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2015-03-31 I&S Committee - Item 4 - Attachment 1 - Flood Mitigation Investigation Ashgrove Dr Cooroy
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Flood Mitigation Investigation: Ashgrove Drive, Cooroy
Flood Mitigation Investigation:
Ashgrove Drive, Cooroy
Prepared By:
Hydrology and Water
Management Consulting Pty Ltd
Prepared For:
Noosa Council
Reference: J00158D1V1
Date: 22 June 2014
Hydrology and Water Management Consulting Pty Ltd
PO Box 120 Coolum Beach Qld 4573
Tel 07 5448 2839 Mob 0405 194 639
Email [email protected]
Web www.hydrologyandwater.com.au
ABN 25 153 466 981 ACN 153 466 981
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Section 2
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
Disclaimer
This report has been prepared on behalf of and for the exclusive use of Noosa Council. It is subject to the provisions of
the agreement between Hydrology and Water Management Consulting Pty Ltd (HWMC) and Noosa Council. HWMC
accepts no liability, or responsibility whatsoever, for it in respect of any use of or reliance upon this report by any third
party. Study results should not be used for purposes other than those for which they were prepared.
© Copyright 2014 Hydrology and Water Management Consulting Pty Ltd.
Copyright
The information and concepts contained in this document are the property of Hydrology and Water Management
Consulting Pty Ltd (HWMC). Use or copying of this document in whole or in part without the written permission of HWMC
constitutes an infringement of copyright.
Report Status
Reference Date Status Author
J00158D1V1 22/6/2014 Draft ________
R Stewart
RPEQ 13272
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Section 3
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
TABLE OF CONTENTS
1 INTRODUCTION ...............................................................................................................................................1
2 AVAILABLE DATA .............................................................................................................................................2
3 EXISTING SITE TOPOGRAPHY AND FLOODING CHARACTERISTICS ....................................................................3
4 FLOOD MITIGATION ANALYSIS ........................................................................................................................5
4.1 METHODOLOGY ..................................................................................................................................................5
4.2 BASE CASE .........................................................................................................................................................5
4.3 OPTIONS ANALYSIS ..............................................................................................................................................5
5 DISCUSSION ON THE PREFERRED OPTION........................................................................................................9
5.1 PEAK FLOOD LEVEL IMPACTS .................................................................................................................................9
6 KEY HYDRAULIC REQUIREMENTS & DESIGN INPUTS FOR THE PREFFERED OPTION ........................................11
7 CONCLUSIONS ...............................................................................................................................................13
8 QUALIFICATIONS & LIMITATIONS ..................................................................................................................14
9 REFERENCES ..................................................................................................................................................15
List of Appendices
Appendix A Existing Case Peak Flood Depth and Flow Velocity Mapping
Appendix B Concept Design of Preferred Mitigation Option
Appendix C Mitigated Case Peak Flood Depth and Flow Velocity Mapping
Appendix D Peak Flood Level Impact Mapping
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Section 4
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
Abbreviations
1D One-Dimensional
2D Two-Dimensional
AEP Annual Exceedance Probability
ARI Average Recurrence Interval
AHD Australian Height Datum
AR&R Australian Rainfall and Runoff
BoM Bureau of Meteorology
DEM Digital Elevation Model
DERM Department of Environment and Resource Management (Queensland)
DIS Duration Independent Storm
DTMR Department Of Transport and Main Roads (Queensland)
GIS Geographic Information Systems
HWMC Hydrology and Water Management Consulting Pty Ltd
IEAust Engineers Australia
IFD Intensity Frequency Duration (Rainfall Intensities)
PMF Probable Maximum Flood
PMP Probable Maximum Precipitation
QRT Quantile Regression Technique
RCP Reinforced Concrete Pipe
RCBC Reinforced Concrete Box Culvert
NC Noosa Council
SPP State Planning Policy
TIN Triangular Irregular Network
QUDM Queensland Urban Drainage Manual
WBNM Watershed Bounded Network Model (Hydrologic Modelling Software)
WSUD Water Sensitive Urban Design
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Section 5
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
1 INTRODUCTION
Hydrology and Water Management Consulting Pty Ltd (HWMC) has been commissioned by Noosa
Council to undertake a hydraulic investigation to explore opportunities for flood mitigation at
Ashgrove Drive in Cooroy.
