Coastal Numerical Modelling ASR

7/27/2019 Coastal Numerical Modelling ASR

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ASR 2002

MODELS AND

PHYSICAL SYSTEMS

Environments

Calibration / Validation

Dr Kerry Black

ASR Ltd


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Storm surge

Tsunamis

Tidal flows

Eddies

Shelf waves

Up/downwelling

Wind-driven flows

Waves

Estuarine salinity intrusion

Water quality

Oil spills

Effluent dispersion

Ocean outfalls

River plumes

Thermal discharges

Larval transport

Seabed erosion/accretion

Bank/delta formation

Sand bar migration

Dredging and spoil disposal

Physical disturbance of ecosystems

Wave climate hindcasts

Coastal hazards

Foreshore impacts

Coastal protection

Coastal structures and reclamations

Longshore sediment transportPorts and marinas

Harbour seiching

3-dimensional flows,

dispersal, short-wave

and ocean/atmosphere

heat transfer model.

Lagrangian 3-dimensional dispersal

model for transport of dissolved,

passive and active material such as

larvae, effluent, bacteria or sediment.

WAM Deep-water spectral wave generation/propagation

SWAN coastal-scale spectral wave generation and propagation

WGEN3DD estuary wave climate

2DBEACH beach circulation and sediment transport

GENIUS sedimentation around coastal structures

RCPWAVE refraction/diffraction of monochromatic waves

WBEND refraction of monochromatic and spectral waves

3DD

POL3DD

WAVE MODELS


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Environments

Models are applied to a broad range of

physical environments.

They operate over a range of spatial and

temporal scales.

The following slides present a sequence ofcommon environments where models are

being regularly used and calibrated.


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Oceans

Ocean-scale wave generation modelling forweather and scientific / public use


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Continental shelf

Upwelling brings nutrients to the coast

Hot

surfacewater

Coldupwelled

water

Auckland


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Gulfs

Hauraki Gulf is a prime fisheries location

Ocean

water levels

lead the

levels in the

inner Gulf

Incoming

flood tide


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Inner shelf

The site for the upcoming AmericasCup yacht race

Waitemata Harbour

Fastcurrents in

the narrow

channelscontrast

with the

shelteredlees of

headlands

and islands


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Estuaries

A large inter-tidal estuary disperses anddilutes effluent from an outfall

Inter-tidal sand

banks

Maximum

effluent

concentrations

around the

outfall dilutedue to

advection and

mixing


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Headlands

Larvae disperse from a marine park


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Australias Great Barrier

Reef

Currents disperselarvae around reefs and

reef groups

B h


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Beaches

A dynamic ocean beach, New ZealandWaves approach the

beach at an angle

Sand

ridge Sand bar


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Sea bed

Predicted micro-scale suspension overripples


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Field programmesField measurements underpin the

development, refinement and application

of numerical models.

For comprehensive models, large fieldprogrammes are needed to

simultaneously measure the complete

range of physical processes.

Field measurements require many

different instruments and techniques.


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Comprehensive field programmes define

the nature of sites to be modelled

Poverty Bay portre-development

study used 3-

dimensional

stratified

temperature and

salinity models

calibrated againstmeasurements


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Hauraki Gulf NOSEX programme

Measurements of

currents, tides,waves,

temperatures and

sedimenttransport over

several months

P t D d S il Di l St d


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Port Dredge Spoil Disposal Study

Sediment traps, wave/current meters,

artificial fluorescent tracer, bathymetry

surveys and side-scan sonar

Waves, currents and

sediment traps

Sediment traps

only

Waves and

sediment traps


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Port

Fluorescent tracers track the movement of dredge

spoil along the high-energy west coast of NZ.

Tracer sampling sites and release points

Tracer release sites


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ALICE

A bottom-mounted

instrumented frame

records currents,

waves, suspendedsediment

concentration,

bedforms andcollects water

samples


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An S4current

meter

retrievedby a

diver


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Cooks Beach


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Sea sled with Acoustic

Backscatter Sensors

and vertical profilermeasure sediment

concentration at high

resolution

Centre of Excellenceautomated water

samplers deployed by

ETS Ltd in UK to assess

impacts of dredge spoildumping


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Sea Bed

Rudolph

Beach sled records waves, currents,

turbulence, and suspended sediment

concentration while observing with shore-linked video.


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Sea bed

RUDOLPH

Beach sled

towed intoposition.

S b d


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Sea bed

High-resolution suspended sedimentconcentrations within millimetres of the sea bed

Sand is suspended by waves

Wave orbital currents

Sea Bed


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Sea Bed

IMAGENEX

Rotary scanning

sonar measuresbedforms in situ.

