Flood Warning Manual
Bay of Plenty Regional Council 5 Quay Street PO Box 364 Whakatāne 3158 NEW ZEALAND
Prepared by Dana Thompson, Flood Management, Project Coordinator
Cover Photo: Surface flooding at Kanuka Place, Edgecumbe - 2004 Flood Event.
Bay of Plenty Regional Council Flood Warning Manual
Status: Revision 4
Date issued: June 2016
Next annual review completion date: August 2017
Prepared by: Dana Thompson Flood Management, Project Co-ordinator
Reviewed by: Mark Townsend Roger Waugh Graeme O’Rourke Mark James
Approved by: ...... Mark Townsend Engineering Manager
REVISION LOG
Date Revision Details Section no. no.
09/08/2013 Flood Warning Manual full review undertaken. New document issued August 2013.
15/10/2013 1 Generic format changes. Section page numbers N/A individually formatted. Flood Warning Guide included in appendices. Notes include Rangitaiki River section update due 31 March 2014. 19/12/2014 1 Annual up of contacts and simplification of SOPs Appendix 1
23/01/2015 2 Flood Warning Message Guide – Version 1, 18 October 2013 (A1684503) superseded by Version 2, 18 December 2014 (A2001882) 11/12/2015 2 Flood Warning Message Guide – Version 2, 18 December Part 15 2014 (A2001882) superceded by Version 2.1, December Flood 2015 (A2214804) Warning Groups 30/03/2016 3 Major updates include: Hours of work Part 2 Flood Forecasting updates Part 3 Name change from Waimana River to Tauranga River Part 8 Staff gauge prompter updates river name change and
NZTA emergency contact number Rangitāiki River section includes updated Trustpower Part 10 contact information, Matahina Dam information taken from Resource Consent 65750 Inclusion of TrustPower Matahina Dam Flood Appendix 3 Management Plan Inclusion of Inter Council Memorandum for Assistance Appendix 11 Updated Emergency Support Contact Details Appendix 13 Updated CDEM Contact Details Appendix 14 Updated RT Call Signs Appendix 18 30/06/2016 4 Major updates include: Addition of flow and level tables including alarm levels in each of the major river sections Updated staff gauge prompters Removal of the date in the footer Part 7 Removal of the flood maps for the Waioeka River due to the poor image quality Part 9 Additional information assosciated with the Whakatane at
Ruatoki Part 13 Updated Lake Okareka procedure
Contents
Part 1: Introduction 1
1.1 Flood Warning Manual purpose 2
1.2 Overview 3
1.3 Background 4
1.4 Rivers and drainage at a glance 4
1.5 Relevant legislation 5
1.6 Health and safety 5
1.7 The climate and weather of the Bay of Plenty region 6
Part 2: Roles and activation 1
2.1 Flood Manager role 2
2.2 Flood Team responsibilities 2
2.3 Sample organisation charts 4
2.4 Flood duty and standby mode 5
2.5 Hours of work during a flood event 5
2.6 Flood Room activation scenarios 5
2.7 Flood management activation flow chart 6
2.8 Civil Defence Emergency Management 6
2.9 New Zealand Police 8
Part 3: Flood Management Tools 1
3.1 Bay of Plenty Regional Council flood forecasting tools 2
3.2 Telemetry sites – Flood Management 5
3.3 Data summaries 11
3.4 Bay of Plenty Regional Council website 11
3.5 Site information 12
3.6 Loncel 12
3.7 Meteorological Office warnings 12
Bay of Plenty Regional Council Flood Warning Manual i
3.8 MetConnect 14
3.9 WaterRide 14
3.10 Assessment of flooding impact (rainfall) 15
3.11 Landslide risk for Eastern Bay of Plenty 16
Part 4: Communications 1
4.1 Introduction 2
4.2 Public information 4
4.3 Bay of Plenty Regional Council website 5
4.4 Issuing messages to the flood warning groups 6
4.5 Decision process for issuing flood warning messages 6
Part 5: Non-scheme areas 1
5.1 Overview 2
5.2 Non-scheme Bay of Plenty Regional Council alarms (action required) 2
5.3 Burt’s rainfall alarm (Waitepuru Stream) 4
5.4 Non-scheme Bay of Plenty Regional Council alarms 4
5.5 Externally received alarms or actions currently in place 5
5.6 Bay of Plenty rivers and streams that have a history of flooding 5
5.7 Rainfall records for the East Coast area 8
5.8 Rainfall records for the Western Bay of Plenty area 9
Part 6: Otara River 1
6.1 Otara Catchment overview 2
6.2 Otara Catchment hydrological characteristics 2
6.3 Warnings and flood warning groups 3
6.4 Otara River telemetry sites 4
6.5 Flood forecast modelling 4
6.6 Current stopbank design level 5
6.7 Predicted warning stages and travel times 7
6.8 Historical floods and travel times 8 ii Bay of Plenty Regional Council Flood Warning Manual
6.9 Critical flood control structures and hotspots 9
6.10 Data records for Otara River 9
6.11 Rainfall records for Otara 9
6.12 Otara River flood event plot July 1998 12
6.13 Otara River flood event plot October 2003 13
6.14 Otara at Browns Bridge rating curve 14
6.15 Rating table for Otara at Browns Bridge 15
6.16 Otara at Browns Bridge staff gauge prompter 16
Part 7: Waioeka River 1
7.1 Waioeka Catchment overview 2
7.2 Waioeka Catchment hydrology 2
7.3 Warnings and flood warning groups 2
7.4 Waioeka telemetry sites 3
7.5 Flood forecast modelling 4
7.6 Predictable warning stages and travel times 6
7.7 Historical floods and travel times 8
7.8 Critical flood structures and hotspots 8
7.9 Data records for Waioeka River 9
7.10 Rainfall records for Waioeka 10
7.11 Waioeka River flood event plot July 1998 11
7.12 Waioeka River flood event plot October 2003 12
7.13 Maximum flood depth profile, predictive scenarios – Waioeka and Otara Rivers 13
7.14 Predicted stopbank overflows 18
7.15 Waioeka at Cableway rating curve 19
7.16 Rating table for Waioeka at Cableway 20
7.17 Waioeka at Cableway staff gauge prompter 22
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Part 8: Tauranga River formerly Waimana River 1
8.1 Tauranga River Catchment overview 2
8.2 Warnings and warning lists 2
8.3 Flood forecast modelling 3
8.4 East Bridge and Matahī Bridge staff gauges 3
8.5 Data records for Tauranga River 4
8.6 Rainfall records for Tauranga River Catchment 4
8.7 Tauranga River flood maps predictive scenarios 5
8.8 Tauranga at Gorge rating curve 9
8.9 Rating table for Tauranga at Gorge 10
8.10 Tauranga at Ranger Station rating curve 12
8.11 Rating table for Tauranga at Ranger Station 13
8.12 Tauranga at Gorge staff gauge prompter 14
8.13 Tauranga at Ranger Station staff gauge prompter 15
Part 9: Whakatāne River 1
9.1 Whakatāne Catchment overview 2
9.2 Warnings and flood warning groups 3
9.3 Whakatāne and Tauranga telemetry sites 4
9.4 Flood forecast modelling 4
9.5 Current stopbank design level 5
9.6 River floods 7
9.7 Flooding at Rūātoki 7
9.8 Historical floods and travel times 10
9.9 Critical flood structures and hotspots 10
9.10 The Whakatāne River Spit 13
9.11 Flood protection stoplog structures 15
9.12 Road closures due to stoplog installation 17
9.13 Whakatāne rural area stoplogs 19 iv Bay of Plenty Regional Council Flood Warning Manual
9.14 Te Rahu Basin and Spillway 19
9.15 Data records for Whakatāne River 22
9.16 Rainfall records for Whakatāne including Tauranga sites 22
9.17 Whakatāne River flood event plot – July 2004 24
9.18 Whakatāne River flood event plot – January 2011 25
9.19 Whakatāne at Whakatane rating curve 26
9.20 Rating table for Whakatāne at Whakatāne 27
9.21 Whakatāne at Whakatane staff gauge prompter 29
9.22 Whakatāne at Wharf staff gauge prompter 30
9.23 Whakatāne at Rūātoki staff gauge prompter 31
Part 10: Rangitāiki River 1
10.1 Rangitaiki Catchment overview 3
10.2 Historical flood protection 3
10.3 Warnings and flood warning groups 3
10.4 Flood forecast modelling 4
10.5 Current stopbank levels of service 5
10.6 Historical floods and travel times 8
10.7 Telemetry sites 9
10.8 Rangitāiki rainfall 9
10.9 Critical control structures and hotspots 9
10.10 Flood control system and Rangitāiki Spillway 10
10.11 Additional road closure 13
10.12 Pressure relief trench monitoring procedure 15
10.13 Hydroelectric dams 19
10.14 Sudden failure procedure 24
10.15 Aniwhenua Dam 26
10.16 Wheao Dam 27
10.17 Data records for Rangitāiki River 28
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10.18 Rainfall records for Rangitāiki 28
10.19 Rangitāiki River flood event plot – 23 July 1998 33
10.20 Rangitāiki River flood event plot – 18 July 2004 34
10.21 Rangitāiki River flood event plot – 23 January 2011 35
10.22 Rangitāiki River flood event plot – 30 January 2011 36
10.23 Rangitaiki at Te Teko rating curve 37
10.24 Rating table for Rangitaiki at Te Teko (NIWA) 38
10.25 Rangitaiki at Murupara rating curve 39
10.26 Rating table for Rangitaiki at Murupara (NIWA) 40
10.27 Waihua at Gorge rating curve 41
10.28 Rating table for Waihua at Gorge (NIWA) 42
10.29 Whirinaki at Galatea rating curve 43
10.30 Rating table for Whirinaki at Galatea (NIWA) 44
10.31 Rangitāiki at Rabbit Bridge staff gauge prompter 45
10.32 Rangitāiki at Te Teko staff gauge prompter 46
Part 11: Tarawera River 1
11.1 Tarawera Catchment overview 2
11.2 Warnings and flood warning groups 2
11.3 Telemetry sites 3
11.4 Rain gauge sites (external) 3
11.5 Flood forecast modelling 3
11.6 Historical floods 4
11.7 Hydrology 4
11.8 Current stopbank levels of service 5
11.9 Data records for Tarawera River 7
11.10 Rainfall records for Tarawera 7
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11.11 Tarawera at Awakaponga rating curve 9
11.12 Rating table for Tarawera at Awakaponga 10
11.13 Tarawera at Awakaponga staff gauge prompter 11
Part 12: Kaituna River 1
12.1 Introduction and history 2
12.2 Warnings and flood warning groups 2
12.3 Flood forecast modelling 3
12.4 Telemetry sites 3
12.5 Historical floods and travel times 4
12.6 Current stopbank levels of service 5
12.7 Critical control structures and hotspots 9
12.8 Data records for Kaituna River 15
12.9 Rainfall records for Kaituna 15
12.10 Kaituna River flood event plot July 1998 18
12.11 Kaituna River flood event plot May 1999 19
12.12 Kaituna River flood event plot January 2011 20
12.13 Kaituna at Te Matai rating curve 21
12.14 Rating table for Kaituna at Te Matai 22
12.15 Mangorewa at Saunders rating curve 24
12.16 Rating table for Mangorewa at Saunders 25
12.17 Kaituna at Te Matai staff gauge prompter 28
12.18 Mangorewa at Saunders staff gauge prompter 29
Part 13: Lakes 1
13.1 Lakes rainfall 2
13.2 Lake Rotoiti 3
13.3 Okere Gates operation 3
13.4 Lake Okareka 9
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Part 14: Coastal 1
14.1 Introduction 2
14.2 River levels 3
14.3 Astronomical tide 3
14.4 Astronomical tide tables 3
14.5 Barometric pressure 4
14.6 Wind setup 5
14.7 Wave conditions 6
14.8 Estuary effects 6
14.9 Tsunami 6
14.10 Types of tsunami notifications - MCDEM 7
14.11 Calculation of event sea water level 8
14.12 Bay of Plenty coastal areas of concern 8
14.13 Post event data collection 9
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Appendices
Appendix 1 – Flood Warning Guide 3
Appendix 2 – Standard Operating Procedures 5
Appendix 3 – Notes page 13
Appendix 4 – Lake Matahina Flood Management Plan 15
Appendix 5 – Flood Warning Manual Improvement Plan 17
Appendix 6 – Acronyms 19
Appendix 7 – References 21
Appendix 8 – Useful links 23
Appendix 9 – Flood Room Resources 25
Appendix 10 – Flood equipment list: Rivers and Drainage 27
Appendix 11 – Inter Council Memorandum for Assistance 29
Appendix 12 – Flood Team contact list 31
Appendix 13 – Emergency Support Contact Details 33
Appendix 14 – Civil Defence Emergency Management contacts 35
Appendix 15 – Radio station contacts 37
Appendix 16 – Essential contacts 39
Appendix 17 – Contractor and equipment contacts 45
Appendix 18 – RT Call Signs 53
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Part 1: Introduction
Chapter summary
1.1 Flood Warning Manual purpose 2
1.2 Overview 3
1.3 Background 4
1.4 Rivers and drainage at a glance 4
1.5 Relevant legislation 5
1.6 Health and safety 5
1.7 The climate and weather of the Bay of Plenty region 6
Bay of Plenty Regional Council Flood Warning Manual 1
1.1 Flood Warning Manual purpose
The Flood Management Procedures and associated information contained in this manual are to assist and guide the Bay of Plenty Regional Council (BOPRC) Flood Manager and supporting personnel, during flood events within the Bay of Plenty region. All actions described in this manual should be undertaken in the most efficient and safest way possible.
The objective is to mitigate or reduce the risk to life and property during a flood event, while fulfilling the Council’s obligations as defined in the BOPRC’s Ten-Year Plan.
1.1.1 Document structure
Figure 1 Flood Warning Manual relationship to Bay of Plenty Regional Council plans and polices.
1.1.2 Ten-Year Plan 2015 – 2025
Level of service Key Performance Indicator Target
All flood warnings at pre-determined levels are given in accordance with the flood warning 90% manual.
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1.1.3 Special notes
The manual provides broad coverage across the region focusing on the main Bay of Plenty river schemes. Specific information relating to flooding and flood warnings is also covered in the non-scheme, coastal and lakes sections.
Note 1 Pre-set flood warning trigger levels are displayed on the staff gauge prompter pages in each river section. Several trigger levels that fall outside of the scheme or river monitoring network are detailed in the non-scheme section.
Note 2 All the instructions for issuing flood warning messages and contact lists for the flood warning groups is located in the Flood Warning Guide. The guide can be found in the Appendices section of the Flood Warning Manual.
Note 3 For tsunami advisory protocols, please refer to 14.9 and for associated Whakatāne River stoplog information, please refer to section 9.10.
Note 4 For information on dams - consult the appropriate river section.
Note 5 Multiple contact lists are included at the back of this manual, these include the BOPRC Flood Team, Civil Defence Emergency Management (CDEM), essential services and partner agencies.
Note 6 Updates to the manual will be issued as required. A review of all contacts lists and any changes that affect the contents of manual will be undertaken each year as part of an annual maintenance programme.
1.1.4 Disclaimer
The Integrated Catchments Group is responsible for the preparation, circulation and management of the Flood Warning Manual. This is an internal reference and operational document that has been prepared for the use of the BOPRC Flood Management Team. This is a quality controlled document. Council requests that if excerpts or inferences are drawn from this document for further use by individuals or organisations, due care should be taken to ensure that the appropriate context has been preserved, and is accurately reflected and referenced in any spoken or written communication. The Bay of Plenty Regional Council has exercised all reasonable skill and care in controlling the contents of the manual. Council accepts no liability for loss, damage, injury or expense (whether direct, indirect, or consequential) arising out of the provision of this information, or its use by you or any other party.
1.2 Overview
This document provides background information to support a response to a river flooding event in the Bay of Plenty region, including:
Overview of the river flood risk that affects the Bay of Plenty region. Roles and responsibilities during a flood event. Standard Operating Procedures (SOPs). Rainfall, river level and flow data. Pre-set alarm levels and the process to issue flood warnings.
Bay of Plenty Regional Council Flood Warning Manual 3
1.3 Background
Bay of Plenty Regional Council manages the Kaituna, Rangitāiki-Tarawera, Whakatāne-Tauranga, Waioeka-Otara River Schemes and the Rangitāiki Drainage Schemes. There have been numerous minor flood events and several significant ones that have had a widespread impact on the community.
As part of the Regional Council flood risk reduction, an ongoing 24/7 flood warning service is maintained to provide early advice to the landowners, general public and emergency management authorities within the schemes of impending flood threats.This manual sets out the operating protocols and warnings to be issued during flood events and describes the responses required to manage the schemes’ flood defence and drainage assets during events.
Figure 2 Flooding on the Rangitāiki Plains – July 2004.
1.4 Rivers and drainage at a glance
Major rivers and drainage schemes and drainage areas within the regional boundaries of BOPRC include:
Kaituna Catchment Control Scheme Rangitāiki-Tarawera Rivers Scheme Whakatāne-Tauranga Rivers Scheme Waioeka-Otara Rivers Scheme Rangitāiki Drainage Scheme
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There are also a number of minor rivers and drainage schemes that complete the rivers and drainage network in the Bay of Plenty. The minor drainage schemes are not part of the Rivers and Drainage Asset Management Plan (AMP). Bay of Plenty Regional Council do not own these assets, but sometimes manage them on behalf of these schemes. Each scheme has the discretion to use Council or others to manage their scheme.
Figure 3 Bay of Plenty Rivers Schemes and Drainage Districts (C2264).
1.5 Relevant legislation
Bay of Plenty Regional Council has a mandate under three Acts of Parliament to monitor waterways for river flood events:
The Soil Conservation and Rivers Control Act 1941 states that regional councils (formally Catchment Boards) should prevent/minimise damage by floods. The Resource Management Act 1991 (RMA) gives regional councils, functions to control the use of land for avoidance and/or mitigation of natural hazards. The Civil Defence and Emergency Management Act 2002 placed an increased focus on reduction and readiness activities.
1.6 Health and safety
Health and Safety Employment Act 2016 (HSE Act).
Staff deployed in the field, face serious health and safety risks in a flood event. The Council or contractors engaging staff in the field remain responsible for their health and safety.
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For more information refer to the BOPRC Health and Safety information - refer to the intranet (SAM).
Note: The BOPRC vehicles are equipped with Global Positioning System (GPS) tracking. All vehicles can be tracked using this system during a flood event.
1.7 The climate and weather of the Bay of Plenty region
The Bay of Plenty generally has one of the sunniest climates in New Zealand, especially in coastal areas where dry spells have been traditionally quite common place. Annual rainfall follows variations in topography and varies from 1,400 mm near the coast to 4,000 mm on the highest parts of the Raukumara Ranges.
Indications of climate change by the Intergovernmental Panel on Climate Change (IPCC) are that the Bay of Plenty region may receive less rainfall in the future. However, the intensity and frequency of high rainfall events are likely to increase. Sea level is predicted to rise with increased magnitude of tidal storm surges.
The region has lower than average wind. Temperature inversions trap warm air under a layer of cold air in many places, particularly in winter. Examples of storm types typical of the Bay of Plenty weather described in ‘The Climate and Weather of the Bay of Plenty Region’, a Meteorological Service Publication by A M Quayle - Bay of Plenty Regional Council Library Number 1523 or 15629, are summarised below.
1.7.1 Typical weather patterns
Because the Bay of Plenty is sheltered by high country to the west, south and east, day-to-day variations of the weather are largely determined by the direction of the wind. While high country areas may receive rain with airstreams from any direction, most of the Bay of Plenty area receives a large part of its annual rainfall during periods of onshore north to northeast winds.
1.7.2 North to northeast airstreams
Airstreams from the north to northwest frequently have long trajectories over the warm ocean to the north of New Zealand and, as a result, the air flowing onto the Bay of Plenty under these conditions is very humid. As the whole region is exposed to the north, these airstreams often produce widespread and heavy rain when the moist air is forced to ascend over the rising ground of the North Island. Such flows are normally associated with one of two types of situation.
When a cold front, orientated north south, is approaching from the west, the northerly winds ahead of the front spread over the region, bringing widespread rain until the passage of the front has passed.
The second type occurs when depressions cross the northern half of the North Island. These lows often move only slowly east, and the north to northeast flows on the eastern side of the centre may bring prolonged rain to the region.
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1.7.3 Disturbed west to southwest flows
This common situation occurs most frequently during the spring months, but because the Bay of Plenty is sheltered by high ground to the south and west, only a few showers are normally experienced.
Figure 4 Metservice weather map – 18 July 2004.
1.7.4 Tropical cyclones
Occasionally, during the months November to April, cyclones originating in the tropics move onto northern New Zealand. Because of their origin over very warm tropical oceans, these depressions normally contain very moist air. Although the structure of tropical cyclones is much modified as they move into higher latitudes, they may still produce very strong winds and heavy rain (Lew's rule of thumb - if they come down from New Caledonia, to the West of Lord Howe Island, and then start heading east - WATCH OUT).
When rainfall over a river catchment area is exceptionally large, the resulting river discharge can exceed the capacity of the usual river channel, and flooding of land adjacent to the channel occurs. When exceptional tides combine with storm surges, flooding of low-lying coastal regions occurs. Such flooding is a naturally occurring hazard.
Factors causing flooding to be New Zealand’s Number One Hazard Alistair I. McKerchar and Charles P. Pearson National Institute of Water and Atmospheric Research (NIWA)
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Part 2: Roles and activation
Chapter summary
2.1 Flood Manager role 2
2.2 Flood Team responsibilities 2
2.2.1 Flood Manager 2
2.2.2 Logistics 3
2.2.3 Communications 3
2.2.4 Field Operations - Rivers and Drainage (Edgecumbe) 3
2.2.5 Technical Support (Data Services) 3
2.2.6 Technical Support (Engineering) 4
2.3 Sample organisation charts 4
2.3.1 Sample organisational structure for a minor flood event 4
2.3.2 Sample organisation chart for a significant flood event 4
2.4 Flood duty and standby mode 5
2.5 Hours of work during a flood event 5
2.6 Flood Room activation scenarios 5
2.7 Flood management activation flow chart 6
2.8 Civil Defence Emergency Management 6
2.9 New Zealand Police 8
Bay of Plenty Regional Council Flood Warning Manual 1
2.1 Flood Manager role
Bay of Plenty Regional Council has a duty Flood Manager on standby 24-hours a day, every day of the year for emergency flood events. The Flood Manager responds to weather warnings, predetermined HydroTel™river level and rainfall alarms and media or landowner enquires, as set out in the procedures in this manual.
Coordination of the monitoring, preparation and activation of the BOPRC’s Flood Team’s response is carried out by the Flood Manager. The level of activity can vary greatly due to the unpredictable weather patterns and other factors such as; intense cells of rain, structure failures, tidal influences and drainage capacity. Small events can be managed within a business as usual structure. The Flood Manager may need some assistance during smaller scale events while high rainfall and river level events will require significant support. Please refer to Figure 5, Figure 6 and Figure 7 organisational chart examples. The Flood Manager will decide what resources are required to respond quickly and effectively during a flood event.
Figure 5 Typical Flood Team structure.
2.2 Flood Team responsibilities
2.2.1 Flood Manager
Monitors and acts upon Metservice - weather watches and severe weather warnings. Ensures all hardware and software used by the Flood Manger is fully operational at all times. Maintains all the individual passwords needed during a flood event. Determines level of response and mobilises teams as required. Chairs pre-event meetings. Monitors and manages Lake Rotorua/Rotoiti level controls. Assumes control of the BOPRC response to a flood event. Oversees any health and safety issues. Takes precautionary actions as defined in the Flood Warning Manual. Logs messages, information and actions. Issues warnings in line with Flood Warning Manual. Liaises with territorial authorities (TAs) and Civil Defence Emergency Management.
2 Bay of Plenty Regional Council Flood Warning Manual
Coordinatesflood forecasting. Issues situation reports (Sitreps). Liaises with BOPRC management as required. Liaises with TrustPower (Matahina Dam) and NOVA (Aniwhenua Dam). Approves aerial surveillance. Approves press releases and follow-up statements. Conducts briefings during the event. Conducts the debrief after the flood event.
2.2.2 Logistics
Conducts monthly checks of Flood Room equipment and resources. Logs messages, information and actions. Sends out flood warning to predetermined groups. Organises catering and vehicles. Manages Flood Team and Rivers and Drainage staff rosters. Organises and issues extra personnel protective clothing. Provides support to the field staff when required.
2.2.3 Communications
Prepares media releases in consultation with the Flood Manager. Acts as liaison with local and national media. Informs media of contact procedure. Assists with community relations where required. Ensures staff and councillors are kept informed. Maintains their own staff roster during the event.
2.2.4 Field Operations - Rivers and Drainage (Edgecumbe)
Issue warnings to direct contractors – earthmoving, river works. Inspect floodgates and set as necessary. Monitors erosion, flooding, seepage and stopbank stability. Supervise temporary remedial works. Field liaison – landowners, territorial authorities and emergency services. Maintains own staff roster until the Flood Room is activated.
2.2.5 Technical Support (Data Services)
Provides a 24-hour monitoring service. Maintains HydroTel™. Provides rainfall and river flow and level data as requested. Maintains their own staff roster during the event.
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2.2.6 Technical Support (Engineering)
Provides technical modelling and flood forecasting. Stopbank stability monitoring. Flood level pegging. Assist with lake level control. Provides support to Field Operations as required.
2.3 Sample organisation charts
2.3.1 Sample organisational structure for a minor flood event
Figure 6 Sample organisation chart – minor flood event.
2.3.2 Sample organisation chart for a significant flood event
Figure 7 Sample organisation chart – significant flood event.
Organisation Chart Significant Flood Event – Flood Room Activated Multiple flood sites, road closures, possible CDEM declaration and evacuations, high media involvement.
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2.4 Flood duty and standby mode
There is a Duty Flood Manager and a Duty Flood Officer (Data Services) on call 24 hours a day.
The Flood Manager will place support staff on standby as a precautionary measure if it looks likely that assistance could be required. Standby allowances as set out in CEA would be applicable.
2.5 Hours of work during a flood event
A work roster shall be established to ensure that:
No person is to be permitted or compelled to work more than 12 hours in a 24-hour period. If a person has reached 12 hours, there must be a minimum of 8 hours break before another work period begins. If a person has reached 60 hours over a five-day period, there must be a minimum of 24 hours rest period.
2.6 Flood Room activation scenarios
Forecast Rainfall > 150 mm forecasted for next 24 hours. High river levels predicted, multiple alarms and notifications received. Road closures started.
Forecast for significant rainfall over the next 48 hours. Drainage over capacity in a number of locations across the region. Stopbank integrity being monitored. Flood King tides, saturated catchments and severe weather warnings in place. Media Room interest high. Field staff deployed. Support staff required. Activation
Severe flooding in urban and rural areas. Evacuations started in mulitple areas. CDEM emergency declared.
Figure 8 Scenarios where the Flood Room would be activated.
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2.7 Flood management activation flow chart
2.8 Civil Defence Emergency Management
Under the Civil Defence Emergency Management (CDEM) Act 2002, the BOPRC is required to participate in and administer a Civil Defence Emergency Management Group for the region. For the purposes of this manual, the relationship and communication between the Flood Manager and/or their delegate, and CDEM Duty Managers, and Controllers needs to be understood.
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Communication with CDEM Local and Group Duty Managers should begin at the initial stages of a flood event.
Note – This does not include situations where a severe weather warning has been issued by Metservice but the combination of catchment conditions, river levels and other contributing factors are unlikely to prompt any significant response from the Flood Team.
Flood warnings must be sent to the CDEM Duty Managers at Group (Regional) and Local (District) level where the nature or extent of the flooding has the potential to isolate communities, disrupt lifeline utilities, damage properties, or require the evacuation of residents.
The CDEM Group and Local CDEM Duty Managers are to be included and/or notified when:
A pre-event briefing is held. A Sitrep is circulated. The Flood Room is activated. Flood forecasting shows possible flooding of areas that could cause evacuations or critical roads to be closed. A debrief is held. Significant information comes to hand that is likely to have serious consequences either locally or across the Bay of Plenty region.
The CDEM Group and local offices look to the Flood Team to provide warnings, forecasting and technical advice during flood events. Examples of information the Controller may request from the Flood Team:
Areas affected by flooding. Forecasted extent and new areas at risk of flooding. Predicted duration of flooding. Areas of concern. Confirmation of reported incidents from our field staff. Flooding infrastructure issues. Safe areas away from flooding for welfare centre establishment or evacuees.
Civil Defence Emergency Management will use the information from the Flood Team to plan how they respond during a flood.
Note – If evacuations, infrastructure fails (electricity etc.), roads are closed and the local EOC or Group GECC are activated, consider appointing a liaison role in the Flood Room to assist with the added responsibilities. This will allow for the normal Flood Team responsibilities to be taken care of while providing information to the Controller within the timeframes required.
For more information please refer to “Bay of Plenty Civil Defence Emergency Management Group Plan 2012/2017” Civil Defence Publication 2012/01.
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2.9 New Zealand Police
There have been times when the Flood Manager has been contacted or has had to contact the Police. This is often to share information around road closures, traffic management or potentially dangerous situations that our staff may be working on.
Refer to contact list at the back of this manual for contact details.
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Part 3: Flood Management Tools
Chapter summary
3.1 Bay of Plenty Regional Council flood forecasting tools 2
3.2 Telemetry sites – Flood Management 5
3.3 Data summaries 11
3.4 Bay of Plenty Regional Council website 11
3.5 Site information 12
3.6 Loncel 12
3.7 Meteorological Office warnings 12
3.8 MetConnect 14
3.9 WaterRide 14
3.10 Assessment of flooding impact (rainfall) 15
3.11 Landslide risk for Eastern Bay of Plenty 16
Bay of Plenty Regional Council Flood Warning Manual 1
3.1 Bay of Plenty Regional Council flood forecasting tools
Bay of Plenty Regional Council maintains a range of flood forecasting tools:
Automatic computer hydrologic models are run every two hours on computers in Whakatāne Quay Street offices. Their results are displayed on the HydroTel™ user interface and automatically generated reports are archived immediately to a commonly available network location. Bay of Plenty Regional Council subscribes to EcoConnect, NIWA’s web-based service, displaying results of atmospheric and river models that are run every three hours in Wellington.This currently covers only the Rangitāiki River; although good displays of rain forecasts are available for the whole country. Currently, (March 2016) the subscription to EcoConnect has lapsed but is scheduled to be renewed in 2016. Bay of Plenty Regional Council subscribes to the New Zealand MetService’s MetConnect; a web-based service providing weather forecasts and visual display of rain radar data. A manually-run computer model of the Rangitāiki Catchment using InfoWorks software can be run by trained staff. This section outlines the current operational models/services and how to access their results. Details of the models are also included in this manual within the relevant river chapters.
Flood modelling computer
Username Password
3.1.1 Unit Hydrograph models (UHG)
The Unit Hydrograph Model runs automatically every two hours on the Flood Room Flood Forecasting BRWS 001254. Every time it runs (manually or automatically) a text-file log is updated in C:/Flood_Forecasting. If an error occurs at some stage in the run cycle, it should show on the log. An automatic backup runs every two hours on BRCWS000201 in room 1.15 West Wing First Floor. This system also stores a log file in C:/Flood_Forecasting. Currently, the backup system will produce a forecast report and store it to the O: Drive network location (below) if the primary system fails to do so. In the near future it will also send results to Hydrotel if it finds that the primary system has failed to do so.
The rivers currently modelled by UHG methods (automatically run at Quay Street) are Otara, Waioeka, Tauranga, Whirinaki, Waihua, Horomanga and Rangitāiki. These operate on telemetered river/rain gauge information and seasonal factors. Forecast rain amounts can be manually entered. These models offer very robust forecasts but are strongly impacted by how well the sparse rain gauge information compares with actual rainfall over quite large areas.
The latest forecasts are posted on HydroTel™. To view these, expand the “flow” item in the explorer window under the river you are interested in and select “UHG Modelled Flow”. This forecast includes “landed” rain only.
