Unibest-CL+

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Unibest-CL+

Coastline development



An increasing number o people live and work in

coastal areas. The natural environment makes it an

attractive place to settle. The coastal areas are also

essential or the worlds industries, as they largely

depend on the sea transport routes. This results in

an expansion o urban and industrial developments

along the coast. Consequently, questions will

emerge with respect to saety, recreation, urban

planning, port design and ecological impacts o

human induced changes.

Coastlines are dynamic systems requiring state-o-

art models to address coast related questions. This

holds especially or ‘so’ coastlines like beaches

which mainly consist o sediments. The existing

shoreline position is oen the result o a delicate

balance between eroding and accreting orces.

Changes in position o the shoreline may thereore

occur on dierent temporal scales (months to

decades). The driving actors or these changes can

be natural or due to human induced measures.

Both natural and human induced changes to

coastlines have been studied by Deltares in a

wide variety o research and engineering projects.

Throughout the years, the coastline modelUnibest-CL+

has been developed. In applications on coasts world-

wide it has proven to be a fexible and easy-to-access

tool capable o simulating a large variety o coastal

problems. The model is able to handle complex

coastline shapes, includes state-o-art sediment

transport ormulae and has a fexible user interace.

General

The program Unibest-CL+ is a powerl tool to model longshore

sediment transports and morphodynamics o coastlines. Shoreline

migration is compted on the basis o compted longshore

transports at specic locations along the coast. I reqired

the eect o cross-shore phenomena can be assessed with the

Unibest-TC and Unibest-DE modles. The Unibest-CL+ model rns

are very time-ecient, which allows or the evalation o mltiple

scenarios as well as sensitivity analyses.

• Applications

The shoreline model Unibest-CL+ can be sed or a wide range o

coastal engineering projects. A typical application is the analysis

o the large scale morphology o coastal systems to provide

insight into the cases o coastal erosion or to predict the impact

o planned coastal inrastrctre (sch as a port) on the coast.

Shoreline evoltion comptations can be made over a period o

decades, bt also or considerations on a smaller time and spatial

scale. It is possible to evalate the shoreline evoltion arond

Unibest-CL+

Coastline development

Long Beach Peninsula, Washington, U.S.A. (Courtesy o the Washington State

Department o Ecology, SW Washington coastal erosion study).



coastal protection works (groynes, revetments, river moth

training works and to some extent detached breakwaters).

• Shoreline schematisation

The shoreline is dened relative to a ser-dened reerence line

which may be crved. This enables the modelling o complex

coastal areas sch as deltas, bays, circlar shaped beaches

and even complete islands. In these comptations changes in

the longshore transports with time de to re-orientation o the

shoreline are taken into accont.

Processes

Longshore crrents and sediment transports generated by

obliqely incoming waves are compted. Frthermore, the eect

o the tide can be inclded. The reslting gradients in the (time-

dependent) transports are sed as inpt or the shoreline model.

The model incldes a wave propagation modle to transorm the

oshore wave climate to the sr zone (assming airly niorm

depth contors) and to compte the srzone dynamics, according

to the Battjes-Stive model (1984) or wave propagation and wave

decay. Principal processes are acconted or, sch as changes

in wave energy as a reslt o bottom reraction, shoaling and

dissipation indced by wave breaking and bottom riction. The

inence o the rotation o the active part o the cross-shore

prole on wave reraction is acconted or throgh an atomatic

determination o the dynamic bondary. The distribtion o the

longshore crrent along the coastal prole is derived rom the

depth-averaged momentm eqation alongshore. A nmber o

wave-crrent interaction models (Solsby et al., 1993) can be sed

to compte the relevant bed shear stresses.

Longshore transport and its distribtion along the coastal prole

can be evalated according to several sediment transport ormlae.

This concerns ormlations that relate transport o sediment

to wave energy (like CERC and Kamphis 1991) or process based

ormlations (like Bijker, Solsby/Van Rijn, van Rijn 1992, Van Rijn

1993 and Van Rijn 2004). Frthermore, a ormlation or gravel

transport is available (Van der Meer & Pilarczyk).

Illustration o curvilinear gr id

Examples o computed distributions o longshore transport, wave height and

longshore current along the prole



The transports respond to local wave- and crrent conditions in

an instantaneos, qasi-steady way. The net longshore transport

can be compted on the basis o (p to) hndreds o combinations

o wave- and tidal conditions. Also the gross contribtions in both

directions can be derived.

An essential aspect o coastline modelling is the strong relationship

between the orientation o the coast and the longshore transport

or each cross-shore ray. This relationship is presented in a so-

called S-ϕ crve. This crve orms the basis or the shoreline

modelling since it provides inormation on transport gradients

cased by a crvatre o the coastline, as well as on the time-

dependent response o the longshore transport on changes o the

coast-orientation with time.

The shoreline movement in the coastline model is compted on the

basis o a continity eqation or sediment, compted longshore

transports (rom the S-ϕ crve) and an active prole height.

