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Revision 0 – 30-Jun-2015 Prepared for – Auckland Council – ABN: N/A

Doc No. RPT-CI-1106_0_MODEL_RPT

Te Auaunga Awa - Walmsley and Underwood Reserves Project

Hydraulic Modelling Report

AECOM

Oakley Stage 1 Design

Te Auaunga Awa - Walmsley and Underwood Reserves Project – Hydraulic

Modelling Report


Te Auaunga Awa - Walmsley and Underwood Reserves Project Hydraulic Modelling Report

Client: Auckland Council

ABN: N/A

Prepared by

AECOM New Zealand Limited

T +64 9 967 9200 F +64 9 967 9201 www.aecom.com

Quentin Barbier

In association with

Boffa Miskell Limited

30-Jun-2015

Job No.: 60323936

AECOM in Australia and New Zealand is certified to the latest version of ISO9001, ISO14001, AS/NZS4801 and OHSAS18001.

© AECOM New Zealand Limited (AECOM). All rights reserved.

AECOM has prepared this document for the sole use of the Client and for a specific purpose, each as expressly stated in the document.

No other party should rely on this document without the prior written consent of AECOM. AECOM undertakes no duty, nor accepts any

responsibility, to any third party who may rely upon or use this document. This document has been prepared based on the Client’s

description of its requirements and AECOM’s experience, having regard to assumptions that AECOM can reasonably be expected to

make in accordance with sound professional principles. AECOM may also have relied upon information provided by the Client and other

third parties to prepare this document, some of which may not have been verified. Subject to the above conditions, this document may be

transmitted, reproduced or disseminated only in its entirety.

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Modelling Report


Quality Information

Document Te Auaunga Awa - Walmsley and Underwood Reserves Project

Ref 60323936

Date 30-Jun-2015

Prepared

by Quentin Barbier

Reviewed

by James Hughes

Revision History

Revision Revision Date Details

Authorised

Name/Position Signature

A 30-Apr-2015 Draft for Review James Hughes

Design Manager

0 30-Jun-2015 Final Shaun Jones

Project Manager

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Modelling Report


Table of Contents

Executive Summary i 1.0 Introduction 1 2.0 Scope 2 3.0 Methodology 2 4.0 Model inputs 3 5.0 Model schematisation 3

5.1 Model components 3 5.1.1 Mike Urban 3 5.1.2 Mike 11 3 5.1.3 Mike 21 4

5.2 Model updates and assumptions 4 5.2.1 Model updates 4 5.2.2 Model assumptions and limitations 5

6.0 Model Peer Review 5 7.0 Model Results 6

7.1 Model validation (FHM comparison) 6 7.2 Model results 6 7.3 Discussion 7

8.0 Downstream Flood Effects 7

Appendix A Mannings Roughness Values A

Appendix B Peer Review Correspondence B

Appendix C Flood maps C

Appendix D Hendon Park Flood Modelling Results D

Appendix E Flood Hazard Map (FHM, 2011) E

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Modelling Report


i

Executive Summary

AECOM have been engaged by Auckland Council to carry out detail design of the Oakley/Te Auaunga Creek

rehabilitation project. This project involves widening and naturalising the watercourse running through

Walmsley and Underwood Reserves (between Sandringham and Richardson Rds).

This report covers the detailed hydraulic modelling undertaken which assesses the proposed channel

widening and its impacts on flooding.

The scope of the modelling work undertaken was as follows:

1) Develop a cutdown model from the original FHM model incorporating additional, more accurate details

such as survey data, updated LiDAR data and refined catchments.

2) Develop a new, widened channel cross section using 12D software, identifying specific hydraulic control

points where the channel capacity is insufficient to contain flood flows within the reserve area.

3) Develop design solutions to address the particular areas of reduced hydraulic capacity.

4) Incorporate the new channel design into the hydraulic model and rerun to confirm they achieve the

desired outcomes.

5) Extract, analyse and present findings.

Model Results

To evaluate the impacts on flood plains as a result of the design, the following design scenarios were run:

1) Existing 1 in 100yr ARI flows with existing stream

2) Existing 1 in 100yr ARI flows with proposed stream works

3) Proposed 1 in 100yr ARI ‘Pass forward’ flows (including MPD and climate change) with proposed stream

works.

The following tables summarise the results.

Table E1 Summary of flooded habitable floors and floors at risk

Scenario Habitable

floor at risk* Within 500mm

1) Existing Stream - Ex Flows 55 144

2) Existing Stream - PF Flows 82 143

3) Design stream - PF Flow 3 75

*Floors at risk: this indicates where the flood level is above the habitable floor level.