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A detailed report of each river forecast is also archived to O: drive if significant rain has fallen. The report shows results from landed rain as well as manually-entered forecast rain. The Network location is:
\\WHKNEARLINE\Flood Forecasting\Herbst Models\Archived Forecasts\ Auto_Forecast_yyyymmdd_hhmm.xls
A semi-manual version is available for modelling of forecast rainfall scenarios; alternative rain-gauge allocations; or rainfall loss parameters. A readme file stored alongside the model provides the necessary directions. The scenario model is stored at:
\\WHKNEARLINE\Flood Forecasting\Herbst Models\UHGModels_20110817_ScenarioMaster.xlsm
3.1.2 Non-linear Reservoir models (NLR)
3.1.3 These models offer a higher degree of detail than the UHG models and typically provide a more reliable river forecast. Currently run automatically on the computers listed above for the Rangitāiki and Kaituna Catchments using telemetered gauge data, radar rain data and manually-entered metservice spatially distributed forecast rain data. Landed-only Results from the radar rain and forecast rain scenario are posted to HydroTel™ (as “NLR Modelled Flow”). Detailed reports that also include results from gauges-only and landed-only forecast rain scenarios and output from the dam management tools are posted to the network location:
\\WHKNEARLINE\Flood Forecasting\Rangitāiki NLR Model\Archived Forecasts\Auto_Forecast_yyyymmdd_hhmm.xls
A semi-manual version is available for modelling of forecast rainfall scenarios; alternative rain-gauge allocations; rainfall loss parameters; or dam management criteria. A readme file stored alongside the model provides the necessary directions. The scenario model is stored at:
\\WHKNEARLINE\Flood Forecasting\Rangitāiki NLR Model\Rangitaiki_NLR_20121019.xlsm
3.1.4 EcoConnect
Currently (March 2016) the subscription to EcoConnect has lapsed but is scheduled to be renewed 2016.
EcoConnect’s forecast Rangitāiki River flows are from NIWA’s TOPNET hydrological model, run on results from their atmospheric weather predicting model NZLAM. The weather model is very advanced, producing good rain forecasts and the catchment model is comprehensive, however, rain-gauge inputs are not used in this system. Bay of Plenty Regional Council staff feel that this impacts on reliability of the river forecasts.
To access EcoConnect, launch from Application Launcher and enter your (assigned) individual username and password. The explorer bar is self-explanatory. The “product menu” icon (top left in the main window) includes a very useful retrospective function “modify date range”.
Username Password
Bay of Plenty Regional Council Flood Warning Manual 3
3.1.5 Manually-run InfoWorks model of Rangitāiki River
This is a manually run NLR model using InfoWorks software.This is very similar to the automated Rangitāiki NLR model.It runs on a different platform and needs to be operated manually by trained staff.
3.1.6 HydroTel™
Bay of Plenty Regional Council manages and maintains the HydroTel™ telemetry system to monitor environmental information throughout the Bay of Plenty region. The information received by HydroTel™ originates from data recorders strategically located throughout the region.
The purpose of the HydroTel™ telemetry system is:
To allow the automatic collection of data on river levels and rainfall from data recorders. To trigger alarms during events when certain rainfall and river level conditions have been exceeded.
Hydrotel displays raw data. Selected sites are accessible through the BOPRC website.
Username Password Engineer River
Note – Any change to an alarm level must be noted in the Flood Warning Manual. This information is recorded on the staff gauge prompter pages in the river sections. An explanation for the change and any other background information must be added to the notes page.
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3.2 Telemetry sites – Flood Management
Sites (in alphabetical order). East to West.
Site name Comments Agency East Cape Catchments Haparapara at Rain gauge at summit of Haparapara BOPRC Haparapara Catchment in the eastern ranges. Motu at Houpoto NIWA river and rain in the Motu located at NIWA the state highway bridge. Updated 12-hourly. Motu at Waitangirua NIWA river and rain in the Motu near Motu NIWA village. Updated 12-hourly. Waioeka and Otara Catchments Otara at Browns Bridge River level/flow in the lower Otara River but BOPRC above Ōpōtiki township. Otara at Ōpōtiki Wharf River level and rainfall at the confluence of BOPRC the Otara and Waioeka Rivers. Tidal effects present. Otara at Tutaetoko Rain gauge positioned between the Otara BOPRC and Waioeka Catchments. Pakihi at Pakihi Station River level and rainfall in the Pakihi which is BOPRC a major tributary of the Otara. Pakihi at Rakanui Link Rain gauge in the upper Pakihi Catchment BOPRC which is a major tributary of the Otara. Waioeka at Cableway River level/flow and rainfall in the middle of BOPRC the Waioeka Gorge. Waioeka at Koranga Rain gauge situated at the top of the BOPRC Station Waioeka Catchment. Waioeka at Mouth River level and rainfall in the lower Waioeka BOPRC but above Ōpōtiki township. Waimana and Whakatāne Catchments Nukuhou at River level and flow site near BOPRC Glenholme Road Glenholme Road. Feeds into the Ōhiwa Harbour and floods Wainui Road when high. Ōhiwa at Port Ohope Tidal levels at Port Ohope Wharf. BOPRC Tauranga at Mouth of River level in the Tauranga in the middle of BOPRC Gorge the Waimana Gorge. Give approximately 12-18 hours lead into flood peak reaching Whakatāne. Tauranga at Ranger River level/flow and rainfall site on the BOPRC Station Tauranga in the heart of the Urewera National Park. Wainui-te-whara at Level/flow in the Wainui-te-whara which BOPRC Mokorua Gorge feeds the Awatapu lagoons.
Bay of Plenty Regional Council Flood Warning Manual 5
Site name Comments Agency Wainui-te-whara at The rain gauge is situated on the boundary BOPRC/WDC Munroes between the Wainui-te-whara and Maraetōtara Catchments. The site is jointly funded by Whakatāne District Council (WDC) and BOPRC. Whakatāne at Huitieke River level and rainfall situated in the middle BOPRC of the Whakatāne Catchment. Give approximately 12-18 hours lead into flood peak reaching Whakatāne. Whakatāne at Kopeopeo Rainfall in Whakatāne township in Kopeopeo. BOPRC Whakatāne at Rūātoki River level in the Whakatāne at Rūātoki. BOPRC Whakatāne at Town River levels at the lower end of Whakatāne BOPRC Wharf township. Tidal effects present. Whakatāne at Whakatane River level/flow in the Whakatāne at the NIWA/BOPRC upstream end of Whakatāne township. Rangitāiki and Tarawera Catchment Edgecumbe at Rainfall at Edgecumbe BOPRC Depot, BOPRC Edgecumbe situated in the Rangitaiki Catchment area. Galatea Basin Climate Rainfall in Horomanga Road, Galatea Basin, BOPRC situated in the Rangitaiki Catchment area. Okaro at Birchalls Rainfall situated in the Lake Okaro BOPRC Catchment area. ORC at Pump Station River levels and rainfall in the lower BOPRC Tarawera. Tidal effects present. Rangitāiki at Aniwhenua River levels near the Aniwhenua Dam. NIWA Rangitāiki at Kokomoka Rainfall in the upper Rangitāiki near BOPRC Napier/Taupo Highway. Rangitāiki at Matahina River levels above Matahina Dam. NIWA Rangitāiki at Waihau River level and an indicative sensor derived BOPRC Bridge flow. Installed August 2015 Rangitāiki at Murupara Levels/flow in the Rangitāiki at Murupara. NIWA Rangitāiki at Noord Rainfall in lower Rangitāiki Plains area. BOPRC Veirboom Rangitāiki Plains Climate Rainfall and climatic data on Fax Road BOPRC at Flax Road Matata, in the Rangitāiki Catchment area. Rangitāiki at River level and Flow situated in the Rangitāiki BOPRC Rabbit Bridge Catchment. Rangitāiki at Te Teko River level/flow and rainfall in the Rangitāiki NIWA/BOPRC at Te Teko. Rangitāiki at Thornton River level and rainfall in lower Rangitāiki. BOPRC Tidal effects present. Tarawera at Awakaponga River level/flow and rainfall in the central BOPRC Rangitāiki Plains. Tumurau at Lagoon Levels and rainfall in the Tumurau Lagoon BOPRC which flows into the lower Tarawera. Waihua at Clearing Rainfall in the Waihua Tributary of the NIWA Rangitāiki. Representative of mid-catchment rainfall.
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Site name Comments Agency Whakatāne at Rainfall situated between Whakatāne and NIWA Tarapounamu Rangitāiki Catchments. Whirinaki at Galatea River levels/flows and rainfall in the Whirinaki NIWA upstream of the confluence with the Rangitāiki. Kaituna Catchment Kaharoa Rainfall at the top of the Kaituna Catchment. BOPRC Kaituna at Clarke’s River level in the lower Kaituna. Tidal effects BOPRC present. Kaituna at Fords Cut River levels at the bottom of the BOPRC Kaituna Catchment. Tidal effects present. Kaituna at Taaheke River level/flow immediately downstream of NIWA the Okere Gates control structure. Kaituna at Te Matai River level and rainfall site in the lower BOPRC Kaituna Catchment near Te Puke. Lake Rotoiti at Rainfall and lake levels at Okawa Bay. BOPRC Okawa Bay Mangorewa at Saunders River level/flow and rainfall in the Mangorewa BOPRC which is a major tributary of the Kaituna Catchment. Subject to rapid rises in water level up to eight metres. Lake Rotorua at Mission Lake Rotorua at Mission Bay. The lake has a NIWA Bay surface area of 80 km2 and drains 500 km2. The control is by Ohau Channel outlet. Ngongotaha at Water level/flow Ngongotaha Stream at SH 5 NIWA State Highway (SH) 5 bridge, drains 73.3 km2. Pongakawa Rainfall in the mid-Pongakawa Catchment. BOPRC Rotorua at Upper Oturoa Rainfall in the Rotorua Catchment at BOPRC Road Upper Oturoa Road. Utuhina at Depot Street Water level/flow Utuhina at Depot Street, site BOPRC is situated 1.5 km from Lake Rotorua. Waingaehe at SH 30 Water level/flow Waingaehe at SH 30 Bridge, BOPRC Bridge and drains 9.6 km2.Stream is fed by spring inflows. Waitahanui at Water level for Waitahanui River at BOPRC Otamarakau Otamarakau Valley Road. Mangorewa at Waite B Rainfall and soil moisture. BOPRC Kaituna at Rainfall in Rotorua City area. BOPRC Whakarewarewa Western Bay of Plenty Catchments Kopurereroa at SH 29 Water level/flow for Kopurereroa River at BOPRC Bridge SH 29 bridge located 6.3 km from the mouth. It drains 59.75 km2. Rapurapu at Kaimai Rainfall at Kaimai. Waikato Regional Council (WRC) Moturiki Tidal NIWA tidal site at Mount Maunganui. NIWA
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Site name Comments Agency Tauranga Harbour at Water level and storm surge monitoring in the BOPRC Omokoroa Tauranga Harbour, site is situated on the wharf at Kotuku Reserve, Ōmokoroa. Te Mania at SH 2 Water Level/flow at Te Mania at SH 2 Bridge BOPRC it drains 13.1 km2. Tuapiro at Farm Bridge River levels and rainfall in a tributary near BOPRC western end of Tauranga Harbour. Waimapu at McCarrolls River levels/flows and rainfall in a tributary BOPRC Farm near eastern end of Tauranga Harbour. Waipapa at Goodalls River Level/flow of Waipapa Stream at BOPRC Road Goodall Road, situated 11 km from the mouth and drains 8.54 km2. It has a natural bedrock control. Wairoa at above Ruahihi River Level/flow of the Wairoa River and is BOPRC situated 0.5 km upstream of the Ruahihi Power Station.It has a catchment area of 307.5 km2.
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Figure 9 Flood Management telemetry sites.
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3.3 Data summaries
The data summaries provide detailed information about the full monitoring network that includes automatic and manual sites. For specific data requests contact Environmental Data Services.
The last printed copy of the Environmental Data Summaries was 2005.
Objective folder fA243008.
3.4 Bay of Plenty Regional Council website
http://www.boprc.govt.nz/
The BOPRC website provides data directly sourced from HydroTel™. It is displayed in a format that is in most cases easier to read than the HydroTel™format. This can be useful if the information needs to be printed out.
3.4.1 Live monitoring
http://monitoring.boprc.govt.nz/MonitoredSites/cgi- bin/hydwebserver.cgi/districts/details?district=3
3.4.2 Rainfall summary reports
Data for the rainfall summary is exported from HydroTel™ and displayed on the BOPRC website. The rainfall summary is updated every 30 minutes on the web and the data in HydroTel™ is updated every 60 minutes.
http://monitoring.boprc.govt.nz/MonitoredSites/RainfallReport.html
3.4.3 Rainfall summary map
These maps provide an indication of how actual rainfall compares to long-term normal rainfall in the Bay of Plenty region.
The figures shown are the percentage of normal mean rainfall (i.e. 100% is normal) for physical rain gauges in our network. The derived rainfall for the complete region is achieved by applying a Thiessen interpolation between the closest surrounding gauges and as such is indicative only.
Normal rainfall is determined using the full period of record from a site until the end of the 2005 year. Users should note that different lengths of records are available from each station, which makes direct comparison between sites difficult in some cases. Refer to the station details page for each site to identify the length of record available for a site.
More information regarding rainfall can be obtained from the Rainfall Summary Report or by viewing the live rainfall station detail. Historical data is also available.
http://monitoring.boprc.govt.nz/RainfallMap/
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3.5 Site information
Site specific information is available by customising the date range.
3.6 Loncel
A number of pump stations have telemetry installed to provide remote access and control. These stations can be accessed by the operations staff and Flood Managers to inform decisions. All alarms initiated from the stations for failures or high levels are directly sent to operations staff for response.
Access to the website that manages the pump station telemetry is via the URL:https://www.loncel.com/login. A username and password is required.
Username Password
3.7 Meteorological Office warnings
Meteorological Office telephone (04) 470 0783. The Metrological Office issues warnings fall into one of three categories:
3.7.1 Severe weather warning
MetService will issue a severe weather warning whenever there is an expectation that any of the following weather conditions will occur within the next 24 hours:
Widespread* rainfall greater than 50 mm within six hours or 100 mm within 24 hours. Widespread* snowfall below 1,000 m on the North Island or 500 m on the South Island with a snow depth of 10 cm within six hours or 25 cm within 24 hours. Widespread* severe gales with a minimum mean speed of 90 km/hr or frequent gusts exceeding 110 km/hr. *Widespread means over an area of 1,000 km2 or more.
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3.7.2 Severe weather watch
MetService will issue a severe weather watch whenever there is an expectation that conditions may deteriorate to the thresholds specified, for the issue of a severe weather warning:
After the next 24 hours but within 48-72 hours; or If there is a high level of uncertainty within the next 24 hours.
3.7.3 Special weather advisory
MetService will issue a special weather advisory whenever a weather event is likely to cause significant disruption to the general public or specific industry groups within the next 48 hours, but the weather is not expected to deteriorate to an extent that would require the issue of a severe weather warning.
MetService may also issue a special weather advisory following a severe storm that caused widespread disruption and damage in order to assist with any post-storm operations.
http://www.metservice.com/warnings/home http://www.metservice.com/maps-radar/rain-radar/bay-of-plenty http://www.metservice.com/marine-surf/coastal/plenty
3.7.4 Severe weather criteria chart
Definitions
One-day (High) – Within the next 24 hours, with a high level of certainty. One-day (Low) – Within the next 24 hours, but with a low level of certainty. One-two/three days – Between 24 hours and 48-72 hours from now.
Weather event One- One- One- day day[Low] Two/Three [High] Days 1 Rain Severe Severe Severe (over an area of 1,000 square kilometres or weather weather weather more): warning watch watch *50 mm or more in a six-hour period *100 mm or more in a 24-hour period 2 Wind severe gales Severe Severe Severe (over an area of 1000 square kilometres or more weather weather weather with): warning watch watch *Minimum mean speed of 90 km/h, or *Frequent gusts exceeding 110 km/h 7 Weather likely to cause significant disruption Special Special to the general public or specific industry groups weather weather but not expected to deteriorate to the extent of 1, advisory advisory 2, 3, or 4 (for example, following a severe storm that caused widespread disruption and damage)
Source:Metservice website March 2013 Note: Weather events (snow points 3-6) have been excluded.
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The Meteorological Office has been known to fail to issue warnings for what have turned out to be significant events. If the Meteorological Office has not issued a warning and you feel uneasy about the weather conditions - give them a ring, (04) 470 0783.
3.8 MetConnect
www.metconnect.co.nz
Bay of Plenty Regional Council is currently subscribed to MetConnect.
MetConnect is a commercial internet based subscription weather service. MetConnect presents much of the information found on www.metservice.com in much more detail. In addition, a wide range of industry specific weather services are provided.
Features include but are not limited to (refer to the website for the full list of features):
Rainfall accumulation. Lightning maps. One minute observation maps. Seven minute rain radar. Historical weather records. 14 day regional forecasts. Computer generated maps. Industry specified NWP*.
*NWP = Numerical Weather Prediction computer model.
Username Password
3.9 WaterRide
WaterRide is a software package that allows the user to interrogate hydrodynamic modelling results. WaterRide is not a water modelling package but rather a post modelling assessment tool. WaterRide offers value over propriety modelling software and conventional GIS packages by:
Making modelling results available to non-modellers with an easy to use interface (for example showing maximum flood extents and animations of model results); Providing a suite of planning tools including generation of flood planning layers such as freeboard above maximum modelled water level;
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Providing specialist tools for advanced analysis of flood risk and damages including on-the-fly flood forecasting and hazard analysis, with potential for detailed emergency management implementations; and Allowing aspects of modelling project Quality Assurance and results review comparisons quick and easy.
WaterRide requires flood inundation modelling results to be generated by other software packages. These results are then imported to WaterRide for use and assessment. As at May 2013, suitable flood inundation results are available for the following areas:
Lower Waioeka – Otara River – 100-year scenario. Rangitāiki Plains – 300-year scenario, a number of breach scenarios from the Tarawera and Rangitāiki Rivers.
Username Password
3.10 Assessment of flooding impact (rainfall)
Table 1 Assessment of flooding impact from rainfall.
*Flooding Impact *Based on no previous rainfall Rainfall Duration Intensity of and or occurring that could affect total of event falls groundwater/river levels Surface Streams Rivers
50 mm <3 hrs >20 mm p/h Possible Possible Unlikely 100 mm A <6 hrs O >20 mm p/h Probable Probable Unlikely 150 mm N <12 hrs R >20 mm p/h Likely Likely Possible 150 mm D 12 - 24 hrs NA Likely Likely Possible 200 mm <24 hrs >20 mm p/h Likely Likely Probable 200 mm 24 – 48 hrs NA Likely Likely Probable 250 mm <24 hrs >20 mm p/h Likely Likely Likely 250 mm 24 – 48 hrs NA Likely Likely Likely 300 mm + 24 – 48 hrs + NA Likely Likely Likely *(Flooding impact: Unlikely, Possible, Probable, Likely)
Source: Principal Engineering Hydrologist March 2013
Rainfall depths, durations and return periods are provided in the non-scheme and river sections of the manual. The values highlighted in red correspond to levels that are likely to cause flooding.
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3.11 Landslide risk for Eastern Bay of Plenty
The increased likelihood of landslides for rainfalls greater than 100 mm within 24 hours a saturated catchment increases the likelihood of landslides at lower daily rainfall.1
Boffa Miskell. (2013). Landslide and Debris Flow Hazard Management. Tonkin and Taylor. (2013). Managing Debris Flow and Landslide Hazards from the Matata Escarpment. Tonkin and Taylor. (2013). Managing Landslide Hazards from the Whakatane and Ohope Escarpments.
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Part 4: Communications
Chapter summary
4.1 Introduction 2
4.2 Public information 4
4.3 Bay of Plenty Regional Council website 5
4.4 Issuing messages to the flood warning groups 6
4.5 Decision process for issuing flood warning messages 6
Bay of Plenty Regional Council Flood Warning Manual 1
4.1 Introduction
Communication is one of the most important functions undertaken during a flood event. All information coming in and out of the Flood Room must be logged. Actions are noted, passed on to the relevant staff member and tracked through the flood log. All communication records must be retained for auditing purposes.
The administrator for the Flood Team will manage and maintain all the contact lists to assist with the dissemination of information. Contact lists and sample warning messages can be found in the appendices section of the Flood Warning Manual.
Note – It is essential that a log of events is started at the beginning of an event. That includes situations where a “severe weather warning” has been issued but a flood event is unlikely to develop. When information is provided or supplied that should be noted and saved into Objective.
As part of an ongoing improvement plan, Standard Operating Procedures (SOPs) will be developed. The current SOPs are included in the appendices section of the Flood Warning Manual. Where appropriate, SOPs can be displayed in the Flood Room for reference. This will be managed by the flood logistics staff through an internal quality control system.
4.1.1 Internal communication
It is essential to ensure that all parties involved in the BOPRC flood response are contacted and kept up-to-date before, during and after a flood event. Staff must pass on information, complaints and progress updates to the Flood Room.This is particularly important when they have received information either in person or on their mobile phones.
Some of the Rivers and Drainage field staff information will be directed through the Edgecumbe depot but that information must be passed on to the Flood Room on a regular basis.
Field staff will be advised of the time when the latest Sitrep will be sent to them.
4.1.2 Duty Flood Manager contact details
For all urgent flooding and drainage issues please page extension 9845 or 026 252 8438. Freephone: 0800 884 880 (follow the instructions to leave a message for the Duty Flood Manager).
Duty contact webpage links:
http://sam.envbop.net/about-us/what-we-do/on-duty-contacts.aspx
http://www.boprc.govt.nz/council/contact-us/
4.1.3 Briefings
The Flood Manager will hold regular briefings to ensure that all parties involved in the flood response are aware of the current situation and the predictions or forecasts for the event. Briefings provide the opportunity to share information and focus on the priority issues at hand and look forward from a planning prospective.
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Briefings must be timely and concise. They should be inclusive as much as possible. Arrange cover for staff to attend the briefings when that is feasible. Check who is available e.g. some field staff may be in the building or shift handover may be underway.
4.1.4 Briefing structure
1 Overview – Flood Manager (in smaller events they may provide all the supporting information e.g. flood forecasting, staffing capability etc). 2 Updates – Must be to the point, provided by the person in charge of the specific function. 3 Operations – Rivers and Drainage. 4 Technical support. 5 Logistics. 6 Other major functions (determined by need and scale of event e.g. communications, planning, liaison). 7 Questions. 8 Final summary – Flood Manager.
Note: Detailed discussion should be held independently of the briefing. Notes from the briefing must be kept.
4.1.5 Situation reports (sitreps)
The Flood Manager will circulate regular sitreps to ensure that all parties involved in the flood response are aware of the current situation and the predictions and or flood forecasts for the event. Sitreps provide direction and focus resources.
Sitreps must be timely and concise. Whenever possible, they should note the time for the next sitrep. A new sitrep should be issued when there has been a significant change during an event.
Note: If a Local or Group CDEM Controller is activated they will determine when a sitrep to CDEM will be required. The Flood Team sitrep will be incorporated into the CDEM sitrep.
4.1.6 Sitrep structure
Overview. Warnings in place. Predictions including river response, storm surge where appropriate. Rainfall totals – relevant sites and data that adds value to overall picture. River and/or lake levels. Issues and updates. Scheduled time for the next sitrep. Authorisation and sign off.
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The sitrep template is saved in Objective and hardcopy versions are kept in the Flood Room. During a flood event the sitreps should be posted on the board in the Flood Room. The distribution list for the circulation of sitreps should be updated annually.
4.2 Public information
4.2.1 Media releases
Media releases should be prepared where there is longer lead time before an event or after an event to close out communications.
Comments and quotes should be attributed to the Flood Manager.
Note: It is particularly important to avoid jargon and acronyms in media releases about a flood emergency. Also ensure that media releases include the date and (where appropriate) the time.
4.2.2 Issuing warnings to the media (Radio)
Flood warnings may be issued by the Flood Manager or delegated staff member to agreed radio media contacts by email and/or fax. Sample warning messages are in the Flood Warning Guide– Appendix 1, Part 12.
Where possible, the Flood Manager should involve the communications team at the earliest stage.
A list of email and phone contacts are included in Appendix 12 – Flood Team contact list.
Where appropriate, use the confirmation of receipt function or ring and discuss the alert with recipient.
Note: Farmers often milk between 0500 and 0800 and many listen to the radio in the cowshed. Where possible, issue announcements with sufficient time to be broadcast during this period.
Always blind carbon copy (BCC) the Communications Team ([email protected]) when sending these emails. The Communications Team will work with the Flood Manager to decide if wider dissemination of the information on the website or social media is appropriate.
All flood warnings should include date and time of the announcement. Historical examples of flood warning messages are in the Flood Warning Guide – Appendix 1.
Types of warnings likely to be issued during a flood event:
General alert or pre-emptive warning. Specific warning. Extreme warning – this type of warning should be discussed with the CDEM Group Controller before issue. Prediction of peak. Follow-up.
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4.3 Bay of Plenty Regional Council website
The Communications Team will work with the Flood Manager to determine when it is appropriate to raise the profile of the event through the BOPRC website and wider social media.
The BOPRC website needs to be monitored and updated on a regular basis during a flood or heavy rain event.
The Flood Manager should delegate this task to a communications team member where possible. If a communications person is not available, the task of updating the website will need to be carried out by a website editor with edit and publish privileges.
The Latest News Section on the front page should be updated with date and time of announcement and a summary of the latest sitrep. It should also note the approximate time for the next update. This detail should always match the information sent to media.
Once a Civil Defence Emergency is declared, the rostered communications person will be acting in the role of Public Information Manager (PIM). At this point, the BOPRC website should refer to the Civil Defence website where appropriate.
Media releases and warnings released to the media should be updated on the website as normal. These can be linked if appropriate to social media.
4.3.1 Social media
Social media provides a strong and timely method of engaging the community throughout an emergency event. It is two-way communication, so allows and encourages involvement from members of the public.
The BOPRC Facebook page and Twitter should be updated with any information included on the website and linked to Civil Defence where appropriate.
Issues raised through social media (comments on Facebook etc.) should be added to the Flood Room communications log.
All social media should be closed off at the end of the event, with a warning downgrade or some form of closure.
4.3.2 Visiting politicians and dignitaries
The General Manager – Integrated Catchments will be informed through updates from the Flood Manager. The General Manager will update the Executive Leadership Team and Chief Executive of significant developments during a flood event.
With the support of the Communications Team, the General Manager - Integrated Catchment may also elect to inform Councillors and any visiting politicians or dignitaries of the situation.
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4.4 Issuing messages to the flood warning groups
Refer to the Flood Warning Guide in Appendix 1.
4.5 Decision process for issuing flood warning messages
Flood warning level exceeded.
Weather forecast, tides, catchment conditions, river levels and other contributing factors analysed.
Follow the SOPs for Refer to relevant staff issuing flood warning Issue flood Yes gauge prompter page/s messages in the warning? in the Flood Warning Flood Warning Manual for instructions. Messaging Guide.
No
Note – Date, time, flood warning Send flood warning level and reasoning behind not messages to effected issuing the flood warning message group/s and in your flood log. stakeholders.
Complete and save documentation.
If in doubt issue a flood warning
6 Bay of Plenty Regional Council Flood Warning Manual
Part 5: Non-scheme areas
Chapter summary
5.1 Overview 2
5.2 Non-scheme Bay of Plenty Regional Council alarms (action required) 2
5.3 Burt’s rainfall alarm (Waitepuru Stream) 4
5.4 Non-scheme Bay of Plenty Regional Council alarms 4
5.5 Externally received alarms or actions currently in place 5
5.6 Bay of Plenty rivers and streams that have a history of flooding 5
5.7 Rainfall records for the East Coast area 8
5.8 Rainfall records for the Western Bay of Plenty area 9
Bay of Plenty Regional Council Flood Warning Manual 1
5.1 Overview
Bay of Plenty Regional Council operates a number of telemetered rainfall and river gauges across the region, which can provide warning of potential flooding issues.Data from these sites are available via the website to the public and other authorities to access. Where requested, alarms have been setup to allow other authorities and affected interested parties to directly receive this information.The Duty Flood Manager also references information from these sites in regular situation reports that are disseminated during flood events.
Figure10 Matatā flood event, 20 May 2005.
5.2 Non-scheme Bay of Plenty Regional Council alarms (action required)
5.2.1 Nukuhou Stream
Alarm Site Advisory Action settings Nukuhou at Glenholme Road 3.5 m Advise WDC/Police Flood manager to of imminent road contact WDC and closure Police
5.2.2 Kiwirail
Kiwirail need to be notified if high intensity rainfall is being recorded at our telemetry sites along the Tauranga-Kawerau railway line (Eastern Bay of Plenty and Western Bay of Plenty rainfall sites).
The Flood Manager will advise Kiwirail of the areas vulnerable to flooding after assessing the rainfalls and storm track during a flood event.
2 Bay of Plenty Regional Council Flood Warning Manual
In most cases the advice would be “there is major flooding throughout the (X) area and Kiwirail are advised our rainfall records show (X) amount of rainfall”.
Alarm Site Advisory settings Action Eastern Ohinekoao at 30 mm in Kiwirail rainfall Contact Duty Bay of Plenty Harris Saddle 60 mins intensity Network Control alarms Manager Tarawera at 30 mm in (04) 498 2066 or Awakaponga 60 mins Network Control Tumurau at 30 mm in Manager Lagoon 60 mins 021 440 112. Western Pongakawa at 30 mm in Bay of Plenty Pongakawa 60 mins Bush Road Kaituna at 60 mm in Mangorewa 180 mins
Figure 11 Rainfall alarm sites for KiwiRail and Burt’s (Eastern Bay of Plenty) Site 1: Ohinekoao. Site 2: Tarawera at Awakaponga.Site 3: Tumurau Lagoon.
Bay of Plenty Regional Council Flood Warning Manual 3
Figure 12 Rainfall alarm sites for KiwiRail (Western Bay of Plenty). Site 1: Mangorewa. Site 2: Pongakawa.
5.3 Burt’s rainfall alarm (Waitepuru Stream)
(No action required)
Site Alarm settings Advisory Action Tumurau at Lagoon 30 mm in 60 mins Burt’s rainfall No action alarm required by the Tarawera at Awakaponga 30 mm in 60 mins Flood Manager Ohinekaoa at Harris Saddle 30 mm in 60 mins as the alarm goes directly to Pongakawa at Pongakawa 30 mm in 60 mins Arthur Burt. Bush Road
5.4 Non-scheme Bay of Plenty Regional Council alarms
(No action required)
Wetland Alarm recipient Comment Tumurau stoplogs BOPRC Land Management Stoplogs adjust required at the weir, outlet of Tumurau Wetland, Braemar Road.
4 Bay of Plenty Regional Council Flood Warning Manual
5.5 Externally received alarms or actions currently in place
(No action required)
River/stream Alarm recipient Comment Kopurereroa TCC Pumping in the lower catchment Wairoa River TCC Waipuna Hospice
5.6 Bay of Plenty rivers and streams that have a history of flooding
5.6.1 East Coast
Raukokere River Fast reacting river that has caused undermining of hills on right bank near river mouth. Aslso prone to scour into farm land on left bank downstream of SH35 bridge.
Mōtū River
5.6.2 Ōpōtiki
Huntress Creek Private scheme, also known as Kukumoa Stream, joining Waioeka River near river mouth. Floodgates at bottom of scheme area.
Nukuhou Stream Has trigger warning level of 3.5m , Nukuhou at Glenholme telemetry site relating to the flooding issues around SH 2 bridge by Wainui Road intersection, Matekerepu. Flooding issues also around S-bend by Cheddar Valley when flood coinciding with high tides – might be improved now with recent road raising (2015).
Waiotahe River
Waiotahi Drainage Scheme (Waiotahi Main Drain); and some private low level stopbanks along river. Widespread flooding in 2004 (map available in Arc). Can overflow SH 2 between Waiotahi garage and SH 2 bridge. Can also flood Waiotahi Valley Road near bridge by Waiotahi Hall, and Ōhiwa Harbour Road near Ōhiwa Beach Road intersection. At high flows can also flow west into Ōhiwa Harbour across Toone Road and SH 2 east of Kutarere (old flowpath).
5.6.3 Ohope
Maraetōtara Stream
Flood risk to low houses along Bluett Road, Ōhope Hall and Charter Club from overflows onto upstream floodplain. Capacity of stream upstream of houses is ≈10 % AEP. Refer Operations Report 2003/06.
5.6.4 Whakatāne
Wainui-te-whara Stream
Bay of Plenty Regional Council Flood Warning Manual 5
Fast reacting stream (<1hr time of concentration). Capacity of urban channel that stream discharges into is approximately 30m3/s, (WDC upgrading in 2016). Rain gauge in upper catchment and flow gauge at gorge.
