Theoretical Basis

The 1D Sediment Transport Solver is a mobile bed sediment transport solver, which has been designed for the study of channel morphology. It can be widely applied to the study of sedimentation problems in natural and man-made channels. The module has the capability to predict sediment transport rates, bed elevations and amounts of erosion/deposition throughout the channel system. In summary, this is achieved with the following calculations at each timestep:

• Calculate the hydraulic variables of flow, stage, velocity in the usual way.

• Starting at the upstream end of the system, loop around the nodes calculating the sediment transport capacity and solving the sediment continuity equation for depth of erosion/deposition.

• Optionally, update the channel conveyance tables to allow for any calculated deposition or erosion effects on hydraulics at the next timestep.

Various options are available within this module including specification of dredging, cohesive sediment transport and rigid beds.

The main restrictions on the applicability of the software are that:

• Dunes and ripples are not explicitly modelled and therefore the effects of changes in form roughness on the hydraulic resistance is not simulated.

• The following 1D Solver units are currently not permitted in a mobile bed module run: inline RESERVOIRs, INTERPOLATE, REPLICATE, LDPUMP, MUSKINGUM, ABSTRACTION, QH CONTROL, LATERAL and Q RATING.

• Reaches with zero flows are not permitted at present.

• Essentially one-dimensional representations are used (eg cross section averaged velocities) which are not sufficiently accurate for some situations, eg 'local' effects such as scour at bridge piers.

• Sediment transport calculations rely on equations that are uncertain and thus results must be checked for reasonableness and should be used with other supporting information.