In MIKE 2016, we have added state-of-the-art shoreline morphology evolution to our industry leading MIKE 21/3 Coupled Model FM software.

1. ©DHI
In MIKE 2016, we have added state-of-the-art
shoreline morphology evolution to our industry
leading MIKE 21/3 Coupled Model FM software.
WHAT IS THE COUPLED MODEL?
The MIKE 21/3 Coupled Model FM provides a unified platform
for consideration of fully dynamic coupling of waves and tides
plus feedback from sediment transport processes, if desired.
A single interface allows the user to create a model which
takes account of the impact of waves and tides on each other,
in two– or three-dimensions, using dynamically coupled
versions of MIKE 21/3 FMHD and MIKE 21 SW. Sand or mud
transport modules can be added to include the impact of
sediment transport processes on the overall system.
Environmental modules can also be included within the single
interface when considering water quality or the fate of
contaminants, for example.
WHERE DO I FIND THE COUPLED MODEL?
The Coupled Model is located in the MIKE 21/3 Integrated Models folder of the MIKE Zero New Files dialog. It is listed as Coupled
Model FM (.mfm).
WHY WOULD I USE THE COUPLED MODEL?
When a project simply requires the hydrodynamics or wave climate to be described, the relevant individual module is usually an
appropriate tool. However, some projects, such as nearshore sediment transport and morphology studies, are more complex and
require characterisation of the interactions of waves and tides. When the impact of water level or current variations on wave
propagation is important, or equally, when the effect of wave-driven currents must be included in the overall flow field, and when
instantaneous feedback between the two processes is required, the coupled model is the best tool for the job. The coupled model
describes the interactions of all the relevant physical processes and therefore provides the closest approximation to reality for your
project.
HOW DO I ADD THE COUPLED MODEL TO MY
LICENCE?
The pre-requisites for the Coupled Model are MIKE
21/3 FMHD and MIKE 21 SW. If you have these on
your licence, you can start using the Coupled Model
today. Add-on modules, such as MIKE 21 FMST, can
expand the range of projects for which the Coupled
Model becomes your tool of choice.
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TAKING THE COUPLED MODEL TO THE NEXT LEVEL
Introducing the MIKE 21 Shoreline Morphology Module
INCREASING PERFORMANCE WITH GRAPHICAL PROCESSING UNITS
In MIKE 2016, we have made it possible to use multiple GPU cards with both
MIKE 21 FMHD and MIKE 3 FMHD. Additionally, we employ an unique hybrid
GPU-CPU approach so that the MIKE 21/3 Coupled Model FM supports GPU
technology for hydrodynamics and multiple core CPU technology for waves,
sediments and other processes / modules.

2. 2
CASE STUDY: DAWLISH WARREN
A Practical Application of the Shoreline Model in a UK &
Ireland Context
Site Description
Dawlish Warren is a small seaside resort on the south coast of
Devon in England, located at the mouth of the Exe Estuary. It has
a beach, a National Nature Reserve spanning 2 km2
and a golf
course amongst other amenities.
Dawlish is famous for its sand spit which works together with the
beach to protect the estuary from flooding and to shelter the
existing main railway line. A beach management scheme is in
place and ongoing, operated by the Environment Agency and
partner Teignbridge District Council.
The past mobility of the beach at Dawlish Warren is apparent
from the presence of groynes and, being currently topical, the site
provides a suitable case study to demonstrate the application and
benefits of DHI’s Shoreline Morphology module.
Planning the Study
Efficient use of the SM module requires careful consideration of
the conditions you wish to represent and a good understanding of
the physical processes that govern sediment transport and
morphology. Approximations and assumptions must usually be
made in order to arrive at a model that will simulate coastal
evolution in a timely manner, for example:
 The duration of the planned study must be considered and a
suitable wave climate developed.
 The relative contributions of tidal and wave-driven forcing to
the nearshore sediment transport regime should be
considered and, if tidal forces can reasonably be neglected,
the new quasi-stationary FMHD solver should be used.
 The speed up factor available in the FMST module should be
used whenever possible to reduce the number of time steps
required.