This project follows on from HWMC’s December 2013 review of flood mitigation opportunities for
Cooroy. The 2013 review identified that the upcoming upgrade to the Bruce Highway at Cooroy
presents an opportunity to mitigate Cooroy Creek flooding of the existing residential properties on
Ashgrove Drive.
HMWC have attended meetings with Noosa Council, the Department of Transport and Main Roads
(DTMR) and their civil engineers, GHD to discuss this opportunity and the mitigation options
analysed for this investigation have been selected in consultation with these organisations.
The flood models used for the design of the Bruce Highway Upgrade have provided by GHD for
use in this investigation. With these models, HWMC have been able to do a comparison of the
existing scenario flooding characteristics with the upgraded highway in conjunction with Ashgrove
Drive flood mitigation works.
The purpose of this investigation is as follows:
Test a number of flood mitigation options for Ashgrove Drive and select a preferred
mitigation option;
Develop a preliminary concept design for the preferred mitigation option
Carry out flood modelling to demonstrate the associated flood impacts and flood benefits
across a range of magnitude flood events.
Describe the key hydraulic requirements of the flood mitigation option and detail relevant
hydraulic parameters to guide future detail design of these works, which HWMC understand
will be carried out by DTMR’s civil engineers, GHD.
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Section 6
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
2 AVAILABLE DATA
A description of the data used in this investigation is tabulated below.
Table 2-1 Data Utilised for the Investigation
Item
Data Description
No.
The hydraulic model (TUFLOW) and the hydrologic model (XP-RAFTS) used by GHD for
1 the modelling of the Bruce Highway Upgrade have been provided by GHD for use in this
investigation.
A 1 meter resolution digital elevation model (DEM) based on Aerial LiDAR survey captured
2
in 2008.
Aerial photography captured in 2008 by the QLD Government department formerly known
3
as DERM.
GHD’s Report for DTMR: Bruce Highway (Cooroy to Curra) Upgrade, Section A (Cooroy
4 Southern Interchange – Sankeys Road); Hydraulic Analysis Supplementary Report
(November 2012)
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Section 7
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
3 EXISTING SITE TOPOGRAPHY AND FLOODING CHARACTERISTICS
The Ashgrove Drive estate is built across a small tributary of Cooroy Creek which also forms an
active flow path of the Cooroy Creek floodplain during times of flood. The location of the study
area is shown on Image 3-1 below which also shows surrounding topography (1m contours with
thematic mapping) and the path of the local tributary through the estate.
The current drainage easements and infrastructure at Ashgrove Drive are not sufficient to convey
Cooroy Creek flows and consequently floodwaters enter the surrounding residential properties.
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Image 3-1 Study Focus Area Location and Surrounding Topography
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Section 8
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
Existing scenario Cooroy Creek flooding characteristics through the study area are shown in
Appendix A. Results are presented for the following design flood events:
10% Annual Exceedance Probability (AEP) design flood. A flood of this magnitude has a
1 in 10 chance of occurring every year.
1% AEP design flood. A flood of this magnitude has a 1 in 100 chance of occurring every
year.
0.05% AEP design flood. A flood of this magnitude has a 1 in 2000 chance of occurring
every year.
Results show that under existing conditions, major floods overtop the Bruce highway to the east of
Cooroy Creek and are directed straight towards the Ashgrove Drive Estate.
Aerial imagery of the study focus area is provided on Image 3-2.
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Image 3-2 Aerial Imagery of the Study Focus Area
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Section 9
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
4 FLOOD MITIGATION ANALYSIS
4.1 Methodology
Flood mitigation analysis has been undertaking utilising the hydraulic and hydrologic models setup
by GHD for modelling of the Bruce Highway Upgrade. These models have been provided for the
existing case and the highway upgrade case.