5.6.5 Matata
Awatarariki Stream Matatā urban stream vulnerable to flash flooding (short steep catchment) posing risk to residential homes and SH 2 route security. Whakatane District Council have completed mitigation works but flood conveyance under the SH 2 box culvert has not been tested under extreme conditions. Large mobile boulders are high risk factor which may block bridges and culverts. Waitepuru Stream This stream caused flooding in eastern Matata in 2005. A large bund created by WDC now directs excess flow down a diversion channel parallel to Burt Road. Not tested as at June 2016. Ohinekaoa Stream
Vulnerable to flash flooding, short steep catchment with threat to SH 2 and Kiwirail’s coastal trunk line. Rainfall intensity alarm in place.
5.6.6 Western Bay of Plenty
Kopurererua Stream Long narrow catchment with development occurring in the downstream floodplain. Tauranga City Council have a flood model of the urban area Wairoa River
Waimapu Stream Large catchment that had high rainfall in June 2014 that resulted in flooding at Sexame Place and Maleme Street. Both of these areas are still very flood prone. Part of the Flood Risk Project that BOPRC is leading.Tauranga City Council have a flood model of the uran area and upper catchment.
Uretara Stream The Uretara stream is located at the Northern end of the Katikati Township; it flows under SH 2 and into the Tauranga Harbour. The 25.3 km2 Uretara Stream Catchment has two main parts; a steep, densely vegetated hill sub-catchment covering roughly 60%; and a flatter pasture and orchard-covered area at the foot of the hills (40%). The soils are volcanic sandy loams with little to no cohesion. Although this would normally indicate a highly permeable surface, it is expected that weathering on the steep vegetated slopes has caused a reduced infiltration capacity in the upper catchment.
The Uretara is prone to erosion in its lower reaches upstream of Katikati township, particularly around the two bridges at Wharawhara Rd and Rewaka Drive. Gravel extraction occurs in this vacinity to reduce risk.
Operations Publication 2006/07, Uretara Stream Capacity Review
6 Bay of Plenty Regional Council Flood Warning Manual
5.6.7 Rotorua
Utuhina Stream
Ngongotahā Stream
Bay of Plenty Regional Council Flood Warning Manual 7
5.7 Rainfall records for the East Coast area
The values highlighted in red in the following tables indicate rainfall depths, durations and return periods that are 100 mm or greater that are likely to cause flooding.
5.7.1 Motu @ Houpoto
Rainfall depths (mm) NZMG Easting 2918100 Northing 6360900 – Site # 63
ARI (y) aep 1hr 2hrs 6hrs 12hrs 24hrs 48hrs 72hrs 1.58 0.633 24.8 35.6 63.1 90.5 129.9 166 191.6 2 0.5 27 38.6 68.2 97.6 139.7 178.6 206.1 5 0.2 34.8 49.5 86.5 123 175 223.6 258.1 10 0.1 41.2 58.3 101.3 143.4 203.1 259.6 299.6 20 0.05 48.4 68.3 117.8 166.1 234.3 299.4 345.6 50 0.02 59.7 83.7 143.2 200.9 281.9 360.3 415.9 100 0.01 69.8 97.6 165.8 231.7 323.8 413.9 477.7
5.7.2 Motu @ Waitangirua
Rainfall depths (mm) NZMG Easting 2914700 Northing 6323300 – Site # 65
ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 24.4 34.6 60 85 120.4 153.2 176.5 2 0.5 26.5 37.4 64.7 91.3 129 164.3 189.2 5 0.2 33.8 47.5 81.2 113.9 159.8 203.5 234.3 10 0.1 39.8 55.6 94.4 131.8 184.1 234.4 270 20 0.05 46.5 64.7 109.1 151.7 210.9 268.5 309.2 50 0.02 57 78.7 131.6 181.9 251.4 320.1 368.7 100 0.01 66.3 91.2 151.4 208.4 286.8 365.2 420.6
5.7.3 Haparapara at Haparapara
Rainfall depths (mm) NZMG Easting 2936700 Northing 6361700 – Site # 64
ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 28.7 45.3 93.3 147.2 232.2 312.9 372.6 2 0.5 31.1 49 100.7 158.7 250 337 401.2 5 0.2 39.6 62.2 127.3 199.9 313.9 423.1 503.8 10 0.1 46.5 72.9 148.6 232.9 365 491.9 585.7 20 0.05 54.3 84.9 172.5 269.7 421.7 568.4 676.8 50 0.02 66.3 103.4 209 326 508.5 685.3 816 100 0.01 76.9 119.8 241.5 375.9 585 788.5 938.8
8 Bay of Plenty Regional Council Flood Warning Manual
5.8 Rainfall records for the Western Bay of Plenty area
5.8.1 Tuapiro at Farm Bridge
Rainfall depths (mm) NZMG Easting 2765460 Northing 6406520 – Site # 1
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 28.6 39.6 66.5 92.2 127.8 159.7 181.9 2 0.5 31.3 43.3 72.6 100.5 139.1 173.8 198 5 0.2 41.3 57 94.9 130.9 180.4 225.5 256.8 10 0.1 49.7 68.4 113.3 155.9 214.4 267.9 305.2 20 0.05 59.3 81.4 134.4 184.4 253 316.1 360 50 0.02 74.6 102 167.6 229.2 313.4 391.5 445.9 100 0.01 88.6 120.9 197.7 269.7 367.9 459.6 523.5
5.8.2 Tauranga Harbour at Omokoroa
Rainfall depths (mm) NZMG Easting 2778890 Northing 6389230 – Site # 3
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 27.2 35.8 55.3 72.7 95.6 116.7 131.2 2 0.5 29.6 38.9 60.1 79 103.9 126.8 142.5 5 0.2 38.3 50.4 77.6 102 134.1 163.6 183.8 10 0.1 45.5 59.7 92 120.8 158.7 193.7 217.6 20 0.05 53.6 70.3 108.3 142.1 186.6 227.7 255.9 50 0.02 66.2 86.9 133.6 175.3 230.1 280.8 315.5 100 0.01 77.6 101.8 156.5 205.2 269.2 328.5 369.1
5.8.3 Waipapa at Goodalls Road
Rainfall depths (mm) NZMG Easting 2773790 Northing 6382630 – Site # 5
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 27.2 37.4 61.9 85.1 116.8 147.5 169.1 2 0.5 29.5 40.6 67 92.1 126.4 159.6 182.9 5 0.2 37.9 52 85.7 117.4 161 203.3 233 10 0.1 44.7 61.2 100.8 138 188.9 238.5 273.4 20 0.05 52.4 71.7 117.7 161 220.3 278.1 318.8 50 0.02 64.3 87.9 144 196.7 268.7 339.3 388.9 100 0.01 75 102.4 167.5 228.5 311.8 393.7 451.3
Bay of Plenty Regional Council Flood Warning Manual 9
5.8.4 Waimapu at McCarrolls Farm
Rainfall depths (mm) NZMG Easting 2787100 Northing 6377000 – Site # 7
Duration
ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 26.7 36.3 58.8 79.8 108.3 128.3 141.6 2 0.5 29.2 39.5 63.9 86.6 117.3 138.9 153.3 5 0.2 38.2 51.4 82.5 111.1 149.7 177.2 195.6 10 0.1 45.6 61.2 97.6 131 175.9 208.3 229.9 20 0.05 54.1 72.3 114.7 153.5 205.4 243.2 268.5 50 0.02 67.4 89.8 141.5 188.4 251 297.2 328.1 100 0.01 79.6 105.6 165.5 219.7 291.7 345.4 381.3
5.8.5 Rapurapu at Kaimai
Rainfall depths (mm) NZMG Easting 2768420 Northing 6364830 – Site # 9
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 25.3 36.3 64.1 91.8 131.4 161.1 181.6 2 0.5 27.5 39.3 69.4 99.2 142 174.1 196.1 5 0.2 35.5 50.5 88.6 126.3 180 220.8 248.7 10 0.1 42 59.7 104.2 148.2 210.7 258.3 291.1 20 0.05 49.3 70 121.8 172.7 245 300.4 338.5 50 0.02 60.8 86 148.9 210.6 297.8 365.2 411.5 100 0.01 71.1 100.3 173.1 244.3 344.7 422.7 476.3
10 Bay of Plenty Regional Council Flood Warning Manual
Part 6: Otara River
Chapter summary
6.1 Otara Catchment overview 2
6.2 Otara Catchment hydrological characteristics 2
6.3 Warnings and flood warning groups 3
6.4 Otara River telemetry sites 4
6.5 Flood forecast modelling 4
6.6 Current stopbank design level 5
6.7 Predicted warning stages and travel times 7
6.8 Historical floods and travel times 8
6.9 Critical flood control structures and hotspots 9
6.10 Data records for Otara River 9
6.11 Rainfall records for Otara 9
6.12 Otara River flood event plot July 1998 12
6.13 Otara River flood event plot October 2003 13
6.14 Otara at Browns Bridge rating curve 14
6.15 Rating table for Otara at Browns Bridge 15
6.16 Otara at Browns Bridge Staff Gauge prompter 16
Bay of Plenty Regional Council Flood Warning Manual 1 1
6.1 Otara Catchment overview
The Waioeka-Otara Catchment covers an area of approximately 1,130 km2,much of which is steep and well forested. Roughly 70% of the catchment is covered by conservation estate in the form of the Urewera National Park and Waioeka Gorge Scenic Reserve. The geology is characterised by alluvium on the floodplain, Kaharoa ash on the lower foothills and greywacke in the upper catchment.
Although there is some exotic pasture, both the Waioeka (upstream of the cableway recorder) and the Otara (upstream of the Browns Bridge recorder) are predominantly covered by scrub and indigenous forest. It is due to this forest cover that the catchments have a high capacity to absorb rainfall, delaying runoff and potential flooding downstream. The steep, rugged character of the catchment has the effect of increasing erosion.
6.2 Otara Catchment hydrological characteristics
The Otara Catchment is made up of three, roughly parallel sub-catchments which join within a 5.6 km reach of the river. From east to west the sub-catchments are:
Subcatchment Distance Pakihi Sub-catchment 140.0 km2 Te Waiti Sub-catchment 96.0 km2 Tutaetoko Sub-catchment 59.0 km2 TOTAL 295.0 km2
Relevant river distances (measured from the confluence of the Otara River with the Waioeka River) are as follows:
River section Distance Otara/Waioeka confluence 0 km Upper limit of town 5.50 km Start of urban banks 8.70 km Start of rural banks 17.20 km Tutaetoko confluence 17.95 km Browns Bridge telemetry site 19.00 km Pakihi confluence 22.90 km
The present telemetry system includes water level recorders on the Pakihi River (at Pakihi Station (approximately 6.2 km up the Pakihi River) and at Browns Bridge (approximately 1.0 km upstream of the Tutaetoko confluence).
The best guess at this stage should be based on an estimated contribution of Tutaetoko = 17% of Browns Bridge (this is based on transformation by catchment size) but it could be as high as 30% (Freeman 2008).
ANY assessment of flooding is based on the Browns Bridge recorder and an estimate of what is coming down the Tutaetoko Stream.
2 Bay of Plenty Regional Council Flood Warning Manual
6.3 Warnings and flood warning groups
1 When a pre-set alarm level is reached, HydroTel™ sends an automated message to the Flood Duty pager. If the pager shows a message to notify someone or issue a warning, an action will be required. 2 The actions related to the alarm levels are described on the individual staff gauge prompter pages. The river rising notification is sent automatically to the Duty Flood Manager, Principal Works Engineer and the Works Co-ordinators. This alarm signals a first response in the river level/s Monitoring activity will increase following this alarm. 3 All information related to the issuing of flood warning messages and the current contact details for the members of the flood warning groups are located in the Flood Warning Guide.
Note: The majority of the alarms are within the Rivers and Drainage Scheme areas and catchments. There are additional alarms set up outside of these areas, (refer to non-scheme section) some of these alarms do require some action.
Communication including but not limited to warnings, updates and information sharing will be focused around these groups:
(a) Bay of Plenty Regional Council Rivers and Drainage staff, regular contact with the Principal Works Engineer is recommended. (b) Flood warning groups (farmers and other key stakeholders). (c) Bay of Plenty Regional Council Communications staff. (d) Ōpōtiki District Council. (e) Local Civil DefenceEmergency Management (ODC). (f) Bay of Plenty Regional Council contractors working in vulnerable areas. (g) Police. (h) Radio stations.
NOTE: Ōpōtiki District Council is responsible for contacting any contractors they have working in the field.
IMPORTANT – The Principal Works Engineer must be notified early (at first warning level) so that the Rivers and Drainage staff can check relevant floodgates, pumps and weedscreens.
Because the time of concentration in these catchments is so short, any rainfall event that looks like it will cause river levels to rise to the first warning, should be responded to by issuing a warning. As a rule, if in doubt, we should issue a warning (particularly if nightfall is approaching). Farmers prefer to be warned – even if nothing eventuates, rather than not be warned and get caught out.
Bay of Plenty Regional Council Flood Warning Manual 3 3
6.4 Otara River telemetry sites
Data Services Channel 1 – E191 – BOPRC Telemetry Channel
Site name Comments Agency Otara Catchment Rain gauge in the upper Pakihi Catchment Pakihi at Rakanui Link BOPRC which is a major tributary of the Otara. River level and rainfall in the Pakihi which is Pakihi at Pakihi Station BOPRC a major tributary of the Otara. River level/flow in the lower Otara River but Otara at Browns Bridge BOPRC above Ōpōtiki township. Rain gauge positioned between the Otara Otara at Tutaetoko BOPRC and Waioeka Catchments. River level and rainfall at the confluence of Otara at Ōpōtiki Wharf the Otara and Waioeka Rivers. Tidal effects BOPRC present.
In addition to the above sites, the Waioeka at Cableway rain gauge, Mouth of Gorge rain gauge, and the Waioeka at Koranga Station rain gauge may help to better define total catchment rainfall.The Tutaetoko rain gauge is sited on the ridge between the Tutaetoko and Te Waiti Sub-catchments.
6.5 Flood forecast modelling
Automated flood forecast modelling is run every two hours for several rivers in the Bay of Plenty including the Otara.The Otara Unit Hydrograph model uses telemetered data from rain gauges and river gauges.Previous results for the Otara River have been varied to date mainly due to the difficulty in determining representative rainfall in the catchment – the types of storms that resonate with the Otara’s short responsive catchment are able to slip between the relatively sparse network of gauges.
The latest forecasts are posted on HydroTel™.To view these expand the “flow” item in the explorer window and select “UHG Modelled Flow”.This forecast includes “landed” rain only.
A more detailed report is also archived to O: drive if significant rain has fallen.The report shows results from landed rain in all of the UHG modelled catchments as well as manually entered forecast rain.The network location is:
\\WHKNEARLINE\Engineering\Flood Forecasting\Herbst Models\Archived Forecasts\ Auto_Forecast_yyyymmdd_hhmm.xls
4 Bay of Plenty Regional Council Flood Warning Manual
6.5.1 Flood forecasting sites on HydroTel™ – Otara River
Figure 13 Otara at Browns Bridge telemetry site.
6.6 Current stopbank design level
Otara River Scheme.
Meets design Nominal design Location Design flow plus freeboard standard (in level in 2014 2014) Otara urban left 1% AEP (100 yr) 1,111 m3/s at Browns Bridge Yes bank plus 450mm freeboard Otara rural right 5% AEP (20 yr) Downstream tide 1.5 m RL Yes bank downstream plus 300mm upstream of Gow Road freeboard 840 m3/s at Browns Bridge Otara rural coastal 50% AEP (2 yr) Downstream tide 1.42 m Yes right bank plus 300mm (Moturiki Datum), upstream freeboard 443 m3/s at Browns Bridge Otara rural left bank 10% AEP (10 yr) 721m3/s at Browns Bridge Yes plus 300mm freeboard Otara rural right 10% AEP (10 yr) 721 m3/s at Browns Bridge Yes bank plus 300mm freeboard Gault ring bank 2% AEP (50 yr) 995 m3/s at Browns Bridge Yes plus 400mm freeboard
Reference: Rivers and Drainage Schemes Asset Management Plan – June 2015
Location Design level
Bay of Plenty Regional Council Flood Warning Manual 5 5
Figure 14 Stopbank and return period plan for Waioeka – Otara Rivers Scheme. Bay of Plenty Regional Council Asset Management Plan.
6 Bay of Plenty Regional Council Flood Warning Manual
6.7 Predicted warning stages and travel times
Historical data together with hydrological model simulations have been used to predict flood warning stages and lag time.
6.7.1 Flood warning stages
The Otara River Flood Warning System is based almost entirely on the stage at Browns Bridge. This is a reliable site with an accurate rating curve for levels below 4.5 m to which it has been gauged.
The site has two main disadvantages:
1 It is above the confluence of the Tutaetoko Stream, which can contribute about another 17% of Browns Bridge flow (based on transformation by catchment size). 2 There is very little warning time.
6.7.2 Stage relating to rural overflow
There is no set stage at Browns Bridge for which overflow of the rural banks will occur due to the uncertainty of the contribution from the Tutaetoko Stream. The overflow of the rural scheme is most likely to occur for stages at Browns Bridge of above 5 m.
6.7.3 Stage relating to urban overflow
The left bank urban stopbanks were restored to the 100 year level plus 450 mm freeboard in 2001/2002. (Lower reaches near confluence actually upgraded to 200 year + 450 mm freeboard).
Therefore overflow of the right bank is most likely to occur well before the left bank.Overflow of the urban banks is unlikely to occur until stage levels in excess of 6.0 m occur at Browns Bridge.The lower reaches are influenced by the Waioeka River.
Probably a more reliable indicator of the likelihood of flooding of the town is rural overtopping as this takes into account such uncertainties as the Tutaetoko discharge. It seems likely that if significant overflow occurs in the rural area and the stage at Browns Bridge continues to rise, the urban banks will be overtopped. This may also give additional warning time.
6.7.4 Time of travel
Typical travel times for flood waters are as follows: Pakihi to Browns Bridge 1.5 to 3 hours Browns Bridge 5.3 m until urban overflow 2 to 3 hours Urban overflow until water in town 1 to 2 hours Rural overflow until urban overflow 2 to 3 hours Rural overflow until water in town 3 to 5 hours
Note ‒ A breach of the town banks could occur at any time without warning.
Bay of Plenty Regional Council Flood Warning Manual 7 7
6.7.5 Discussion of results
The close proximity of the Browns Bridge staff gauge to the scheme, combined with the catchment characteristics, makes for very short warning times. Assuming an urban warning level of 6.0 m this would give two to three hours until overflow of the scheme banks and three to five hours before water enters the town. There is of course no certainty that flooding will occur for this level and so there may be a longer warning period or no flooding at all.
6.8 Historical floods and travel times
6.8.1 Top 16 recorded flood level for the Otara River
Otara River Flood Peak Stage and Discharge RecordBrowns Bridge Travel Time Rank Month Year Stage Discharge to Ōpōtiki Wharf 3 (m) (m /s) (hrs) 1 Mar 1964 984 2 1965 765 3 Oct 2003 5.11 728 3.0 4 10-Jul 1998 4.50 550 3.0 5 Nov 1999 4.39 519 1.5 6 Jan 1989 4.76 517 7 1976 4.50 512 8 Jun 1986 4.68 496 9 May 1996 4.64 483 10 Aug 2006 4.13 452 1.0 11= 1966 (≈4.25) 447 11= 1967 (≈4.25) 447 13 Dec 2004 4.10 445 3.5 14 2-Jul 1998 4.10 444 5.5 15 Apr 1985 4.42 427 16 May 2011 4.59 422 3.4 Average Time 3.0 Minimum Recorded Time 1.0
Note – Tidal influence for Otara River at Ōpōtiki Wharf
8 Bay of Plenty Regional Council Flood Warning Manual
6.9 Critical flood control structures and hotspots
The rivers and drainage field staff are responsible for the inspection of pump stations, floodgates and culverts. Inspections are made in response to a severe weather warning or following heavy rainfall.
Otara Bridge (State Highway 35) normally doesn’t require any monitoring.
6.9.1 Vulnerability of Gault Road
Gault Road is located to the east of Ōpōtiki township. It is often impassable due to surface flooding on the landward side of the stopbank.This is Ōpōtiki District Council's (ODC) responsibility.
6.10 Data records for Otara River
Data on the following pages cover:
Otara and Waioeka rainfall records – depth duration and frequency. For East Coast rainfall records refer to the non-scheme section. Flood event plots – July 1998 and October 2003. Otara at Browns Bridge rating curve.
Note – Pakihi Stream at Pakihi Station rating curve to be included when available.
Predictive scenarios for the Otara River are located in back of Waioeka section. For the full report please refer to BOPRC Operations Report 99/05, Towards a Waioeka-Otara Floodplain Management Strategy.
6.11 Rainfall records for Otara
The values highlighted in red in the following tables indicate rainfall depths, durations and return periods that are 100mm or greater that are likely to cause flooding.
6.11.1 Otara at Ōpōtiki Wharf
Rainfall depths (mm) NZMG Easting 2886100 Northing 6346900 – Site # 55
ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 23.8 31.6 49.4 65.5 86.9 100.8 109.9 2 0.5 26.1 34.5 53.7 70.9 93.7 108.7 118.5 5 0.2 34.5 45.2 69.1 90.4 118.2 137 149.4 10 0.1 41.6 54 81.7 106.1 137.8 159.7 174.1 20 0.05 49.7 64.1 96 123.8 159.6 185.1 201.7 50 0.02 62.6 80 118.2 151.1 193.2 223.9 244.1 100 0.01 74.4 94.5 138.1 175.4 222.8 258.3 281.5
Bay of Plenty Regional Council Flood Warning Manual 9 9
6.11.2 Otara at Browns Bridge
Rainfall depths (mm) NZMG Easting 2889300 Northing 6337800 – Site # 56
ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 26.5 35.9 58.1 78.7 106.7 129.2 144.5 2 0.5 28.7 38.7 62.4 84.4 114 138.1 154.5 5 0.2 36.4 48.8 77.8 104.4 140 169.6 189.7 10 0.1 42.6 56.9 89.9 120.1 160.4 194.2 217.3 20 0.05 49.6 65.9 103.4 137.5 182.7 221.3 247.5 50 0.02 60.3 79.7 123.9 163.7 216.3 261.9 293 100 0.01 69.8 91.8 141.8 186.6 245.4 297.2 332.5
6.11.3 Pakihi at Pakihi Station
Rainfall depths (mm) NZMG Easting 2897900 Northing 6332500 – Site # 58
ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 28.5 40.1 69.1 97.3 137.1 168.8 190.6 2 0.5 30.7 43.2 74.1 104.1 146.3 180.1 203.3 5 0.2 38.8 54.2 91.8 128.1 178.6 219.9 248.2 10 0.1 45.4 63 105.8 146.9 203.9 250.9 283.3 20 0.05 52.6 72.7 121.3 167.6 231.4 284.8 321.6 50 0.02 63.8 87.6 144.7 198.7 272.7 335.6 378.9 100 0.01 73.7 100.7 165.2 225.7 308.4 379.5 428.4
6.11.4 Otara at Tutaetoko
Rainfall depths (mm) NZMG Easting 2892600 Northing 6328200 – Site # 59
ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 29.1 41.2 71.6 101.4 143.6 180.5 206.3 2 0.5 31.3 44.3 76.7 108.5 153.4 192.7 220.2 5 0.2 39.4 55.4 95 133.5 187.7 235.8 269.5 10 0.1 45.8 64.2 109.4 153.2 214.5 269.5 308.1 20 0.05 53 73.9 125.3 174.8 243.8 306.4 350.2 50 0.02 64 88.8 149.3 207.3 287.9 361.7 413.4 100 0.01 73.6 101.8 170.3 235.6 326 409.6 468.2
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6.11.5 Pakihi at Rakanui Link
Rainfall depths (mm) NZMG Easting 2906300 Northing 6321900 – Site # 61
ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 24.8 34.4 57.9 80.4 111.7 140.6 160.8 2 0.5 26.8 37.2 62.4 86.4 119.7 150.7 172.4 5 0.2 34.2 47.1 78.2 107.7 148.4 186.8 213.7 10 0.1 40.1 55.1 90.9 124.7 171.1 215.3 246.3 20 0.05 46.8 64 105 143.4 196.1 246.8 282.3 50 0.02 57.1 77.7 126.5 172 233.9 294.4 336.8 100 0.01 66.3 89.8 145.4 197 267 336 384.4
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6.12 Otara River flood event plot July 1998
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6.13 Otara River flood event plot October 2003
Return Period Discharge (years) (m3/s) 2.33 5 463 10 562 20 666 30 50 812 100 932
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6.14 Otara at Browns Bridge rating curve
6
5
4 Return Stage Discharge 3 Period (m) (m /s) (years) 2.8 1st Warning Level 157
Stagemetres 4.2 2nd Warning Level 426 3 4.35 463 5 562 10 666 20 30 2 812 50 932 100
1 0 100 200 300 400 500 600 700 800 Flow m3/s Otara River at Browns Bridge. 29-Jul-2005 01:15:00 Indicator Stage 1.991
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6.15 Rating table for Otara at Browns Bridge
Stage Discharge Reference Stage Discharge Reference (m) (m3/s) (m) (m3/s) 1.5 25 3.2 220 1.6 32 3.3 238 1.7 38 3.4 256 1.8 46 3.5 275 1.9 54 3.6 295 2 63 3.7 315 2.1 72 3.8 336 2.2 82 3.9 357 2.3 93 4 379 2.4 105 4.1 402 2.5 117 4.2 426 2nd Warning Level 2.6 130 4.3 450 2.7 143 4.35 463 5 year Return Period 2.8 157 1st Warning Level 4.4 475 2.9 172 4.5 501 3 187 4.6 527 3.1 204 4.65 541
Bay of Plenty Regional Council Flood Warning Manual 15
6.16 Otara at Browns Bridge staff gauge prompter
16 Bay of Plenty Regional Council Flood Warning Manual – July 2013
Part 7: Waioeka River
Chapter summary
7.1 Waioeka Catchment overview 2
7.2 Waioeka Catchment hydrology 2
7.3 Warnings and flood warning groups 2
7.4 Waioeka telemetry sites 3
7.5 Flood forecast modelling 4
7.6 Predictable warning stages and travel times 6
7.7 Historical floods and travel times 8
7.8 Critical flood structures and hotspots 8
7.9 Data records for Waioeka River 9
7.10 Rainfall records for Waioeka 10
7.11 Waioeka River flood event plot July 1998 11
7.12 Waioeka River flood event plot October 2003 12
7.13 Maximum flood depth profile, predictive scenarios – Waioeka and Otara Rivers 13
7.14 Predicted stopbank overflows 18
7.15 Waioeka at Cableway rating curve 19
7.16 Rating table for Waioeka at Cableway 20
7.17 Waioeka at Cableway staff gauge prompter 22
Bay of Plenty Regional Council Flood Warning Manual 1
7.1 Waioeka Catchment overview
The Waioeka-Otara Catchment covers an area of approximately 1,130 km2, much of which is steep and well forested. Roughly 70% of the catchment is covered by conservation estate in the form of the Urewera National Park and Waioeka Gorge Scenic Reserve. The geology is characterised by alluvium on the floodplain, Kaharoa ash on the lower foothills and greywacke in the upper catchment.
Although there is some exotic pasture, the Waioeka (upstream of the cableway recorder) is predominantly covered by scrub and indigenous forest. It is due to this forest and scrub cover that the catchments have a high capacity to absorb rainfall, delaying runoff and potential flooding downstream. The steep, rugged character of the catchments has the effect of increasing erosion.
7.2 Waioeka Catchment hydrology
7.2.1 Waioeka Catchment characteristics
The Waioeka Catchment is bulbous in shape and extends inland from the sea for about 60 km. Catchment widths range from 10 km wide for the 28 km nearer the coast, to 20 km wide throughout most of the southern part of the catchment. Relevant river distances (measured from the confluence of the Otara River with the Waioeka River) are as follows:
River location Distance Otara/Waioeka confluence 0.0 km Upper limit of town 2.10 km Start of urban banks 2.65 km Start of rural banks 11.25 km Gorge Mouth telemetry site 12.10 km Pakihi confluence 22.90 km Waioeka Cableway telemetry site 35.10 km
The present telemetry system includes water level and rainfall recorders on the Waioeka River at the mouth of the gorge as well as at 'Cableway' in the middle of the catchment.
7.3 Warnings and flood warning groups
1 When a pre-set alarm level is reached, HydroTel™ sends an automated message to the Flood Duty pager. If the pager shows a message to notify someone or issue a warning an action will be required. 2 The actions related to the alarm levels are described on the individual staff gauge prompter pages. The river rising notification is sent automatically to the Duty Flood Manager, Principal Works Engineer and the Works Coordinators. This alarm signals a first response in the river level/s. Monitoring activity will increase following this alarm. 3 All information related to the issuing of flood warning messages and the current contact details for the members of the flood warning groups are located in the Flood Warning Guide.
2 Bay of Plenty Regional Council Flood Warning Manual
Communication including but not limited to warnings, updates and information sharing will be focused around these groups:
(a) Bay of Plenty Regional Council Rivers and Drainage staff, regular contact with the Principal Works Engineer is recommended. (b) Flood warning groups (Farmers and other key stakeholders). (c) Bay of Plenty Regional Council Communications staff. (d) Ōpōtiki District Council (ODC). (e) Local Civil Defence Emergency Management - ODC. (f) Bay of Plenty Regional Council contractors working in vulnerable areas. (g) Police. (h) Radio stations.
IMPORTANT – The Principal Works Engineer must be notified early (at first warning level) so that the Rivers and Drainage staff can check relevant floodgates, pumps and weedscreens.
7.4 Waioeka telemetry sites
Data Services Channel 1 – E191 – BOPRC Telemetry Channel
Site name Comments Agency Waioeka Catchment Rain gauge situated at the top of the Waioeka at Koranga Station BOPRC Waioeka Catchment. River level/flow and rainfall in the middle Waioeka at Cableway BOPRC of the Waioeka Gorge. Rain gauge positioned between the Otara Otara at Tutaetoko BOPRC and Waioeka Catchments. River level and rainfall in the lower Waioeka at Mouth of Gorge BOPRC Waioekabut above Ōpōtiki township. River level and rainfall at the confluence Otara at Ōpōtiki Wharf of the Otara and Waioeka Rivers. Tidal BOPRC effects present.
In addition to the above sites, the Otara at Browns Bridge rain gauge and to some degree the Pakihi rain gauge may help to better define total catchment rainfall.
The Waioeka at Cableway site has additional telemetry equipment that is operated by NIWA. In the event of a failure at Cableway, telephone:
NIWA – Rotorua (07) 346 1950 After hours (Wayne McGrath) (07) 07 542 5514 After hours (Graham Timpany) (07) 348 8829
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7.5 Flood forecast modelling
Automated flood forecast modelling is run every two hours for several rivers in the Bay of Plenty including the Waioeka. The Waioeka Unit Hydrograph (UHG) model uses telemetered data from rain gauges and river gauges. Results for the Waioeka River are more reliable than for Otara River but still suffer from the difficulty in determining representative rainfall in the catchment from the sparse number of rain gauges.
The latest forecasts are posted on HydroTel™.To view these expand the “flow” item in the explorer window and select “UHG Modelled Flow”. This forecast includes “landed” rain only.
A more detailed report is also archived to “O:” drive if significant rain has fallen. The report shows results from landed rain in all of the UHG modelled catchments as well as manually-entered forecast rain.The network location is: \\WHKNEARLINE\Engineering\Flood Forecasting\Herbst Models\Archived Forecasts\ Auto_Forecast_yyyymmdd_hhmm.xls
7.5.1 Flood forecasting sites on HydroTel™ – Waioeka River
Waioeka at Cableway
7.5.2 Current stopbank levels of service
Waioeka River Scheme
Location Nominal design level Design flow plus Meets design in 2014 freeboard standard (in 2014) Waioeka urban 1% AEP (100 yr) plus 1,915 m3/s at Cableway Yes right bank 450mm freeboard Waioeka rural left 5% AEP (20 yr) plus 1,380 m3/s at Cableway Yes and right bank 300 mm freeboard Waioeka rural 50% AEP (2 yr) plus Tide 1.42 m RL or Yes coastal left bank 300mm freeboard 766 m3/s at Cableway Waioeka left bank 20% AEP (5 yr) plus 980 m3/s at Cableway Yes for 1 km upstream 300mm freeboard of SH 2 bridge Mill Stream right 1% AEP (100 yr) plus Downstream where Yes bank downstream 450mm freeboard Waioeka River dominant of Clark Cross 1,915 m3/s atCableway. Road Upstream where Mill Stream dominant 60.8 m3/s at Mill Stream Mill Stream 5% AEP (20 yr) plus Downstream where Yes downstream of 300mm freeboard Waioeka River dominant Matchett Road 1,380 m3/s at Cableway. Upstream where Mill Stream dominant 28.5-47.6 m3/sMill Stream Peterson’s ring 20% AEP (5 yr) plus 1.5 m RL at Ōhiwa tide Yes bank 300mm freeboard gauge
Reference: Rivers and Drainage Schemes Asset Management Plan
4 Bay of Plenty Regional Council Flood Warning Manual
Location Design level Figure 15 Stopbank and return period plan for Waioeka – Otara Rivers Scheme. Bay of Plenty Regional Council Asset Management Plan
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Figure 16 Five-year rural bank Waioeka River.