Concentric rings

are 1 m apart and

centred on ALICE

Bedform measurements during a tropical cyclone


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Models develop over decades

This photograph shows waves being recorded at AlaMoana in Hawaii in the early 70s by J.K.K. Look

Laboratory. The data was used for development of the

numerical wave model 2DBeach.


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Calibration / Validation

Ensures that the model is

accurate

Guides model development and

refinement

Ensures that model constants are

correct for each location modelled

Oceans


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500 km

10 20 30 40 50

5

10

15

20

25

30

35

40

45

i

j

Wave height

Wave direction

Wave period

Oceans

Ocean wave models are

calibrated against long-term wave measurements

Continental shelf


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Coastal upwelling model is compared to sea

surface temperatures viewed from space

Satellite imageModel

Gulfs


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Tidal models are calibrated against

measured long-term tides

Tidal phase Tidal amplitude

Field

sites

Inner shelf


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Inner shelf

Predicted wind and shelf currents arecompared to measurements

Inner shelf


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Inner shelf

The prediction of bedform geometryon the inner continental shelf is

confirmed against observations

70 60 50 40 30 20 10 00

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

(B)

2 m, 9 s wave

3 m, 9 s wave

4 m, 9 s wave

2 m, 12 s wave

3 m, 12 s wave

4 m, 12 s wave

East Gippsland data

Coastal embayments


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y

3-dimensional baroclinic models are compared tocurrents, temperatures, and many other physical

variables

Currents

Temperatures

Coastal embayments


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y

Models are compared to measured waves.

Wave advance

Wave height and direction

Wave advance

Coastal embayments


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0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 0.05 0.1 0.15

ErrorValu

e

CF

Value

Coastal embayments

Errors are minimised systematically by

successive adjustment of model constants

Estuaries


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Flo

wd

irecti

on

Plume models

are compared to

dye releases


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Ports

Wave excitation models

of a port are compared to

measured spectra of seasurface conditions

Sea bed


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Micro-scale sediment transport models are

compared to high-resolution data, at 10 Hz within

10 mm of the seabed

Sedimen

tconcentr

ations

Physical model


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Reef

Physical model

Mathematical model

Beaches

Mathematical models are sometimes

compared to laboratory physical models

Beaches


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Micro-scale suspension phenomena lead tomeasured shoreline evolution. Here, measured

profiles are compared to model predictions

0 5 1 0 1 5 2 0 -0 .0 6

-0 .0 4

-0 .0 2

0

0 .0 2

0 .0 4

0 .0 6

0 .0 8

Accretion

(m)

X (m )


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Numerical models provide :

confident predictions ofnatural processes.

spatial and temporal

resolution improvement

Calibration ensures that the

model is accurate

Storm surge

3DD


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Tsunamis

Tidal flows

Eddies

Shelf waves

Up/downwelling

Wind-driven flows

Waves

Estuarine salinity intrusion

Water quality

Oil spills

Effluent dispersion

Ocean outfalls

River plumes

Thermal discharges

Larval transport

Seabed erosion/accretion

Bank/delta formation

Sand bar migration

Dredging and spoil disposal

Physical disturbance of ecosystems

Wave climate hindcasts

Coastal hazards

Foreshore impacts

Coastal protection

Coastal structures and reclamations

Longshore sediment transport

Ports and marinas

Harbour seiching

3-dimensional flows,

dispersal, short-wave

and ocean/atmosphere

heat transfer model.

Lagrangian 3-dimensional dispersal

model for transport of dissolved,

passive and active material such as

larvae, effluent, bacteria or sediment.

WAM Deep-water spectral wave generation/propagation

SWAN coastal-scale spectral wave generation and propagation

WGEN3DD estuary wave climate

2DBEACH beach circulation and sediment transport

GENIUS sedimentation around coastal structures

RCPWAVE refraction/diffraction of monochromatic waves

WBEND refraction of monochromatic and spectral waves

3DD

POL3DD

WAVE MODELS

Thanks to the Centre of Excellence


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Thanks to the Centre of Excellence

in Coastal Oceanography and Marine Geology

and

John Oldman

for assisting with the display preparation and

Richard GormanTerry Hume

James Hutt

Judith BoglePeter McComb

for providing images.


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For enquiries contact:

Prof Kerry Black

ASR LtdPO Box 67, Raglan, New Zealand

[email protected]

Documents

Coastal Numerical Modelling ASR