Table E2 Summary of flooded area and volume within floodplain

Scenario Area (ha) Volume of water (m3)

1) Existing Stream - Ex Flows 29.21 142,383

2) Existing Stream - PF Flows 30.77 167,642

3) Design stream - PF Flow 20.76 67,223

As shown within the above tables the proposed stream works achieve a significant reduction in both habitable

floors at risk and those within 500 mm of flooding. Main results are summarised as follows:

- With no change to the stream capacity, flooded floors would increase by around 50% (from 55 to 82).

There is little change to the number of floors within 500mm of flooding.

- The proposed stream works reduce the floors at risk by around 90% when compared to the existing

situation (from 55 to 3). Floors within 500mm are reduced by around 50% (from 144 to 75).

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Modelling Report


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- The proposed works reduce the flooded area by around 30% (29ha to 21ha) and the flooded volume by

around 50% (140,000m3 to 70,000m3).

Discussion

The proposed stream works have resulted in a significant reduction in the extent of the hazardous flood plain.

A potential consequence of this is that restrictions on development may be able to be reduced, which in turn

will enable future intensification within the area. This opportunity is not discussed further in this report,

however will be discussed in more detail as part of the Business Case for the project.

The proposed works have reduced flooding directly caused by the under-capacity of the stream channel and

associated culverts/bridges. There is still remaining flooding within the catchment caused by overland flow and

local depressions, particularly within the O’Donnell Rd area. This can be managed and addressed through

separate works, and will be part of additional investigations and analysis. These works will further reduce the

flood plain extent.

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Modelling Report


1

1.0 Introduction

The Oakley Creek project will achieve flood protection for a large proportion of the urban catchment to both

the north and the south of the creek. This report provides details of the development of the hydraulic model

and the comparison of the existing flood plain with that following the Oakley Creek widening works.

More recently, the extent of the floodplain has become a critical element of the project and reducing this has

become a key project driver. A cut-down model has been developed from the originally developed FHM model

(AECOM, 2013) and has been used as the base model to assess the extent of flood plain reduction. Refer

Figure 1 and Figure 2 below.

Figure 1 Cut-down model extent.

Cut-down model

Oakley Catchment

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Modelling Report


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Figure 2 Cut-down model extent

2.0 Scope

The scope of the modelling work was as follows:

- Review the existing catchment-wide FHM model including hydrological assumptions.

- Build a base ‘cut-down’ model with refined network, inletting and hydrology and boundary conditions.

- Model the existing scenario and map the flood plain

- Model the proposed ‘Pass Forward’ scenario within the extsing Oakley Creek

- Model the proposed ‘Pass Forward’ scenario (including Oakley Creek widening, MPD land use and

climate change) and map the floodplain

- Assess flood plain area reductions and floor flooding

3.0 Methodology

The following methodology has been employed to determine pre and post development flood plain extents:

1) Develop a cutdown model from the original FHM model incorporating additional, more accurate details

such as survey data, updated LiDAR data and refined catchments.

2) Develop a new, widened channel cross section using 12D software, identifying specific hydraulic control

points where the channel capacity is insufficient to contain flood flows within the reserve area

3) Develop design solutions to address the particular areas of reduced hydraulic capacity

4) Incorporate the new channel design into the hydraulic model and rerun to confirm they achieve the

desired outcomes.

5) Extract, analyse and present findings

Cut-down model

extent

Oakley Creek

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4.0 Model inputs

The following information has been brought into the cut-down base model:

- Data from previous FHM model (Boundary conditions: inflow hydrographs and water level time series)

- Updated GIS network data from Auckland Council (08/10/2014)

- Lidar Data (2013)

- AECOM Surveyed data (11/2014)

- Proposed 12D earthworks model

5.0 Model schematisation

5.1 Model components

The flood model is a 3 way coupled (MU, M11, M21) hydraulic and hydrological model. The following

summarises each component and Figure 3 below shows the extent of each.

Figure 3 Mike Flood representation of the three way coupled model

5.1.1 Mike Urban

All underground infrastructure is represented in Mike Urban including pipes, manholes and outlets. In addition,

all hydrology from the local catchments is represented in the Mike Urban model.

5.1.2 Mike 11

The stream and culverts/bridges at Sandringham Road extension, Beagle Avenue and Richardson Road are

all represented in the Mike 11 model. All sections have been extended beyond the extent of earthworks in

order to represent the same extent of the flood plain in both the existing and proposed models. Mike 11

sections have been extracted at 5m centres using the Mike 11 extraction tool in 12D.

Mike 11 network

Mike 21 bathymetry

Mike urban network

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Table 1 below summarises the range of cover types used, and the associated mannings roughness numbers.

These values are based on those provided by Auckland Council (23 Jan 2014) and take into consideration the

range of surfaces proposed within the flood plain.

In the existing model, the stream roughness have been set to 0.033, as an average value of the reserve

roughness.