7.6 Predictable warning stages and travel times
Historical data together with hydrological model simulations have been used to predict flood warning stages and lag time.
7.6.1 Waioeka flood warning sites
Waioeka River flood warning is based primarily on the Cableway site, located approximately 21 km upstream of the scheme, with a secondary site at the gorge mouth (at the top of the scheme). Approximately 15% of the catchment area at the gorge mouth lies between the two sites.
6 Bay of Plenty Regional Council Flood Warning Manual
The Cableway site is the most important for flood warning. It is reliable (and has NIWA backup) and offers a reasonable length of warning. The gorge mouth site is really only useful as a backup.
River stage records have been kept for the Cableway site by the Ministry of Works Department (and its successor) since 1958. In 1987 major changes were made to the upper end of the rating curve, which had the effect of reducing the estimated discharges of larger events (including the floods of 1964 and 1967).
The gorge mouth site was established in 1984 and is really only useful for flood warning as a rainfall recorder and as a backup to the Cableway site. Being right at the start of the scheme, it offers virtually no warning time to farms on the Plains and very limited time to the township. No gauging is possible at the site so no rating curve exists. The reach on which the site is located is prone to erosion of the banks and aggradation and degradation of the riverbed. There are also a number of stub groynes upstream of the site (S H 2 protection), which can have a marked effect on river levels. It has been useful in estimating the time of travel from the Cableway site.
7.6.2 Stages relating to rural overflow
The rural stopbanks are designed to a 5% AEP with 300 mm freeboard.
Overflow of the left bank of the scheme is likely to occur for stages at Cableway of above 7.8 m. This does not discount the possibility of it being lower or higher because of the influence of the catchment below Cableway.
Overflow of the rural scheme may occur at stages at Cableway above about 9.2 m.
Table 1 - River Levels
Stage Cableway Time of Affect on Date G/Mouth Travel (mins) Rural Scheme Dec 87 8.22 m 5.37 m 90 Top of Harfords banks (2.25 mile) plus trickle at river bank 5.25 mile cross section July 88 7.79 m 5.08 m 93 Overflow at Harfords (2.25 mile) requiring sandbags.
Table 2 - Rainfall.
Waioeka at Date GorgeMouth Tutaetoko Cableway Koranga Station December 1987 44 mm 139 mm 213 mm 181 mm July 1988 154 mm 196 mm 201 mm 153 mm
7.6.3 Stages relating to urban overflow
The right bank stopbanks were restored to the 1% AEP plus 450 mm freeboard in the construction seasons in 2011/2012. Overflow of the urban banks is unlikely to occur until stage levels in excess of 13 m occur at the Waioeka Cableway Recorder Site. The lower reaches are influenced by the Otara River and tides.
Bay of Plenty Regional Council Flood Warning Manual 7
If high tide or the peak of the Otara occurs at the same time as the peak of the Waioeka, this will have the effect of raising the water levels in the lower reaches of both rivers.
7.7 Historical floods and travel times
7.7.1 Top 21 floods and travel times for the Waioeka River
Waioeka River Flood Peak Stage and Discharge Record Cableway Mouth Ōpōtiki Wharf Travel Time Rank Month Year Stage Discharge Stage Discharge Stage Discharge Cableway to Mouth From Mouth to Wharf Cableway to Wharf (m) (m3/s) (m) (m3/s) (m) (m3/s) (hrs) (hrs) (hrs) 1 2-Jul 1998 10.53 1521 6.77 2.74 3.00 1.75 4.75 2 Mar 1964 10.67 1494 3 1967 10.42 1447 4 24-Jan 2011 8.00 1030 5.65 3695 2.31 1.58 5 29-Jan 2011 8.00 1029 5.79 3887 2.38 3.00 1.92 4.92 6 Dec 1987 8.22 1026 5.37 7 Sep 1995 7.96 1002 5.40 2.04 1.65 1.27 2.92 8 May 2011 7.84 999 5.43 3400 2.53 1.25 1.92 3.17 9 1970 7.96 976 10 Jul 1988 7.79 943 5.08 11 1958 7.62 911 12 4-Oct 2003 7.36 907 5.16 2.26 1.75 2.00 3.75 13 Feb 1991 7.50 887 5.43 2.34 2.00 3.42 5.42 14 Nov 1999 7.23 882 5.48 2.55 1.75 15 11-Jul 1998 7.26 850 5.21 2.31 1.25 1.50 2.75 16 Jul 2004 6.94 828 4.63 1.72 0.50 2.75 3.25 17 Aug 2010 6.78 799 5.09 2976 2.59 1.25 2.58 3.83 18 12-Oct 2003 6.73 791 5.02 1.95 1.25 1.75 3.00 19 Aug 1991 6.90 773 4.81 2.03 2.25 20 Jul 2008 6.45 740 4.16 1824 1.90 2.25 21 Jan 2012 6.35 720 4.51 2301 1.88 1.25 4.67 5.92 Average Time 1.7 2.3 4.0 Minimum Recorded Time 0.5 1.3 2.8
7.8 Critical flood structures and hotspots
The Rivers and Drainage staff are responsible for the inspection of pump stations, floodgates and culverts. Inspections are made in response to a severe weather warning, following heavy rainfall or in response to instructions from the Flood Manager or the Principal Works Supervisor.
7.8.1 Duke Street Pump Station
Asset ID 10257.
Duke Street Pump Station provides flood pumping for the southern rural drainage system. It’s located on the Waioeka River upstream of SH 2 Bridge on the urban boundary. The pumpstation is jointly managed with Ōpōtiki District Council.
Power outages have been a common occurrence in past flood events. The pump station has been wired for a mobile generator. Ōpōtiki District Council will provide a generator in an emergency. Field staff will monitor the pump station.
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Figure 17 Duke Street Pump Station.
7.8.2 Vulnerability of Waioeka State Highway 2 Bridge
The bridge has a low soffit, as well as a large number of piers. In large flood events the bridge is vulnerable and will need to be closed if water is high enough. In 1998, for instance, the bridge was closed and diggers were used to clear debris from the bridge.
Also potential for State Highway 2 on the Whakatāne side to go under water and/or for the Waioeka Gorge to be affected.
7.9 Data records for Waioeka River
Data on the following pages cover:
Waioeka and Otara rainfall records – depth duration and frequency. For East Coast rainfall records refer to the non-scheme section. Flood event plots – Waioeka July 1998 and October 2003. Maximum flood depth profile, predictive scenarios – Waioeka and Otara Rivers. Correlation between Mouth of Gorge and Cableway sites. Waioeka at Cableway rating curve.
Bay of Plenty Regional Council Flood Warning Manual 9
7.10 Rainfall records for Waioeka
The values highlighted in red in the following tables indicate rainfall depths, durations and return periods that are 100 mm or greater that are likely to cause flooding.
7.10.1 Waioeka at Cableway
Rainfall depths (mm) NZMG Easting 2887800 Northing 6322200 – Site # 60
ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 27.4 39.9 72.7 106 154.6 193.1 219.9 2 0.5 29.5 43 77.9 113.5 165.2 206.4 235.1 5 0.2 37.1 53.8 96.7 140.1 202.9 253.4 288.6 10 0.1 43.3 62.4 111.6 161 232.4 290.3 330.6 20 0.05 50.1 72 128 184.1 264.7 330.7 376.6 50 0.02 60.5 86.6 152.9 218.9 313.4 391.4 445.8 100 0.01 69.7 99.4 174.6 249.2 355.6 444.1 505.8
7.10.2 Waioeka at Mouth of Gorge
Rainfall depths (mm) NZMG Easting 2886100 Northing 6346900 – Site # 57
ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 26.4 35.4 56.5 75.9 101.9 123.7 138.6 2 0.5 28.4 38.1 60.6 81.3 109.1 132.4 148.3 5 0.2 35.5 47.5 75.2 100.6 134.4 163.1 182.7 10 0.1 41.2 55 86.8 115.7 154.3 187.3 209.8 20 0.05 47.5 63.3 99.5 132.4 176.2 213.9 239.5 50 0.02 57.2 75.9 118.8 157.6 209.2 253.9 284.4 100 0.01 65.6 86.9 135.6 179.6 237.9 288.7 323.4
7.10.3 Waioeka at Koranga Station
Rainfall depths (mm) NZMG Easting 2888300 Northing 6302600 – Site # 62
ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 23 33.3 60 86.9 125.9 163.1 189.7 2 0.5 25 36.2 64.9 93.8 135.6 175.7 204.4 5 0.2 32.4 46.5 82.6 118.6 170.4 220.8 256.8 10 0.1 38.4 54.9 96.9 138.6 198.3 256.8 298.8 20 0.05 45.2 64.5 113 160.9 229.3 296.9 345.4 50 0.02 55.9 79.3 137.8 195.2 276.6 358.3 416.8 100 0.01 65.6 92.6 159.8 225.6 318.5 412.5 479.8
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7.11 Waioeka River flood event plot July 1998
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7.12 Waioeka River flood event plot October 2003
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7.13 Maximum flood depth profile, predictive scenarios – Waioeka and Otara Rivers
7.13.1 Waioeka 1% AEP Otara 5% AEP Tide 5% AEP plus allowance for climate change sea level rise
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7.13.2 Waioeka 1% AEP Otara 5% AEP Tide 5% AEP, Allowance for climate change sea level rise.
Profile along Church Street - from Bridge Street (left) to Otara stopbank (right).
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7.13.3 Waioeka 5% AEP Otara 1% AEP Tide 5% plus Allowance for climate change sea level rise
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7.13.4 Waioeka 5% AEP Otara 5% AEPTide 1% AEP plus Allowance for climate change sea level rise
7.13.5 Waioeka 5% AEP Otara 5% AEP Tide 5% AEP
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7.13.6 Waioeka 5% AEP Otara 1% AEP Tide 5% AEP plus Allowance for climate change sea level rise Otara Stopbank Breach at Richard Street
7.13.7 Waioeka 5% AEP Otara 1% AEP Tide 5% AEP plus Allowance for climate change sea level rise Otara Stopbank Breach between Wellington and Bridge Streets
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7.13.8 Waioeka 1% AEP Otara 5% AEP Tide 5% AEP plus Allowance for climate change sea level rise Waioeka Stopbank Breach at Union Street
7.14 Predicted stopbank overflows
For more information, refer Towards Waioeka-Otara Floodplain Management Strategy – Review of the Current Flood Hazard and Existing Responses, Operations Report 99/05.
Figure 18 Waioeka River, 29 January 2011.
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7.15 Waioeka at Cableway rating curve
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8
Discharge Return Stage (m3/s)(Freeman Period (m) 6 2008). (years) 4.1 335 1st Warning Level Stagemetres 6.11 678 2.33 6.56 760 7.15 4 868 5 2nd Warning Level 8.05 1040 10 8.97 1221 20 1480 50 2 1695 100 1928 200 1 2268 500 0 100 200 300 400 500 600 700 800 900 1000 1100 1300 Flow m3/s Waioeka at Cableway 12-Dec-2005 20:00:00 Indicator Stage 2.377
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7.16 Rating table for Waioeka at Cableway
Stage Discharge (m3/s) Reference Stage Discharge (m3/s) Reference (m) (m) 1.4 8 3.3 208 1.5 11 3.4 223 1.6 17 3.5 239 1.7 23 3.6 255 1.8 30 3.7 271 1.9 37 3.8 288 2.0 45 3.9 304 2.1 54 4.0 319 2.2 64 4.1 335 First Warning Level 2.3 75 4.2 351 2.4 87 4.3 368 2.5 100 4.4 384.1 2.6 112 4.5 400.6 2.7 125 4.6 417.3 2.8 138 4.7 434.3 2.9 151 4.8 451.3 3.0 165 4.9 468.6 3.1 179 5.0 486.0 3.2 193 5.1 502.9
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Stage (m) Discharge (m3/s) Reference Stage (m) Discharge (m3/s) Reference 5.2 519.9 7.15 868.2 5 year Return Period 5.3 537.1 7.2 877.6 5.4 554.4 7.3 896.3 5.5 571.6 7.4 915.1 5.6 589.0 7.5 934.0 5.7 606.5 7.6 952.9 5.8 624.0 7.7 971.9 5.9 641.6 7.8 991.0 6.0 659.3 7.9 1010.0 6.1 677.1 8.0 1029.0 6.11 678.9 2.33 year Return Period 8.05 1039.0 10 year Return Period 6.2 694.9 8.1 1049.0 6.3 712.8 8.2 1068.0 6.4 730.8 8.3 1088.0 6.5 748.9 8.4 1107.0 6.56 759.8 2nd Warning Level 8.5 1127.0 6.6 767.0 8.6 1146.0 6.7 785.3 8.7 1166.0 6.8 803.6 8.8 1186.0 6.9 821.9 8.9 1206.0 7.0 840.4 8.97 1220.0 20 year Return Period 7.1 858.9 9.0 1226.0
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7.17 Waioeka at Cableway staff gauge prompter
22 Bay of Plenty Regional Council Flood Warning Manual
Part 8: Tauranga River formerly Waimana River
Chapter summary
8.1 Tauranga River Catchment overview 2
8.2 Warnings and warning lists 2
8.3 Flood forecast modelling 3
8.4 East Bridge and Matahī Bridge staff gauges 3
8.5 Data records for Tauranga River 4
8.6 Rainfall records for Tauranga River Catchment 4
8.7 Tauranga River flood maps predictive scenarios 5
8.8 Tauranga at Gorge rating curve 9
8.9 Rating table for Tauranga at Gorge 10
8.10 Tauranga at Ranger Station rating curve 12
8.11 Rating table for Tauranga at Ranger Station 13
8.12 Tauranga at Gorge staff gauge prompter 14
8.13 Tauranga at Ranger Station staff gauge prompter 15
Bay of Plenty Regional Council Flood Warning Manual 1
8.1 Tauranga River Catchment overview
The Tauranga “formerly Waimana” River valley floor is narrow and has few areas of river flats in the upper 48 km, but after leaving the main range the floor widens and for the next 19.5 km the river channel is wide and braided. The final 13 km of the Tauranga River are through a gorge with the exception of the last 1.6 km, where it empties out of the gorge on to the valley floor just upstream of the confluence with the Whakatāne River.
Extensive flooding occurs across the TaurangaRiver Floodplain particularly in the lower half downstream of the Parau Stream in events greater than the five-year flood. Road access through the Waimana Gorge to the Tauranga Floodplain between Tāneatua and Waimana townships is cut off, thus isolating the floodplain community. Road access through Nukuhou to the Tauranga River Floodplain is potentially cut off. Several buildings in the Tauranga River Floodplain may be at risk from flooding.
Reference: Operations Publication 2005/09.
8.2 Warnings and warning lists
1 When a pre-set alarm level is reached, HydroTel™ sends an automated message to the Flood Duty pager. If the pager shows a message to notify someone or issue a warning an action will be required. 2 The actions related to the alarm levels are described on the individual staff gauge prompter pages. The river rising notification is sent automatically to the Duty Flood Manager, Principal Works Engineer and the Works Coordinators. This is alarm signals a first response in the river level/s. Monitoring activity will increase following this alarm. 3 All information related to the issuing of flood warning messages and the current contact details for the members of the flood warning groups are located in the Flood Warning Guide.
Note: The majority of the alarms are within the Rivers and Drainage Scheme areas and catchments. There are additional alarms set up outside of these areas, (refer to non-scheme section). Some of these alarms do require some action.
Communication including but not limited to warnings, updates and information sharing will be focused around these groups:
(a) Bay of Plenty Regional Council Rivers and Drainage staff, regular contact with the Principal Works Engineer is recommended. (b) Flood warning groups (Farmers and other key stakeholders). (c) Bay of Plenty Regional Council Communications staff. (d) Whakatāne District Council (WDC). (e) Local Civil Defence Emergency Management (WDC). (f) Bay of Plenty Regional Council contractors working in vulnerable areas. (g) Whakatane District Council has the responsibility to warn any of their contractors that may be working in vulnerable areas. (h) Police. (i) Radio station.
2 Bay of Plenty Regional Council Flood Warning Manual
IMPORTANT – The Principal Works Engineer must be notified early (at first warning level) so that the Rivers and Drainage staff can check relevant floodgates, pumps and weedscreens.
Note ‒Cell phone and internet coverage in the Waimana area is inconsistent. Contact using the phone landline network is still the most reliable means of communication.
8.3 Flood forecast modelling
Automated flood forecast modelling is run every two hours for several rivers in the Bay of Plenty including the Tauranga.The Unit Hydrograph (UHG) model uses telemetered data from rain gauges and river gauges.Results for the Tauranga River are reasonably reliable.There was a weakness in the model identified during the 2004 flood when very high rainfall intensities occurred in the lower Tauranga River Catchment that were not well represented by telemetered gauges (mainly in the upper catchment). As a consequence the river rose higher and earlier than anticipated – be aware of this potential if rain appears to be mainly coastal.
The latest forecasts are posted on HydroTel™.To view these, expand the “flow” item in the explorer window and select “UHG Modelled Flow”.This forecast includes “landed” rain only.
A more detailed report is also archived to O: drive if significant rain has fallen. The report shows results from landed rain in all of the UHG modelled catchments as well as manually-entered forecast rain.The network location is:
\\WHKNEARLINE\Enigneering\Flood Forecasting\Herbst Models\Archived Forecasts\ Auto_Forecast_yyyymmdd_hhmm.xls
8.3.1 Flood forecasting sites on HydroTel™ – Tauranga River
Tauranga at Gorge.
Note‒Telemetry sites and rain gauges are described in the Whakatāne River section together with "Time of Travel" analyses etc.
8.4 East Bridge and Matahī Bridge staff gauges
New staff gauges have been fitted to the piers of the East and Matahī Bridges. They have been fitted to assist the local community, CDEM and the Flood Team in determining at what level the flood waters will inundate the access roads. Waimana is oftencut off from the rest of the district. The markers show the road levels and road access levels.
Note ‒ The flood levels need to read off the staff gauges during the next flood event. Contact Waimana Community Liaison: Dianne Ruru, Senior Administrator, Te Waimana Kaaku Tribal Executive Day phone number (07) 312 3700 and after hours (07) 312 3130.
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Please refer note A1, notes page in the appendices.
8.5 Data records for Tauranga River
Data on the following pages covers:
Tauranga rainfall records – depth duration and frequency. Tauranga at Gorge rating curve. Tauranga at Ranger station rating curve. Flood maps, Q50, Q100, Q200 – note that the flood extent shown is limited to the available ground level data. For more detailed information, refer to Operations Publication 2006/02, Hydraulic Modelling of the Waimana River and Floodplain.
8.6 Rainfall records for Tauranga River Catchment
The values highlighted in red in the following table indicate rainfall depths, durations and return periods that are 100 mm or greater that are likely to cause flooding.
8.6.1 Tauranga at Ranger Station
Rainfall depths (mm) NZMG Easting 2869600 Northing 6315400 – Site # 52
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 29.6 41.5 70.9 99.4 139.2 170.5 192 2 0.5 31.9 44.7 76.3 106.9 149.8 183.5 206.5 5 0.2 40.1 56.2 95.7 134 187.6 229.8 258.7 10 0.1 46.7 65.3 111.2 155.6 217.8 266.7 300.2 20 0.05 54 75.5 128.4 179.6 251.2 307.6 346.3 50 0.02 65.1 91 154.7 216.2 302.2 370.1 416.7 100 0.01 75 104.7 177.9 248.5 347.2 425.2 478.7
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8.7 Tauranga River flood maps predictive scenarios
8.7.1 Tauranga River flood map 20-year event
For more information, refer to Hydraulic Modelling for the Waimana River and Floodplain, Operations Publication 2006/02.
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8.7.2 Tauranga River flood map 50-year event
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8.7.3 Tauranga River flood map 100-year event
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8.8 Tauranga at Gorge rating curve
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Return 5 Stage Discharge Period (m) (m3/s) (years) 365 2.33 4 4.0
Stagemetres 408 SH2 Alarm Level 4.54 520 5 3 5.23 670 10 5.9 820 20 2 6.34 920 30 6.9 1050 50
1 1240 100
0 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 Flow m3/s Waimana River at Waimana Gorge 20-Jul-1978 16:01:00 Indicator Stage 1.819
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8.9 Rating table for Tauranga at Gorge
Stage (m) Discharge(m3/s) Reference Stage (m) Discharge (m3/s) Reference 0.6 1 2.8 200 1 18 2.9 215 1.1 23 3 230 1.2 29 3.1 245 1.3 35 3.2 261 1.4 43 3.3 278 1.5 51 3.37 290 1.6 60 3.4 295 1.7 69 3.5 313 1.8 78 3.6 332 1.9 88 3.7 351 2 98 3.78 365 2.33 year Return Period 2.1 109 3.8 369 2.2 120 3.9 389 2.3 133 4 408 SH 2 Alarm Level 2.4 145 4.1 428 2.5 158 4.18 444 2.6 172 4.2 448 2.7 186 4.3 469
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Stage (m) Discharge(m3/s) Reference Stage (m) Discharge (m3/s) Reference 4.4 490 6 842 4.5 511 SH 2 Inundation Level 6.1 865 4.55 520 5 yr Return Period 6.2 888 4.6 533 6.3 910 4.7 554 6.34 920 4.73 561 6.4 933 4.8 576 6.5 957 4.9 598 6.6 980 5 619 6.7 1003 5.1 641 6.8 1026 5.2 663 6.9 1050 50 year Return Period 5.25 670 10 yr Return Period 7 1073 5.3 685 7.1 1097 5.4 708 7.12 1102 5.5 730 5.6 752 5.7 774 5.8 797 5.9 819 20 yr Return Period
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8.10 Tauranga at Ranger Station rating curve
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5 Return Discharge Stage (m) Period (m3/s) Stagemetres 4 (years) 3.0
First Warning Level 4.62 290 5 3 5.05 365 10 5.45 445 20 560 50 2
1 0 100 200 300 400 500 600 700 800 900 1000 Flow m3/s Site 15544 Waimana at Ranger Stn Gaugings from 20060101 to 20051231 20050919 020000 Indicator Stage 3.123
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8.11 Rating table for Tauranga at Ranger Station
Stage (m) Discharge(m3/s) Reference Stage (m) Discharge(m3/s) Reference 1.5 1 6.5 672 1.6 2 6.6 696 1.7 4 6.7 721 1.8 7 6.8 746 1.9 11 6.9 771 2 14 7 797 3 82 First Warning Level 7.1 823 4 197 7.2 850 4.62 290 5 year Return Period 7.3 877 5 356 7.4 904 10 year Return 5.05 365 7.5 932 Period 20 year Return 5.47 445 7.6 960 Period 6 556 7.7 988 6.1 579 7.8 1017 6.2 601 7.9 1047 6.3 624 7.95 1061 6.4 648
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8.12 Tauranga at Gorge staff gauge prompter
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8.13 Tauranga at Ranger Station staff gauge prompter
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Part 9: Whakatāne River
Chapter summary
9.1 Whakatāne Catchment overview 2
9.2 Warnings and flood warning groups 3
9.3 Whakatāne and Tauranga telemetry sites 4
9.4 Flood forecast modelling 4
9.5 Current stopbank design level 5
9.6 River floods 7
9.7 Flooding at Rūātoki 7
9.8 Historical floods and travel times 10
9.9 Critical flood structures and hotspots 10
9.10 The Whakatāne River Spit 13
9.11 Flood protection stoplog structures 15
9.12 Road closures due to stoplog installation 17
9.13 Whakatāne rural area stoplogs 19
9.14 Te Rahu Basin and Spillway 19
9.15 Data records for Whakatāne River 22
9.16 Rainfall records for Whakatāne including Tauranga sites 22
9.17 Whakatāne River flood event plot – July 2004 24
9.18 Whakatāne River flood event plot – January 2011 25
9.19 Whakatāne at Whakatane rating curve 26
9.20 Rating table for Whakatāne at Whakatāne 26
9.21 Whakatāne at Whakatane staff gauge prompter 29
9.22 Whakatāne at Wharf staff gauge prompter 30
9.23 Whakatāne at Rūātoki staff gauge prompter 31
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9.1 Whakatāne Catchment overview
The Whakatāne River System itself broadly comprises two main branches; the Tauranga River and the Whakatāne River. The Tauranga River Catchment covers 440 km2, extending 77 km from the confluence to the upper tributaries, while the Whakatāne area above Valley Road recorder covers approximately 1,100 km2 and extends 112 km to its upper tributaries. Both catchments are relatively narrow and the tributaries are short and steep, draining extensive bush covered catchments.
The two branches rise in the Huiarau and Ikawhenua Ranges some 113 km inland and run due north along the Tauranga and Whakatāne fault lines until they converge at Tāneatua, 26 km from the sea. Below this point, streams flowing from the foothill catchments augment the river. The main foothill streams are the Owhakatoro (74 km2), the Waioho (89 km2), Te Rahu (30 km2), Wainui Te Whara (6 km2) and Wairere (3 km2).
The former Bay of Plenty Catchment Commission (BOPCC) commented on flooding issues associated with the streams and canals feeding into the Whakatāne River:
The Waioho and Te Rahu flow in from the west and give rise to serious flooding problems where they traverse the Rangitāiki Plains while the Wainui and Wairere cause similar problems in the Borough of Whakatāne. Further downstream, two large drainage canals the Kopeopeo and Orini flow in from the west. These waterways are the drainage outlets for 15,000 acres (or 6,070 ha) of flat land and most water is pumped from this area.(BOPCC, 1957, page 1).
9.1.1 Whakatāne River
The Whakatāne River rises in the Huiarau Range and quickly drops into a deeply incised valley and with the exception of small areas of rolling hill country at Ruatahuna and Maungapohatu; there are no significant river flats for the next 64 km until the river flows out of the main range at the upper Rūātoki Valley.
At this point the valley floor widens out to an average width of 1,600 m before widening out again at the limeworks. At the same time, the catchment cover changes from indigenous forest at the ranges (which incorporate the Urewera National Park) to scrub and grasslands of the foothills.
Below this for the next 6.5 km, the river has developed a wide meander belt with considerable areas of shingle bed and marginal river flats.
Below the Rūātoki Bridge, which is 32.6 km from the sea, the river is generally more confined until it reaches the confluence with the Tauranga River.
Downstream of the confluence the river continues for another 3.5 km before it reaches the Pekatahi Bridge and below this the river is stopbanked.
The Whakatāne River System flows along the graben that is located where the volcanic zone intersects the coast. Geological investigation suggests that the graben is subsiding at a rate of 2-3 mm per year. (Gibbons, 1990, page 1). Normally settlements of this nature would reduce the amount of freeboard available for flood protection purposes, however, since flow capacity is relative to the channel cross-sectional profile capacity assessment becomes independent of region-wide settlement.
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9.2 Warnings and flood warning groups
1 When a pre-set alarm level is reached, HydroTel™ sends an automated message to the Flood Duty pager. If the pager shows a message to notify someone or issue a warning an action will be required. 2 The actions related to the alarm levels are described on the individual staff gauge prompter pages. The river rising notification is sent automatically to the Duty Flood Manager, Principal Works Engineer and the Works Coordinators. This alarm signals a first response in the river level/s. Monitoring activity will increase following this alarm. 3 All information related to the issuing of flood warning messages and the current contact details for the members of the flood warning groups are located in the Flood Warning Guide.
Note: The majority of the alarms are within the Rivers and Drainage Scheme areas and catchments. There are additional alarms set up outside of these areas, (refer to non-scheme section) some of these alarms do require some action.
Communication including but not limited to warnings, updates and information sharing will be focused around these groups:
(a) Bay of Plenty Regional Council Rivers and Drainage staff, regular contact with the Principal Works Engineer is recommended. (b) Flood warning groups (farmers and other key stakeholders). (c) Bay of Plenty Regional Council Communications staff. (d) Whakatāne District Council (WDC). (e) Local Civil Defence Emergency Management (WDC). (f) Bay of Plenty Regional Council contractors working in vulnerable areas. (g) Police. (h) Radio station.
IMPORTANT – The Principal Works Engineer must be notified early (at first warning level) so that the Rivers and Drainage staff can check relevant floodgates, pumps and weedscreens.
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9.3 Whakatāne and Tauranga telemetry sites
Data Services Channel 1 – E191 –BOPRC Telemetry Channel
Data Services Channel 2 – E115 – NIWA Telemetry Channel
Site name Comments Agency
Tauranga and Whakatāne Catchments Nukuhou at Glenholme Road River level and flow site near the BOPRC SH 2 bridge. Feeds into the Ōhiwa Harbour and floods Wainui Road when high. Whakatāne at Huiarau Summit Rainfall at the top of the Whakatāne BOPRC Catchment. Tauranga at Ranger Station River level/flow and rainfall site on BOPRC the Tauranga in the heart of the Urewera National Park. Whakatāne at Huitieke River level and rainfall situated in the BOPRC middle of the Whakatāne Catchment. Give approximately 12-18 hrs lead into flood peak reaching Whakatāne. Tauranga at Gorge River level in the Tauranga in the BOPRC middle of the Tauranga Gorge. Give approximately 12-18 hrs lead into flood peak reaching Whakatāne. Whakatāne at Rūātoki River level in the Whakatāne River at BOPRC Rūātoki. Located mid-catchment approximately 9.4 km upstream of the rivers confluence with the Tauranga River. Whakatāne at Whakatane River level/flow in the Whakatāne at NIWA/BOPRC the upstream end of Whakatāne township. Formerly known as Whakatane at Valley Road. Whakatāne Airmon Rainfall in Whakatāne town. BOPRC Wainui-te-whara at Level/flow in the Wainui-te-whara BOPRC/WDC Mokorua Gorge which feeds the Awatapu lagoons. Wainui-te-whara at Munro’s Located on the boundary between BOPRC/WDC the Wainui-te-whara and Maraetotara Catchments. Whakatāne at Town Wharf River levels at the lower end of BOPRC Whakatāne township. Tidal effects present.
9.4 Flood forecast modelling
Automated flood forecast modelling is run every two hours for several rivers in the Bay of Plenty but not for Whakatāne directly. Petrus Herbst, who built the first UHG models recommended that in lieu of a Whakatāne model, results from his Tauranga model could be doubled. The Tauranga is a major tributary to the Whakatāne River, joining it at Tāneatua.
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The latest Tauranga River forecasts are posted on HydroTel™.To view these, expand the “flow” item in the explorer window and select “UHG Modelled Flow”. This forecast includes “landed” rain only.
A more detailed report of Tauranga model results is also archived to “O” drive if sufficient rain has fallen to cause flooding. The report shows results from landed rain in all of the UHG modelled catchments as well as manually-entered forecast rain.
The network location is:
\\WHKNEARLINE\Engineering\Flood Forecasting\Herbst Models\Archived Forecasts\ Auto_Forecast_yyyymmdd_hhmm.xls
9.5 Current stopbank design level
Whakatāne ad Tauranga River Schemes
Location Nominal design Design flow plus freeboard Meets level in 2014 design standard (in 2014) Whakatāne right bank 1% AEP (100 yr) 2,820 m3/s at Valley Road Yes downstream of yacht plus 600 mm club Freeboard Whakatāne right bank 1% AEP (100 yr) 2,820 m3/s at Valley Road Yes from Landing Road plus 800 mm bridge to yacht club freeboard Whakatāne left bank 1% AEP (100 yr) 2,820 m3/s at Valley Road Yes downstream of plus 500 mm Right bank rural Pekatahi Bridge SH 2 freeboard Rural Banks (no design criteria, existing RL maintained) Whakatāne right bank 1% AEP (100 yr) Right bank urban area Yes from Pekatahi bridge plus 500 mm 2,820 m3/s at Valley Road (SH 2) to Freeboard Right bank rural Landing Road Bridge Rural Banks (no design criteria,existing RL maintained) Waioho Canal 1% AEP (100 yr) 132 m3/s at SH 2 Yes plus 600 mm freeboard Te Rahu Canal 1% AEP (100 yr) 22.4 m3/s Yes downstream of SH 2 at plus 600 mm Awakeri freeboard Kopeopeo Canal (east) 20% AEP (5 yr) Eastern drain gravity inflow Yes plus 270 mm 6.3 m3/s plus pumped inflow freeboard (drainage co-efficient 28 mm/d for 3-day storm) Kopeopeo Canal (west) 20% AEP (5 yr) Gravity inflow plus pumped Yes plus 270 mm inflow (28 mm/d for 3-day freeboard storm)
Reference: Rivers and Drainage Schemes Asset Management Plan – June 2015
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Figure 19 Stopbank and return period plan for Whakatāne-Tauranga Rivers Scheme –BOPRC Asset Management Plan.