The flood mitigation options have been assessed by incorporating them into the highway upgrade
case flood model. This enables flood impact mapping to be produced showing the overall
combined impact of the Bruce highway upgrade in conjunction with the flood mitigation works. This
approach has been chosen based upon the assumption that the mitigation works will be
constructed at the same time as the highway upgrade.
Analysis of various flood mitigation options has been carried out and from these, a preferred option
has been selected in consultation with Noosa Council.
4.2 Base Case
The base case models used for the current project are a copy of existing case models supplied by
GHD. Models has been re-established and run the 10%, 1% and 0.05% AEP design events as
detailed in Section 3.
The hydrologic model has been run for the full range of standard design storm event durations and
the critical event duration has been used for the hydraulic analysis. The critical event durations for
the 10%, 1% and 0.05% AEP are 24hr, 24hr and 2hr respectively.
The base case model results are provided in Appendix A.
4.3 Options Analysis
The following flood mitigation options have been assessed for this project:
Option 1 – Diversion Channel Parallel to Bruce Highway (Preferred Option)
This is the preferred flood mitigation option coming out of this project. A concept design drawing
is provided in Appendix B. The objective of this option is to collect floodwaters and convey in north-
west direction, parallel to the Bruce Highway towards Cooroy Creek.
In the low lying ground situated in the eastern area of these works, the diversion channel has been
formed with an earth embankment running along the eastern side of the channel. In the western
region of these works the channel can be constructed in cut and it is likely that a bund will not be
required to contain flows (subject to survey of ground and final design of channel).
The basic line-work applied in the TUFLOW flood modelling is shown on Image 4-1 below along
with the mitigated case 1% AEP flooding characteristics. This image shows how the diversion
channel effectively captures flood waters, diverts them away from Ashgrove Avenue and directs
flow to Cooroy Creek
Peak flood depth and flow velocity vector mapping is provided in Appendix C for this preferred
mitigation option. Peak flood level impacts maps are provide in Appendix D. These reflect the
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overall combined impact of the mitigation works in conjunction with the Bruce Highway Upgrade.
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Section 10
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
Image 4-1 Option 1 Flood Model Line-work and Associated 1% AEP Flood Characteristics
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Section 11
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
Option 2 – Resumption of 25 Ashgrove Drive
This option involved resumption of the existing residential property at 25 Ashgrove Drive in order
to provide a flood corridor through the estate with sufficient width to cater for Cooroy Creek flood
waters. In addition to this, it was assumed that an earth bund would be constructed along the rear
of the Ashgrove Drive lots to direct flows to the flood corridor.
This flood mitigation option was not selected as the preferred mitigation option because it caused
flood impacts over the existing residential properties downstream of Ashgrove Drive. There would
also be a high cost associated with the property resumption.
The basic line-work applied in the TUFLOW flood modelling is shown on Image 4-2 below along
with the mitigated case 1% AEP flooding characteristics.
Image 4-2 Option 2 Flood Model Line-work and Associated 1% AEP Flood Characteristics
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Section 12
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
Option 3 – Ashgrove Drive Culvert Upgrade with Inlet Works & Upstream Bunds
This option is similar to Option 2 expect that a property resumption is not required. Instead, flood
waters are directed to the existing drainage easement at Ashgrove Drive and upgraded culverts
convey flow through the estate. Flood waters are captured with a bund extending to the Bruce
Highway and an improved inlet channel would be constructed leading into the upgraded culverts.
This flood mitigation option was not selected as the preferred mitigation option because it caused
flood impacts over the existing residential properties downstream of Ashgrove Drive.
The basic line-work applied in the TUFLOW flood modelling is shown on Image 4-3 below along
with the mitigated case 1% AEP flooding characteristics.
Image 4-3 Option 3 Flood Model Line-work and Associated 1% AEP Flood Characteristics
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Section 13
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
5 DISCUSSION ON THE PREFERRED OPTION
5.1 Peak Flood Level Impacts
The flood mapping figures provided in the appendices of this report demonstrate that the diversion
channel is effective at diverting floodwaters away from Ashgrove Drive and is effective for events
with magnitudes of up to the 0.05% AEP event (1 in 2000 chance every year).
