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 Marti
Supervisors, Centre for Water Research
Motivation
Purpose of Research
• 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.
Study Domain
Area of Research
500 m
SOURCE: Google Maps & Google Earth
Current Proposal
Conceptual Design for the current proposal
BEFORE
SOURCE: nearmap.com
AFTER
Objective
Goals of Research
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.
Approach
Research Methodology
Wave Model - SWAN
Description of model
Wave breaking, bottom
friction, reflection, diffraction,
refraction and triad
Validation:
Cottesloe
Wave Station
Outputs:
Significant
wave
height,
period and
direction
Wind Field
Wind Field
Nesting
Spectrum
Field Data from
Carnac Wave Logger
SOURCE: Google Earth
Wave Model - SWAN
Control Case
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Grid size: 5 x 5 m uniform grid
Quadruplets turned off due to
shallow water
Model groyne as obstacle
Size: 550 x 1010
Modified Case
•
•
Pool’s wall added
Submerged reef near tip
of groyne to ensure high
waves near tip of groyne
SOURCE: ARMS
Hydrodynamics Model - ELCOM
Modified Case
Control Case
•
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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
SOURCE: ARMS
ELCOM
Tracers
4
4
3
3
2
2
1
1
5
5
6
SOURCE: ARMS &
Google Earth
6
CWR’s Cottesloe Wave Logger
Description of Validation Tool
• 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
CWR’s Cottesloe Wave Logger
Example of Outputs
RESULTS AND DISCUSSION
SWAN Results
Discussion of SWAN Outputs – Significant Wave Height
Control Case
SOURCE: ARMS
Modified Case
SWAN Results
Comparison of the two cases
SOURCE: ARMS
SWAN Results
Comparison of the two cases
SOURCE: ARMS
Higher waves within
submerged reef region
SWAN Results
Comparison of the two cases
SOURCE: ARMS
Higher waves near pool
wall
Higher waves within
submerged reef region
SWAN Results
Comparison of the two cases
SOURCE: ARMS
Similar wave conditions
nearshore
SWAN Results
Wave near pool edge
SOURCE: ARMS
SWAN Results
Phase Differences between High and Low Water
1 2
H
η = sin(𝑘𝑥 − 𝜔𝑡)
2
𝑘=
2𝜋
𝐿
2𝜋
𝜔=
𝑇
Graph generated by Matlab
SWAN Results
Data Validation
SOURCE: ARMS
SWAN Results
Discussion of SWAN Outputs – Mean Wave Period
Control Case
SOURCE: ARMS
Modified Case
ELCOM Results
Example of Tracer Outputs
ELCOM Results
Example 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
Details of Realtime 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
SWAN Wave Model
Details of Realtime Model
Model located under
Simulations
Model
runs as
nested
domain
in PCM
Select COT-GROYNE
for Control Case,
COT-POOL for
Select variable to be
viewed
Public Engagement
Description of Website
• 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/
Public Engagement
Description of Website
Acknowledgement
I would like to say thanks to:
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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
Questions?
CWR’s Cottesloe Wave Logger
Description of Wave Logger
CWR’s Cottesloe Wave Logger
Description of Wave Logger