Varios initial and bondary conditions may be introdced so as to

represent a variety o coastal sitations. A non-niorm oshore

or nearshore wave climate along the coast (e.g. de to strctres)

and reslting gradients in the longshore transport can be modelled.

Gis unctionality

Unibest-CL+ incldes GIS nctionality (MAP-Objects™), which allows

or setting p models in a graphical way. The ser can se satellite

images, maps or AtoCAD drawings as a basis or the model. The

location o the coastline and strctres can then be specied

interactively on the map. Layers with dierent parts o the model

can be switched on and o depending on the ser’s preerences.

Unibest-CL+ plots the model reslts, like accretion and erosion rates

along the coastline, directly on top o the backgrond layers (maps,

images or AtoCAD drawings). Movies with compted coastline

changes can be created with the ser interace.

Tables and graphs can be created which present longshore sediment

transport, coastline position or rates o coastline change (accretion

or erosion). Detailed inormation can be exported to otpt les in

ASCII or comma seperated ormat.

Link with other models

Unibest-CL+ oers the option to retrieve inormation rom the

sophisticated 2DH wave propagation model Delft3D-WAVE (based

on SWAN). This model can be sed or the wave transormation

or sitations with complex bathymetries or large strctres

(harbor moles or oshore breakwaters). The ser can extract wave

climates at nearshore points in an interactive manner rom the

2DH wave elds. The GIS nctionality o Unibest-CL+ allows or the

visalisation o local wave climates and bathymetry o D elft3D-

WAVE otpt les.

S-ϕ curve, providing insight in salient or tombolo ormation

Coastline changes and sediment transport can be visualised in graphs or or

predened sections along the coast (red/blue = erosion; yellow = accretion).

Visualise and retrieve wave data rom Delft 3D-WAVE



With this option the development o the shoreline in and adjacent

to the shadow zones o oshore islands, harbor moles and (large)

detached breakwaters can be compted on the basis o detailed

wave modelling in a time-ecient and exible way.

Future developments

A nmber o enhancements are worked on or the next release.

This incldes, amongst others, an option to se wave time-series

instead o wave climates. Frthermore, practical nctionality will

be added like simple diraction and sheltering rotines near to

coastal strctres, improved inpt and otpt denition and batch

nctionality.

Model organisation

unibest-CL+ rns on Windows-based systems and is controlled by

a ser-riendly interace in which inpt les can be created and

edited, simlations made and model reslts graphically inspected.

The varios inpt elds are stored in dierent ASCII les, enabling

the ser to store and link dierent inpt combinations to the rns.

This inormation is administrated in special les which allows or the

creation o scenarios (combinations o measres) in the coastline

model. For the longshore transport comptations a acility is

provided to execte a large nmber o consective (sensitivity) rns.

Model input:

• wave climate: signifcant wave height, wave period, wave direction

and percentage o occurrence o each condition

• tidal regime: current velocities, water levels and percentage o

occurrence o each condition

• coastal profle shape, active zone and active profle height

• sediment: characterist ics o sand or gravel (non-cohesive sediment)

• parameters related to the selected sediment transport ormula

• parameters or wave propagation

• coastline shape / position

• boundary conditions or shoreline model

• structures: groynes, oshore breakwaters, revetments, sources/

sinks

• scenarios defning the coastline model runs (with combinations o

above input)

Model output:

• wave characteristics along the coastal profle

• cross-shore distribution o the longshore currents (wave-induced

and tidal)

• cross-shore distribution o the longshore transport

• relations between longshore transport and coast-orientation

• gradients in longshore transport along the coastline

• coastline position, migration and orientation between grid points

• coastline migration rates between grid points

Manual

Unibest-CL+ comes with a digital user & Technical manal, which

contains all necessary inormation to se the program and

nderstand the nderlying model. This manal is available in

pd-ormat.

System requirements

Unibest-CL+ is spported on Microsof Windows XP or higher. The

advised minimm reqirements are a congration consisting o:

Minimal

Processor 1 GHz

Memory (RAM) 2 GB

Disk ree 1 GB

License

For this sofware package, node locked and oating licences can

be issed. For more inormation on how to prchase this package

please contact: [email protected] or visit or web site:

www.deltaressystems.nl

Support

Deltares systems tools are spported by Deltares. A grop o 70

people in sofware development ensres continos research and

development. Spport is provided by the developers and i necessary

by the appropriate Deltares experts. These experts can provide

consltancy backp as well.

Wave eld behind an ofshore breakwater (Delft 3D-WAVE)

Longshore sediment transport or coastline with ofshore breakwater



Photo by: BeeldbankVenW.nl, Rijkswaterstaat.

PO Box 177

2600 MH Delf

Rotterdamseweg 185

2629 HD Delf

The Netherlands

+31 (0)88 335 83 00

[email protected]

www.deltaressystems.nl

Unibest-CL+

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