The peak flood level impact figures provided in Appendix D represent the overall combined impact
of the mitigation works in conjunction with the Bruce Highway Upgrade.
The only adverse offsite flood impact which is predicted to be caused by the diversion channel is
a 25mm increase in the peak 1% AEP flood level over Cooroy Creek, west of Ashgrove Drive. This
impact occurs over the Greenwood Grove development site however it is in an area that is
designated for open space / drainage reserve so it is likely that agreement could be reached with
the developer (PEET) for these impacts.
5.2 GHD and DTMR Comments
DTMR and their engineers have reviewed the results and the modelling of the preferred mitigation
option and provided a number of comments. These are listed here below along with a HWMC
response:
Table 5-1 GHD Comments and HWMC Response
DTMR / GHD Comment HWMC Response
The surface water levels are reduced in Ashgrove
Agreed
Drive
Increased water levels in Cooroy Creek do not
adversely impact any existing homes or
infrastructure. The impacts are over land owned by
The surface water levels are increased in Cooroy
a developer in areas that are to be designated as
Creek downstream of the Bruce Highway (afflux
open space / drainage reserve however Council will
increases from 10 mm to 25 mm)
need to seek permission for these impacts from the
developer (PEET) and ensure flood freeboard to
future lots will be achieved.
Considerable amount of vegetation needs to be
cleared to construct drain. Environmental impacts Council to action.
will need to be considered
There is potential to construct this drain entirely in
cut however this will mean an earthworks balance is
not achievable. Furthermore, it would no longer be
possible to direct environmental low flows along the
Drain consists of a bund on the eastern side (i.e.
existing Ashgrove Drive tributary. Due to water
drain is not all cut down below existing ground level)
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levels in Cooroy Creek it is expected that
construction of a bund will allow a better level of
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flood immunity to Ashgrove Drive however a design
without a bund may still be able to provide a
significant improvement.
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Section 14
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
There is potential to modify the channel
configuration during detail design.
Material for the construction of the “bund”, as well Agree - the proposed bund is essentially a flood
as maintenance aspects related to the bund, need levee and will require on-going monitoring to ensure
to be considered (stability, scour potential, long structural integrity is maintained. Detail design
term erodibility) channel should address stability, erosion and scour.
Flood modelling of the current project predicts 1%
AEP flow velocities are less than 1m/s and
therefore grass lining or native planting would be
Is lining of drain required to protect against sufficient. Some local scour protection may be
scour/erosion? required at inlet/outlet subject to final detailed
design.
To be addressed at detailed design stage.
Community impacts (if any) need to be considered,
including consultation Council to Action
Yes there is likely to be environmental benefits
however this may be difficult to achieve if a bund is
excluded from the design.
Proposed work changes the overland flow path
regime in this area. Are there benefits from low flow
Council may wish to assess environmental value of
events still draining toward Ashgrove Drive?
the Ashgrove Drive tributary downstream of the
diversion to determine whether low flow diversion is
desirable.
Access needs to be considered to maintain drain.
Are TMR responsible for maintenance of drain, Council and DTMR to negotiate.
considering it is in the road reserve?
HWMC do not believe extension of the bund is
TMR would not be responsible for any effects required. All lots on the eastern side of Cooroy
caused by surface water levels increases in Cooroy Creek (i.e. Ashgrove Drive lots) receive an overall
Creek downstream of the Bruce Highway (afflux benefit from the works. Land on the western side of
increases from 10 mm to 25 mm). Note: Could Cooroy Creek is owned by a developer and it is
bunding be extended to shield the closest expected that negotiation with the developer would
structures/properties to Cooroy Creek. be the best option here (noting impacts are over
land designated as open space / drainage reserve)
Noosa Shire Council to consult with Ashgrove Drive
Council to Action
residents to gauge acceptance of proposal.