The proposed roughness values were determined from the preliminary design landscape plans in

collaboration between the hydraulic modeller and landscape architect.

Appendix A summarises the Manning’s roughness values for the stream low flow channel, and both the left

and right flood plain independently – along the project length.

Table 1 Manning's Roughness

Main type of Coverage Assumed manning’s value

Low flow channel 0.03

Grass Floodplain 0.03

Light brush and trees 0.04 - 0.045

Medium to dense brush and trees 0.05

Exposed basalt 0.025

Concrete paths and wall panels 0.02 - 0.025

5.1.3 Mike 21

The remaining catchment topography (with the exception of the area covered by Mike 11) is represented in

Mike 21. The ground topography is represented in a 1m square grid developed using the 2013 LiDAR data.

Where available, the topographical survey has been spliced into the dataset and this is generally within the

reserve areas.

5.2 Model updates and assumptions

5.2.1 Model updates

The following table summarises the changes made, and compares the original FHM model with the ‘cut-down’

model.

Table 2 Summary of Model Changes

Items Original FHM Model Setup Model Updates for

Cut-Down Base Model

General Model Extent Oakley Catchment Model has been cut down to the extent of the

O’Donnell sub-catchment

Modelling Software Software Suite Mike by DHI version

2009. (Mike Urban, Mike 21 and

Mike 11).

Software suite Mike by DHI version 2012

with Service Pack 3. (Mike Urban, Mike 21

and Mike 11).

Hydrology Model B + RDI (with calibration) Model B hydrology only

Hydraulic Model –

Pipe Network

Refer to the section 3.4, in the OAK

SW Modelling Development Report

(AECOM, 2010).

Additional network (sourced from 2014 AC

GIS data) brought into the cut-down model to

refine the drainage representation within the

sub-catchment.

Hydraulic Model –

Surface Model

Mike 21 grid model (3m by 3m

square grid) generated from 2006

Lidar and SH20 design bathymetry

Mike 21 grid model (1m by 1m grid)

generated from 2013 Lidar.

Hydraulic Model – Modelled in Mike 11. Modelled in M11 based on topographical

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Items Original FHM Model Setup Model Updates for

Cut-Down Base Model

Creek survey for existing and 12D design model for

future scenario.

Hydraulic Model –

Boundary conditions

N/A - Upstream boundary: Mike 11 inflow

were set from the original ‘Pass-

forward” model (based on MPD and

climate change factors)

- Downstream boundary: Water levels

were set from the same model as

above.

Hydraulic Model –

Soakage

- Private Soakage : can accept

the 10 yr. ARI flow

- Public Soakage : can accept

the10 yr. ARI flow

- Private Soakage : can accept the 2 yr.

ARI flow

- Public Soakage : can accept the2 yr.

ARI flow

Hydraulic Model –

1D and 2D Coupling

Refer to the section 3.9, in the OAK

SW Modelling Development Report

(AECOM, 2010).

- 20L/s inletting regulation applied per

catchpit on the manholes

5.2.2 Model assumptions and limitations

The following additional assumptions and limitations apply to the modelling work undertaken to date. Please

note that these need to be read in conjunction with the model assumptions and limitations specified in the

previous Oakley FHM model build report (AECOM, 2010).

- It is assumed that the boundary conditions at the study area are not changed by the works within the

study area.

- Streamworks design carried out in 12D

- Bridges have been designed with freeboard and single span such that the flow is essentially free surface

flow in open channels. As such we have represented the flow under each bridge in as open channel

sections in Mike 11. The existing and proposed box culverts at Sandringham Rd have been modelled

accurately.

6.0 Model Peer Review

A model peer review was carried out By Auckland Council in order to confirm fit for purpose. The findings from

this peer review were considered and incorporated were appropriate. An iteration of this review was carried

out and agreement was reached that the model is fit for purpose.

Correspondence related to the Peer Review is contained in Appendix B.

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Modelling Report


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7.0 Model Results

7.1 Model validation (FHM comparison)

In order to check and validate the cut-down model, this was compared with the original FHM model. As can be

seen in Figure 4 below, the flood extents are similar. There are differences in flood depths in places, and

much of this can be attributed to the improved accuracy of the terrain within the cut-down model.

Figure 4 Map showing comparison of original FHM results and result from ‘cut-down’ model

7.2 Model results

To evaluate the impacts on flood plains as a result of the design, the following design scenarios were run:

4) Existing 1 in 100yr ARI flows with existing stream

5) Existing 1 in 100yr ARI flows with proposed stream works

6) Proposed 1 in 100yr ARI ‘Pass forward’ flows (including MPD and climate change) with proposed stream

works.

The following tables summarise the results.

