evolution in flood modelling based on the example of the...

Evolution in flood modelling

based on the example of the Bruce

Highway Crossing over the Eudlo Creek

Anne Kolega, BMT

2019 IPWEAQ Annual Conference, 22 - 24 October 2019

Acknowledgement

• I would like to acknowledge for their support in this project and

willingness to share the presentation:

– Department of Transport and Main Roads

– WSP Australia Pty Limited

Thank you!

Presentation Outline

• Why? - Drivers and benefits of the Evolution of Flood Modelling

• Location

• Data

• Modelling guidelines - ARR 1987, ARR 2016/2019, Monte Carlo

• Modelling approaches - Software Evolution in Eudlo Creek

• Hardware Evolution - TUFLOW Classic versus TUFLOW HPC

• Importance of model calibration

• New 2019 modelling features – TUFLOW HPC Sub-grid sampling / Quadtree

• Summary

• Why have we invested so much

money and effort into hydraulic

modelling

• What are the benefits

• What can we learn from this?

Why? - Benefits of the Evolution of Flood Modelling

Brisbane January 2011

Centenary Highway Mt Ommaney

Why?

January 2011 Flood in Brisbane

Benefits for future assessment - learnings

• More development pressure

• More people living in Australia

• Higher flood risk

• More safety required

• We seek to reduce uncertainties

• Use of additional data collected over the last 30 years - rainfall and river

gauge data

• Significantly increased flood damages

• Affect of climate change is likely to worsen the above

• Better data and more certainty



• Location

• Data






• Summary

Location Bruce Highway Crossing over the Eudlo Creek

• Bruce Highway one lane

• Bruce Highway Duplication

• Business Case and Detail

Design of Eastern and

Western Service Roads

• Potential Future Raising of the

Bruce Highway



• Location

• Data






• Summary

Data

In the 1990:

• Ground survey

• Contours

• Photos

Now:

• LiDAR covering large areas

• Additional ground survey

• Bathymetry

• Aerial imagery

• Vegetation layers

44

44.5

45

45.5

46

46.5

47

47.5

48

48.5

49

49.5

0 5 10 15 20 25



• Location

• Data





• New 2019 modelling features - TUFLOW HPC Subgrid sampling / Quadtree

• Summary

Modelling Guidelines – ARR and Monte Carlo

Reducing uncertainty / Increasing defensibility

?

Time

Flo

w

Monte Carlo

Thousands of

hydrographs per AEP

Vary all major factors

1977 1987

Single hydrograph per duration

per AEP

Time

Flo

w

All inputs fixed

2016/2019

Time

Flo

w

Ensemble 10

hydrographs per

duration per AEP

Vary temporal patterns

Modelling Guidelines – ARR and Monte Carlo

?

Monte Carlo

Thousands of

hydrographs per AEP

1977 1987

Single hydrograph per duration

per AEP

2016/2019

Ensemble 10

hydrographs per

duration per AEP

Hydro

RobustusHydro

Erectus

Hydro

Neanderthalensis

Hydro

Sapiens

Reducing uncertainty / Increasing defensibility



• Location

• Data






• Summary

Hydraulic Modelling Approaches – Software Evolution

• Modelling approaches used for Eudlo Creek:

– 1D model

– 1D/2D TUFLOW Classic

– 1:30 scale Physical Model for verification

– TUFLOW HPC

– TUFLOW FV

TUFLOW Numerical Models used in Eudlo Creek

1D/2D TUFLOW Classic

/ HPCGPU Hardware

AD

TUFLOW FVAD / Sediment Transport /

Morphology / Water Quality

Fixed Grid Flexible Mesh

1D ESTRYOpen channel

Pipe network

1D

Why 2D Modelling instead of 1D?