Any resident complaints in regard to loss of
vegetation or perceived increased noise levels to be Council to Note
referred to Noosa Shire Council
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Section 15
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
6 KEY HYDRAULIC REQUIREMENTS & DESIGN INPUTS FOR THE
PREFFERED OPTION
HWMC have developed a preferred flood mitigation concept for Ashgrove drive. Detail design of
this mitigation concept has not been included in the current scope of works because it is expected
that DTMR’s civil engineers will be best placed to finalise the design to ensure it ties in appropriately
with their design of the Highway Upgrade.
To assist DTMR’s civil engineers, HWMC provide the following information which may be used to
guide detail design of the mitigation works.
Channel Lining
Hydraulic modelling of the concept design has allowed for a manning’s ‘n’ hydraulic roughness
value of 0.1 which assumes the channel will become re-vegetated. This has been chosen on the
basis that it is conservative in relation to overall channel capacity and peak flood level predictions.
It is noted that the choice of channel lining can be selected during detail design of the diversion
channel with consideration given to cost and on-going maintenance requirements.
Due to the channel’s flat grade (approximately 0.5%) and the relatively shallow flow depths
(approximately 1m for 1% AEP event), peak flow velocities are predicted to be less than 1 m/s and
should therefore not require any scour protection. Peak flow velocities should be checked for the
final channel configuration developed during detail design and it is also noted that some localised
scour protection may be required at transitions into and out of the channel.
Peak Flow Rates:
Peak flow rates through the diversion channel for the 10%, 1% and 0.05% design events
respectively are; 0.9m3/s, 6.8m3/s, 10.4m3/s.
Peak Flood Levels:
Peak design event flood levels at key locations for the mitigated case are tabulated below and are
also plotted on the longitudinal channel profile on Image 6-1.
Table 6-1 Peak Flood Levels
Location 10% AEP 1% AEP 0.05% AEP
Downstream extent of diversion channel
111.2 m AHD 111.5 m AHD 111.7 m AHD
(immediately adjacent to Cooroy Creek)
Upstream extent of diversion channel 111.7 m AHD 112.3 m AHD 112.5 m AHD
Peak Flow Velocities:
Peak flow velocities through the diversion channel for the 10%, 1% and 0.05% design events
respectively are; 0.5m/s, 0.9m/s, 1.0m/s. Peak flow velocities should be checked for the final
channel configuration developed during detail design and it is noted that some localised scour
protection may be required at transitions into and out of the channel.
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Section 16
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
Channel Geometry:
For the purpose of this investigation, the cross section of the diversion channel has been assumed
to be a trapezoid with a top width of 13m and a base width of 7m. The depth of cut required to
form the channel varies along the length of the channel and ranges between approximately 0.5m
and 2m.
The design bed level at the upstream extent of the channel is 111.5 m AHD. At the downstream
extent of the channel the bed level reduces to 110.5 m AHD.
The channel has a total length of nearly 200m. A long section of the channel concept design is
provided in Image 6-1 below. It also shows the natural surface profile (based on aerial LiDAR) and
the predicted peak flood surface profiles.
Image 6-1 Longitudinal Channel Profile
Bund Requirements:
The concept design allows for an earth bund along the northern side of the channel. It is
recommended that the height of this bund should be at least 300mm above the predicted 1% AEP
flood level, the profile of which is shown on Image 6-1.
If the existing Ashgrove Drive tributary holds environmental value downstream of the diversion,
then it may be worth incorporating a low flow diversion culvert that would allow environmental flows
to continue along the existing tributary. This will be difficult to achieve if the channel is not formed
using a bund.
There is potential to negate the need for this bund by forming the channel entirely in cut by lowering
the bed level of the channel however the effectiveness of the channel without a bund will need to
be assessed.
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Section 17
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
7 CONCLUSIONS
HWMC have developed a concept design for a flood mitigation option at Ashgrove Drive, Cooroy.
This investigation has been carried out for Noosa Council and the mitigation options assessed for
this investigation have been developed in consultation with Council, DTMR and GHD.
The preferred mitigation option involves a diversion channel running parallel to the Bruce Highway
which will convey floodwaters in a north-westerly direction towards the main channel of Cooroy
Creek.