Table 3 Summary of flooded habitable floors and floors at risk

Scenario Habitable

floor at risk* Within 500mm

4) Existing Stream - Ex Flows 55 144

5) Existing Stream - PF Flows 82 143

6) Design stream - PF Flow 3 75

*Floors at risk: this indicates where the flood level is above the habitable floor level.

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Table 4 Summary of flooded area and volume within floodplain

Scenario Area (ha) Volume of water (m3)

4) Existing Stream - Ex Flows 29.21 142,383

5) Existing Stream - PF Flows 30.77 167,642

6) Design stream - PF Flow 20.76 67,223

As shown within the above tables the proposed stream works achieve a significant reduction in both habitable

floors at risk and those within 500 mm of flooding. Main results are summarised as follows:

- With no change to the stream capacity, flooded floors would increase by around 50% (from 55 to 82).

There is little change to the number of floors within 500mm of flooding.

- The proposed stream works reduce the floors at risk by around 90% when compared to the existing

situation (from 55 to 3). Floors within 500mm are reduced by around 50% (from 144 to 75).

- The proposed works reduce the flooded area by around 30% (29ha to 21ha) and the flooded volume by

around 50% (140,000m3 to 70,000m3).

Flood hazard maps showing flooded floors and those at risk for each scenario, are included within Appendix

C.

7.3 Discussion

The proposed stream works have resulted in a significant reduction in the extent of the hazardous flood plain.

A potential consequence of this is that restrictions on development may be able to be reduced, which in turn

will enable future intensification within the area. This opportunity is not discussed further in this report,

however will be discussed in more detail as part of the Business Case for the project.

The proposed works have reduced flooding directly caused by the under-capacity of the stream channel and

associated culverts/bridges. There is still remaining flooding within the catchment caused by overland flow and

local depressions, particularly within the O’Donnell Rd area. This can be managed and addressed through

separate works, and will be part of additional investigations and analysis. These works will further reduce the

flood plain extent.

8.0 Downstream Flood Effects

The development of the project will result in increased peak flood flows at Richardson Road Bridge and

entering Hendon Reserve. This increase in peak flows, and the planning and design of mitigation has been

undertaken by the Well Connected Alliance as part of the Waterview Connection work.

The Well Connected Alliance has confirmed that the design and assessment of all work downstream of

Richardson Road has been undertaken for 100 year ARI peak flows of 58m3/s. This flow was stipulated by

Auckland Council during the design of Waterview Connection.

Due to design refinements since the Waterview Assessment of Effects was carried out, peak flows have

reduced to 54.4m3/s.

The Well Connected Alliance has designed and assessed a flood protection bund along the true right bank

downstream of Richardson Rd (refer Figure 5) in order to contain the peak flows within the reserve, and

protect properties along Hendon Ave. The modelling results developed by them are shown in Figure 5 below

and summarised in a memo (refer Appendix D). It should be noted that there is overland flow from Hendon

Ave that impounds behind the bund, however, this will be addressed by the Well Connected Alliance to

comply with Building Code requirements for management of surface flow and is not directly affected by the

stream flooding.

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Modelling Report


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The Auckland City Flood Hazard Mapping project carried out in 2011 shows a smaller flood extent in the area

(for a peak flow of around 32m3/s). This is shown in Figure 6. The comparison between the two maps

illustrates that the impact of the increase in peak flow can successfully mitigated via the construction of the

bund.

Figure 5 Flood Modelling Results in Hendon Reserve

Figure 6 100yr ARI Flood Plain (ACC FHM, 2011)

Proposed

flood bund

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Modelling Report


Appendix A

Mannings Roughness Values

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Modelling Report


A-1

Appendix A Mannings Roughness Values

Chainage LH Flood Manning’s Low Flow Manning’s RH Flood Manning’s

10 0.03 0.03 0.03

60 0.05 0.03 0.05

90 0.03 0.03 0.035

110 0.045 0.03 0.045

180 0.045 0.03 0.05

240 0.045 0.03 0.045

310 0.05 0.03 0.05

350 0.05 0.03 0.045

390 0.03 0.03 0.03

400 0.05 0.03 0.045

460 0.04 0.03 0.05

500 0.03 0.03 0.03

510 0.02 0.03 0.02

540 0.04 0.03 0.05

550 0.03 0.03 0.03

570 0.045 0.03 0.04

670 0.045 0.03 0.03

760 0.045 0.03 0.05

800 0.05 0.03 0.05

900 0.045 0.03 0.05

960 0.03 0.03 0.03

980 0.025 0.03 0.03

1100 0.045 0.03 0.03

1340 0.03 0.03 0.03

1370 0.045 0.03 0.03

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Modelling Report


Appendix B

Peer Review Correspondence

Peer review comment AECOM response Outcome

The threshold values for flow exchangesbetween Mike Urban nodes and M21Bathymetry specified in the model varyfrom 0.5 to 3 cumecs. It is considered thatit would be difficult and expensive toprovide inletting capacities to this order.Please reconsider these values as thesehave an impact on the extent of flood plain.