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9.6 River floods
9.6.1 Minor floods
Note: When the current analysis is completed these numbers are likely to change.
200-300 cumecs Tauranga River 400-600 cumecs Whakatāne River
Low-lying land adjacent to the rivers is likely to be flooded when above flows are reached. Warnings are not normally required unless a rapid rise in water level is expected during the hours of darkness, in which case:
See graph of gauge height at Valley Road versus effect on land.
9.6.2 Floods up to 10-year bank (rural bank)
300-600 cumecs Tauranga River 600-1,200 cumecs Whakatāne River
Widespread flooding of all flat land adjacent to rivers will occur when river flows specified above are reached.
Flat land in the Tāneatua, Rūātoki and Tauranga areas where no 10-year banks (rural banks) exist will be most affected.
Warnings should be much the same as for minor floods except that the warning should be a little stronger in its wording.
See graph of gauge height at Valley Road versus effect on land.
9.6.3 Floods 1,200 cumecs (rural bank level) and above
Twenty four hour rainfalls will likely need to be in excess of 100 mm over the main part of the catchment to cause floods above the rural bank level. First indications are usually from the Waimana area.
Suitable warnings should be broadcast over local radio, refer to the Flood Warning Guide for details.
When floods are greater than the rural bank level, preparations should be made to ensure that the urban stoplogs and Waioho Stream are readily available should they be required.
If necessary a staff member can be sent to the Rūātoki Bridge to read the staff gauge.
9.7 Flooding at Rūātoki
9.7.1 Rūātoki flood warning level
The warning level of 2.3 m stage height allows for approximately 3.5 hours warning prior to reaching a five year flood level at the Ohutu Bridge site. This is calculated at the most extreme rate of rise recorded up to October 2011. During most floods this level would afford about six hours warning prior to a five year flood level and nearly
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four hours warning before Reid Road is overtopped near the Waimana Confluence. It is important to note that the inundation of Reid Road is also caused by flooding from the Tauranga River, so the Rūātoki flood warning level cannot be solely relied upon to provide an early warning trigger level, for the imminent flooding around both Reids and Awahou Roads intersection. These two roads provide access to Rūātoki and are regularly closed during flood events. This causes the township to be cut off from emergency services support.
Figure 20: Historical road inundation sites south of Taneatua
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Figure 21: Deflector bank location adjacent to Rūātoki township
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9.8 Historical floods and travel times
9.8.1 Top 21 floods and travel times for the Whakatāne and Tauranga Rivers
Note: *Cyclone Wilma –29 January 2011.
9.9 Critical flood structures and hotspots
The Rivers and Drainage staff are responsible for the inspection of pump stations, floodgates, and culverts. Inspections are made in response to a severe weather warning, following heavy rainfall or in response to instructions from the Flood Manager or the Principal Works Supervisor.
A number of pump stations have telemetry installed to provide remote access and control. Access to the website that manages the pump station telemetry is via the URL: www.loncel.com/login.
The Rivers and Drainage staff check all the floodgates in the lower reaches of the Whakatāne River including the floodgates on the river side of the Whakatāne township floodgates.
9.9.1 Kope Orini floodgate
The Kope Orini system receives water from a number of the Rangitāiki Plains drains. It is located in the lower reaches of the Whakatāne River. Rivers and Drainage staff check that the floodgate is closed if there is a severe weather warning issued or they have been contacted by the Flood Manager.
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Figure 1 Kope Orini floodgate.
Note – Always confirm the Kope Orini gates have been checked. Access to the main Kope Orini floodgate is via the 100-year stopbank off Keepa Road. (The gate may be locked – standard stopbank key).
9.9.2 Orini Canal
The Orini Canal can overtop Thornton Road by Powdrell Road. There is no alarm capability for this canal. Thornton Road is the main road into Whakatāne from the west, it is worth noting that this is a low lying area. No direct action is required from the Flood Team.
9.9.3 Kope East systems
Kope East system is expected to be near capacity once flows in the Whakatāne River is expected to exceed 1,400 m3/s at Valley Road and in excess of 100 mm rainfall has occurred on the Plains. Rivers and Drainage staff monitor the Kope East system staff gauges. At times when the drainage system is reaching full capacity, owners of private pumps may be instructed to turn their pumps off.
9.9.4 Kope East sluice gate
Asset ID 10129.
Rivers and Drainage staff monitor water levels each side of the sluice gate. Water is able to be diverted to either the east or west side depending on the available capacity in the drainage system. It is possible that there may be no storage capacity either side. The site is subject to tidal influence.
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9.9.5 Eastern drain
The existing banks were formed using drain cleanings and are considered to be in an informal state. Future improvements works are scheduled to increase the security of these banks.
Once the staff gauge at the Powdrell Road Bridge gets to approximately 1.350 m it will overtop the right bank near the sluice gate at the west end of the Kope Canal.
9.9.6 Western drain diversion
Asset ID 101366.
The drain capacity was reduced following the 1987 earthquake. The diversion was installed to divert water from the Western Drain directly to Reids Central Canal via the Western Drain diversion. The diversion is a culvert throttling mechanism with a lateral overflow weir.
9.9.7 Whakatāne River flood relief structures (containers)
Two containers have been installed to allow flood water trapped behind the rural stopbanks to drain back into the Whakatāne River once it has receded.
Taneatua Road Easting 1950672.302 Northing 5785611.233
Rewatu Road Easting 1949265.522 Northing 5782953.025
There is no formal agreement in place. Opening and closing of the containers will be undertaken by the landowner.
Figure 2 Flood water control container structure – left bank Whakatāne River.
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9.10 The Whakatāne River Spit
9.10.1 Background
The Whakatāne Harbour mouth is continually constricted by the movement of sand along the beach from the west. The steady sand movement has formed a sand spit that impacts on flood conveyance at the mouth due to narrowing; but also on vessel navigation through shallowing.
During large floods such as 1970, the spit had been observed to erode rapidly enough to accommodate the peak of the flood. The natural mechanism of erosion is thought to be a side-ways action at the tip that widens the channel. The rocks at the spit, Turuturu (Statue Rock) and others do impede this action but not critically during large floods.
The general process by which the spit fuse erodes, is that the energy within the flood flow attacks the eastern end of the spit adjacent to the river. The eastern end of the spit is essentially ‘peeled back’ by the river energy. At some stage during this process, the end of the spit is eroded sufficiently so that the flood flows can pass to the west of Statue Rock and out to sea. This process is dependent on the status of the spit, magnitude of the flood flow and sea conditions. Once flood flows have opened the fuse, the end of the spit continues to erode to a state that can accommodate the flood flows and balance the sea state.
The existing western spit training wall is located in such a way that it provides a barrier between the river flood flow and the end of the spit. The maximum erosive forces within the flood flow cross-section are below the top level of the current wall. Consequently, the river has difficulty opening the spit fuse with western spit training wall in place.
With the western spit training wall in place, the current spit opening process is more related to a head differential across the spit, between the flood water level on the inland side of the spit and the open sea level (including the storm influenced sea state). It has been noted, during several recent flood events, that the spit fuse does not blow until low tide, because that situation is required to provide sufficient head differential across the spit, especially when there are rough sea conditions elevating the average sea level. Also, overtopping surface erosion is aided during the receding tide because of elevated pore-pressure, (relative to sea level) within the spit sand mass assisting in ‘softening’ the spit structure.
9.10.2 Flood management
The overall intent of the Spit Fuse Flood Management Plan is to lower the level of the eastern end of the spit, to encourage the river to overtop during flood events and then erode an overflow path (on the western side of Statue Rock) as required.
There are two main aspects to the lowering of the eastern end of the spit:
1 Flood management - lowering spit level and form a fuse-channel immediately prior to a forecast rainfall/flood event. 2 Maintenance management - pre-emptive lowering of spit level when sand volumes and/or crest levels increase aimed at reducing the time required to complete flood management preparations.
Prior to a predicted flood event, a fuse-channel is constructed through the eastern end of the spit. The purpose of the fuse-channel is to provide a path for the river to flow to the sea and commence eroding the spit.
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The fuse-channel is constructed when a flood event is likely to occur. Trigger levels for the construction of the fuse-channel are:
A predicted rainstorm event which is expected to exceed 100 to 150 mm of rainfall in the Whakatāne and Waimana Catchments, as directed by the BOPRC Flood Manager. Whakatane District Council and BOPRC staff will liaise prior to the predicted rainstorm event, to determine details of the spit fuse preparation to account for flood flows. Sufficient lead time needs to be included in the fuse-channel construction process. Machinery should be mobilised and the channel completed during daylight hours prior to the flood flow arriving at the river mouth. Machinery should be left in a safe area close to the spit to allow further adjustments to the channel if required and safe e.g. if the sea closes the fuse-channel. For more information refer to Operations Publication 2013/01.
9.10.3 Responsibility
Whakatane District Council have the responsibility to maintain the fuse-channel. This responsibility is defined under Condition Number 10 of Resource Consent Number 62893 for which WDC is the consent holder.
However, during the flood warning phase for the Whakatāne River System the BOPRC Flood Manager will work in conjunction with WDC to ensure that the spit has been prepared correctly.
Also both WDC and BOPRC will monitor sand build-up on the spit and liaise with regard to maintenance management requirements. It is WDC responsibility to undertake pre-emptive spit lowering construction works.
Figure 20 Whakatāne Spit Fuse Channel location.
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9.10.4 Flood history
During the 1998 flood the sand spit widened by lateral erosion from the tip once river levels enabled a flow path to form behind the training wall. Although a similar flood size to 1970, peak levels were approximately 0.5 m higher in 1998 in the lower river.This difference was attributed to the effect of the western training wall.
During the July 2004 flood the sand spit did not erode significantly until after river levels had reached 3.05 m and the tide was well receded. Overtopping of the river bank at Mataatua Reserve caused flooding of houses along Muriwai Drive. Sandbagging efforts narrowly averted flooding of Quay Street and the Whakatāne CBD. Unfortunately evacuation efforts had not been adequately prepared, due in part to confidence in the spit fuse. Once the spit eroded the river levels dropped by more than a metre in 1.5 hours. Due to the darkness, the action of the spit fuse was not observed.
Figure 21 Lowering of the Whakatāne Spit Fuse, 14 August 2010.
9.11 Flood protection stoplog structures
9.11.1 Whakatāne urban area stoplogs (flood and tsunami defence)
The Whakatāne River Flood Protection System relies on stoplogs being fitted at multiple locations as follows (note all levels quoted in the lower river are in terms of the Moturiki Datum, including the wharf gauge).
Install the stoplogs at the BOAT RAMP slot first as the rising water arrives at this slot earlier, and install the rest travelling upstream from there. The stoplogs take approximately one hour to fit.
The Flood Management Pager System is set to send an alert when the Whakatāne at Wharf gauge reaches 1.7 m RL Moturiki Datum.This is to allow at least two hours before flood waters reach the level of the boat ramp car park stoplog sill at 2.2 m RL. During the 17 July 2004 flood it took just over two hours for the river to rise over this range (from 1.7 m to 2.2 m). During the 2 July 1998 flood it took a little under four hours. The 11 July 1998 flood did not reach 2.2 m at the wharf but its fastest rate of raise over 0.5 m was just under two hours.
It is recommended to install the stoplogs at the entrance closest to the Heads first as its sill level is lower. Bolts to secure the Whakatāne Boat ramp stoplogs in place are kept in the Flood Room.
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The Flood Manager should contact Rivers and Drainage staff to initiate stoplog installation.
Stoplog Number of Trigger Invert Stored Fitting Contact one of location stoplogs level method the listed people to organise the stoplogs Whakatāne 5 logs @ 2 1.7m @ 2.2m The five Crane Andrew Pawson Boat Ramp locations Wharf stoplogs (three or (boat trailer gauge at boat ramp slot *TMP - Stanley August parking Shoulder or and two at waka area) shelter slot) are or closed to if Valley be used located adjacent Arthur Rangihika Road is to the two slots. expected Whakatāne 1 to 2.7 m The gate is Closed by Wharf exceed padlocked open hand, use 6.5m. when not in use, stopbank needs to be padlock unlocked and key padlocked closed until the flood peak passes. Whakatāne 1 2.5m The stoplog is Hiab Fishing Club *TMP 3 to located on site Truck be used adjacent to the slot. Quay Street 2 2.6m The stoplogs are Hiab (in front of located on site Truck BOPRC adjacent to the office) slot. Information 1,a small 2.8m The gate is Closed by *TMP Traffic Centre – hinged padlocked open hand, use Management Whakatāne gate when not in use, stopbank Plan Green Wharf needs to be padlock unlocked and key padlocked closed until the flood peak passes.
Figure 22 Downstream end of Quay Street, outside BOPRC offices. Note the stoplog to the left of the photo.
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A hiab truck fitted with lifting chains and shackles is required to lift and place the stoplogs (BW formerly Sisson Engineering) 308 5596 (work), 308 6134 (home) or 027 522 2897 is familiar with fitting these stoplogs. Carl Butler (Mahy Crane Hire) 307 0858 is used for the stoplogs at the Whakatāne Boat Ramp.
9.12 Road closures due to stoplog installation
Rivers and Drainage staff will contact Beca to advise them that the stoplogs will be installed. The Flood Manager or their delegate will contact the local radio station to advise them that the stoplogs will be installed and traffic movements around the stoplogs will be limited.
Figure 23 2004 Flood event, Whakatāne on the left looking north-west.
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Figure 24 Whakatāne River urban stoplogs.
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9.13 Whakatāne rural area stoplogs
The water levels are monitored by the operations field staff who under the direction of the Flood Manager will install the stoplogs. The Principal Works Engineer should contact the Flood Manager to confirm that the stoplogs are in place.
Stoplog Number of Trigger Level Stored Fitting Contact person Location Stoplogs Method Te Rahu 4 No trigger level yet, Stored at Lightweight Andrew Pawson Canal, Paroa Field staff should be BOPRC’s aluminium or Road Bridge asked to monitor Edgecumbe so can be site at the same Maintenance fitted by Stanley August time as monitoring Depot hand (two or the Waioho Canal person Arthur Rangihika site. crew minimum). Waioho 4 Stoplogs to be Canal, installed if water Rewatu level rises above Road Bridge 5.4 m at site, about 7.1 m on the gauge at Valley Road OR if levels rise above 6.8 m at Valley Road, the stoplogs should be installed. The extra rise is likely to take at least an hour.
9.13.1 Road closures due to stoplog installation
Rivers and Drainage staff will contact Beca to advise them that the stoplogs will be installed. The Flood Manager or their delegate will contact the local radio station to advise them that the stoplogs will be installed and traffic movements around the stoplogs will be limited.
9.14 Te Rahu Basin and Spillway
The Te Rahu Catchment has its origin in the hills above Awakeri. It has a catchment area of 30 km2 and includes the Otarere, Mangaroa, and Upper Te Rahu Streams.
The Te Rahu was formed as part of the Whakatāne River Major Scheme. The Basin consists of 405 ha ponding and storage area that is expected to function about once every 20 or 25 years when water levels in the Te Rahu Canal exceed design levels.
Discharge into the basin occurs through the Te Rahu Spillway that has been constructed upstream of Te Rahu Road. The spillway is 600 m long and has a base level that is 0.76 m below the design stopbank level of 4.57 m. Any water flowing into the basin will find its way to the Whakatāne River by either:
Flowing back into the Te Rahu Canal when water levels in the canal recede. Flowing towards, and being pumped by, the Te Rahu Pump Station. Contact Scottie McLeod if it is predicted that the spillway will come into operation. Scottie McLeod, Te Rahu Road, telephone: 308 7731 or 0274 905 823.
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Figure 25 Te Rahu Spillway, 29 January 2011.
Note – Water will rise quite slowly in ponding area and is unlikely to cause any real problems unless it occurs overnight.
20 Bay of Plenty Regional Council Flood Warning Manual
Figure 26 Te Rahu Storage Basin, spillway and stoplogs.
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9.15 Data records for Whakatāne River
Data on the following pages covers:
Whakatāne and Tauranga rainfall records – depth, duration and frequency. Whakatāne at Whakatane rating curve. Two graphs of previous events – July 2004 and January 2011.
9.16 Rainfall records for Whakatāne including Tauranga sites
The values highlighted in red in the following tables indicate rainfall depths, durations and return periods that are 100 mm or greater that are likely to cause flooding.
9.16.1 Whakatāneat Huiteke Upper
Rainfall depths (mm) NZMG Easting 2860600 Northing 6308000 – Site # 53
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 24.7 33.9 56 76.8 105.4 122.4 133.6 2 0.5 26.6 36.5 60.3 82.7 113.5 131.8 143.9 5 0.2 33.7 46.1 75.9 104 142.5 165.5 180.7 10 0.1 39.3 53.8 88.5 121.1 165.8 192.5 210.1 20 0.05 45.6 62.3 102.4 140.1 191.6 222.5 242.8 50 0.02 55.2 75.5 123.8 169.1 231 268.3 292.9 100 0.01 63.8 87.1 142.6 194.7 265.8 308.8 337
9.16.2 Whakatāne at Huiarau Summit
Rainfall depths (mm) NZMG Easting 2862800 Northing 6278600 – Site # 54
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 19.8 28.7 51.8 75.3 109.3 143.9 169.1 2 0.5 21.6 31.3 56.2 81.3 117.6 154.8 181.8 5 0.2 28.5 40.8 71.9 102.8 147.1 193.7 227.5 10 0.1 34.3 48.6 84.7 120.2 170.6 224.7 263.9 20 0.05 40.8 57.5 99.1 139.6 196.7 259 304.3 50 0.02 51.3 71.5 121.4 169.4 236.5 311.4 365.9 100 0.01 60.8 84.2 141.3 195.9 271.5 357.6 420
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9.16.3 Whakatāne at Kopeopeo
Rainfall depths (mm) NZMG Easting 2859900 Northing 6352500– Site # 46
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 23.1 30.8 48.5 64.7 86.2 103.6 115.4 2 0.5 25.1 33.5 52.7 70.2 93.6 112.5 125.3 5 0.2 32.6 43.3 68.1 90.5 120.4 144.7 161.2 10 0.1 38.7 51.4 80.6 107.1 142.3 171 190.5 20 0.05 45.6 60.5 94.8 125.8 167 200.7 223.6 50 0.02 56.5 74.9 117 155 205.4 247 275.1 100 0.01 66.3 87.7 136.9 181.2 239.9 288.5 321.3
9.16.4 Wainui Te Whara at Munro’s
Rainfall depths (mm) NZMG Easting 2862728 Northing 6350202 – Site #
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 23.1 30.8 48.5 64.7 86.2 103.6 115.4 2 0.5 25.1 33.5 52.7 70.2 93.6 112.5 125.3 5 0.2 32.6 43.3 68.1 90.5 120.4 144.7 161.2 10 0.1 38.7 51.4 80.6 107.1 142.3 171 190.5 20 0.05 45.6 60.5 94.8 125.8 167 200.7 223.6 50 0.02 56.5 74.9 117 155 205.4 247 275.1 100 0.01 66.3 87.7 136.9 181.2 239.9 288.5 321.3
9.16.5 Tauranga at Ranger Station
Rainfall depths (mm) NZMG Easting 2869600 Northing 6315400 – Site # 52
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 29.6 41.5 70.9 99.4 139.2 170.5 192 2 0.5 31.9 44.7 76.3 106.9 149.8 183.5 206.5 5 0.2 40.1 56.2 95.7 134 187.6 229.8 258.7 10 0.1 46.7 65.3 111.2 155.6 217.8 266.7 300.2 20 0.05 54 75.5 128.4 179.6 251.2 307.6 346.3 50 0.02 65.1 91 154.7 216.2 302.2 370.1 416.7 100 0.01 75 104.7 177.9 248.5 347.2 425.2 478.7
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9.17 Whakatāne River flood event plot – July 2004
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9.18 Whakatāne River flood event plot – January 2011
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9.19 Whakatāne at Whakatane rating curve
8
7
6
5
Return Stage Discharge Period 4 (m) (m3/s) (years)
Stagemetres 810 2.33 3 6.3 1190 5 6.7 1580 10 6.99 1960 20 2 2180 30 7.5 2450 50 1 2820 100
0 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3200 Flow m3/s Whakatane River at Whakatane 11-Feb-2006 12:00:00 Indicator Stage 1.052
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9.20 Rating table for Whakatāne at Whakatāne
Stage Discharge Reference Stage Discharge Reference (m) (m3/s) (m) (m3/s) 1 75 2.9 296 1.1 84 3 311 1.2 94 3.1 326 1.3 104 3.2 341 1.4 115 3.3 357 1st Warning Level 1.5 125 3.4 373 1.6 136 3.5 389 1.7 146 3.6 405 1.8 157 3.7 422 1.9 168 3.8 438 2 179 3.9 456 2.1 190 4 473 2.2 202 4.1 491 2.3 214 4.2 509 2.4 227 4.3 527 2.5 240 4.4 546 2.6 254 4.5 565 2.7 267 4.6 584 2.8 281 4.7 604
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10 year Return 4.8 626 6.7 1580 Period 4.9 648 6.8 1700 5 671 6.9 1831 20 year Return 5.1 695 6.99 1956 Period 5.2 720 7 1970 5.3 745 7.1 2092 30 year Return 5.4 771 2180 Period 5.5 797 2nd Warning Level 7.2 2220 5.6 833 7.3 2350 50 year Return 5.7 871 2450 Period 5.8 912 7.4 2479 5.9 955 7.5 2612 6 1000 7.6 2744 6.1 1061 7.7 2878 6.2 1124 7.8 3016 5 year Return 6.3 1190 Period 6.4 1274 6.5 1367 6.6 1469
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9.21 Whakatāne at Whakatane staff gauge prompter
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9.22 Whakatāne at Wharf staff gauge prompter
9.23 Whakatāne at Rūātoki staff gauge prompter
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Part 10: Rangitāiki River
Chapter summary
10.1 Rangitaiki Catchment overview 3
10.2 Historical flood protection 3
10.3 Warnings and flood warning groups 3
10.4 Flood forecast modelling 4
10.5 Current stopbank levels of service 5
10.6 Historical floods and travel times 8
10.7 Telemetry sites 9
10.8 Rangitāiki rainfall 9
10.9 Critical control structures and hotspots 9
10.10 Flood control system and Rangitāiki Spillway 10
10.11 Additional road closure 13
10.12 Pressure relief trench monitoring procedure 15
10.13 Hydroelectric dams 19
10.14 Sudden failure procedure 24
10.15 Aniwhenua Dam 26
10.16 Wheao Dam 27
10.17 Data records for Rangitāiki River 28
10.18 Rainfall records for Rangitāiki 28
10.19 Rangitāiki River flood event plot – 23 July 1998 33
10.20 Rangitāiki Riverflood event plot – 18 July 2004 34
10.21 Rangitāiki River flood event plot – 23 January 2011 35
10.22 Rangitāiki River flood event plot – 30 January 2011 36
10.23 Rangitaiki at Te Teko rating curve 37
10.24 Rating table for Rangitaiki at Te Teko (NIWA) 38
10.25 Rangitaiki at Murupara rating curve 39
Bay of Plenty Regional Council Flood Warning Manual 1
10.26 Rating table for Rangitaiki at Murupara (NIWA) 40
10.27 Waihua at Gorge rating curve 41
10.28 Rating table for Waihua at Gorge (NIWA) 42
10.29 Whirinaki at Galatea rating curve 43
10.30 Rating table for Whirinaki at Galatea (NIWA) 44
10.31 Rangitāiki at Rabbit Bridge staff gauge prompter 45
10.32 Rangitāiki at Te Teko staff gauge prompter 46
10.1 Rangitaiki Catchment overview
The Rangitāiki River is one of the three major rivers, which cross the Rangitaiki Plains. It has a catchment area of approximately 3,000 km2 rising in the Central Volcanic Plateau region of the North Island. Its main tributaries rise in the bush covered greywacke country of the Ikawhenua Ranges. The river flows down through a gorge, where it is harnessed for hydro-electric power generation then onto the Rangitāiki Plains, past the townships of Te Teko, Edgecumbe and Thornton. The Rangitāiki River flows across the central part of the plains and is sourced on the Kaingaroa Plateau. It has a very high bed load of coarse pumice sands and had undoubtedly been the major contributor of alluvial sediments to the plains. The Rangitāiki River is perched above the surrounding plains making flooding an ever present threat.
The Rangitāiki Plains cover an area of approximately 270 km2. They are an in-filled graben, filled by a combination of alluvial and marine processes. In many areas substantial swamps have contributed to the infilling and thick layers of peat being built up.
10.2 Historical flood protection
Early attempts to provide flood protection and drainage of the Rangitāiki Plains were begun around the turn of the century by the Rangitāiki Drainage Board. The Rangitāiki Drainage Board was taken over in 1911 by the Lands and Survey Department, and by 1924 a new mouth was cut for the Rangitāiki River. This was a major project and had a significant effect on lowering the water table and discharging floodwaters to the sea at a much faster rate. In addition, a number of drainage canals were constructed using floating draglines. Because of the perched nature of the river systems the canal outlets had to be as close as practicable to their point of discharge to the sea.
10.3 Warnings and flood warning groups
1 When a pre-set alarm level is reached, HydroTel™ sends an automated message to the Flood Duty pager. If the pager shows a message to notify someone or issue a warning an action will be required. 2 The actions related to the alarm levels are described on the individual staff gauge prompter pages. 3 All information related to the issuing of flood warning messages and the current contact details for the members of the flood warning groups are located in the Flood Warning Guide. 4 The Rangitāiki River levels are influenced by the dams in the upper catchment. River level warnings and road closure notifications are provided by the Flood Manager under certain circumstances. 5 Note: The majority of the alarms are within the Rivers and Drainage Scheme areas and catchments. There are additional alarms set up outside of these areas, (refer to non-scheme section) some of these alarms do require some action.
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Communication including but not limited to warnings, updates and information sharing will be focused around these groups:
(a) Bay of Plenty Regional Council Rivers and Drainage staff, regular contact with the Principal Works Engineer is recommended. (b) Flood warning groups (farmers and other key stakeholders). (c) TrustPower and Nova (dam owners). (d) Bay of Plenty Regional Council Communications staff. (e) Whakatāne District Council. (f) Local Civil Defence Emergency Management (WDC). (g) Bay of Plenty Regional Council contractors working in vulnerable areas. (h) Police. (i) Radio stations.
IMPORTANT – The Principal Works Engineer must be notified early (at first warning level) so that the Rivers and Drainage staff can check relevant floodgates, pumps and weedscreens.
10.4 Flood forecast modelling
There are currently four different flood forecast models available for use in the Rangitāiki Catchment:
10.4.1 Unit Hydrograph (UHG) model
This includes automated Unit Hydrograph (UHG) models of Waihua, Whirinaki and Horomanga sub-catchments; along with an amalgamation/routing component to give results at Matahina Dam and Te Teko.These models work well in the Rangitaiki River for widespread relatively steady rainstorms of over about 150 mm.
This system runs every two hours on computers at BOPRC’s Quay Street offices. Results are posted to HydroTel™ (landed rainfall scenario only) and detailed reports are filed on the computer network if significant rain has fallen. A back-up computer steps in if the primary computer becomes compromised. The detailed reports are stored at:
\\WHKNEARLINE\Engineering\Flood Forecasting\Herbst Models\Archived Forecasts\Auto_Forecast_YYYYMMDD_HHMM.xls
A semi-manual version is available for modelling of forecast rainfall scenarios; alternative rain-gauge allocations; or rainfall loss parameters. A readme file stored alongside the model provides the necessary directions. The scenario model is stored at:
\\WHKNEARLINE\Engineering\Flood Forecasting\Herbst Models\UHGModels_20110817_ScenarioMaster.xlsm
10.4.2 Non-Linear Reservoir (NLR) model
This is an automated Non-Linear Reservoir (NLR) model with 141 sub-basins comprehensively routed to points of interest in the Rangitāiki Catchment. This model
can better respond to localised and shorter duration storms (than the UHG models). The model makes use of spatially distributed forecast rain data from NZ MetService and radar rain observations (gridded data). The radar data is adjusted to match telemetered raingauge data as it arrives in Whakatane.
The model runs every two hours automatically (with backup), posting results to HydroTel™ (forecast rain and gauge-corrected radar-based rain scenario) and storing a detailed report on the computer network.
This model also includes a dam management function for Lake Matahina that optimises lake storage for flood attenuation and power generation purposes, based on the range of modelled river forecasts. It automatically accounts for all current physical and regulatory restrictions on dam operation.
Detailed model results reports are stored at:
\\WHKNEARLINE\Engineering\Flood Forecasting\Rangitaiki NLR Model\Archived Forecasts\Auto_Forecast_YYYYMMDD_HHMM.xls
A semi-manual version is available for modelling of forecast rainfall scenarios; alternative rain-gauge allocations; rainfall loss parameters; or dam management criteria. A readme file stored alongside the model provides the necessary directions. The scenario model is stored at:
\\WHKNEARLINE\Engineering\Flood Forecasting\Rangitaiki NLR Model\Rangitaiki_NLR_20151112.xlsm
10.4.3 InfoWorks model
This is a manually run NLR model using InfoWorks software. This is very similar to the automated Rangitāiki NLR model. It runs on a different platform and needs to be operated manually by trained staff.
10.4.4 EcoConnect
Bay of Plenty Regional Council subscribes to NIWA’s EcoConnect web-based forecast service. It includes river forecasts for Whirinaki at Galatea; Rangitāiki River at Murupara, Aniwhenua and Te Teko; and Waihua Stream. Also of use to flood management staff are the atmospheric forecast maps for New Zealand and the Tasman Sea. The models are run every three hours in Wellington.
EcoConnect’s forecast river flows are from the TOPNET hydrological model run on results from their atmospheric weather predicting model NZLAM. The weather model is very advanced, producing good rain forecasts and the catchment model is comprehensive, however, rain-gauge inputs are not used in this system. Bay of Plenty Regional Council staff feel that this impacts on reliability of the river forecasts.
To access EcoConnect, launch it from BOPRC’s Application Launcher and enter your (assigned) individual username and password. The explorer bar is self- explanatory. The “product menu” icon (top left in the main window) includes a very useful retrospective function “modify date range”.
EcoConnect is currently out-of-action pending a new subscription contract.
10.5 Current stopbank levels of service
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Rangitāiki Tarawera Rivers Scheme
Location Nominal design level Design flow Meets design in 2014 plus freeboard standard (in 2014) Tarawera right bank 1% AEP (100 yr) plus 95 m3/s at Yes downstream of SH 30 300mm Freeboard Awakaponga Tarawera left bank 1% AEP (100 yr) plus 95 m3/s at Yes downstreamof SH2 300mm Freeboard Awakaponga Tarawera left bank from 1% AEP (100 yr) plus 95 m3/s at Yes SH30 toSH2 150mm Freeboard Awakaponga Rangitāiki River – rural 1% AEP (100 yr) plus 780 m3/s at No from SH30 to mouth 300mm Freeboard Te Teko Rangitāiki River – urban 1% AEP (100 yr) plus 780 m3/s at No (Te Teko, Edgecumbe, 600mm Freeboard Te Teko Thornton) Rangitāiki Floodway 1% AEP (100 yr) plus 190 m3/s in No 300mm Freeboard floodway when 780 m3/s at Te Teko Awaiti, Omeheu, 109 20% AEP (5 yr) plus Drainage co- Yes except a canals 300mm Freeboard efficient of section of 28 mm/day for Omeheu right 3-day storm bank Awakaponga 10% AEP (10 yr) plus Yes 300mm Freeboard Right bank no, (owners didn’t want it) Old Rangitāiki Channel 20% AEP (5 yr) plus Yes 150mm Freeboard (coinciding with 50%AEP in Tarawera river and 50%sea level) Wilson’s Creek 10% AEP (10 yr) plus Yes 300mm Freeboard (coinciding with 50% AEP in Tarawera river and 50% sea level)
Reference: Rivers and Drainage Schemes Asset Management Plan – June 2015
Figure27 Stopbank and return period plan for Rangitāiki-Tarawera Rivers Scheme. Bay of Plenty Regional Council Asset Management Plan.