The 25mm peak flood level impact for the 1% AEP event across the future open space / drainage
reserve of the Greenwood Grove development site will need to be approved by the developer
(PEET).
It is expected that the mitigation concept developed for this investigation will be subject to detail
design by GHD who are the civil engineers for the Bruce Highway Upgrade.
It is expected that these mitigation works will be constructed at the same time as the Bruce Highway
Upgrade.
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Section 18
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
8 QUALIFICATIONS & LIMITATIONS
This report has been prepared by HWMC specifically to provide advice to Noosa Council, DTMR
and GHD in relation to a preferred flood mitigation option for Ashgrove Drive Cooroy.
Our analysis and overall approach have been specifically tailored to the particular requirements of
this project and may not be applicable beyond this scope. For this reason, this report is not
authorised to be utilised for any purpose other than for the purpose stated in this report.
The design options presented in this report are concept designs only and additional investigation
and design is required prior to construction.
The investigation and modelling procedures adopted for this study follow current industry best
practice. However, the inherent uncertainties within an investigation of this nature should be taken
into account when interpreting the results outlined in this report.
This investigation is based upon various sources of data, information and assumptions which are
outlined within this report. The accuracy of this report is reliant upon the accuracy of this
information.
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Section 19
Flood Mitigation Investigation: Ashgrove Drive, Cooroy
9 REFERENCES
1. Austroads, 1994, “Waterway Design”
2. BMT WBM, 2010, “TUFLOW User Manual”
3. Bureau of Meteorology, Online Rainfall IFD Data System
‘http://www.bom.gov.au/hydro/has/cdirswebx/cdirswebx.shtml’
4. Engineers Australia, 1987, “Australian Rainfall and Runoff”
5. Engineers Australia, June 2012, “Australian Rainfall and Runoff Revision Project 5:
Regional Flood Methods, Stage 2 Report”
6. Engineers Australia, November 2012, “Australian Rainfall and Runoff Revision Project 5:
Two Dimensional Modelling in Urban And Rural Floodplains, Stage 1&2 Report”
7. GHD, May 2013, 'Hydraulic Analysis of the Cooroy Northern Interchange’ (Bruce Highway,
Cooroy to Curra, Upgrade Section A, Cooroy Southern Interchange - Sankeys Road)
8. Queensland Government – Natural Resources and Water, 2008, “Queensland Urban
Drainage Manual , 2nd Edition” (QUDM)
9. Queensland Government, 2010, “Increasing Queensland’s resilience to inland flooding in
a changing climate: Final report on the Inland Flooding Study”
10. SCARM, 2000, “Floodplain Management in Australia: Best Practice Principals and
Guidelines”
11. W.J. Syme, 2001, “Modelling of Bends and Hydraulic Structures in a Two-Dimensional
Scheme”
12. W.J. Syme, 2011, “Modelling Structures”, ASFPM SMS Workshop USA;\
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Section 20
APPENDICES
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A.
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orSection 21
APPENDIX A
Existing Case Peak Flood Depth and Flow
Velocity Mapping
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APPENDIX A
Existing Case Peak Flood Depth and Flow
Velocity MappingSection 22
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APPENDIX B
Concept Design of
Preferred Mitigation Option
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APPENDIX B
Concept Design of
Preferred Mitigation OptionSection 26
PSM No PSM
T
0 10 20 30m
(AHD)RL RL PLAN
Scale 1:500 @A1
AF
SURVEYED aerial photo contours 2011
E DRAWN AH Enter Name 5/2014 Project Number
D FACTORY STREET - POMONA
C
B
CHECKED ADT
PROJECT REVIEW
Signature
Signature
5/ 2014
5/ 2014 Noosa Council
COOROY FLOOD MITIGATION OPTIONS INVESTIGATION CM0028
R
PO Box141
ENG. CERTIFICATION Signature 5/ 2014 TEWANTIN QLD 4565
ASGROVE DRIVE GULLY WIDENING Drawing Sheet No.