 If tidal forcing is important, this is usually completely
independent of the wave climate and so a typical tidal cycle
can be used in conjunction with the speed up factor to reduce
run times.
It is essential that there is a good understanding of the
requirements of the study and that the methodology to achieve
those requirements is carefully planned before model
construction begins.
©Erni/Shutterstock.com
INTRODUCING THE SHORELINE MORPHOLOGY MODULE
At Present
Until now, there were two traditional approaches to simulating
nearshore sediment transport depending on the timescale to
be considered.
The 1D n-line approach of the Littoral Processes FM Coastline
Evolution module is ideal for considering development on
decadal timescales but is limited to straight coastlines with
simple bathymetries due to the approximations made during
the calculation of the 2D sediment transport processes.
The full 2/3D Coupled Model with waves, tides and sediment
transport (FMHD, SW and FMST) gives detailed patterns of
sediment transport and instantaneous updates to morphology
over the duration of a storm or a few weeks at most. Model
run time is usually considered to be the key limiting factor for
the duration over which the Coupled Model is run. In fact, the
morphological evolution of the cross-shore profile breaks
down over time so the shape of the resulting coastal profile
becomes unrealistic.
The Future… is Now Available!
MIKE 2016 sees the introduction of the MIKE 21 Shoreline
Morphology module (MIKE 21 SM). The Shoreline Morphology
(SM) module introduces a new approach to modelling long-
term shoreline morphology which overcomes the limitations of
both the 1D and the 2/3D approaches outlined above.
The SM module is applied via the 2D Coupled Model as it
uses the sediment transport rates calculated by the FMST
module to overcome the limitations of the 1D approach above,
allowing more complex bathymetries and coastline shapes to
be considered. Furthermore, the SM module provides an
alternative to the instantaneous morphological updating that is
currently applied in the Coupled Model. The sediment volume
deposited during each time step is integrated across sections
of the coastline and the resulting change to the local
morphology is updated using a predefined cross-shore profile,
which eliminates unrealistic changes to the profile and allows
for long-term simulations.
Given that the SM module is an add-on to the Coupled Model,
runs times can be similar to using FMST for long-term
simulations. However, the addition of a quasi-stationary mode
for the HD module in MIKE 2016 can reduce run times under
appropriate conditions.
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3. 3
©DHI
Model Construction
As with all numerical models, the first requirement is data, lots of
data! With the advent of the UKHO Inspire and the EMODnet
bathymetry portals, OS OpenData from the Ordnance Survey and
opening up of LIDAR from the Environment Agency, the
availability of free online data has never been so plentiful. Using
these sources, plus the Channel Coastal Observatory for wave
observations, all the data required to construct the Dawlish model
was obtained and fed into the Mesh Generator to start the model
build process.
The Mesh Generator in MIKE 2016 has added functionality to
support the SM module. A new menu has been included which
allows the user to create the elements required for a SM module
during the mesh creation process. The image below shows the
Baseline (red), Coastline (blue) and Edge Map extent (cyan) arcs
for the Dawlish example model together with two representative
profiles (red, perpendicular to baseline). It also shows the area of
fine resolution mesh which is required within the breaker zone in
order to adequately resolve the nearshore sediment transport
regime.
Having created a suitable mesh and SM module inputs, including
the edgemap dfsu (which provides elements in the SM module
area with their corresponding vertex number along the coastline
arc) and profiles, the Coupled Model interface is used to define
the model. The three standard modules for sediment transport
modelling are chosen (FMHD, SW and FMST) and, in addition,
the check box for Shoreline Morphology is ticked. This allows
access to the SM module section of the interface where the arcs
and files created in the Mesh Generator can be loaded, as shown
below.
Model Outputs
When the SM module is activated, specified line outputs can be
selected in addition to the standard options. Transport values
along the SM module coastline
region can be exported, as well
as the evolution of the coastline
arc location over the run
duration.