The Values have been changed in themodel.

Made changes asrequested by Larry Shui

No open boundary has been set in themodel. When the results were inspected,it was found that land cell wall at theboundary damming up flows and evenbounce flows backwards and formed alarge ponding area as seen in the picturebelow.Suggest adding an open boundary at thislocation to enable drainage at thedownstream end of the bathymetry.M11 Model

Open boundary has been added. Made changes asrequested by Larry Shui

The DX value has been set at 10,000 mwhich is considered too large for a coupledmodel. The AC modelling specificationsuggest DX at Grid Size, in this case a DXvalue at 2m ~4m may be consideredappropriate

The Dx value have been set to 4 m Made changes asrequested by Larry Shui

Only the Sandrigham Road Culvert isincluded in the ‘Design’ model, none of thedownstream culvert or bridge structureshave been included in the model. Wouldsuggest that these structures be explicitlymodelled in M11, even that the flow willnever overtop, the entry and exit lossesshould be taken into account

The missing structures have beenadded


An only positive flow regulation has beenimposed on culvert and weir structures inthe ‘Existing’ model. If possible, these flowregulations should be removed

The flow regulations have beenremoved


Private and public soakage systems havebeen modelled with 10yr peak flowcapacity. It is considered that 2yr capacitymay be appropriate when modelling floodrisk given the often poor maintenance andpoor performance associated with agedsoakage system

The flow capacity has been adjustedon the 2y peak flow


Manhole cover type has been set asnormal. As this model will be coupled with2D terrain, it is considered that sealedcover top is more appropriate to avoid theartificial inundation cone automaticallyadded on top of manhole when overflowsin the Mouse Engine

The problem has been discussed withDragan from DHI and the manholesetup when coupled needs to be setas normal.

No changes have beenmade

Model B has been used as thehydrological model for this catchment.Default Model B parameters have beenadopted for all catchment’s, despite ofmany other set of Model B parametersdefined in the model file. Please alsochoose three example catchments andcompared the peak discharges with thosefrom TP108 analysis. As this model will beused to design new Stormwater pipes andall other Stormwater drainage pipes inAuckland Region are designed inaccordance peak flows from TP108analysis

Hi Quentin,It appears from your comparison ofthree subcatchments, the Model Bflow is higher than the TP108 peakflows by ~20%. We thereforeconsider that the flood risk from localcatchment predicted by the currentModel (model B) will be conservative,thus potentially err on the right side.

Based on above, my recommendationis continue on with the currenthydrological model (Model B) untilsuch time instructed by AC to switchto TP108 model for the whole Oakleycatchment.

Regards

Larry ShuiSWMPO

Provided the informations,no changes were required

Please confirm if AC Climate Changerainfall temporal patterns have been usedin the model

Climate change patterns have beenused in the model No changes required

I noticed an Evapo-Transpiratin time serieshave been included in the model, pleasecheck if this can be removed

The Evapo-transpiration have beenremoved


Terrain modifications at Walmsley Parkand Underwood Park included in themodel bathymetry changes but unable toverify due to the lack of design informationother than the model bathymetry.Consider modelling stream channel andstructures in 1D in M11.

The stream channel has beenmodelled in M11


Roughness grids representing the ultimategrowth in the reserve should be prepared.Roughness at the proposed overland flowpath and existing/future building platformsshould also be modelled appropriately.Correct representation of roughness inflood plain and overland flow paths.

This point hasn’t been addressed. No changes have beenmade

The upstream and downstream modelboundaries should be extended further outto ease out any errors in terms of hydraulicgrade lines at the area of concern due toincorrect conditions set at the boundary.Correct representation of upstreaminflow/hydraulic limitation and downstreamwater level conditions.

The bathymetry have been extendedfurther upstream


Peak water level from the local catchmenthas achieved. Although due to emission ofthe stream channel, the peak water levelsin the main channel flood plain areincorrect.Include the main stream channel in 1DM11 and couple 1D channel with M21.

The stream channel has beenmodelled in M11


No report on the initial condition. It isunclear whether any differences existbetween the initial water surface and thebathymetry terrain model.Please report on differences between theinitial water surface and the bathymetry.

There is no initial water surface in thestream, only around the boundarycondition for stability purposes.

Explanations provided

Suggest extending the bathymetry beyondRichardson Road bridge to minimiseeffects from assumptions of tail watererrors.

The bathymetry have been extended Made changes asrequested by Larry Shui

Further explanation of the “Pass Forward”flow required. Suggest considering usingmore self-explanatory terms, e.g. “Existing,MPD or MPD with network upgrade plans”

“Past forward” have been used in thereport used as it is the previous nameused in the model we extracted thedata.Is the flow crossing Sandrigham roadin the FHM model with an MPDscenario 100yr ARI + climat change +catchment wide mitigation scheme inplace.

