Erosion and deposition of sand greatly contributes to many challenges related to coastal and port engineering. This can be in relation to shoreline management (including protection against erosion), sedimentation in dredged channels or port entrances, and undertaking of construction works in the coastal zone.

The Sand Transport (ST) and Shoreline Morphology (SM) modules in DHI’s industry-recognised modelling application MIKE 21 will help you model all areas of non-cohesive sediment dynamics.

MIKE 21 ST is an advanced 2D sand transport model that simulates sand transport under the influence of currents and waves.

MIKE 21 SM is a unique tool that makes it possible – for the first time – to undertake long-term shoreline morphodynamic simulations in 2D environments.

Together, these modules can be combined in an unparalleled combination that allows for the most advanced studies of real-life engineering problems.


Detailed and timely knowledge of erosion, transport and deposition of sediments in the sea is crucial to a number of human activities. Amongst these are protection measures against coastal erosion, establishment and conservation of beaches, maintenance of depths in harbours, or control of sediment spreading from dredging operations.

Due to climate change and shoreline evolution, there is also an increasing need to forecast the impacts of coastal structures on coastal processes. Valid predictions of long-term shoreline movements are vital to mitigate or prepare for erosion and changes in coastal stability.


Introducing MIKE 21 ST/SM, the industry-recognised sand transport and shoreline morphology modules with several accepted formulations for current as well as current-wave generated transport, including 3D description of sediment transport rates and the option to prescribe the coastal profile.

The modules are particularly suitable for use in the morphological optimisation of port layouts, impact of shore protection schemes, stability of tidal inlets and much more.

The MIKE 21 ST/SM modules allow you to model:

  • Sand transport rates
  • Shoreline management
  • Optimisation of port layouts
  • Shore protection schemes
  • Sedimentation in dredged channels and port entrances
  • Erosion over buried pipelines
  • River and estuarine morphology


Ability to model sand transport in combined waves and currents
Our pioneering intra-wave sand transport model, which calculates sand transport due to the combined effect of waves and currents using the integrated wave boundary layer approach is used to describe the movement of sand in the model.

Supports efficient parallelisation techniques for high performance computing
MIKE 21 ST/SM takes advantage of the efficient parallelisation techniques that are implemented in MIKE 21 for the use of multiple cores and GPUs. At the same time, MIKE 21 ST/SM is a seamless integration for dynamically coupled modelling, including hydrodynamics and waves. Special techniques have been developed to enhance calculation speed also within the morphological modelling.

Capability to combine different types of morphological modelling in the same model
This is a revolutionary technique that is highly effective in areas where 2D morphology is important and which makes it possible to employ efficient modelling in a large number of real-life problems. This feature makes it possible to undertake long-term predictions, such as of port sedimentation.

Ability to use bed level sources/sinks to add beach nourishment or channel dredging to the simulation
- Nourishment: model the dynamic effects of beach nourishment.
- Dredging: model the dynamic effects of maintaining a certain depth (for example, of a navigation channel) and the amount of dredging necessary.

Ability to prescribe the coastal profile
This allows the model to be used for making long-term predictions of shoreline morphology in complex 2D settings which are challenging for standard one-line shoreline models. The 2D nature of the shoreline morphology module allows for robust predictions of the long-term impact of complex coastal structures

Inclusion of a dune erosion model
The dune erosion model can be used to calculate the erosion of the dune during storm conditions.

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