cross-shore and longshore velocities, orbital velocities, friction factors and sediment parameters. The net (averaged over the wave period) total sediment transport is obtained as the sum of the net bed load (q_b) and net suspended load (q_s) transport rates. The net bed-load transport rate is obtained by time-averaging (over the wave period) of the instantaneous transport rate using a formula-type of approach.

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