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10.6 Historical floods and travel times
10.6.1 Top 27 recorded flood levels on the Rangitāiki River
Rangitaiki River Flood Peak Stage and Discharge Record Whirinaki @Galatea Te Teko Travel Time Rank Month Year Stage Discharge Stage Discharge Galatea to Te Teko (m) (m3/s) (m) (m3/s) (hrs) 1 Jul 2004 4.10 387 6.40 770 9.25 2 Aug 1970 2.08 285 5.47 637 10.67 3 Feb 1965 2.53 315 5.56 596 21.00 4 Feb 1967 2.18 309 5.49 567 18.25 5 Jul 1998 3.09 233 5.71 464 13.00 6 May 1971 1.48 117 4.92 457 7.40 7 Dec 1958 2.21 223 4.69 409 27.00 8 Jun 1962 1.34 69 4.92 406 18.00 9 24-Jan 2011 3.03 114 5.01 400 4.00 10 29-Jan 2011* 2.96 108 4.92 387 5.75 11 Feb 1958 2.42 73 4.54 380 24.00 12 May 1962 1.65 113 4.54 374 27.00 13 Oct 1983 1.65 158 4.45 371 21.25 14 Jan 2012 2.55 67 4.79 370 13.50 15 2-Oct 1970 1.56 133 4.58 367 23.18 16 Dec 1995 2.20 128 5.43 349 6.00 17 Aug 2010 3.22 119 4.62 348 28.75 18 Jul 1953 1.14 67 4.27 331 6.00 19 Jun 1971 1.14 69 4.40 330 20 Apr 1974 1.29 101 4.32 316 12.65 21 Jul 1951 5.35 309 22 Feb 1976 1.76 193 4.39 306 29.72 23 May 2011 3.06 119 4.24 305 24.00 24 30-Oct 1970 1.02 56 4.24 302 4.85 25 Oct 2011 2.24 43 4.09 288 26 Jun 1970 1.23 93 4.27 288 6.07 27 Apr 2008 2.42 54 3.92 279 8.50 Average Time 15.4 Minimum Recorded 4.0 Time
Note: *29 January 2011 – Cyclone Wilma.
10.7 Telemetry sites
Data Services Channel 1 – E191 – BOPRC Telemetry Channel Data Services Channel 2 – E115 – NIWA Telemetry Channel
Site name Comments Agency Rangitāiki Catchment Rangitāiki at Kokomoka Rainfall in the upper Rangitāiki near BOPRC Napier/Taupo Highway. Rangitāiki at Murupara Levels/flow in the Rangitāiki at NIWA Murupara. Edgecumbe at Edgecumbe Monitors windspeed, wind direction BOPRC and other meteorological parameters. Whakatāne at Tarapounamu Rainfall situated between Whakatāne NIWA and RangitāikiCatchments. Whirinaki at Galatea River levels/flows and rainfall in the NIWA Whirinaki upstream of the confluence with the Rangitāiki. Galatea Basin Climate Rainfall in Horomanga Road, Galatea BOPRC basin situated in the Rangitaiki Catchment area. Waihua at Clearing Rainfall in the Waihua tributary of the NIWA Rangitāiki. Representative of mid-catchment rainfall. Rangitāiki at Aniwhenua River levels near the Aniwhenua Dam. NIWA Rangitāiki at Waihua Bridge River levels at Waihau Bridge BOPRC Rangitāiki at Matahina River levels above Matahina Dam. NIWA Rangitāiki at Te Teko River level/flow and rainfall in the NIWA/BOPRC Rangitāiki at Te Teko. Rangitāiki at Noord Veirboom Rainfall in lower Rangitāiki Plains area. BOPRC Rangitaiki atThornton River level and rainfall in lower BOPRC Rangitāiki. Tidal effects present.
10.8 Rangitāiki rainfall
Selected rain gauge observers contact BOPRC in the event of heavy rainfalls or when more than 50 mm has fallen in the previous 24 hours. Generally no appreciable floods are anticipated until reports of 125 mm in 24 hours are received. If the rainfall on the previous day has also been heavy, then some estimation of the flood should be made.
Reports of heavy rainfall should be forwarded to TrustPower at Matahina Dam and the station may be brought onto full load.
10.9 Critical control structures and hotspots
Staff should be aware of the large number of culverts, pump stations, and floodgates in the lower Rangitāiki Catchment. These structures are regularly checked. Refer to the Rangitāiki Plains drainage maps for culvert, pumpstation and control structure locations. Copies of the maps are stored in the Flood Room.
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10.9.1 Omeheu and Awaiti Canals
The flood pumps are often turned off once the drainage canals have reached their full capacity. This is to stop circular pumping. Landowners can get irritated when this occurs. The Omeheu Canal overtops and the flooding near the one lane bridge on Gow Road can cause Gow Road to be closed.
Omeheu East Pump Station is monitored regularly because of the risk of flooding over farmland but there is potential to flood parts of Edgecumbe.
Figure 28 Omeheu Canal and pump station during flooding
10.10 Flood control system and Rangitāiki Spillway
The flood control system on the lower Rangitāiki River relies initially on flood forecasting methods to determine the expected flood size, which enables the required amount of storage in Matahina Dam to be provided. Flood estimates must initially be based upon rainfall as the river gauges at Whirinaki, Murupara and Aniwhenua peak too late to enable full storage to be provided in the dam. Storage needs to be provided in the dam for floods with a peak greater than about 500 cumecs (20-year return period).
From the dam the flood wave passes along 11.3 km of natural channel where it attenuates slightly before entering the stopbanking system immediately above the TeTeko Bridge. Full flood capacity is available in the stopbank system down to 14.9 km above the mouth, where, at a predetermined discharge, a passively controlled overflow of the right bank will occur ,which will discharge into the floodway. The floodway will reduce the volume of water in the lower river so that levels do not exceed the known safe limits. The floodway rejoins the river 600 m from its point of discharge to the ocean.
The floodway also provides a drainage outlet for some 3,700 ha on the plains, the main drainage systems being Reid's Central Canal (2,490 ha), Kopeopeo West Canal, and Western Drain (1,237 ha).
10.10.1 Purpose of floodway
The main Rangitāiki River channel from Edgecumbe township to the coast has limited conveyance and is unable to carry the full ‘100-year’ (1% AEP) design flood flow. The Rangitāiki Floodway (also known as Reids Floodway) has been designed to convey the excess floodwater required to achieve the design ‘100-year’ flood protection standard. 85 cubic metres per second (m3/s) will flow down the floodway during a ‘100-year’ event. The remaining 719 m3/s will flow down the main river channel.
The Rangitāiki Floodway is located on the east side of the Lower Rangitāiki River and flows in parallel with the river from Kokohinau to its outlet at Thornton Hall Road (600 m upstream from the river mouth).
10.10.2 Description of spillway structure
The spillway structure is located at the point where floodwater is allowed to spill out of the main river channel near Kokohinau (refer floodway map below). The maximum flow estimated to pass across the spillway during a ‘100-year’ event is 85 m3/s.
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Figure 29 Rangitāiki River Spillway location.
10.10.3 Flood warning procedure
Flood warnings are issued to farmers grazing the stopbanks along the lower Rangitāiki River and the Rangitāiki Floodway. Instructions to send out flood warnings are in the Flood Warning Message Guide in Appendix 1.
10.10.4 Preparations for floodway operation
As soon as it is evident that flow down the floodway is likely, the warning will be provided to landowners and major stakeholders below.
This warning must be issued at least four hours prior to the estimated flow commencement, to allow farmers time to remove all stock from the floodway and for Whakatāne District Council time to action road closure procedures. If possible, the warning should be given prior to nightfall so stock movement can be carried out during daylight hours.
10.10.5 Road closures
Road closures will be required at the following sites when flow commences down the floodway:
Hydro Road McCracken Road McLeans Road
Whakatāne District Council and Whakatāne Police shall be notified prior to activating the floodway and shall arrange for “road closed” signage and warning lights to be set up.
10.11 Additional road closure
Thornton Hall Road: In extreme flows down the floodway, floodwaters may discharge out to the Rangitāiki River across Thornton Hall Road just above the Reids Canal Bridge. Whakatāne District Council shall be notified to arrange for “road closed” signs. General public that become cut off by floodwaters crossing Thornton Hall Road can retreat back to Thornton Highway via the east side stopbank on Reids Canal. Civil Defence Emergency Management shall be notified when this occurrence is expected. Bay of Plenty Regional Council Operations staff shall open gates and remove any obstructions from the east stopbank if it is expected to be required for public retreat.
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10.11.1 Rangitāiki River Catchment showing hydrological sub-basins
Figure 30 Map of Rangitāiki River Catchment showing hydrological sub-basins shaded as per flood travel times; times to Matahina Dam shown in hours (downstream basins read -1).
1 If the storm is widespread with similar depths of rain over the whole catchment, the time of travel from Galatea is approximately 18 to 24 hours and the peak at Galatea is about half the peak at Te Teko. 2 If the storm is centred to the north of the catchment, the travel time is short and the Galatea peak is much smaller than that at Te Teko. 3 If the storm is centred to the south, the time of travel is longer and the peak at Galatea is comparatively larger.
10.12 Pressure relief trench monitoring procedure
When the Rangitāiki River level rises through Edgecumbe to above the toe of the stopbank it is recommended that the following monitoring procedure be carried out.
1 Make regular inspections of the pressure relief trench outlet drains. 2 Record the river level when flow is first observed from each outlet drain. 3 At regular intervals while the river level remains above the toe of the stopbank: measure the turbidity of the water flowing from the drains; measure the flow coming from each drain; and record the river level at the time the measurements were taken. 4 Analyse the information to see if the assumptions made during design appear to be conservative and to enable re-estimation of likely outflows when the river reaches its peak design level. 5 If there is increasing turbidity of the outflow water or if excessive outflow volumes are expected consider further remedial measures for that section of stopbank.
Bay of Plenty Regional Council Flood Warning Manual 15
Figure 31 2004 flood, Edgecumbe Sub-station, Rangitāiki River to the left.
Figure 32 Reid’s Central Canal and Rangitāiki Floodway map.
Bay of Plenty Regional Council Flood Warning Manual 17
10.13 Hydroelectric dams
10.13.1 Introduction
Matahina Dam is owned and operated by TrustPower Limited and comprises an earth dam, a concrete spillway structure and hydroelectric power station. The dam is approximately 80 m high and impounds Lake Matahina. The lake is approximately 3 6 km long with a volume of 55,000,000m . TrustPower has a comprehensive Emergency Action Plan (EAP) and procedures that outline how floods, earthquakes and volcanic activity will be jointly managed by its own management staff, emergency services, WDC and BOPRC. A copy of the EAP is kept in the Flood Room library.
Discharges from the dam spillway gates and power station penstocks under predetermined flood conditions are covered by resource consent 65750 conditions. TrustPower Lake Matahina Flood Management Plan sets out the dam operating procedures during flood events.
10.13.2 Coordination with Matahina Dam
Management of the Matahina Dam during river flooding is well defined in conditions of the dam’s operating resource consent 65750. These conditions include decision trigger points, management roles and constraints for the operation of the dam penstocks and spillways. The operational relationship between the dam operator and the Regional Council Flood Manager is well defined.
Note – There is a confidentiality agreement between TrustPower and the Bay of Plenty Regional Council. TrustPower provide confidential data from the Matahina Dam, that information is embargoed for 24 hours. The data has been provided for flood forecasting and flood management purposes during flooding.
10.13.3 Operation of Matahina Dam during floods (RC65750)
The following information is taken directly out of the Lake Matahina Flood Management Plan. Refer to Appendix 4 for the full version of the plan.
Dam Operation - All Floods
(a) TrustPower shall advise the Chief Executive of BOPRC if it is proposed, as a consequence of a flood event, to increase the level of Lake Matahina above RL1 76.2 m (max control level). In all but exceptional circumstances, this advice shall occur in advance of the lake level exceeding RL1 76.2m. (b) In all except “Emergency Condition2” situations, the level of Lake Matahina shall not exceed RL 76.8 m (design flood level). (c) Lake lowering - The maximum rate of lake drawdown shall not exceed 0.3 m/hr (equivalent to 180 m3/s greater than inflow), except when a “flood event” arises (e.g. where inflow to Lake Matahina is forecast to exceed 500 m3/s) a drawdown rate of up to 0.5 m per hour is permitted (equivalent to 300 m3/s greater than inflow).
Bay of Plenty Regional Council Flood Warning Manual 19
(d) Lake filling - The maximum rate of river level drawdown shall not exceed 1.2 m per eight hours at the tailrace of the dam. Drawdown to such a maximum may be made in a period of 30 minutes, provided the outflow is kept constant for the following 7.5 hours. (e) More detailed instructions in relation to the main stages of flood management are provided in Figure 33 below. Figure 34 demonstrates the process for estimating minor or major flood flows.
Dam operation - minor floods (>300m3/s) - RC65750 Condition 42A
(a) Where a minor flood is forecast within 24 hours to exceed 300m3/s, lake drawdown will be managed by TrustPower to reach and maintain a lake level below RL 73.15 m (i.e. at the bottom of the normal operating range) before inflow is expected to exceed 300 m3/s. (b) The minimum lake level will be RL 73.15 m unless it is agreed with BOPRC that it is necessary to reduce the level further. The absolute minimum level during a minor event will be RL 71.60 m. (c) For floods less than 500 m3/s, refilling of lake storage should, where practical, be scheduled to reduce peak scheme discharge with particular focus on the hours of darkness or high tides. (d) TrustPower shall advise the Chief Executive of BOPRC of the proposed lake drawdown strategy in advance of flood flows arriving at Lake Matahina.
1 As highlighted in RC65750 Condition 8, all Reservoir Levels (‘RL’) are stated in metres above Moturiki Datum.
2 “Emergency conditions”, as identified by resource consent RC65750 condition 8, occur when:
(a) Plant within the Matahina Hydroelectric Power Scheme has failed; (b) The electrical network or transmission system has become constrained or unavailable; (c) A natural event, such as a flood, restricts the ability to operate all or any aspect of the Matahina Hydroelectric Power Scheme safely; or (d) When a flood event is forecast, storage needs to be provided in accordance with Conditions 42, 42A and 43 of this resource consent and with a methodology set out in a flood management plan that is certified under conditions 44 or 45 of this resource consent. 3 A “flood event”, as identified by resource consent RC65750 condition 19, shall mean a flood of greater than 500 cubic metres per second (cumecs) into Lake Matahina.
Dam operation – major floods (>=500 m3/s) – RC65750 Condition 42 and 43
(a) When a major flood is forecast, TrustPower shall, following a request from BOPRC or as part of TrustPower’s own flood management purposes, provide storage in Lake Matahina. (b) Where a major flood is forecast within the next 48 hours, lake drawdown will be managed by TrustPower to reach and maintain a lake level below RL 74.5 m (i.e. within the bottom third of the normal operating range) at least 24 hours before the predicted time that inflow is forecast to exceed 500 m3/s.
20 Bay of Plenty Regional Council Flood Warning Manual
(c) Where inflow is forecast to exceed 500m3/s within the next 24 hours, lake drawdown will be managed by TrustPower to reach and maintain a lake level between RL 71.6 m and RL 70.0 m before inflows exceed 500 m3/s. (d) TrustPower shall not however, lower the lake level such that it falls below RL 71.6 m, without the prior approval of the Chief Executive of BOPRC. (e) For floods greater than 500 m3/s, as well as targeting peak discharge, liaison with BOPRC shall be undertaken to determine if there are any particular periods that, due to public safety or community vulnerability concerns, discharge should be minimised, provided this does not compromise dam safety. (f) TrustPower shall advise the Chief Executive or delegate of BOPRC of the proposed lake drawdown strategy, and provide regular updates, in advance of flood flows arriving at Lake Matahina.
Bay of Plenty Regional Council Flood Warning Manual 21
Figure 33 Stages of Flood Management for Matahina Scheme (TrustPower Matahina Dam Flood Management Plan, Figure 1).
22 Bay of Plenty Regional Council Flood Warning Manual
Figure 34 Deviation of minor or major floods (TrustPower Matahina Dam Flood Management Plan, Figure 2).
Bay of Plenty Regional Council Flood Warning Manual 23
10.14 Sudden failure procedure
TrustPower have outlined the potential consequences of a sudden failure of Matahina Earth Dam on a sunny day in the EAP. The EAP also documents the emergency management controls TrustPower will implement in such an event. If a large flood causes the Emergency, then the incremental consequence will be less at most but not all downstream locations. A flood map showing inundated areas resulting from a dam break of Matahina Dam during a dry day is shown in Figure 35.
Figure 35 Dam failure inundation map, drawing 8/1275/92 TrustPower.
Note: A copy of the Bay of Plenty Region, Emergency Action Plan and Procedures Manual is kept in the Flood Room.
10.14.1 Telephonecommunication
Telephone communication is available under normal circumstances. The lines are however, vulnerable to storm damage and cannot be fully depended upon. Matahina Dam phone (07) 322 8014, fax (07) 322 8024).
Note – Te Maunga 24 hour Control Centre phone (07) 574 7958 or 021 739 915
10.14.2 Radio communication (Emergency RT communications with TrustPower)
Matahina Dam has a radio telephone set which is normally switched to Channel E115 - a NIWA frequency. Channel 7 on the BOPRC fleet radios is programmed with E115 and should therefore be able to communicate with Matahina. Matahina and Te Maunga can also contact each other and via their Fleetphone trunk radio system.
24 Bay of Plenty Regional Council Flood Warning Manual
Figure 36 Simplex Radio Telephone coverage area for emergency contact with Matahina Dam.
Bay of Plenty Regional Council Flood Warning Manual 25
10.15 Aniwhenua Dam
Water Right 190
Aniwhenua Power Station is controlled and monitored from Nova EnergyControl Room at Commerce Street, Whakatāne. The control room is manned on normal working days between 0730 and 1700 hrs.
The information regarding any aspect of the scheme that is monitored via SCADA can be gained from the control room by telephoning (07) 3062705. If calling outside normal working hours, there may be a delay in response as the telephone transfers to the Duty Controller’s mobile telephone.
Aniwhenua Power Station attendants can be reached via the control room, or at the Power Station (telephone (07) 366 4782).
Ask to be put in touch with someone from generation.
10.15.1 Inflows to Lake Aniwhenua
The continuous readout in the control room is based on the water level at Bay of Plenty Electricity's (BOPE) gauge on the Rangitāiki River at Galatea (near the Galatea Sub-station). The water levels at this site are measured with a pressure transducer and telemetered back to the control room via their own Leeds and Northrup telemetry system, through UHF radios.
The rating curve for this site has not been derived by normal gauging methods. The discharge for the stage/discharge relationship has been calculated by:
Noting the discharge at the tailrace at which the lake level is constant and plotting this discharge against gauge height at the Galatea site. The Galatea site cannot record over 100 cumecs and because of its position, does not take into account flooding on the Horomanga.
The BOP Electricity's water right states that inflow to Lake Aniwhenua shall be calculated according to the equation:
Inflow = 1.35 G + 1.49 M + 3.54 cumecs
Where G is the flow in cumecs in the Whirinaki at the Galatea gauging station and M is the flow in cumecs in the Rangitāiki River at the Murupara gauging station. This equation is only suitable for use with mean daily flows and should not be used for calculating flood flows.
10.15.2 Outflow from Aniwhenua
Outflow from the lake can be either through the radial gates at the northern end of the lake, or along the canal and down through the powerhouse to the tailrace. Provision has also been made for emergency discharges from the lake through an emergency gate that is tripped at a predetermined water level.
(i) Radial Gates: The setting of the gates is telemetered back to Whakatāne and BOPE has a relationship between gate setting and discharge.
26 Bay of Plenty Regional Council Flood Warning Manual
(ii) Tailrace: Bay of Plenty Electricity and NIWA have telemetered flow sites at the outlet. These record total river flow: generation and spillway flow.
10.15.3 Aniwhenua Dam: Water Right 190
This Water Right was issued in December 1975 with a later variation in December 1981.
The excerpts contained below are the relevant conditions set out in Water Right 190 as they relate to the control of the dam during flood flows.
1.1 The rate of taking and using of water from Pahekeheke headpond and the discharge from the powerhouse shall not exceed 75 m3/s. The rate of change of discharge from the powerhouse shall not exceed 10 m3/s per minute. 2.2 The water level in Lake Aniwhenua shall be maintained between 146.6 m and 146.8 m under normal operating conditions, except during the period 28 April 1997 and 30 April 1997 when the maximum lake water level may be raised to 147.0 m. 3 The spillway gates incorporated in the dam must be capable of passing a flow of 850 m3/sat a water level of 146.8 m. Additional spillway capacity must be provided so that a total flow of 1,270 m3/s can safely pass through, or over the dam at a water level not exceed 147.5 m. Under normal operating conditions, the rate of opening the spillway gates shall ensure that the rate of change of discharge from all spillway structures shall not exceed 60 m3/s per minute. The opening and closing mechanism of all spillway gates shall be provided with an alternative means for their operation in the event of any electrical power failure. 8(b) The 'grantee' shall provide BOPRC with information regarding "the occasions when water was discharged through the spillway structures and an estimate of such discharges and their duration."
10.16 Wheao Dam
10.16.1 General
The Wheao Power Station is situated on the left bank of the Wheao River approximately 25 km south of Murupara. The station is controlled from the TrustPower offices in Te Maunga.
The Wheao River is partially sourced from the high run-off areas of the Urewera Ranges, whereas the nearby Rangitāiki River originates in the low run-off Volcanic Plateau. The Flaxy Dam is too small to affect the height or timing of floods. In extreme events, an emergency spillway will divert water from the Flaxy system past the powerhouse to the Wheao River.
Time of travel between Wheao Dam and Murupara is of the order of six to eight hours at normal flows.
See consent number 1370 02 0253.
Bay of Plenty Regional Council Flood Warning Manual 27
10.16.2 Contact numbers
Te Maunga 24 hour Control Centre phone (07) 574 7958 or 021 739 915.
10.16.3 Rainfall and discharge data
TrustPower have two flow sites that are telemetered back to their Te Maunga offices. (The telemetry system is not one of ours).
(i) Wheao River downstream of the powerhouse (i.e. total flow of Wheao River and powerhouse); (ii) Rangitāiki River at above Wheo Canal intake (i.e. Total Rangitāiki River flow). This site was not rated until late 1988. (iii) Flow at the Wheao/Rangitāiki confluence is therefore both these rates added together, minus the diversion in the canal (maximum 21 m3/s). (iv) Rainfall information can also be attained by telephoning either the dam direct or via the Rotorua Control Room. There is a rain gauge at the dam site (manual, to be automated 1997). Rangitāiki at Te Teko staff gauge.
10.17 Data records for Rangitāiki River
Data on the following pages cover:
Rangitāiki rainfall records – Depth duration and frequency. Flood event plots – 23 July 1998, 23 January 2011. Rangitāiki at Te Teko rating curve. Rangitāiki at Murupara rating curve. Waihua at Gorge rating curve – NIWA site. Whirinaki at Galatea rating curve – NIWA site.
10.18 Rainfall records for Rangitāiki
The values highlighted in red in the following tables indicate rainfall depths, durations and return periods that are 100 mm or greater that are likely to cause flooding.
10.18.1 Rangitāiki at Kokomoka
Rainfall depths (mm) NZMG Easting 2812900 Northing 6259200 Site # 43.
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 23.4 29.8 44 56.2 71.8 94 110 2 0.5 25.6 32.6 47.8 60.9 77.5 101.5 118.8 5 0.2 33.9 42.8 61.8 77.9 98.2 128.5 150.5 10 0.1 40.9 51.2 73.2 91.7 114.8 150.3 176 20 0.05 48.9 60.9 86.1 107.2 133.4 174.7 204.5 50 0.02 61.7 76.2 106.3 131.3 162 212.1 248.4 100 0.01 73.4 90.1 124.5 152.8 187.4 245.4 287.3
28 Bay of Plenty Regional Council Flood Warning Manual
10.18.2 Rangitāiki at Tarapounamu
Rainfall depths (mm) NZMG Easting 2847300 Northing 6280300 Site # 42
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 18.4 25.5 43 59.8 83.1 108.7 127.2 2 0.5 20 27.8 46.7 64.9 90 117.7 137.6 5 0.2 26.2 36.2 60.3 83.2 114.8 150.1 175.5 10 0.1 31.3 43.1 71.3 98.1 134.8 176.3 206.2 20 0.05 37.1 50.9 83.8 114.9 157.4 205.7 240.7 50 0.02 46.3 63.2 103.3 140.9 192.2 251.3 293.9 100 0.01 54.7 74.3 120.8 164.3 223.3 291.9 341.5
10.18.3 Whirinaki at Galatea
Rainfall depths (mm) NZMG Easting 2837000Northing 6296000 – Site # 39
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 17.9 23.9 38.1 51 68.4 85.3 97.1 2 0.5 19.4 26 41.3 55.4 74.2 92.5 105.3 5 0.2 25.1 33.6 53.2 71.2 95.2 118.7 135.1 10 0.1 29.8 39.8 62.9 84.1 112.3 140.1 159.4 20 0.05 35 46.8 73.9 98.6 131.6 164.2 186.8 50 0.02 43.3 57.7 90.9 121.2 161.6 201.5 229.4 100 0.01 50.7 67.5 106.3 141.5 188.5 235 267.5
10.18.4 Galatea Basin Climate
Rainfall depths (mm) NZMG Easting 2841400 Northing 6307710 – Site # 38
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 21.9 29.1 45.5 60.3 80 96.4 107.5 2 0.5 23.7 31.5 49.2 65.3 86.7 104.4 116.5 5 0.2 30.2 40.1 62.9 83.5 110.8 133.5 148.9 10 0.1 35.5 47.1 73.9 98.2 130.4 157.1 175.2 20 0.05 41.4 55 86.3 114.7 152.4 183.6 204.8 50 0.02 50.5 67.2 105.5 140.3 186.5 224.7 250.6 100 0.01 58.7 78.1 122.7 163.1 217 261.4 291.6
Bay of Plenty Regional Council Flood Warning Manual 29
10.18.5 Rangitāiki at Aniwhenua
Rainfall depths (mm) NZMG Easting 2841800 Northing 6316300 – Site # 36
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 23.4 31.4 50 67 89.7 105.8 116.5 2 0.5 25.3 33.9 53.9 72.3 96.9 114.2 125.7 5 0.2 32 42.9 68.2 91.4 122.5 144.4 159 10 0.1 37.4 50.1 79.7 106.8 143.1 168.7 185.8 20 0.05 43.5 58.2 92.6 124 166.2 195.9 215.7 50 0.02 52.8 70.7 112.3 150.5 201.6 237.6 261.6 100 0.01 61 81.7 129.9 173.9 233 274.6 302.4
10.18.6 Waihua at Clearing
Rainfall depths (mm) NZMG Easting 2847100 Northing 6317100 – Site # 35
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 25.9 35.8 59.9 82.9 114.6 137.5 152.9 2 0.5 27.9 38.6 64.6 89.3 123.6 148.2 164.8 5 0.2 35.2 48.7 81.4 112.6 155.7 186.8 207.7 10 0.1 41 56.7 94.8 131.2 181.5 217.7 242.1 20 0.05 47.5 65.7 109.8 152 210.3 252.1 280.4 50 0.02 57.4 79.4 132.8 183.8 254.3 305 339.1 100 0.01 66.1 91.5 153.2 211.9 293.3 351.7 391.1
10.18.7 Okaro at Birchalls
Rainfall depths (mm) NZMG Easting 2806120 Northing 6317100 – Site # 41
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 20.7 28.1 45.5 61.7 83.7 102.4 115.2 2 0.5 22.5 30.5 49.4 67 90.8 111.1 125.1 5 0.2 28.9 39.1 63.5 86.1 116.8 143 160.9 10 0.1 34.1 46.2 75 101.7 138.1 168.9 190.1 20 0.05 39.9 54.2 87.9 119.4 162 198.3 223.1 50 0.02 49.1 66.6 108.1 146.8 199.3 243.9 274.5 100 0.01 57.2 77.7 126.2 171.4 232.8 284.8 320.6
30 Bay of Plenty Regional Council Flood Warning Manual
10.18.8 Rangitaiki at Te Teko
Rainfall depths (mm) NZMG Easting 2843600 Northing 6344400 – Site # 33
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 25 33.5 53.3 71.3 95.5 110 119.4 2 0.5 26.9 36.1 57.6 77.4 103.8 119.5 129.7 5 0.2 33.8 45.6 73.5 99.3 134.1 154.3 167.6 10 0.1 39.2 53.2 86.3 117.1 158.9 182.8 198.5 20 0.05 45.3 61.7 100.7 137.2 186.9 215.1 233.6 50 0.02 54.5 74.7 122.9 168.4 230.6 265.5 288.2 100 0.01 62.7 86.2 142.8 196.3 270 310.8 337.5
10.18.9 Edgecumbe at Edgecumbe
Rainfall depths (mm) NZMG Easting 2846510 Northing 6350740 – Site # 32
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 26.3 34.6 53.4 70.2 92.3 107.4 117.3 2 0.5 28.4 37.4 57.8 76.1 100.2 116.5 127.2 5 0.2 35.7 47.2 73.6 97.3 128.7 149.6 163.4 10 0.1 41.6 55.2 86.3 114.5 151.9 176.5 192.8 20 0.05 48.1 64 100.6 133.8 178 207 226 50 0.02 58.1 77.6 122.7 163.8 218.7 254.2 277.6 100 0.01 67 89.6 142.4 190.6 255.2 296.6 323.9
10.18.10 Rangitāiki at Noord Veirboom
Rainfall depths (mm) NZMG Easting 2850300 Northing 6356000– Site # 31
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 26.3 34.6 53.3 70 92 107.6 118 2 0.5 28.5 37.5 57.8 76.1 100 117 128.3 5 0.2 36.5 48.1 74.5 98.2 129.4 151.4 165.9 10 0.1 42.9 56.7 88 116.2 153.4 179.5 196.8 20 0.05 50.2 66.4 103.4 136.7 180.7 211.4 231.7 50 0.02 61.5 81.5 127.2 168.5 223.2 261.2 286.3 100 0.01 71.6 95 148.7 197.2 261.6 306.1 335.5
Bay of Plenty Regional Council Flood Warning Manual 31
10.18.11 Rangitaiki at Thornton
Rainfall depths (mm) NZMG Easting 2850800 Northing 6357900 – Site # 30
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 26 34 51.9 67.8 88.6 103.7 113.7 2 0.5 28.3 36.9 56.5 73.8 96.4 112.9 123.7 5 0.2 36.3 47.6 72.9 95.5 125 146.3 160.4 10 0.1 42.9 56.2 86.4 113.2 148.4 173.7 190.5 20 0.05 50.3 66 101.6 133.3 175 204.8 224.6 50 0.02 61.8 81.3 125.4 164.8 216.6 253.6 278 100 0.01 72.2 95 146.8 193.2 254.2 297.5 326.2
32 Bay of Plenty Regional Council Flood Warning Manual
10.19 Rangitāiki River flood event plot – 23 July 1998
Bay of Plenty Regional Council Flood Warning Manual 33
10.20 Rangitāiki River flood event plot – 18 July 2004
34 Bay of Plenty Regional Council Flood Warning Manual
10.21 Rangitāiki River flood event plot – 23 January 2011
Bay of Plenty Regional Council Flood Warning Manual 35
10.22 Rangitāiki River flood event plot – 30 January 2011
36 Bay of Plenty Regional Council Flood Warning Manual
10.23 Rangitaiki at Te Teko rating curve
7
6
5
4
Discharge Return Period 3
Stagemetres (m /s) (years) 3 320 5 410 10 2 505 20 565 30 650 50 1 780 100
0 30 100 200 300 400 500 600 700 850 Flow m3/s Rangitaiki at Te Teko 13-Feb-2006 20:30:00 Indicator Stage 1.353
Bay of Plenty Regional Council Flood Warning Manual 37
10.24 Rating table for Rangitaiki at Te Teko (NIWA)
Stage Discharge Reference Stage Discharge Reference (m) (m3/s) (m) (m3/s) -0.125 14.6 4.5 Inspection Alarm Level 0.02 18.4 4.87 380 0.1 21.2 5.85 540 0.24 27 6.5 665 0.4 34.6 3.75 255 0.615 46 320 5 yr Return Period 0.8 56.4 4.87 380 1 68 410 10 yr Return Period 1.4 92 505 20 yr Return Period 1.78 115 5.85 540 Floodway Warning Level 2.2 141 565 30 yr Return Period 2.6 1st Warning Level 650 50 yr Return Period 2.8 180 6.5 665 3.2 208 780 100 yr Return Period 3.75 255
38 Bay of Plenty Regional Council Flood Warning Manual
10.25 Rangitaiki at Murupara rating curve
3
2.5
2
1.5 Discharge Period Return 3 Stagemetres (m /s) (years)( 40 2.33 1 52 5 62 10 73 20
0.5 79 30 87 50 99 100
0 0 10 20 30 40 50 60 70 80 Flow m3/s Rangataiki at Murupara 16-Nov-2004 12:00:00 Indicator Stage 0.376
Bay of Plenty Regional Council Flood Warning Manual 39
10.26 Rating table for Rangitaiki at Murupara (NIWA)
Stage Discharge Reference (m) (m3/s) 0.3 9.57 0.35 10.75 0.4 12.11 0.5 14.75 0.6 17.5 0.7 20.35 0.8 23.32 0.9 26 1 29.2 1.1 32.1 1.2 35.1 1.3 38 1.4 40.6 2.33 year Return Period
40 Bay of Plenty Regional Council Flood Warning Manual
10.27 Waihua at Gorge rating curve
5
4
3
Discharge Return Period 3
Stagemetres (m /s) (years) 2 46 2.33 65 5 85 10 107 20 1 121 30 141 50 171 100
0 0 20 40 60 80 100 120 140 160 Flow m3/s Waihua at Gorge 27-Oct-2005 07:30:00 Indicator Stage 1.346
Bay of Plenty Regional Council Flood Warning Manual 41
10.28 Rating table for Waihua at Gorge (NIWA)
Stage Discharge Reference Stage Discharge Reference (m) (m3/s) (m) (m3/s) 0.4 0.2 1.9 0.45 0.4 2 0.5 0.6 46 2.33 year Return Period 0.55 0.9 2.5 0.6 1.2 65 5 year Return Period 0.65 1.6 3 85 10 year Return Period 0.7 2.0 3.35 0.8 2.9 107 20 year Return Period 0.9 4.0 3.5 1 5.5 121 30 year Return Period 1.1 7.1 3.8 1.25 10.0 4 1.35 12.3 141 50 year Return Period 1.5 16.2 4.2 1.6 19.1 171 100 year Return Period 1.7 22.2 1.8 25.8
42 Bay of Plenty Regional Council Flood Warning Manual
10.29 Whirinaki at Galatea rating curve
5
4.5
4
3.5
3 Discharge Return Period Stagem (m3/s) (years) 100 2.33 2.5 165 5 215 10
2 265 20 295 30 330 50 1.5 380 100
1 0 50 100 150 200 250 300 350 400 450 500 550 600 Flow m3/s Whirinaki at Galatea 23-May-2006 16:30:00 Indicator Stage 2.763
Bay of Plenty Regional Council Flood Warning Manual 43
10.30 Rating table for Whirinaki at Galatea (NIWA)
Stage Discharge Reference Stage Discharge Reference (m) (m3/s) (m) (m3/s) 1.3 2.3 3.7 223.5 1.35 3.2 265 20 year Return Period 1.4 4.2 3.886 272 1.5 6.8 295 30 year Return Period 1.6 10.5 330 50 year Return Period 1.7 14.8 4.086 344 1.8 19.6 380 100 year Return Period 2 29.8 4.586 594 2.1 35.4 2.2 41.3 2.4 55.8 2.6 72.2 100 2.33 year Return Period 2.9 102 3.1 124.2 165 5 year Return Period 3.4 166.4 215 10 year Return Period
44 Bay of Plenty Regional Council Flood Warning Manual
10.31 Rangitāiki at Rabbit Bridge staff gauge prompter
Bay of Plenty Regional Council Flood Warning Manual 45
10.32 Rangitāiki at Te Teko staff gauge prompter
46 Bay of Plenty Regional Council Flood Warning Manual
Part 11: Tarawera River
Chapter summary
11.1 Tarawera Catchment overview 2
11.2 Warnings and flood warning groups 2
11.3 Telemetry sites 3
11.4 Rain gauge sites (external) 3
11.5 Flood forecast modelling 3
11.6 Historical floods 4
11.7 Hydrology 4
11.8 Current stopbank levels of service 5
11.9 Data records for Tarawera River 7
11.10 Rainfall records for Tarawera 7
11.11 Tarawera at Awakaponga rating curve 9
11.12 Rating table for Tarawera 10
11.13 Tarawera at Awakaponga staff gauge prompter 11
Bay of Plenty Regional Council Flood Warning Manual 1
11.1 Tarawera Catchment overview
The headwaters of the Tarawera River include Lakes Okataina, Okareka, Tikitapu (Blue Lake), Rotokakahi (Green Lake) and Rotomahana. These lakes all drain into Lake Tarawera (elevation of just under 300 m), from where the Tarawera River begins.
