Consolidation is the process of the compaction through the expulsion or pore water resulting in an increase in bed dry bulk density and bed material strength. The consolidation process in the upper sediment layer is modelled in order to calculate the compaction, increase in dry bulk density, and shallow subsidence. The mass continuity equation for the surface sediment layer is given by
| 1) |
\frac{\partial }{\partial t}\int _{z_{0}}^{z_{b}}\rho _{d}dz=0 |
where
t : time [T]
ρd : dry bulk density [M/L3]
z0 : bottom of surface sediment layer [L]
zb : bed surface elevation [L]
z : vertical coordinate [L]
Consolidation is computed utilizing a user-specified curve of dry bulk density as a function of time
where
ρd : dry bulk density [M/L3]
f : consolidation function
t : time [T]
The approach therefore ignores variables such as self-weight, bed composition, water temperature, etc. Although simplistic, the approach captures the general behavior of consolidation and is easy to specify. During the model simulation, the bed dry bulk density is used to estimate a corresponding time, then the time is advanced by a computational time step, and the curve is again used to compute a new dry bulk density. If the bed dry bulk density is higher than the largest value on the curve, then no consolidation occurs.