A
Rv DATE REVISIONS REC. APPR. RPEQ No. 6069 (Alexander Toth)
OFFICE:
Tewantin
TELEPHONE:
(07) 5329 6501
FAX:
(07) 53296501 PRELIMINARY ESTIMATE LAYOUT /10 Rv._
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Section 27
APPENDIX C
Mitigated Case Peak Flood Depth and Flow
Velocity Mapping
T
AF
R
D
APPENDIX C
Mitigated Case Peak Flood Depth and Flow
Velocity MappingSection 28
0 20 40 60 (m)
1:2000 (A3)
Legend
DCDB
Future Greenwood Grove Estate Lots
Mitigation Option Model Line W ork
Flow Velocity Vector
Depth (m)
6.0
2.0
0.5
0.0
© Hydrology and Water Management Consulting Pty Ltd (HWMC) 2014.
HWMC endeavours to ensure that the inf ormation contained in this
f igure is correct at the time of publication. Furthermore, HWMC
makes no representations, w arranties or guarantees about its
accuracy, reliability, completeness or suitability for any
particular purpose. HWMC accepts no liability or responsibility
w hatsoever f or it in respect of any use of , or reliance upon,
this f igure by any third party.
Flood M itigation Investigation
Ashgrove Drive, Cooroy
Peak Flood Depth and
Flow Velocity M apping
T
10% Annual Exceedance Probability
Design Flood Event
AF
(1 in 10 Chance Every Year)
M itigation Case D01b
Client: Noosa Council
R
D
C:\HWMC\Projects\J00158_Cooroy _Mitigation_f or_Noosa_Council\Calcs\MapInf o\Figures
Section 29
0 20 40 60 (m)
1:2000 (A3)
Legend
DCDB
Future Greenwood Grove Estate Lots
Mitigation Option Model Line W ork
Flow Velocity Vector
Depth (m)
6.0
2.0
0.5
0.0
© Hydrology and Water Management Consulting Pty Ltd (HWMC) 2014.
HWMC endeavours to ensure that the inf ormation contained in this
f igure is correct at the time of publication. Furthermore, HWMC
makes no representations, w arranties or guarantees about its
accuracy, reliability, completeness or suitability for any
particular purpose. HWMC accepts no liability or responsibility
w hatsoever f or it in respect of any use of , or reliance upon,
this f igure by any third party.
Flood M itigation Investigation
Ashgrove Drive, Cooroy
Peak Flood Depth and
Flow Velocity M apping
T
1% Annual Exceedance Probability
Design Flood Event
AF
(1 in 100 Chance Every Year)
M itigation Case D01b
Client: Noosa Council
R
D
C:\HWMC\Projects\J00158_Cooroy _Mitigation_f or_Noosa_Council\Calcs\MapInf o\Figures
Section 30
0 20 40 60 (m)
1:2000 (A3)
Legend
DCDB
Future Greenwood Grove Estate Lots
Mitigation Option Model Line W ork
Flow Velocity Vector
Depth (m)
6.0
2.0
0.5
0.0
© Hydrology and Water Management Consulting Pty Ltd (HWMC) 2014.
HWMC endeavours to ensure that the inf ormation contained in this
f igure is correct at the time of publication. Furthermore, HWMC
makes no representations, w arranties or guarantees about its
accuracy, reliability, completeness or suitability for any
particular purpose. HWMC accepts no liability or responsibility
w hatsoever f or it in respect of any use of , or reliance upon,
this f igure by any third party.