Within 6.5 km of leaving Lake Tarawera, the river has fallen to a level of 150 m. From this point to Kawerau, the river falls steadily and moderately steeply through deep pumice country. The river valley is well developed and the bed lined with large boulders and aquatic plants. Below Kawerau, the grade is gentler and the bed is perched above the general level of the Rangitāiki Plains on a ridge formed from flood deposits. (The lower Rangitāiki River is similarly perched). Below the State Highway 30 Bridge, the river is stopbanked.
The total catchment of the Tarawera is approximately 990 km2. Significant tributaries are the Mangawhio, the Waiwhakapa and the Mangamate upstream of Kawerau, the Mangaone and the Ruruanga near Otakiri, and Awakaponga Stream near Matata. The deep pumice of the Tarawera Catchment, together with the ponding effect of the lake, regulates the run-off from heavy storms so the maximum-recorded floods are only two to three times the normal flow.
The Tarawera Catchment also includes much of the drainage network on the Rangitāiki Plains. This network has been configured from the network of streams and river channels that existed in the Nineteenth Century. Major canals in the current network, constructed in the early Twentieth Century, include the Awaiti, Omeheu, Awakaponga and the 109. The Old Rangitāiki Channel, the path of the Rangitāiki before it was diverted into the cut at Thornton, also forms part of the Tarawera Catchment.
11.2 Warnings and flood warning groups
1 When a pre-set alarm level is reached, HydroTel™sends an automated message to the Flood Duty pager. If the pager shows a message to notify or issue a warning an action will be required. 2 The actions related to the alarm levels are described on the individual staff gauge prompter pages. The river rising notification is sent automatically to the Duty Flood Manager, Principal Works Engineer and the Works Coordinators. This alarm signals a first response in the river level/s. Monitoring activity will increase following this alarm. 3 There are no flood warning groups set up for the Tarawera River. There are rainfall alarms set up for specific warnings, please refer to the non-scheme section.
Communication including but not limited to warnings, updates and information sharing will be focused around these groups:
(a) Bay of Plenty Regional Council Rivers and Drainage staff, regular contact with the Principal Works Engineer is recommended. (b) KiwiRail and the Burt family (refer to the non-scheme section). (c) Bay of Plenty Regional Council Communications staff. (d) Whakatāne District Council.
2 Bay of Plenty Regional Council Flood Warning Manual
(f) Local Civil Defence Emergency Management (WDC). (g) Bay of Plenty Regional Council contractors working in vulnerable areas. (h) Police. (i) Radio stations.
IMPORTANT – The Principal Works Engineer must be notified early(at first warning level) so that the Rivers and Drainage staff can check relevant floodgates, pumps and weedscreens.
11.3 Telemetry sites
Data Services Channel 1 – E191 –Bay of Plenty Regional Council Telemetry Channel
Site name Comments Agency Tarawera Catchment Tarawera at Awakaponga River level/flow and rainfall in the central BOPRC Rangitāiki Plains. Tumurau at Lagoon Levels and rainfall in the Tumurau Lagoon BOPRC which flows into the lower Tarawera. ORC at Pump Station River levels and rainfall in the lower BOPRC Tarawera. Tidal effects present.
The rating curve at Awakaponga varies considerably with changing bed levels. The latest HydroTel™ rating is likely to be the most accurate way of relating stage to flow, although high flows may not have been calibrated. Several but not all previous floods have had an increase of stage of around 0.15 m per 10 m3/s at higher flow rates.
11.4 Rain gauge sites (external)
Lake Rerewhakaaitu S Wicks (07) 366 6753 Waiotapu Timberlands (07) 343 1070 Tarawera (Kawerau) Carter Holt Harvey Tasman (07) 306 9050
11.5 Flood forecast modelling
There is currently no flood forecast modelling available for use on the Tarawera River.
Bay of Plenty Regional Council Flood Warning Manual 3
11.6 Historical floods
11.6.1 Top 15 recorded flood levels for the Tarawera River
Tarawera River @ Awakaponga Flood Peak Stage and Discharge Record Rank Month Year Discharge (m3/s) 1 Jun 1962 92.4 2 Jun 1971 83.5 3 Aug 1970 79.6 4 Mar 1962 77.5 5 Mar 1972 77.1 6 5-Dec 1962 76.6 7 20-Dec 1962 75.7 8 Dec 1995 74.2 9 Feb 2006 73.7 10 Jan 2011 73.5 11 Jul 1951 70.9 12 May 1962 70.8 13 Jul 2004 70.2 14 Jul 1998 68.9 15 Jul 1953 67.9
11.7 Hydrology
Two rated water level recording stations are located on the Tarawera River. Downstream of the outlet of Lake Tarawera is the Lake Outlet recorder site (NIWA). Further downstream near the Edgecumbe/Matata Highway is the Awakaponga recorder site (BOPRC).
11.7.1 Tarawera at lake outlet recorder site
Minimum Q 3.8 cumecs Mean Q 6.7 cumecs Maximum Q in 1972 15.7 cumecs Average annual flood 9.8 cumecs
11.7.2 Tarawera at Awakaponga recorder site
Minimum Q 15.3 cumecs Mean Q 30.2 cumecs Maximum Q in 1962 92.4 cumecs Average annual flood 54.8 cumecs
Data source: BOPRC Data Summaries 2010
4 Bay of Plenty Regional Council Flood Warning Manual
The above data should demonstrate that floods are caused in the catchment below the lake outlet site rather than in the lake itself. It is generally felt that the portion of the catchment that most contributes to flooding is that area between Kawerau and the lake outlet. A typical Awakaponga hydrograph is extremely long and flat and generally occurs over days rather than hours.
11.8 Current stopbank levels of service
Rangitāiki and Tarawera Rivers Scheme
Location Nominal design level Design flow plus Meets design in 2014 freeboard standard (in 2014) Tarawera right bank 1% AEP (100 yr) plus 95 m3/s at Yes downstream of SH 30 300mm freeboard Awakaponga Tarawera left bank 1% AEP (100 yr) plus 95 m3/s at Yes downstream of SH 2 300mm freeboard Awakaponga Tarawera left bank from 1% AEP (100 yr) plus 95 m3/s at Yes SH 30 to SH 2 150mm freeboard Awakaponga Rangitāiki River – rural 1% AEP (100 yr) plus 780 m3/s at Te Teko No from SH 30 to Mouth 300mm freeboard Rangitāiki River – urban 1% AEP (100 yr) plus 780 m3/s at Te Teko No (Te Teko, Edgecumbe, 600mm freeboard Thornton) Rangitāiki Floodway 1% AEP (100 yr) plus 190 m3/s in floodway No 300mm freeboard when 780 m3/s at Te Teko Awaiti, Omeheu, 109 20% AEP (5 yr) plus Drainage co-efficient Yes except a canals 300mm freeboard of 28 mm/day for section of three-day storm Omeheu right bank Awakaponga 10% AEP (10 yr) plus Yes 300mm freeboard Right bank no, (owners didn’t want it) Old Rangitāiki Channel 20% AEP (5 yr) plus Yes 150mm freeboard (coinciding with 50% AEP in Tarawera River and 50% sea level) Wilson’s Creek 10% AEP (10 yr) plus Yes 300mm freeboard (coinciding with 50% AEP in Tarawera River and 50% sea level)
Reference: Rivers and Drainage Schemes Asset Management Plan – June 2015
Bay of Plenty Regional Council Flood Warning Manual 5
Figure 37 Stopbank and return period plan for Rangitāiki-Tarawera Rivers Scheme. Bay of Plenty Regional Council Asset Management Plan.
6 Bay of Plenty Regional Council Flood Warning Manual
11.9 Data records for Tarawera River Data on the following pages covers:
Tarawera rainfall records – Depth duration and frequency. Tarawera at Awakaponga rating curve.
11.10 Rainfall records for Tarawera The values highlighted in red in the following tables indicate rainfall depths, durations and return periods that are 100 mm or greater that are likely to cause flooding.
11.10.1 Tarawera at Awakaponga
Rainfall depths (mm) NZMG Easting 2841200 Northing 6355600 – Site # 28
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 28.7 36.8 54.7 70.1 89.9 103 111.5 2 0.5 30.8 39.6 58.9 75.7 97.3 111.4 120.6 5 0.2 38.3 49.5 74.3 96 124 142 153.7 10 0.1 44.3 57.4 86.6 112.3 145.6 166.7 180.4 20 0.05 50.8 66.1 100.3 130.5 169.8 194.5 210.5 50 0.02 60.8 79.4 121.4 158.6 207.3 237.3 256.9 100 0.01 69.5 91.1 140 183.6 240.7 275.6 298.3
11.10.2 Rangitāiki Plains Climate at Flax Road
Rainfall depths (mm) NZMG Easting 2841380 Northing 6358410 – Site # 27
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 28.6 36.9 55.1 71 91.4 105.1 114 2 0.5 30.8 39.7 59.5 76.8 99 113.8 123.4 5 0.2 38.5 49.9 75.4 97.7 126.6 145.5 157.8 10 0.1 44.7 58.1 88.1 114.6 149 171.2 185.7 20 0.05 51.5 67.2 102.4 133.6 174.2 200.2 217.1 50 0.02 61.9 81.1 124.4 162.8 213.2 245 265.7 100 0.01 71.1 93.4 143.8 188.9 248.1 285 309.2
Bay of Plenty Regional Council Flood Warning Manual 7
11.10.3 ORC at Pump Station
Rainfall depths (mm) NZMG Easting 2843400 Northing 6360600 – Site # 26
Duration
ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 28 35.9 53.2 68.3 87.6 100.7 109.3 2 0.5 30.2 38.8 57.6 74 95 109.3 118.6 5 0.2 38.1 49.1 73.5 94.7 122.1 140.4 152.4 10 0.1 44.4 57.4 86.3 111.5 144.2 165.8 180 20 0.05 51.5 66.8 100.7 130.5 169.1 194.5 211.1 50 0.02 62.4 81.1 123 159.9 207.9 239.1 259.4 100 0.01 72 93.9 142.8 186.2 242.6 279 302.8
Figure38 Tarawera River looking towards the Manawahe Hills.
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11.11 Tarawera at Awakaponga rating curve
3
2.5
2
Discharge Return Period (m3/s) (years) 1.5 52 2.33
Stagemetres 61 5 71 10 1 78 20 83 30 90 50 0.5 100 100
0 20 25 30 35 40 45 50 55 60 65 70 75 80 85 Flow m3/s Tarawera at Awakaponga 16-May-2006 13:00:00 Indicator Stage 2.921
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11.12 Rating table for Tarawera at Awakaponga
Stage Discharge Reference Stage Discharge Reference (m) (m3/s) (m) (m3/s) 0 11 1.7 49 0.1 13 1.8 52 0.2 14 1.9 55 0.3 16 2 58 0.4 17 2.1 61 0.5 19 2.2 64 0.6 21 2.3 68 0.7 24 2.4 71 0.8 26 2.5 74 0.9 28 2.6 77 1 31 2.7 81 Inspection Alarm Level 1.1 33 2.8 84 1.2 35 2.9 88 1.3 38 3 91 1.4 41 3.1 95 1.5 43 3.17 98 1.6 46
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11.13 Tarawera at Awakaponga staff gauge prompter
Bay of Plenty Regional Council Flood Warning Manual 11
Part 12: Kaituna River
Chapter summary
12.1 Introduction and history 2
12.2 Warnings and flood warning groups 2
12.3 Flood forecast modelling 3
12.4 Telemetry sites 3
12.5 Historical floods and travel times 4
12.6 Current stopbank levels of service 5
12.7 Critical control structures and hotspots 9
12.8 Data records for Kaituna River 15
12.9 Rainfall records for Kaituna 15
12.10 Kaituna River flood event plot July 1998 18
12.11 Kaituna River flood event plot May 1999 19
12.12 Kaituna River flood event plot January 2011 20
12.13 Kaituna at Te Matai rating curve 21
12.14 Rating table for Kaituna at Te Matai 22
12.15 Mangorewa at Saunders rating curve 24
12.16 Rating table for Mangorewa at Saunders 25
12.17 Kaituna at Te Matai staff gauge prompter 28
12.18 Mangorewa at Saunders staff gauge prompter 29
Bay of Plenty Regional Council Flood Warning Manual 1
12.1 Introduction and history
The Kaituna River Catchment occupies some 1,250 km2 in the Bay of Plenty region of the North Island, draining lakes Rotorua and Rotoiti and surrounding lands. The river rises at the Lake Rotoiti outlet and flows 51.5 km to the sea near Maketu with several tributaries draining the adjacent area.
For the first half of its course, the river flows in a deep gorge through steep bush- covered terrain. It then emerges onto a gradually widened flood plain. The lower half of the river originally suffered from a tortuous alignment and inadequate flow capacity. The resulting high water levels restricted drainage from the adjoining low lying flat lands and caused frequent overtopping of the banks with consequent extensive flooding.
In 1980 the Bay of Plenty Catchment Board began the construction of a major stopbanking and drainage system.
As at May 2016, Resource Consent 67958 to redivert the Kaituna River into the Maketu Estuary via a modified culvert structure at Fords Road has been granted but is under appeal. Part of the proposal is that the Fords Road culverts will be closed during high sea and river flood conditions. It is proposed that the Duty Flood Manager and Rivers and Drainage field staff will be responsible for culvert closure. More detailed flood management information will be added as soon as it is available.
12.2 Warnings and flood warning groups
1 When a pre-set alarm level is reached, HydroTel™ sends an automated message to the Flood Duty pager. If the pager shows a message to notify someone or issue a warning, an action will be required. 2 The actions related to the alarm levels are described on the individual staff gauge prompter pages. The river rising notification is sent automatically to the Duty Flood Manager, Principal Works Engineer and the Works Coordinators. This alarm signals a first response in the river level/s. Monitoring activity will increase following this alarm. 3 All information related to the issuing of flood warning messages and the current contact details for the members of the flood warning groups are located in the Flood Warning Guide. Note: The majority of the alarms are within the Rivers and Drainage Scheme areas and catchments. There are additional alarms set up outside of these areas, (refer to non-scheme section) some of these alarms do require some action.
Communication including but not limited to warnings, updates and information sharing will be focused around these groups:
(a) Bay of Plenty Regional Council Rivers and Drainage staff, regular contact with the Principal Works Engineer is recommended. (b) Flood warning groups (farmers and other key stakeholders). (c) Bay of Plenty Regional Council Communications staff. (d) Western Bay of Plenty District Council. (e) Local Civil Defence Emergency Management (WBOPDC). (f) Bay of Plenty Regional Council contractors working in vulnerable areas. (g) Police.
2 Bay of Plenty Regional Council Flood Warning Manual
12.3 Flood forecast modelling
There is currently no flood forecast modelling available for use on the Kaituna River.
This is an automated Non-Linear Reservoir (NLR) model with 143 sub-basins comprehensively routed to points of interest in the Kaituna Catchment. The model makes use of spatially distributed forecast rain data from NZ MetService and radar rain observations (gridded data). The radar data is adjusted to match telemetered rain gauge data as it arrives in Whakatane.
The model runs every two hours automatically (with backup), posting results to HydroTel™ (forecast rain and gauge-corrected radar-based rain scenario) and storing a detailed report on the computer network.
Detailed model results reports are stored at:
\\WHKNEARLINE\Engineering\Flood Forecasting\Kaituna NLR Model\Archived Forecasts\Auto_Forecast_YYYYMMDD_HHMM.xls
A semi-manual version is available for modelling of forecast rainfall scenarios; alternative rain-gauge allocations; rainfall loss parameters; or dam management criteria. A readme file stored alongside the model provides the necessary directions. The scenario model is stored at:
\\WHKNEARLINE\Engineering\Flood Forecasting\Kaituna NLR Model\Rangitaiki_NLR_20151030.xlsm
12.4 Telemetry sites
Data Services Channel 1 – E191 –Bay of Plenty Regional Council Telemetry Channel.
Data Services Channel 2 – E115 – NIWA Telemetry Channel.
Site name Comments Agency Kaituna Catchment Kaituna at Rainfall in Rotorua City area. BOPRC Whakarewarewa Lake Rotoiti at Rainfall and lake levels at Okawa Bay. BOPRC Okawa Bay Mangorewa at Rainfall at the top of the Kaituna Catchment. BOPRC Kaharoa Kaituna at Taaheke River level/flow immediately downstream of the NIWA Okere Gates control structure. Mangorewa at River level/flow and rainfall in the Mangorewa which BOPRC Saunders is a major tributary of the Kaituna Catchment. Subject to rapid rises in water level up to 8 m. Pongakawa at Rainfall in the mid Pongakawa Catchment. BOPRC Pongakawa Bush Road Lake Rotorua at Lake Rotorua at Mission Bay. The lake has a NIWA Mission Bay surface area of 80 km2 and drains 500 km2. The control is by the Ohau Channel outlet stoplog structure.
Bay of Plenty Regional Council Flood Warning Manual 3
Ngongotaha at SH 5 Water level/flow at Ngongotaha Stream at SH 5 NIWA bridge, drains 7.3 km2. Rotorua at Upper Rainfall in the Rotorua Catchment at BOPRC Oturoa Road Upper Oturoa Road. Utuhina at Water level/flow at Utuhina at Depot Street, site is BOPRC Depot Street situated 1.5 km from lake Rotorua. Kaituna at Clarke’s River level in the lower Kaituna. Tidal effects BOPRC present. Kaituna at Te Matai River level and rainfall site in the lower BOPRC Kaituna Catchment near Te Puke. Waingaehe at SH 30 Water level/flow Waingaehe at SH 30 bridge and BOPRC Bridge drains 9.6 km2. Kaituna at Fords Cut River levels at the bottom of the BOPRC Kaituna Catchment. Tidal effects present.
12.5 Historical floods and travel times
12.5.1 Top 16 floods and travel times for the Kaituna River
Kaituna River Flood Peak Stage and Discharge Record Mangorewa at SaundersKaituna at Te Matai Travel Time Rank Month Year Stage Discharge Stage Discharge Saunders to Te Matai (m) (m3/s) (m) (m3/s) (hrs) 1 Jun 1962 3.54 377 2 Feb 1967 3.35 280 3 May 1999 11.27 835 4.72 257 7.25 4 May 1956 3.23 225 5 29-Jan 2011* 8.51 495 4.69 196 6.57 6 Aug 1970 4.67 157 3.10 194 6.78 7 24-Jan 2011 5.81 239 4.47 179 10.75 8 Apr 1959 3.05 178 9 Jul 1998 4.57 151 3.41 170 7.75 10 Dec 1962 2.99 168 11 May 1962 2.96 162 12 Aug 1990 6.48 295 3.23 158 7.25 13 Mar 1972 3.77 105 2.91 156 14 Dec 1995 4.82 168 3.18 155 8.50 15 Feb 1958 2.93 155 16 Jan 2012 4.39 140 3.96 150 9.75 Average Time 8.08 Minimum Recorded Time 6.57
Note: *29 January 2011 – Cyclone Wilma Kaituna influenced by control gate constructed in 1982 Kaituna @ Te Matai has tidal influence Changes are likely due to a predicted change in the rating curve (June 2013).
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12.6 Current stopbank levels of service
Kaituna River Scheme
Meets Nominal design level Design flow plus design Location in 2014 freeboard standard (in 2014) Kaituna River: 10% AEP (10 yr) no 207 m3/s at Te Matai Yes (in Mangorewa to freeboard 2009) Te Matai, Mangorewa River for 600 m Kaituna River: 1% AEP plus 500mm 500 m3/s at Te Matai Yes (in downstream of freeboard 2009) Te Matai Bells Road No.1 drain 20% AEP (5 yr) Drainage co-efficient of Yes 37.5mm/day for 3-day storm Singletons drain 10% AEP (10 yr) no Drainage co-efficient of Yes freeboard 37.5mm/day for 3-day storm Parawhenuamea 10% AEP (10 yr) no 29 m3/s Yes Stream freeboard Waiari Stream 10% AEP (10 yr) no 72 m3/s Yes upstream of SH 2 freeboard Waiari Stream 1% AEP (100 yr) plus 148 m3/s (when Yes downstream of SH 2 300mm freeboard 300 m3/s in Kaituna) or 86 m3/s (when 500 m3/s in Kaituna) Ohineangaanga 1% AEP (100 yr) plus 87 m3/s Yes downstream of SH 2 300mm freeboard Raparapahoe 1% AEP (100 yr) plus 110 - 136 m3/s at Yes downstream of SH 2 300mm freeboard Raparapahoe drop structure (110 when Kaituna at 500 m3/s) Raparapahoe from 10% AEP (10 yr) no 66 m3/s at Raparapahoe Yes SH 2 to Quarry Road freeboard drop structure Kopuroa downstream 1% AEP (100 yr) plus 76 m3/s at SH 2 (not No of SH 2 300mm freeboard gauged) when Kaituna 500 m3/s at Te Matai
Bay of Plenty Regional Council Flood Warning Manual 5
Lower Kaituna Drainage
Meets Nominal design level Design flow plus design Location in 2014 freeboard standard (in 2014) Drains, canals and 20% AEP (5 yr) Drainage co-efficient of Yes pumpstations, Lower 37.5 mm/day for 3-day Kaituna storm
Upper Kaituna
Meets design Nominal design level Design flow plus Location standard (in in 2014 freeboard 2014) Waingaehe – 1% AEP (100 yr) plus 17.2 m3/s at SH 30 Yes downstream of SH30 500 mm freeboard (not gauged) Puarenga – 1% AEP (100 yr) plus 53.2 m3/s No small section downstream of SH 30 500 mm freeboard of RB Utuhina – downstream 1% AEP (100 yr) plus 55 m3/s at Utuhina No of SH 5 500 mm freeboard Waiowhiro – 1% AEP (100 yr) 36 m3/s (estimated Yes meets downstream of SH 5 1998) design standard. No stopbank required Ngongotaha – 1% AEP (100 yr) plus 67 m3/s (estimated Yes downstream of 500 mm freeboard 2001) Ngongotaha Road Waiteti – downstream 1% AEP (100 yr) 105.4 m3/s Yes meets of Ngongotaha Road design standard No stopbank required Streams of 10% AEP (10 yr) + Not assessed Yes meets Haupara Bay – 600 mm freeboard recently design standard downstream of SH 30 No stopbank required Streams of 10% AEP (10 yr) Not assessed Yes meets Gisborne Point – recently design standard downstream of SH 30 No stopbank required
Reference: Rivers and Drainage Schemes Asset Management Plan – June 2015
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Figure 39 Stopbank and return period plan for Kaituna Rivers Scheme (Lower) Asset Management Plan.
Bay of Plenty Regional Council Flood Warning Manual 7
Figure 40 Stopbank and return period plan for Kaituna Rivers Scheme (Upper) Asset Management Plan.
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12.7 Critical control structures and hotspots
Lower Kaituna River sensitive areas
These areas either have caused problems in the past, or are considered to have potential tocause problems.
12.7.1 Upper Ohineangaanga
This stream is subject to debris blocks in the upper catchment with rapid release of flood waters as they burst. In the area around the Te Puke, and upstream of the town where there are numerous orchards and deer farms that suffer flooding and erosion problems. The stream is considered too 'flashy' for warnings to be issued.
The Kopuroa, Raparapahoe, Parawhenuamea, and the Waiari are also considered to be in this 'too flashy' category.
12.7.2 Maketu area
The drainage in this area is serviced by three main pump stations, Diagonal Drain, Ford Road and Maketu. Each station is telemetered and is monitored by the Kaituna Works Supervisor. Floodgates also require checking before and during events. Problems can occur when more than 70 mm of rain falls over a couple of days and the catchment is moderately saturated.
The area also relies on gravity drainage out into the Maketu Estuary through a number of floodgated culverts. In the past these have become silted up causing problems. An ongoing desilting program is in place but during events where water is lying on farms they should be checked at low tide for siltation. Contact the Kaituna Works Supervisor to arrange this.
The Maketu Diversion Gates were installed in 1992 to improve the ecology of the estuary following deterioration from the diversion of the Kaituna to the Te Tumu Cut in the 1950's. The gates are commonly referred to as Ford’s Cut.
These culverts are due to be replaced as part of the Kaituna Re-diversion Project.
Left bank sand dunes
The sand hills on the left bank of the lower Kaituna, from Fords Cut up to Bell Road may be susceptible to scour in high flows.
12.7.3 Kaituna Wetland culverts
Four culverts let water into the Kaituna Wetland: two 600 mm pipes at the upstream loop, a 1.8 m pipe into the middle loop and a 450 mm balancing culvert at the downstream loop. The 450 mm and 600 mm pipes have floats that are designed to close at levels above 1.5 m. The 1.8 m pipe has a sluice gate that will need closing manually. The 450 mm culvert lets water back out if the level in the wetland is above 1 m (and river levels are less than 1 m).
A water level recorder inside the wetland monitors the level and this along with river levels is used to initiate a closure of the sluice gate. The target level in the wetland is 0.87 m (Moturiki) and overtopping of the stopbanks around the wetland should be monitored once the level has reached 1.1 m (Moturiki).
Bay of Plenty Regional Council Flood Warning Manual 9
It is not expected there will be excess inflow through the Kaituna Wetland culverts unless levels rise above 1.5 m R.L in the river. This is expected to require at least 200 m3/s (10-year flood) at Te Matai (3.5 m on the gauge), or levels above 1.3 m at Fords Cut during a storm surge event for a number of high tide cycles. Note: this information will need to be updated once the Kaituna River re-diversion structures are in place.
12.7.4 Bell Road area
This area is serviced mainly by gravity drainage into the Kaituna River. There are also low stopbanks along the main Bell Road Drain that overtop in medium sized coastal rainfall events, or if the lower Kaituna River is high because of storm surge or river floods. Floodgates require checking in this area before and during events. A key contact for this area is Lindsay Marshall, phone (07) 573 4465.
Two small pump stations also exist and are looked after by on-site caretakers.
A new pump station has been installed at Bell Road bringing the number of pumps to three. Significant development is underway in this area, in particular the Tauranga Eastern Link (TEL) Highway and new Kaituna River Bridge. At the moment (June 2013) supplementary pumping is required if the area receives rainfall in the range of 50-150 mm. Draining the excess water can take up to four to six days.
Figure 41 Bell Road Pump Station.
12.7.5 Upstream of Te Matai
These are various areas upstream of Te Matai with only 10-year banks or no stopbanking at all.
The Mangorewa River is a short catchment and subject to high intensity rainfalls in the southern catchment bordering Lake Rotorua. This river has the potential to cause large floods in the middle reaches of the Kaituna River. An overflow channel exists just upstream of the confluence, with the Kaituna that spills water when the Saunders water level recorder reaches approximately 4.5 m.
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See chapter 13 regarding the lakes. Note that during high flows from the Mangorewa River and middle Kaituna area, the increase from opening Okere Gates is a very small percentage of the overall flow.
12.7.6 Flood pumps
Two Doda flood pumps are stored in the Lower Kaituna area for use in flood events. Contact the Kaituna Works Supervisor to discuss deployment.
Figure 42 Doda flood pump.
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Figure 43 Kaituna Pump Station locations.
Bay of Plenty Regional Council Flood Warning Manual 13
12.8 Data records for Kaituna River Data on the following pages covers:
Kaituna rainfall records – Depth duration and frequency. Kaituna River event plots –July 1998, May 1999, January 2011. Kaituna at Te Matai rating curve. Mangorewa at Saunders rating curve.
