10 Nov 2015

Using MIKE 11 Sediment Transport module for river channel improvements

The application of MIKE 11 Sediment Transport (ST) module to a MIKE 11 model used for flood analysis – as seen in a New Zealand case study – can greatly aid river improvement modelling studies.

Improvements to river channels carried out for flood mitigation will generally have some effect on transport of the gravel bedload. Many rivers carry gravel bedloads and present management challenges both in flood mitigation and in controlling gravel budgets. The gravel resource is often in demand as gravel extraction lowers flood risk.

However, too much extraction can cause undermining of bridge piers, stopbanks and other infrastructure. Any resulting changes in bed levels can in turn affect flood levels, possible diminishing the effect of channel improvements over time. The ST module in MIKE 11 is able to easily and quickly estimate these effects.

With the application of MIKE 11 ST, information can be provided to the client at the options stage, showing the extent of loss of the flood level gains over a typical five-year period. The modelling can also provide an indication of the annual gravel extraction needed to avoid this loss. This solution will highly benefit river management authorities, river engineering consultants, central government environmental agencies, gravel extraction companies and other independent companies dealing in aspects of river modelling.