Explanations provided

Further comments that did not required corrective action :

Model feature / parameter reviewedCorrectiveactionrequired

Comments / Review findings Expected Outcome

Software version and type ofbathymetry (classic, flexi mesh). No Mike Flood 2012/M21 classic grid used

appropriately

Model provided runs on AucklandCouncil computer system. How longdoes it take to run?

NoModel has been set up on ACcomputer; no simulation run has beenperformed.

Grid Size No 1m x 1m grids usedEddy viscosity No 0.1 usedWet and Dry threshold No 0.02 and 0.03m usedRainfall Used NoSimulation duration. Is thisappropriate? No 12 hr – simulation duration appropriate

Bathymetry drains appropriately at thefinal time step in the simulation No Ponding in depressions identified as

expected.

Obstructions such as buildings areappropriately modelled. Storage andvelocity are affected appropriately.

NoA roughness value of 0.2 is used tomodel resistance at current buildingplatforms.

Model fit for purpose? No

The current model lacks representationof the main stream channel and keyroad crossing structures. Likelyflooding of the area from the mainstream channel flood plain has notbeen modelled. The boundaryconditions especially at the downstreamside also requires further consideration.

Amended modelschematic to includemain stream channeland structures in M11coupled to M11. Useappropriate boundaryconditions.

Primary network ‘free ends’ No

1D Pipe network extends sufficientlyupstream to allow modelling of alloverland flow paths.

No

Network is sufficiently trimmedupstream. Catchpits are notmodelled.

No

All significant depressions and naturalponding areas are included in themodel extent.

No

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Modelling Report


Appendix C

Flood maps

Oakley Creek Flood Extents

007

Existing Stream with Existing Flows

Project:

Title:

Status: Map No. Rev.Draft ARev. By App. Description

© Copyright AECOM New Zealand Limited, 2014. This map is confidential and shall only be used for the purposes of this project. © Copyright AECOM New Zealand Limited 2014.This map is confidential and shall only be used for the purpose of this project. The information contained orreferred to in this drawing-report was developed for use in the project. AECOM New Zealand Limited does notaccept any responsibility for the use of the information by any other parties and state expressly that they donot warrant the accuracy of the information. Any use of the information by other parties is at their own risk.The signing of this title block confirms the design and drafting of this project have been prepared and checkedin accordance with the AECOM Quality Assurance system certified to AS/NZS ISO 9001:2000.No part of this drawing/report may be copied or used without the prior written consent of AECOM New ZealandLimited.

Map features depicted in terms of NZTM projection.

Data Sources:NZ Topographical Features – LINZ NZ National Topo Dataset 2012Cadastral Boundaries – LINZ NZ Cadastral Dataset 2014

Scale:

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Stoddard Road

Mount Albert Road

Sand

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O'Donnell Avenue

Owairaka Avenue

Parkinson Avenue

Farrel lyAvenue

Potte

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Hendon Avenue

Beag

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Aurora Avenue

Hedley Road

Triton Avenue

Tyburnia Avenue

Sheppard Avenue

LorraineA

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Hallam

Street

Denize

Road

Holdsworth Avenue

Taumata Road

Jessop Street

SkeatesAvenue

Belcher Street Shearer Street

Wainw

right Avenue

Thom

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Mountfield

Terrace

Christ

iniSt

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Fletcher Street

McG

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Delphine Close

Betts

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Buccaneer Street

Existing Stream with Existing FlowsFlooding Depth

0.0001 - 0.05

0.05 - 0.1

0.1 - 0.3

0.3 - 0.5

0.5 - 1

1 - 2

Floor Category

Within 500mm

Floor at risk

A QB JH For Options Report

0 60 12030 Meters1:3,000


007

Existing Stream with Pass Forward Flows

Project:

Title:



Map features depicted in terms of NZTM projection.

Data Sources:NZ Topographical Features – LINZ NZ National Topo Dataset 2012Cadastral Boundaries – LINZ NZ Cadastral Dataset 2014

Scale:

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SheetNo.