Map outputs are also useful to show areas where accretion and
erosion occur as well as the overall sediment transport regime. In
this case study, the north
-eastward transport
resulting from the applied
annual wave climate
(right) can be clearly
seen in the model
outputs below, together
with areas of accretion
(yellow). This process is
a key factor in the
creation and
development of the spit over the entrance to the Exe estuary.
Additional features, including spit creation and development, time
-varying profiles and dune erosion are planned for future releases
of the SM module.
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FURTHER READING
A comprehensive presentation of the technical background
and application of the new Shoreline Morphology module was
presented by Kasper Kaergaard at the 2015 UK & Ireland
Symposium and a copy of his presentation can be found here.

4. 4
©DHI
DHI Water Environments (UK) Ltd
Ocean Village Innovation Centre
Ocean Way, Southampton
SO14 3JZ
Tel: +44 (0)2380 381961
mike.uk@dhigroup.com
http://www.mikepoweredbydhi.com/
FREQUENTLY ASKED QUESTIONS
1) What MIKE Powered by DHI version do I need in order to use
the Shoreline Morphology module?
The Shoreline Morphology (SM) module was introduced in MIKE 2016
and can be only run in MIKE 2016 or later.
2) What are the pre-requisite modules for the SM module?
MIKE 21 FMHD, MIKE 21 FMST and MIKE 21 SW.
3) What should I do if I do not have all of the above modules in
my installation at present?
Any or all of the pre-requisite modules can be purchased or rented as
required, together with the SM module. Please contact us for a
bespoke quotation.
4) We already own LITPACK, why would we use the SM module?
The new Shoreline Morphology module addresses the main limitations
of both LITPACK and MIKE 21 FMST to provide a more advanced tool
for investigating long-term shoreline evolution.
5) Does the introduction of the SM module mean LITPACK is no
longer supported?
LITPACK will continue to be supported throughout MIKE 2016. As
with any product, we reserve the right to withdraw it in the future as
and when appropriate.
6) Do I need to keep my LITPACK installation if I purchase the SM
module?
LITPACK is a different product from the SM module so, if you
envisage continuing to use LITPACK, you should maintain your
existing LITPACK installation.
7) Can I upgrade from LITPACK to the SM module?
The SM module and LITPACK are distinct products so there is no
direct upgrade path available.
8) If the SM module is new, has it been tested and used in real
world examples?
All our software is quality assured and the Shoreline Morphology
module has been used extensively within DHI in real world projects
during its development. It has now been released to our wider
customer base.
9) Have any papers been published on the SM module?
You may find the following papers of interest:
Kristensen et al (2010) Long Term Morphological Modelling,
International Conference Coastal Engineering, 2010.
Grunnet et al (2012) Evaluation of nourishment schemes based on
long-term morphological modelling. International Conference Coastal
Engineering, 2012.
Kristensen et al (2012) Morphological Modelling of the response to a
ship wreck—A case study at Cape Town International Conference
Coastal Engineering, 2012.
Kaergaard et al (2014) Long term morphological modelling using a
hybrid concept. Coasts, Marine Structures and Breakwaters (2013)
Kaergaard et al (2013) A numerical shoreline model for shorelines
with a large curvature. Coastal Engineering 74 (2013) 19-32
10) What does the Shoreline Morphology module cost?
Add-on and package pricing is available, please contact us for a
bespoke quotation on +44 2380 381961 or mike.uk@dhigroup.com.
SUPPORT
As with the entire MIKE Powered by DHI software suite,
local support for the Shoreline Morphology module is
available from the UK & Ireland team of Steve Flood,
Suzie Clarke and Mark Bailes with full back up provided
by Head Office in Denmark. We are here to provide help
in getting your software up and running as well as
technical support and guidance on optimising model
construction and configuration. The UK & Ireland support
team can be contacted on +44 2380 381961 or by email
at mike.uk@dhigroup.com.
TRAINING
In addition to the
standard support
services, a
training course has been developed to ensure new users
get the most out of the new SM module, with emphasis on
hands-on exercises. This course is recommended for
anyone considering purchasing the SM module. If you
are interested in attending the training course, please just
let us know on +44 2380 381961 or by email at
mike.uk@dhigroup.com.
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