Assessment of Swan and Canning River Tidal and Storm Surge Water Levels - Alan Forster (URS). Presented at the 2014 MIKE by DHI UK Symposium on 13th to 14th May 2014.

1. Presentation Title
Assessment of Swan and Canning River Tidal and Storm Surge
Water Levels
13 May 2014
Acknowledgements
Australian Government Funding
Commonwealth: Natural Disaster Resilience Program
State: Department of Water
Data Sources
WA Department of Transport: Coastal Data Centre
WA Department of Water
URS Perth
Hydraulic Modelling Team

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Outline
1. Objective
2. Background
3. The Solution
4. Results
5. Challenges

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1. Objective
•Provide quantitative information that the Department of Water could use
to provide planning policy advice with respect to future flood levels in
the Swan and Canning River System.
•Achieved through a strategic level study of the Swan and Canning Rivers
to understand the role of:
-River flows
-Marine surges
-Wind and
-Sea level rise
-On the water level in the
river system

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2. Background: Location
Darlingscarp‘Thehills’
Fremantle
Swan River
Canning River
Perth CBD

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2. Background: Location
Mill Point 1926

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2. Background: Location

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2. Background: Location

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2. Background: Location
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Photographs from Brearly, 2005, “Ernest Hodgkin’s Swanland:
Estuaries and Lagoons of South-western Australia”, UWA Press.

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2. Background: Water Level Forcing
Meadow Street
Existing tidal limit

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3. The Solution: MIKE21HD(FM)
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MeadowStreet
BarrackStreet
Fremantle

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3. The Solution: MIKE 21HD (FM)
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Meadow Street
Barrack Street
Fremantle

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3. The Solution: MIKE21 SW and Overtopping Analysis

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3. The Solution: MIKE21 SW and Overtopping Analysis
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(72 km/hr)

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4. Results: Flood Maps
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4. Results: Maximum Speed
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4. Results: Long Sections
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4. Results: Wave overtopping
Overtopping Rates (litres / sec / m)

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5. Challenges: Client’s Brief and Expectations
•Client requested
- Wave setup
•Client Assembled ‘all’ input data
- Water level and flow (hydrology) data
- Bathymetry data
• LiDAR
• Bathymetric surveys
• River cross-sections (1980’s)
- No allowance for additional survey works
- Aerial photographs
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5. Challenges: Bathymetry
•Highly vegetated river valleys with no cross-section or reliable LiDAR
data
•Very shallow (<0.2m) difficult to distinguish a ‘main’ channel
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5. Challenges: Hydrology
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5. Challenges: Calibration
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5. Challenges: Calibration
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5. Challenges: Development
•Attempt 1: MIKE Flood
- Coupled model u/s of Meadow Street/MIKE21HD d/s
- Calibrated for all but high fluvial flow
- Unstable along coupling for rising flows
•Attempt 2: MIKE11 linked to MIKE21 HD(FM)
- Very poor calibration at Meadow Street for high fluvial flow
- Unsure if the model would reproduce tidal limit for sea level rise
scenarios
•Attempt 3: MIKE 21 HD (FM)
- Model A: Quadrangular mesh for channel
- Model B: Triangular mesh for channel
• Stable throughout model
• Best overall calibration
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6. Conclusion
•Project was a success for the DoW
•MIKE21HD (FM) model delivered to the DoW
•Issues with bathymetry highlighted and overcome
•Established hydrology challenged and up for review
•Identified:
- River flooding the largest risk but
- Sea level rise will have significant impact on long-
term development
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Questions?
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