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Stoddard Road

Mount Albert Road

Sand

ringh

amRo

adEx

tens

ion

O'Donnell Avenue

Owairaka Avenue

Parkinson Avenue

Farrel lyAvenue

Potte

r Ave

nue

Hendon Avenue

Beag

leAv

enue

Aurora Avenue

Hedley Road

Triton Avenue

Tyburnia Avenue

Sheppard Avenue

LorraineA

venue

Hallam

Street

Denize

Road

Holdsworth Avenue

Taumata Road

Jessop Street

SkeatesAvenue

Belcher Street Shearer Street

Wainw

right Avenue

Thom

son

Stre

et

Mountfield

Terrace

Christ

iniSt

reet

Fletcher Street

McG

ehanC

lose

Delphine Close

Betts

Aven

ue

Buccaneer Street

Existing Stream with Pass Forward FlowsFlooding Depth

0.0001 - 0.05

0.05 - 0.1

0.1 - 0.3

0.3 - 0.5

0.5 - 1

1 - 2

Floor Category

Within 500mm

Floor at risk

A QB JH For Options Report

0 60 12030 Meters1:3,000


007

Design Stream with Past Forward Flows

Project:

Title:



Map features depicted in terms of NZTM projection.Data Sources:NZ Topographical Features – LINZ NZ National Topo Dataset 2012Cadastral Boundaries – LINZ NZ Cadastral Dataset 2014

Scale:

P:\60

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3239

36\4.

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Design stream with Past Forward FlowsFlooding Depth

0.0001 - 0.050.05 - 0.10.1 - 0.30.3 - 0.50.5 - 11 - 2

Floor CategoryWithin 500mmFloor at risk

A QB JH For Options Report0 60 12030 Meters1:3,000

AECOM



Modelling Report


Appendix D

Hendon Park Flood Modelling Results

140-J003-WMS

The Well-Connected Alliance 150-152 Stoddard Road, Mt Roskill, Auckland 1041 Private Bag 76914, Manukau Mail Centre 2104 P +64 9 621 1730 E [email protected]

www.nzta.govt.nz/waterviewconnection www.twitter.com/wcnow Rev 3 January 2015

1

……………………………………………………..……………………………………………………………………………………………………………………………………………………………………

MEMO ….……………………………………………………………………………………………………………………………………………………………………………………………………………………….

Doc No.:

400-CMT-M-09524.

To: Auckland Council c/o – Tom Mansell

Cc: Sumi Eratne (NZTA) Shaun Jones (Aecom)

From: Keane Kannan

Date: 10/05/2013 3:00:00 pm Subject: Hendon Park Flood Modelling Results

IntroductionThe following memorandum has been provided to Auckland Council (Council) for information. We understand

that Council propose to use this information to assess flood levels within the wider Hendon Reserve area in

particular to the north of the reserve.

The purpose of our assessment was for the design of the bund along the northern and western extents of the

reserve to confine Oakley Creek flows and protect the southern approach trench and tunnel portal from flood

inundation.

The model run assessed is the 100 year ARI climate change adjusted model with MPD. This includes the pass

forward flows from the upstream development of the Oakley Creek above Richardson Road. The peak pass

forward flow assessed is for 58 m3/s as provided by Council. We note that the flood level within Hendon Park

is controlled downstream by the SH20 Oakley Bridge which has been designed to pass this peak flow.

ModellingResultsThe following figures 1 and 2 show the modelled flood depths and flood elevations within the Hendon

Reserve. The flood map shows all flood depths greater than 50 mm in accordance with Council modelling

guidelines.

We note that in Figure 2, the wider flood plain shows the maximum flood elevation and includes areas that are

subject to 50mm of flooding and less.

DisclaimerThe modelling undertaken by the Well Connected Alliance has been prepared for a specific purpose and brief.

The information provided may not be suitable for use outside of the subject area and if used should be

checked independently.

2

Figure 1 – 100 year ARI flood depths within Hendon Park

Figure 2 – 100 year ARI Flood Elevations within Hendon Park

Water depth

(m)

Water level

(m RL)

AECOM



Modelling Report


Appendix E

Flood Hazard Map (FHM, 2011)