Flood M itigation Investigation
Ashgrove Drive, Cooroy
Peak Flood Depth and
Flow Velocity M apping
T
0.05% Annual Exceedance Probability
Design Flood Event
AF
(1 in 2000 Chance Every Year)
M itigation Case D01b
Client: Noosa Council
R
D
C:\HWMC\Projects\J00158_Cooroy _Mitigation_f or_Noosa_Council\Calcs\MapInf o\Figures
Section 31
APPENDIX D
Peak Flood Level Impact Mapping
T
AF
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APPENDIX D
Peak Flood Level Impact Mapping
“
ey
QSection 32
0 30 60 90 (m)
1:3,000 (A3)
Legend
DCDB
Future Greenwood Grove Estate Lots
Mitigation Option Linework
Flow Velocity Vector
Impact
(m)
> 0.20
0.15 to 0.20
0.10 to 0.15
0.05 to 0.10
0.01 to 0.05
-0.05 to -0.01
-0.10 to -0.05
-0.15 to -0.10
-0.20 to -0.15
< -0.20
W as Dry, Now W et
W as W et, Now Dry
© Hydrology and Water Management Consulting Pty Ltd (HWMC) 2014.
HWMC endeavours to ensure that the inf ormation contained in this
f igure is correct at the time of publication. Furthermore, HWMC
makes no representations, w arranties or guarantees about its
accuracy, reliability, completeness or suitability for any
particular purpose. HWMC accepts no liability or responsibility
w hatsoever f or it in respect of any use of , or reliance upon,
this f igure by any third party.
Flood M itigation Investigation
Ashgrove Drive, Cooroy
Peak Flood Level Impact Map
T
10% Annual Exceedance Probability
Design Flood Event
AF
(Case D01b Vs B01b)
Client: Noosa Council
R
D
C:\HWMC\Projects\J00158_Cooroy _Mitigation_f or_Noosa_Council\Calcs\MapInf o\Figures
Section 33
0 30 60 90 (m)
1:3,000 (A3)
Legend
DCDB
Future Greenwood Grove Estate Lots
Mitigation Option Linework
Flow Velocity Vector
Impact
(m)
> 0.20
0.15 to 0.20
0.10 to 0.15
0.05 to 0.10
0.01 to 0.05
-0.05 to -0.01
-0.10 to -0.05
-0.15 to -0.10
-0.20 to -0.15
< -0.20
W as Dry, Now W et
W as W et, Now Dry
© Hydrology and Water Management Consulting Pty Ltd (HWMC) 2014.
HWMC endeavours to ensure that the inf ormation contained in this
f igure is correct at the time of publication. Furthermore, HWMC
makes no representations, w arranties or guarantees about its
accuracy, reliability, completeness or suitability for any
particular purpose. HWMC accepts no liability or responsibility
w hatsoever f or it in respect of any use of , or reliance upon,
this f igure by any third party.
Flood M itigation Investigation
Ashgrove Drive, Cooroy
Peak Flood Level Impact Map
T
1% Annual Exceedance Probability
Design Flood Event
AF
(Case D01b Vs B01b)
Client: Noosa Council
R
D
C:\HWMC\Projects\J00158_Cooroy _Mitigation_f or_Noosa_Council\Calcs\MapInf o\Figures
Section 34
0 30 60 90 (m)
1:3,000 (A3)
Legend
DCDB
Future Greenwood Grove Estate Lots
Mitigation Option Linework
Flow Velocity Vector
Impact
(m)
> 0.20
0.15 to 0.20
0.10 to 0.15
0.05 to 0.10
0.01 to 0.05
-0.05 to -0.01
-0.10 to -0.05
-0.15 to -0.10
-0.20 to -0.15
< -0.20
W as Dry, Now W et
W as W et, Now Dry
© Hydrology and Water Management Consulting Pty Ltd (HWMC) 2014.
HWMC endeavours to ensure that the inf ormation contained in this
f igure is correct at the time of publication. Furthermore, HWMC
makes no representations, w arranties or guarantees about its
accuracy, reliability, completeness or suitability for any
particular purpose. HWMC accepts no liability or responsibility
w hatsoever f or it in respect of any use of , or reliance upon,
this f igure by any third party.
Flood M itigation Investigation
Ashgrove Drive, Cooroy
Peak Flood Level Impact Map
T
0.05% Annual Exceedance Probability
Design Flood Event
AF
(Case D01b Vs B01b)
Client: Noosa Council
R
D
C:\HWMC\Projects\J00158_Cooroy _Mitigation_f or_Noosa_Council\Calcs\MapInf o\Figures