Environmental Design of Cottesloe Rock Swimming Pool

Final Year Project Presentation

Date: 16th October 2013

Luan Nguyen Presenter, School of Civil and Resource Engineering, the University of Western Australia

Jorg Imberger & Clelia MartiSupervisors, Centre for Water Research

Motivation

• Design of the environmental parameters of a low maintenance/maintenance-free rock swimming pool, constructed as an extension of the existing groyne.

• Conduct structural design and feasibility study of the placement of the structure (to be done by Dan Courtney).

• A facility for public usage as a mean for safe swimming, disability access and recreational activities.

• To reflect the rich culture of Cottesloe and the history of the beach.

Purpose of Research

Study DomainArea of Research

SOURCE: Google Maps & Google Earth

500 m

500

m50

0 m

Current ProposalConceptual Design for the current proposal

75m

SOURCE: nearmap.com

25m

BEFORE AFTER

Objective

Determine environmental and cultural impacts of the placement of the Cottesloe

Rock Swimming Pool by delivering environmental parameters of the system as

inputs for structural design and public engagement techniques.

Goals of Research

ApproachResearch Methodology

Perth Coastal Margin

SWAN

Wave Model - SWANDescription of model

SOURCE: Google Earth

Cottesloe Domain

Weather Forecast and

Research Model (WRF)

Cottesloe Domain

SWAN

Nesting Spectrum

Field Data from Carnac Wave Logger

Wind Field

Wind Field

Wave breaking, bottom friction, reflection, diffraction, refraction and triad

Outputs: Significant wave height, period and direction

Validation: Cottesloe Wave Station

Wave Model - SWANControl Case Modified Case

SOURCE: ARMS

• Grid size: 5 x 5 m uniform grid• Quadruplets turned off due to

shallow water• Model groyne as obstacle• Size: 550 x 1010

• Pool’s wall added • Submerged reef near tip

of groyne to ensure high waves near tip of groyne

Control Case Modified Case

SOURCE: ARMS

Hydrodynamics Model - ELCOM

• Plaid grid size with 50 m coarse grid and 5m fine grid

• Wave forcing from CWR’s Perth Coastal Margin Model

• Wind data from CWR’s Lake Diagnostic System • Default coefficients as given in user manual• Size: 500 x 1000

• Pool’s wall added • Submerged reef near tip of groyne

to ensure high waves near tip of groyne

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ELCOM Tracers

SOURCE: ARMS & Google Earth

CWR’s Cottesloe Wave Logger

• Installed at the corner of SWAN’s domain • Record 15-minute intervals of wave height,

period and direction • Use as a validation tool for the model

Description of Validation Tool

CWR’s Cottesloe Wave LoggerExample of Outputs

RESULTS AND DISCUSSION

SWAN Results

Control Case Modified Case

Discussion of SWAN Outputs – Significant Wave Height

SOURCE: ARMS

SWAN ResultsComparison of the two cases

SOURCE: ARMS

SWAN ResultsComparison of the two cases

SOURCE: ARMS

Higher waves within submerged reef region

SWAN ResultsComparison of the two cases

SOURCE: ARMS

Higher waves within submerged reef region

Higher waves near pool wall

SWAN ResultsComparison of the two cases

SOURCE: ARMS

Similar wave conditions nearshore

SWAN ResultsWave near pool edge

SOURCE: ARMS

SWAN ResultsPhase Differences between High and Low Water

Graph generated by Matlab

1 2

SWAN ResultsData Validation

SOURCE: ARMS

SWAN Results

Control Case Modified Case

Discussion of SWAN Outputs – Mean Wave Period

SOURCE: ARMS

ELCOM ResultsExample of Tracer Outputs

ELCOM ResultsExample of Speed Outputs

SOURCE: ARMS

Conclusion

1. Higher waves are experienced near the tip of the groyne and submerged reef area due to depth-induced breaking

2. Higher waves near tip of groyne and lower wave near side of pool can encourage flushing cycle of the water inside the structure

3. ELCOM results suggested there are changes in current velocity near the bed which can result in changing in shoreline

Recommendations

1. Continue SWAN realtime simulation for at least 6 months to gain enough data for 75-100 years design period

2. Determine sedimentary transport rate using Shield’s parameter and current outputs from ELCOM

3. Preliminary geometric design can still be performed using available logger and model data

SWAN Wave Model

• Visit CWR’s Realtime Management System Online (RMSO)

• Select to view Simulations• Select to view the Perth Coastal Margin• Select GROYNE for control case, POOL for

modified case• Select wave parameter to be viewed

www.rmso.com.au

Details of Realtime Model

SWAN Wave ModelDetails of Realtime Model Model located under

Simulations

Model runs as nested domain in PCM

Select COT-GROYNE for Control Case, COT-POOL for modified case

Select variable to be viewed

Public Engagement

• Use as a tool for public engagement • To be used to educate, communicate to the main

user groups in WA and as a space for the community to contribute inputs to the project

• Still in development stage

www.cwr.uwa.edu.au/cottrock/

Description of Website

Public EngagementDescription of Website

Acknowledgement

• My supervisors Jorg and Clelia• Jorg’s personal assistants: Emilia and Laura T• Project initiator: Tom Locke• CWR’s staffs and field team • Special thanks to Lee and Leticia for modelling help• PhD students for providing technical assistance: Daniel,

Christina, Mahmood, Bronwyn, Vahid • Fellow intern students: Linh, Laura B, Lee, Josh, Saba, Dan,

Taylor, Melanie, Laurianne, Gwendelyn, Geraldine• My friends and family • My workplace• Project supporters including Professor Bloomfield

I would like to say thanks to:

Questions?

CWR’s Cottesloe Wave LoggerDescription of Wave Logger

CWR’s Cottesloe Wave LoggerDescription of Wave Logger