44.12

42.93

9

653

42

1

9

2

57

3

9

4

8

6

7

8

3

5

53

7

10

15

13

59

57

56

62

64

54

2927

3638

40

13

11

1517

3133

35

42

37

39 54

52

50

1113

17 15

162018

55

44

5153

42

1715 2119

30

10

1214

195

215

217

131

124

223

221

190

192

219

236

238

229

231

233

235

116

118

225

227201 19

9

193

189

197

203

183

175177

170172

174

179

171

185

187

191

181

234

211

223

161163

168

164166

173156

167169

171

134

138

142

140

154

165

117

119

121

123

109111

110

112114

113115

174

179

168 170 172

183

189 193

176

185 187

136

160

158

164166

175177

132

126128

132

130

137139

134

143

141

145136

138140

142

147

151149

159161

163

153155

157

144

146148

150

152

143

145

141

139

135

133

125

137

131129

127

130

173

207188

209

211

213

186205

101

102

107

103105

108

4-6

100

195

203199

197

205

206

204

200

196

129

116 118 122120

6-8

195A

217A

113A

128A

203A

129A

58-60

23-25

44-46

10-12

14-16

48-50

32-34

206-210

204-2

08

192-198

210-2

20

212-220

180-182

104-106

192A-202B

HENDON AVENUE

ALAM

EIN

TERR

ACE

CASSINO TERRACE

FLETCHER STREET

BARRYMORE ROAD GL = 43.1m100yr = 43.5m50yr = 43.4m10yr = 43.4m

GL = 45.3m100yr = 46.0m50yr = 45.8m10yr = 45.5m

NL4774

NL4773

NL4740

d010S062_out

d003S059_out

d003S052_out

d003S060_out

NL3382

NL3380

NL3379

NL3377

Node_256

Node_183

Node_179Node_178 Node_177

SENS8512

SENS7795

d010S062

d003S059

d003S052

d003S060

SGNS7795

Node_176

Node_175

CO_NS1199CO_NS1198

CWOAK_DN7

CWOAK_DN4

CWOAK_DN3

SGNS7795Dummy

NS8512Private

CO_CWOAK_DN127CWOAK_DN5

CWOAK_DN2

NS8512DummyNS8512Public

SGNS7795Private

47

50

50

45

41

45

48

42

49

45

47

42

43

48

48

49

47

45

4442

47

50

47

44

49

47

48

44

43

46

49

4348

41

49

52

48

45

46

42

44

49

42

45

42

43

43

43

46

49

46

51

43

53

48

43

47

52

50

42

51

46

47

47

47

48

43

4848

AMENDMENTSREV BY APPd DATE NAME DATE

APPROVED

DRAWNDESIGNEDCHECKEDSTATUSPRINTEDFILE NAME

KEY PLAN

Figure 4.Predicted Maximum Probable Development Flood Hazards

Notes:

Scale:20 0 20 40 60 Metres

1:2,000

© 2010 Metro Water Limited and Auckland City Council. All rights reserved.Information contained in this drawing/report is confidential and proprietary toMetro Water Limited and Auckland City Council. No part of this drawing/reportmay be copied or used without the prior written consent of Metro WaterLimited and Auckland City Council.

Flood plains and overland flow paths represent modelled surface profiles. Freeboard has not been included.The Building Footprint dataset has been digitised from February 2002 orthoimagery. The data has not been updated since. The data accuracy is acombination of spatial accuracy of the orthoimagery and manual digitising.

These maps must be read in conjunction with the Flood Hazard Mapping Report.

GL means Ground level at node point or lowest point on cross-section.

(A3 size)

Map projection is NZTM.

21OAK_Fig4x_MPD_FHM.mxd

FLOOD HAZARD MAPPING OF CATCHMENTSON THE AUCKLAND ISTHMUSOakley Hazard Mapping

The information contained or referred to in this drawing/report was developedfor use in the project known by Auckland City Council and Metro WaterLimited as Flood Hazard Mapping of Catchments on the Auckland Isthmus.Neither Auckland City Council nor Metro Water Limited accept any responsibilityfor the use of the information by any other parties and state expressly that theydo not warrant the accuracy of the information. Any use of the information by other parties is at their own risk.

Areas beyond modelled network may have flood hazards and flood prone areas;These have not been modelled and are therefore not represented.Network usage is as modelled and may differ from AMIS GIS data.

P. Fearon

Final

01/10/2010

4.16

4.21

4.26

4.224.20

4.27

4.15

4.25

4.17

01/10/201001/10/201001/10/201001/10/2010

M. Summerhays

S. JonesP. Fearon

LEGEND:

Modelled Stormwater NodeModelled Soakage (Representative Only)

Property BoundariesSW Catchment Boundary

Survey CrossSection1m LIDAR ContoursModelled Stormwater NetworkModelled Open ChannelModelled Stormwater Culvert

Wastewater Overflow(10, 50 & 100 Year ARI Events)

Building Footprints (Floor Level)

50yr Site assessed floors within 500mm

50yr Site assessed floors at risk

50yr Surveyed floors within 500mm50yr Surveyed at risk

DraftAFinal0

PF MJSPF MJS

30/06/1001/10/10

Layout For "Hazardous Areas"

Flood extent confirmed on site. Contours in thisvicinity not reliable.

Significant Hazard Overland Flowpath (50yr)Significant Hazard Overland Flowpath (10yr)

Significant Hazard Flooding (10yr)Significant Hazard Flooding (50yr)Significant Hazard Flooding (100yr)

Highest Astronomical Tidal Flood Plain

Potential Overland Flowpath or Low Hazard Flooding (50yr)

Potential Overland Flowpath or Low Hazard Flooding (10yr)

Documents

Te Auaunga Awa - Walmsley and Underwood …temp.aucklandcouncil.govt.nz/EN/ratesbuildingproperty/consents...Te Auaunga Awa - Walmsley and Underwood Reserves Project ... Medium to dense