Topography at Bruce Highway over Eudlo Creek

1D Modelling

Basic 1D Network Example


2D Model Example

Better coverage representation

(vegetation cover or elevation)

Requires significantly less engineering judgment to

get the correct answer

2D Modelling Results

Physical Model in Eudlo Creek

Model Configuration with Roughness Elements

Model Bridge Structure Pre-duplication of Highway 1983

Model Bridge Structure for Highway Duplication

Bill Syme comment:

• No one believes a computer model

(except for the modeller)

• but everyone believes a physical

model

(except for the modeller)



• Location

• Data






• Summary

Hardware Evolution -TUFLOW Classic versus HPC

• 1D versus 1D / 2D

• TUFLOW Classic / HPC

• TUFLOW HPC

Central Processing Unit (CPU)

VS

TUFLOW Classic

TUFLOW HPC + GPU Module

Central Processing Unit (CPU) Graphic Processing Unit (GPU)

Hydraulic Modelling Hardware Evolution - CPU vs GPU

VS

Cell Count

7,500 cells

31,000 cells

125,000 cells

750,000 cells

3,100,000 cells

12,500,000 cells

Classic CPU(pre 2017 standard)

0:12 hr

0:15 hr

1:32 hr

15:19 hr

146:0 hr

≈48 days

Speed-upRatio

4

5

23

51

81

86

• Cell Size

• 20m

• 10m

• 5m

• 2m

• 1m

• 0.5m

HPC GPU(current standard)

0:03 hr

0:03 hr

0:04 hr

0:18 hr

1:47 hr

13:18 hr



• Location

• Data


• Modelling approaches and software available and used for Eudlo Creek

• TUFLOW Classic versus TUFLOW HPC



• Summary

Importance of model calibration

• Model calibration was undertaken

for all models TUFLOW Classic, FV

and TUFLOW HPC

• Various historic events were

assessed: 1983, 1992, 1999, 2012,

2013 and 2015

• Good calibration was achieved

for both models



• Location

• Data





• New 2019 modelling features – TUFLOW HPC Sub-grid Sampling /

Quadtree

• Summary

TUFLOW HPC Sub-grid Sampling / Quadtree Features

Sub-grid Sampling TUFLOW GPC Quadtree

Sub-grid Sampling

Cell volume elevation point

Cell face elevation point

Current Cell Volume / Face Schema


• Mesh refinement

• Maximum cell division of 2

across adjacent cells

• Requires user input on where to

refine mesh => easier workflow

than flexible mesh

• Adjustable resolution =

refinement only where necessary

= efficient memory utilisation


Three Tier Quadtree Nesting Benchmark

5m Single domain 5m – 2.5m – 1.25m quadtree domain


Single Domain(current standard)

0:03 hr

0:03 hr

0:04 hr

0:18 hr

1:47 hr

13:18 hr

• Cell Size

• 20m

• 10m

• 5m

• 2m

• 1m

• 0.5m

Speed-upRatio

1.3

3.6

4.1

3.5

HPC Single vs Quadtree Simulation Speed-up

Cell Size

20m / 10m / 5m

10m / 5m / 2.5m

5m / 2.5m / 1.25m

2m / 1m / 0.5m

Quadtree(future standard)

0:03 hr

0:05 hr

0:26 hr

3:47 hr

over 300 times faster than CPU

using a single domain!




• Data





• Future modelling features – TUFLOW HPC Subgrid sampling and Quadtree

• Summary

Summary – Evolution Flood Modelling

Individual development – no common goal

• Evolution in data available

• Evolution in guidelines – Australian Rainfall and Runoff

• Evolution in Hardware

• Evolution in Software

• Evolution in Flood Modelling

Summary Key points and Benefits

• Better data and more certainty

• Better inform development to reduce flood risk and improve safety

• Use of additional data collected over the last 30 years - rainfall and river

gauge data

• Simulate larger areas with more certainty

• Aim to reduce flood damages

• Better inform the effect of climate change

Thank you!!!Anne Kolega

[email protected]

mailto:[email protected]

evolution in flood modelling based on the example of the...

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