Setting the Foundation for ROCKHAMPTON

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Setting the Foundation for ROCKHAMPTON

Stuart Harvey (RRC)

Jordan Maultby (AECOM)

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Structure

1. Background

2. Floodplain Management Services (FMS) Delivery Program

a) Phase 1 b) Phase 2 c) Phase 3

3. Where to from here?

4. Questions

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• Recent History

• Objectives

• Project Design

Background:

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4 FMS: Setting the Foundation for Rockhampton

A (brief) history

2008 Minor River + Major Flash Floods

2011 Major River Flood (TC Yasi)

Queensland Floods Commission of Enquiry

2012 Development of Local Creek Flood Studies

2013 Major Flash Floods (Ex-TC Oswald) Completion of Local Creek Flood Studies

2015 Major Flash Floods (TC Marcia)

Rockhampton / Livingstone 2015 LiDAR Project

2016 Council makes a budget commitment of $3M / year for stormwater projects

2017 Floodplain Management Services Project commences Major River + Minor Flash Floods (Ex-TC Debbie)

2018 Floodplain Management Services Project concludes

2019 Community Consultation

Planning Scheme Implementation

This Study

+ Calibration Data

Previous Study

+ Calibration Data

+ Topographic Data

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Project Context

Since the completion of the previous Flood Studies in 2013, a significant body of work had been completed in the floodplain management area:

• Calibration data from Ex-TC Oswald (2013) & TC Marcia (2015)

• Several significant local catchment flood mitigation projects to a construction stage

• Council had identified several projects in the urban areas of each catchment to address local catchment flooding.

At the completion of the 2013 Flood studies there was a commitment to undertake

regular updates to the flood models to ensure up to date information is available in

each catchment.

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1. Establish high quality, consistent modelling standards

2. Implement Handbook 7:

Guideline to Floodplain Management

a) Update flood models

b) Quantify risk and exposure

c) Identify and progress flash flood mitigation options

Objectives

Phases 1 & 2

Future Works

Phases 2 & 3

FMS: Setting the Foundation for Rockhampton

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Project Design

• Council identified a large body of stormwater and floodplain management work that was to be completed over the 2017-18 period.

• Council decided to bundle projects into a suite of floodplain management services.

• Fixed budget & timeframe

• Flexible program of works

FMS

Industry Advances

New Data

Flood

Studies

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Benefits & Challenges

Benefits Challenges

Consistency Cost savings Ease of procurement Fluidity of program of works Risk sharing

Fluidity of program of works

Fee for services meant a need to carefully project manage

Reduced tender time Long-term resource surety Consistent deliverables & QA Risk sharing

High flexibility required to meet dynamic program

Maintaining consistent team Monitoring / evaluating client relationship

C lie n t C o n sul ta n t

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Project Deliverables

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FMS Delivery Program:

Guideline Reviews &

Workshops

Phase 1 (Baseline Modelling)

Phase 2 (Quantify Flood

Risk)

Phase 3

(Flood Risk

Mitigation)

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ARR 16 Pilot Study - Context

THIS STUDY

(O’Callaghan et al. 2018)

Cumulative

No. of

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ARR 16 Pilot Study - Outcomes

Finding: Slight ▼decrease in flood heights*

Decision: Continue using ARR 87

Develop a plan to implement ARR 16

Reasons: ARR 16 was not consistently

adopted by industry & government Currently in a transition phase

Software catching up

*Study completed in March 2017

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• Overview

• Data Challenges

Phase 1

Flood Model Development:

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Phase 1 - Overview

Key Changes:

• Hydraulic structures

• Finer model grid (from 5m to 3m)

• Topography (2015 LiDAR + survey)

• Re-calibration + validation

Previousstudy’sflood extent Thisstudy’sflood extent

Lumped Hydrology

Rain-on-

Grid

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Community Involvement

• Several locations where no previous calibrated model existed (e.g.):

• South Rockhampton

• West Rockhampton

• Community Doorknock and data collection to

assist model development

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Phase 1 – Data Challenges

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Phase 1 Outcomes

10

updated flood models

10,000 hydraulic structures

53,300 hectares modelled

+17M model grid cells

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• Building Impacts

• Flood Damage

• Detailed Analysis

Phase 2

Flood Hazard & Risk Assessment:

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Phase 2 – Building Impacts

Building inundation due to flash flooding

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Phase 2 – Flood Damages

Total Tangible Flood Damage 1 in 2 $4 M

1 in 5 $12 M 1 in 10 $20 M 1 in 20 $30 M 1 in 50 $45 M 1 in 100 $61 M 1 in 500 $145 M 1 in 2,000 $247 M PMF $949 M

AEP

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Phase 2 – Detailed Analysis

80%

of the total AAD is contributed by

89 buildings*

*Catchment example

Self-scrutinize major flow paths and high-impact buildings!

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Phase 2 Outcomes

$61M tangible flood damage in 1% AEP

815 buildings flooded in 1% AEP

2,404 properties flooded in 1% AEP

$8M

Cumulative average annual damage

identified

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• Overview

• Heatmaps + Precincts

• Mitigation Scheme Effectiveness

Phase 3

Mitigation Options Development :

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Phase 3 – Overview

Flood Damage Heatmaps

Flood Risk Precincts

Project Identification

Project Multi- Criteria Assessment

Project Performance Collaborative Workshops

Phases

1 + 2

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Phase 3 – Heat Maps + Precincts

• Council’s projects

• Flooded buildings

• Flood hazard

• Vulnerable infrastructure

• Evacuation routes

• AAD heatmaps, which identified flood damage hotspots

Flood Mitigation

Projects

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Phase 3 – Flood Mitigation Schemes Effectiveness

5,998 2,318

1,482 600

446 320 214 141 56

6,090 2,477

1,649 815

637 450 304 198 79

PMF 1 in 2000 1 in 500 1 in 100 1 in 50 1 in 20 1 in 10 1 in 5 1 in 2

600 446

320 214 141 56

815 637

450 304 198 79

1 in 100 1 in 50 1 in 20 1 in 10 1 in 5

1 in 2 Existing

Conditions Post-Phase 3 Construction

11 Flood Mitigation Schemes taken forward

Measure 1 in 10 AEP 1 in 100 AEP Mitigation of building floors inundated 90 (30%) 215 (26%)

Mitigation of flood damage $8.6M (43%) $25.5M (42%) Mitigation of average annual damage $2.2M (27%)

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Phase 3 Outcomes

63

Flood risk precincts identified

83 Local Catchment Flood Mitigation

Projects

$120M

capital estimate

11 Schemes taken forward to concept design

$88M

capital

estimate

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Where to from here?

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Strategic Support - RRC Flood Management Strategy (2014)

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Into the Future

• Community Consultation

• Sharing information on flood risk with community

• Community information of flood experiences

• Community involvement in further mitigation projects

• Flood searches

• Land Use Planning and Policy

• Planning Scheme Policy

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