12.9 Rainfall records for Kaituna The values highlighted in red in the following tables indicate rainfall depths, durations and return periods that are 100 mm or greater that are likely to cause flooding.
12.9.1 Kaituna at Te Matai
Rainfall depths (mm) NZMG Easting 2806400 Northing 6373400– Site # 12
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 28.1 37.9 60.8 82 110.6 128 139.4 2 0.5 30.7 41.4 66.3 89.3 120.3 139.2 151.6 5 0.2 40.3 54.1 86.3 115.9 155.7 180.2 196.3 10 0.1 48.2 64.6 102.8 137.8 184.7 213.8 232.9 20 0.05 57.3 76.7 121.6 162.7 217.7 251.9 274.4 50 0.02 71.6 95.6 151.1 201.6 269.1 311.4 339.2 100 0.01 84.7 112.8 177.8 236.8 315.5 365.1 397.7
12.9.2 Mangorewa at Waite B
Rainfall depths (mm) NZMG Easting 2802900 Northing 6363900 – Site # 13
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 28.4 38.3 61.6 83 112 129.7 141.2 2 0.5 31 41.7 66.8 90 121.2 140.2 152.8 5 0.2 40.5 54.3 86.1 115.2 154.2 178.5 194.5 10 0.1 48.4 64.6 101.8 135.7 180.9 209.4 228.1 20 0.05 57.4 76.3 119.6 158.8 210.9 244.1 265.9 50 0.02 71.6 94.6 147.2 194.5 257.1 297.6 324.2 100 0.01 84.5 111.2 172 226.5 298.3 345.3 376.2
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12.9.3 Mangorewa at Saunders
Rainfall depths (mm) NZMG Easting 2804600 Northing 6363400–Site # 14
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 28.2 37.7 59.5 79.4 105.9 121.1 131 2 0.5 30.8 41 64.6 86.1 114.7 131.1 141.9 5 0.2 40.3 53.4 83.4 110.5 146.5 167.5 181.2 10 0.1 48.1 63.5 98.7 130.4 172.2 197 213.1 20 0.05 57 75 116 152.8 201.2 230.1 248.9 50 0.02 71 93.1 143.1 187.6 246 281.3 304.3 100 0.01 83.7 109.5 167.4 218.8 286 327.1 353.8
12.9.4 Pongakawa at Pongakawa Bush Road
Rainfall depths (mm) NZMG Easting 28166600 Northing 6360400 – Site # 16
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 27.9 37 57.9 76.7 101.8 118.3 129.2 2 0.5 30.3 40.1 62.8 83.3 110.5 128.4 140.2 5 0.2 38.9 51.7 80.8 107.2 142.2 165.3 180.5 10 0.1 46 61 95.5 126.7 168.1 195.3 213.3 20 0.05 54 71.7 112.1 148.7 197.3 229.3 250.4 50 0.02 66.5 88.2 138 183 242.8 282.2 308.1 100 0.01 77.6 103 161.2 213.8 283.7 329.6 359.9
12.9.5 Rotorua at Upper Oturoa Road
Rainfall depths (mm) NZMG Easting 2782560 Northing 6347120–Site # 17
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 25.6 35.8 61.2 85.9 120.4 146.3 163.9 2 0.5 27.8 38.9 66.4 93 130.2 158.1 177.2 5 0.2 36 50.2 85 118.6 165.3 200.8 225 10 0.1 42.8 59.5 100.2 139.3 193.6 235.2 263.5 20 0.05 50.4 69.9 117.3 162.6 225.3 273.7 306.6 50 0.02 62.4 86.2 143.8 198.5 274.2 333 373.1 100 0.01 73.2 100.8 167.5 230.6 317.6 385.8 432.2
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12.9.6 Mangorewa at Kaharoa
Rainfall depths (mm) NZMG Easting 2797000 Northing 6349500 – Site # 18
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 26.1 36.4 61.7 86.2 120.2 144.5 160.9 2 0.5 28.4 39.7 67.1 93.6 130.4 156.7 174.5 5 0.2 37.1 51.6 86.8 120.6 167.5 201.3 224.2 10 0.1 44.3 61.4 102.9 142.7 197.8 237.7 264.6 20 0.05 52.4 72.5 121.2 167.6 231.9 278.6 310.2 50 0.02 65.2 90 149.8 206.6 284.9 342.3 381.2 100 0.01 76.8 105.8 175.5 241.5 332.4 399.5 444.8
12.9.7 Lake Rotoiti at Okawa Bay
Rainfall depths (mm) NZMG Easting 2803000 Northing 6344700–Site # 21
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 25.9 35 56.5 76.4 103.4 123.2 136.6 2 0.5 28.1 38.1 61.4 83 112.2 133.7 148.2 5 0.2 36.5 49.3 79.2 106.9 144.3 172 190.7 10 0.1 43.3 58.4 93.8 126.5 170.5 203.2 225.2 20 0.05 51.1 68.8 110.3 148.6 200.1 238.5 264.3 50 0.02 63.3 85.1 136.1 183 246.1 293.3 325.1 100 0.01 74.3 99.8 159.3 213.9 287.4 342.6 379.6
12.9.8 Kaituna at Whakarewarewa
Rainfall depths (mm) NZMG Easting 2795900 Northing 6332900– Site # 23
Duration ARI (y) aep 1 hr 2 hrs 6 hrs 12 hrs 24 hrs 48 hrs 72 hrs 1.58 0.633 24.4 32.5 51.2 68.2 90.9 108.8 121 2 0.5 26.5 35.4 55.8 74.4 99.2 118.9 132.1 5 0.2 34.3 45.9 72.7 97.3 130.1 155.8 173.1 10 0.1 40.6 54.4 86.6 116.1 155.6 186.4 207.1 20 0.05 47.8 64.2 102.4 137.6 184.8 221.3 246 50 0.02 59 79.4 127.3 171.4 230.9 276.5 307.2 100 0.01 69.1 93.2 149.8 202.2 272.8 326.7 363
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12.10 Kaituna River flood event plot July 1998
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12.11 Kaituna River flood event plot May 1999
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12.12 Kaituna River flood event plot January 2011
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12.13 Kaituna at Te Matai rating curve
5
4.5
4
3.5
Return 3 Stage Discharge Stagem Period (m) (m3/s) (years) 2.33 2.5 4.29 170 5 5.06 230 10 2 300 20 405 50 500 100 1.5
1 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Flow m3/s Kaituna River at Te Matai 1-May-1999 22:15:00 Indicator Stage 2.291
Bay of Plenty Regional Council Flood Warning Manual 21
12.14 Rating table for Kaituna at Te Matai
Stage Discharge Reference Stage Discharge (m3/s) Reference (m) (m3/s) (m) 0.4 12 2.4 81 0.5 15 2.5 85 1st Warning Level 0.6 17 2.6 89 0.7 20 2.7 93 0.8 23 2.8 97 0.9 26 2.9 101 1.0 29 3.0 105 1.2 36 3.1 109 1.3 40 3.2 114 1.4 44 3.3 118 1.5 47 3.4 123 1.6 51 3.5 127 2nd Warning Level 1.7 55 3.6 132 1.8 59 3.7 136 1.9 63 3.8 141 2.0 66 3.9 147 2.1 70 4.0 153 2.2 73 4.1 2.3 77 4.2
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Stage Discharge Reference Stage Discharge (m3/s) Reference (m) (m3/s) (m) 4.29 170 5 year Return Period 5 224 4.3 171 5.06 230 10 year Return Period 4.4 177 5.1 233 4.5 183 5.2 242 4.6 191 5.3 251 4.7 199 Highest recorded level 5.4 261 4.8 207 5.5 270 4.9 216
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12.15 Mangorewa at Saunders rating curve
12
10
8
6 Stagem Return Stage Discharge Period (m) (m3/s) (years) 2.5 1st Warning level 4 4.5 2nd Warning Level 5.31 202 5 6.06 259 10 2 6.75 318 20 7.66 403 50
0 0 100 200 300 400 500 600 700 800 900 Flow m3/s Mangorewa River at Saunders Farm 3-Oct-2005 13:45:00 Indicator Stage 3.278
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12.16 Rating table for Mangorewa at Saunders
Stage Discharge Reference Stage Discharge Reference (m) (m3/s) (m) (m3/s) 0.5 2 2.4 45 0.6 3 2.5 49 1st Warning Level 0.7 4 2.6 52 0.8 5 2.7 56 0.9 7 2.8 60 1 8 2.9 64 1.1 10 3 69 1.2 12 3.1 73 1.3 14 3.2 78 1.4 16 3.3 82 1.5 18 3.4 87 1.6 21 3.5 92 1.7 23 3.6 97 1.8 26 3.7 102 1.9 29 3.8 108 2 32 3.9 113 2.1 35 4 118 2.2 38 4.1 124 2.3 41 4.2 130
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Rating table for Mangorewa at Saunders continued
Stage Discharge Reference Stage Discharge Reference (m) (m3/s) (m) (m3/s) 4.3 136 6.06 259 10 year Return Period 4.4 142 6.1 263 4.5 148 2nd Warning Level 6.2 271 4.6 154 6.3 279 4.7 161 6.4 288 4.8 167 6.5 296 4.9 174 6.6 305 5 181 6.7 313 5.1 187 6.75 318 20 year Return Period 5.2 194 6.8 322 5.3 202 6.9 331 5.31 202 5 year Return Period 7 340 5.4 209 7.1 350 5.5 216 7.2 359 5.6 224 7.3 368 5.7 231 7.4 378 5.8 239 7.5 388 5.9 247 7.6 397 6 255 7.66 403 50 year Return Period
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Rating table for Mangorewa at Saunders continued
Stage Discharge Reference Stage Discharge Reference (m) (m3/s) (m) (m3/s) 7.7 407 9.6 616 7.8 417 9.7 628 7.9 427 9.8 641 8 438 9.9 653 8.1 448 10 665 8.2 458 10.1 678 8.3 469 10.2 691 8.4 480 10.3 703 8.5 490 10.4 716 8.6 501 10.5 729 8.7 512 10.6 742 8.8 523 10.7 756 8.9 535 10.8 769 9 546 10.9 782 9.1 557 11 796 9.2 569 11.1 809 9.3 581 11.2 823 9.4 592 11.3 837 9.5 604 11.4 851
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12.17 Kaituna at Te Matai staff gauge prompter
28 Bay of Plenty Regional Council Flood Warning Manual
12.18 Mangorewa at Saunders staff gauge prompter
Bay of Plenty Regional Council Flood Warning Manual 29
Part 13: Lakes
Chapter summary
13.1 Lakes rainfall 2
13.2 Lake Rotoiti 3
13.3 Okere Gates operation 3
13.4 Lake Okareka 9
Bay of Plenty Regional Council Flood Warning Manual 1
13.1 Lakes rainfall
Key telemetered rain gauges for Rotorua lakes:
Mangorewa at Kaharoa. Lake Rotoiti at Okawa Bay.
Figure 44 Telemetry rainfall sites for Upper Kaituna.
13.1.1 Lakes raingauge sites
Site Co-ordinates Method Kaituna at Pendergrast 2793501 6361399 Manual Kaituna at Whakarewarewa 2795911 6332883 Auto Kaituna at Wright, JH 2803901 6348398 Manual Lake Okareka at Blakely, J and F 2803388 6330809 Manual Lake Rotoehu at McMillan, B 2821560 6347220 Manual Lake Rotoiti at Okawa Bay 2803070 6344870 Auto Lake Rotorua at Hamurana 2794947 6346874 Manual Mangorewa at Kaharoa 2797029 6349460 Auto Rotorua at Upper Oturoa Road 2782564 6347121 Auto Utuhina at Hunts Farm 2791085 6333210 Manual Okaro at Birchalls 2806120 6319101 Auto
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13.2 Lake Rotoiti
13.2.1 Rotoiti telemetry
In May 2001, BOPRC established a new site at Okawa Bay to mitigate the lake draw-down effect previously experienced at the original NIWA site immediately upstream of the Okere Gates.
Figure45 Telemetry site at Okawa Bay Marina.
13.3 Okere Gates operation
Bay of Plenty Regional Council revised Operating Guidelines
Operating Guidelines for Okere Gates between Lake Rotoiti and the Kaituna River (as at 21 March 2012).
Objective
To aim for a general target level of 279.10 m to 279.20 m for 70-80% of the time above Moturiki Datum. Check Consent Conditions 7.4 for the remaining 20-30% of the time.
The lake level is measured by Bay of PlentyRegional Council’s lake level recorder at Okawa Bay Marina.
Bay of Plenty Regional Council Flood Warning Manual 3
Guidelines
1 Open or close gates between 8:00 am and 9:00 am or 4:00 pm and 5:00 pm whenever possible. 2 All three gates should be moved in unison. 3 Minimum gate openings are 100-200-100. Check ratings to ensure flow above 7.9 m3/s. 4 Gates may be opened 3 x 100 or 3 x 200 (e.g. if heavy rain is forecast or levels above RL279.200 m are likely). 5 Maximum change in flow rate is 5 m3/s/hr when closing gates (or less/more for flows <15 m3/s–See Consent No. 65979 Clause 7.4 k) and 10 m3/s/hr when opening gates. 6 All three gates open fully when lake rises to RL 279.25 m unless the Flood Manager decides otherwise. 7 Inform all rafting companies by email when gates are to go outside or return to the range 3 x 200 – 3 x 500. 8 Keep a record of enquiries relating to lake levels.
Note – This new set of guidelines has been adjusted to meet the ‘new lake level range’ criteria as set by the 2011-2012 consent.
The original consent focused on a target level of 279.116 m but is now redundant.
Reference: Okere Gates and Ohau Weir Control Structures Operational Management Plan RC 65979 and 65980 Appendix 5.
4 Bay of Plenty Regional Council Flood Warning Manual
Rotoiti minimum and maximum operating levels.
For further information, please refer to ‘Okere Gates Operational Procedures’ Manual.
Copies of the Okere Gates Operational Procedures Manual and the Okere Gates Guidelines are kept in the Flood Room.
Rotoiti control gates
Keys are held by:
Graeme O’Rourke Roger Waugh Rotorua Office (Craig Putt/Richard Mallinson)
The gates record book is in Graeme O’Rourke’s office. The spare key is taped in the back of the book.
Maintenance and repairs can be carried out by:
Engineers:
Unique Sheetmetals John Mawer (07) 349 3426 (07) 348 0464 or Summit Engineering and Hydraulics Ltd Mike Klomp (07) 345 5990 after hours
Bay of Plenty Regional Council Flood Warning Manual 5
Electricians:
Control Tech (Ōpōtiki) Geoff Indcavort 025 9939 44
Discharge through Okere Gates
*Minimum discharge 7.9 cumecs (this equates to gate settings of approximately 100,200,100). Maximum rate of change up 10 cumecs/hr. Maximum rate of change down 5 cumecs/hr. When Okere Gates are less than 15 cumecs, change down rate is then 4 cumecs/hr in any six-hour period – Reference Consent 65979 clause 7.4 (k). When opening the gate settings at Ōkere Falls, you must not exceed a rate of change greater than 10 cumecs in an hour. Discharge through the gates depends on lake level, but the following table should give approximate flows (m3/s).
Figure 46 Okere Gates removal April 2007.
6 Bay of Plenty Regional Council Flood Warning Manual
Gate
setting/Lake
000 200 500
, ,
level ,
200 300 400 500 600 700 800 900 1 1 1
279.116 12 17 21 25 27 29 31 33 34 36 36 279.216 13 18 23 27 30 32 34 36 38 41 44 279.231 14 19 25 29 33 36 39 42 44 48 52
Cumecs (m3/s)
When the Okere Gates are opened to greater than 3 x 200 or 3 x 500, the list of people on the email group in the Outlook Global distribution list @Okere Gates – Kaituna River Rafting, also when they are closed to below these settings:
3 x 200 (13 m3/s) is a minimum rafting flow rate and 3 x 500 (26 m3/s) is the maximum rafting flow rate. Measured at Taaheke. Usually no action required by the Flood Manager as actioned by the Lakes Operator. Refer Operational Management Plan.
Bay of Plenty Regional Council Flood Warning Manual 7
13.3.1 Lake Rotorua - minimum and maximum
Minimum RL 279.466m Maximum RL 280.076m
13.3.2 Lake Rotorua Outlet – (Ohau Weir)
The level of Lake Rotorua is controlled by a permanent 'choke' structure installed in 1989. Its principal purpose is maintenance of lake level during the typical summer low flow period. Fine tuning of this level is attained by installing three single steel stoplogs each 6 m long and 300 mm high. These are installed by crane and dropped into each of the receiving slots.
Figure 47 Ōhau Channel stoplogs installation October 2010.
In order for the structure to discharge, floods stoplogs are removed at trigger level of RL 279.966 m if lake is rising.
The Principal Works Engineer normally handles removal/installation of the stoplogs.
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The crane hire companies familiar with the site are:
Company Contact details Lakeland Steel Phone: (07) 347 9585 Pollock and Sons Crane Hire 6 Rerewai Place, Tauranga Phone: (07) 574 2951 Todd McPhee Crane Hire Limited Phone: 0800 CRANES (0800 272 637) Lakeland Plant Hire Limited 142 View Road, Rotorua Phone: (07) 347 9585 Fax: (07) 347 9846 Bruce Morrison Phone: (07) 348 3658 Teeny Stewart Phone: 027 4924 500
13.4 Lake Okareka
Lake Okareka Outlet – Guidelines for operation of structure
13.4.1 Introduction
Lake Ōkāreka has no natural outlet and outflow is controlled by a valve on a pipe that discharges into the Waitangi Stream (which flows into Lake Tarawera).
Bay of Plenty Regional Council holds consent No. 60776 for this structure, granted in May 2001 and expiring in 2026. Condition 8.2 of the consent includes a requirement for Guidelines for setting of the valve in response to lake level readings.
13.4.2 Target range
Condition 8.1 gives the target range for the lake level as 353.5 m to 353.9 m (Moturiki Datum 1953). The rate of discharge in the Waitangi Stream shall not exceed 239 l per second (Condition 6.1) and as far as practicable have a minimum discharge rate of 100 l per second (Condition 6.2).
13.4.3 Day-to-day management
Responsibility for day-to-day management of the outlet structure is delegated to the Bay of Plenty Regional Council’s Engineering Team.
13.4.4 Monitoring of lake Level
Lake levels are to be checked at least weekly by BOPRC’s Engineering Team. Daily lake levels can be viewed from the telemetry data on BOPRC’s Live Monitoring website.
Bay of Plenty Regional Council Flood Warning Manual 9
13.4.5 Regular checking of pipe intake
The trash rack above the intake structure traps debris. The trash rack is to be checked and cleared weekly when the valve is partially or fully opened. The pipes between Lake Ōkāreka and the canal (above intake structure) will be checked and cleared at the same time as the intake, by a local contractor organised by BOPRC.
13.4.6 Other considerations
Any adjustment of the pipeline valve, i.e. changes to the rate of outflow into Waitangi Stream, will be made after consultation with Fish and Game New Zealand. Fish and Game New Zealand require flow in the Waitangi Stream from April to the beginning of December. 303 Spencer Road through which the Waitangi Stream runs, contains a trout fishery. The peak of the trout spawning season is from May–July inclusive, with eggs hatching August – September and rearing is usually complete by the beginning of December. February and March is the period when the juvenile fish move out of the stream mouth into the lake. If the valve does require closing prior to December, Fish and Game would prefer this to be done in graduated steps.
13.4.7 Valve Operation Guidelines
The valve will be adjusted as needed according to Figure 1 attached.
Figure 1 shows that there shall generally be four settings:
Fully closed Open at approximately 50 l/s Open at approximately 100-150 l/s Fully open (approximately 239 l/s) Discretion is available to vary the settings as considered appropriate, to meet the objectives of maintaining lake levels within the target range and flows in the Waitangi Stream for fish habitat protection.
13.4.8 Communication
The Engineering team (consent holder) shall advise BOPRC’s Consents Team under Condition 11.3 if:
The discharge into Waitangi Stream falls below the minimum 100 litres per second The pipeline has to be closed off for any specific reason When flow through the pipeline resumes. Interested parties will be advised of any adjustment of the pipeline valve, (i.e. changes to the rate of outflow into Waitangi Stream) via the @Okareka Pipeline Operation group email.
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Interested parties include:
Fish and Game New Zealand Department of Conservation Lake Ōkāreka residents Applicable Rotorua Lakes Council and BOPRC staff: . Three Lake Tarawera properties with water takes from Waitangi Stream (includes 303 Spencer Road) . Others requesting to join group email Out of consideration for the downstream properties with water takes, it is helpful to give 1-2 days warning of valve adjustments (particularly closing of the valve or resuming flow).
13.4.9 Monitoring and Review of Guidelines
The operational guidelines shall be reviewed every five years (or earlier as required) by the Bay of Plenty Regional Council (the consent holder).
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Spring/Summer time (approx. Sep – Mar) Autumn/Winter time (approx. Apr – Aug)
Is level < Is level < 353.65? 353.55?
Y N N
Close valve gradually after Is level < Close valve gradually after Is level <
consultation with Fish & Game 353.75? consultation with Fish & Game 353.65? NZ. (Q= 0) NZ. (Q= 0)
Y N Y N
Adjust valve Is level < Adjust valve Is level < (Q~50 l/s) (Q~50 l/s) 353.8? 353.75?
Y N Y N
Adjust valve Open valve fully Adjust valve Open valve fully (Q~100-150 l/s) (Q~239 l/s) (Q~100-150 l/s) (Q~239 l/s)
Figure 1 Valve Operation Guidelines. The flow chart below is a general guide only. The operator is allowed to use their judgement to adjust flows as necessary to meet the purpose of the consent. Consideration of current month, weather forecasts and whether the lake level is rising or falling needs to be taken into account. (Note – all flows are approximate only).
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Part 14: Coastal
Chapter summary
14.1 Introduction 2
14.2 River levels 3
14.3 Astronomical tide 3
14.4 Astronomical tide tables 3
14.5 Barometric pressure 4
14.6 Wind setup 5
14.7 Wave conditions 6
14.8 Estuary effects 6
14.9 Tsunami 6
14.10 Types of tsunami notifications - MCDEM 7
14.11 Calculation of event sea water level 8
14.12 Bay of Plenty coastal areas of concern 8
14.13 Post event data collection 9
Bay of Plenty Regional Council Flood Warning Manual 1
14.1 Introduction
Low-lying areas exposed to coastal processes can potentially be impacted by a number of flooding and coastal related factors including:
Rainfall River levels Astronomical tide Barometric pressure Wind effects Wave run-up Estuary effects Tsunami
Storm surge
Storm surge is the increase in the regional ocean level (excluding the effects of waves). It arises from low barometric pressure (known as the inverse barometric effect) and winds blowing either onshore or alongshore (known as wind stress or wind set-up).
Wave run-up
At the shoreline, the maximum vertical elevation reached by the sea is a combination of wave set-up that is induced landward of the wave breaking zone and wave run-up.
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14.2 River levels
Under 'normal' circumstances rainfall events occur either in the upper catchment or the lower catchment (coastal).
When there are high flows in the major rivers but only moderate to low rainfalls on the coast, with calm sea conditions, there are generally no problems with coastal drainage.
River levels are normally of concern when major rivers are running high (in response to rainfall in the upper catchment) at the same time as coastal areas are receiving significant falls and/or there are active sea conditions.
The effect of this is that where the outlet of a drainage system is dependent on floodgates (i.e. gravity drainage) then drainage will only occur when the river level has fallen or during low tide/sea periods.
14.3 Astronomical tide
The astronomical tidal height is the height that the tide has been forecast to reach under normal weather conditions. Tidal forecasts are provided in the Nautical Almanac and are the height that storm specific weather components build upon.
Note: The tidal heights in the Almanac are given in Chart Datum and will need to be converted into Moturiki Datum; in the Bay of Plenty this is done by subtracting 0.963 from the Almanac height. It should also be noted that the primary level is for Tauranga, there are slight changes in predicted tide elevations and time of peak levels in different locations around the Bay of Plenty Coastline. In general, peak levels predicted for Tauranga are the same as those predicted for Whakatāne, Ōhiwa and the open coastline in between.
Red Alert Dates
Red Alert Dates are predicted by NIWA and constitute higher than normal tides. There is a greater risk of storm surge flooding impacts should a storm pass through the Bay of Plenty around these dates. Red Alert Dates are provided by NIWA at the website:
http://www.niwascience.co.nz
14.4 Astronomical tide tables
Tide tables are provided at the following website links:
http://www.linz.govt.nz/hydro/tidal-info/tide-tables http://www.metservice.com/marine-surf/tides/index
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14.5 Barometric pressure
Astronomical tide predictions are computed for average barometric pressure defined as the standard pressure level (1,014 mb).
As barometric pressure falls below the standard pressure level, sea level responds by rising above normal. The relationship of this response is that for every millibar drop in barometric pressure, sea level rises by 1cm.
Note – 1 mb = 1 hPa (Hector Pascal). Change due to barometric pressure alone seldom exceeds 30 cm.
The sea water level does not adjust itself immediately to a change of pressure but responds to the average change in pressure over a considerable area. The response of sea level to a change in barometric pressure in the Bay of Plenty can range between 2-12 hours (Tonkin and Taylor, 1999).
The 1% AEP barometric pressure is 981 mb, and coverage is thought to be extreme with the central pressures expected to be even lower. Table 2 records some barometric pressures recorded in various storms in the Bay of Plenty.
14.5.1 Recorded barometric pressures for storms in the Bay of Plenty
Table 2 Barometric pressures.
Storm event Minimum barometric pressure Cyclone Giselle (Wahine) 964 (Tauranga) Cyclone Fergus 985.4 (Tauranga) Cyclone Drena 998.8 (Tauranga) Cyclone Ivy 989.6 (Whakatāne) Storm 18 September 2005 976.6 (Omokoroa) Weather Bomb 12June 2006 989.9 (Whakatāne)
A general recommendation:
4 Bay of Plenty Regional Council Flood Warning Manual
1 If a noteworthy weather system is heading towards the Bay of Plenty with barometric pressures below 1,000 mb, it would be wise to assess the magnitude of other associated components (wind speed and direction, predicted tidal level, wave heights etc.) in order to assess the likelihood of a storm surge resulting. 2 If a pressure system has passed through the Bay of Plenty and produced unusually low barometric pressure (say <980), even if the other components are not considered to be out of the ordinary, then it would still be worthwhile collecting surveyed water levels.
14.6 Wind setup
The surface shear stress of the wind travelling over the sea surface drives water in the prevailing wind direction. An onshore wind thus drives a wedge of water against the land. The magnitude of the height of this wedge is called wind setup.
In the Bay of Plenty region, the highest storm surge elevations are recorded in general, when weather systems approach us with winds blowing in the northerly to easterly direction. Winds blowing in these directions have the greatest fetch. Prevailing wind direction in the Bay of Plenty is westerly to south westerly.
The size of the wind setup is complex to calculate and is dependent on several factors including:
intensity, duration and direction of high winds; coastline bathymetry. This affects the way the water interacts with the shoreline and thus the magnitude of set up; and coastline geometry. The concave shape of the Bay of Plenty Coast is likely to enhance setup levels in some locations.
If coastline bathymetry and geometry is considered relatively constant on a day to day basis, then the intensity, duration and direction of winds become the factors of interest when estimating the magnitude of a storm surge. Table 3 gives the return periods of wind speed for the Bay of Plenty region and Table 4 gives some recorded wind data associated with past storm surge events. For more detailed information please refer to AS/NZS 1170:2011.
Table 3 Basic wind speed (m/s) and their associated return periods as reported in section 3, table 3.1 AS/NZS 1170:2011.
Region 5-year 25-year 50-year 100-year Bay of Plenty 32 37 39 41
Table4 Wind speeds recorded in past storm events.
Storm event Wind direction Wind speed (m/s) Cyclone Giselle (Wahine 1968) Northerly 40.3 (gust) Cyclone Fergus (1996) Easterly 26.3 (gust)17 (average) Cyclone Dena (1997) East–north-east 20.6 (gust)14.9 (average) Cyclone Ivy (2004) Easterly 22.14 (gust)14.95 (average) Storm 18 September 2005 Easterly 14.9 (gust) Weather Bomb 12 June 2006 Northerly 29.3 (gust)18.5 (average)
Bay of Plenty Regional Council Flood Warning Manual 5
14.7 Wave conditions
Waves are not specifically a component of storm surge, although during storm surge events wave height is often higher than normal. Due to this, wave characteristics during a storm event can give an indication of a possible storm surge being felt on the coast. Along the open coast especially, the effects of a storm are felt by the combined magnitudes of storm surge and wave run-up, the static water surface is raised due to the storm surge, which then allows the breaking wave heights to be elevated. This increases the amount of wave run-up on beaches and thus the possibility of inundation of assets along the coast.
Bay of Plenty Regional Council has a Wave Buoy located 13 km off the coast of Pukehina Beach in a central position within the curve of the Bay of Plenty. The wave buoy records data such as maximum wave height, average wave height, significant wave height, significant wave period, mean period, water temperature, wave steepness as well as other wave components. This data is useful in gauging the importance of waves during an event.
Note: That due to its distance offshore, the Wave Buoy is not always a direct indicator of wave height at the coastline. Table 5 below gives current estimates of wave height return periods.
Table 5 Wave height return periods (as advised by PLB 27/08/07).
Wave type 2-year 5-year 10-year 20-year 50-year 100-year Hs 3.3 5.4 6.8 8.1 9.9 11.2 H1% (1/100) 4.4 7.9 10.2 12.2 15.2 17.5
Hs = significant wave height.
H1% (1/100) =mean height of the highest one-hundredth of the waves.
Note – at "A" Beacon during Cyclone Fergus the recorded wave heights were Hs = 9.7 m and H1% (1 in 100 waves) = 11.404 m - we also regarded that storm overall as 10% AEP.
14.8 Estuary effects
Within estuaries there may be an additional set-up or set-down (may occur with Tauranga Harbour) of water level due to two components involved in estuary effects:
Hydraulic effects relating to influx of freshwater, outlet controls, depth and channelling of water. Spatial differences in water levels due to the differential effect of wind stress.
14.9 Tsunami
A tsunami is a series of surges generated when a large volume of ocean water is rapidly displaced. A tsunami surge can occur following a large earthquake. These are caused by uplifting or slipping of the seabed.
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There are three types of tsunami that pose a threat to coastal communities along the Bay of Plenty coastline:
Local source: Local source tsunamis occur anywhere from one minute to one hour after the earthquake has occurred. They can be triggered by quakes in fault lines close to the shore, or from areas such as the southern part of the Kermadec Trench. Regional source: Generally, regional source tsunami are generated along the Kermadec/Tongan trench (which includes earthquakes close to the Pacific Islands), which lies to the north-east of New Zealand. Regional source tsunamis have a travel time of between one and three hours, depending on how close the source is to New Zealand. Distant source: Distant source tsunami are generated by earthquakes in other areas of the Pacific, such as Japan, South America or North America. Due to the distance that waves have to travel to reach our shores, we have a much longer time frame in which to respond appropriately.
Check: Predicted arrival time Install the Tsunami warning Areas likely to be affected Whakatāne River stoplogs? received Size of wave No Close floodgates? Tide times Riverflow condition
Monitor the situation
Yes
Call BOPRC Field Operations staff to organise to coordinate installation of stoplogs and floodgates
Monitor the situation
Document actions and communications
Figure 49 Tsunami notification process.
14.10 Types of tsunami notifications - MCDEM
Depending on the assessment of the information received for an earthquake, MCDEM may issue one or more of the following notifications:
National advisory - Tsunami: No threat to New Zealand. National advisory - Tsunami: Potential threat to New Zealand. National warning - Tsunami threat to New Zealand. National warning - Tsunami marine and beach threat. National warning - Tsunami marine and land threat.
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National advisory - Tsunami cancellation message. National warning - Tsunami cancellation message. Request for the broadcast of an emergency announcement.
For more information, refer to MCDEM, Tsunami Advisory and Warning Plan, (SP 01/09): Version 5.0 May 2012.
14.11 Calculation of event sea water level
Prior to the arrival of a rainfall or coastal event, an assessment of the likely sea water level should be completed. The steps in this process are:
1 Check astronomical tidal heights and red alert dates around the time the storm is going to pass over the Bay of Plenty. If the tides are already higher than normal, monitor the situation carefully. 2 If a cyclone or tropical cyclone weather system is heading towards the Bay of Plenty with barometric pressures below 1,000 mb, then look at the magnitude of other associated components (wind speed and direction, predicted tidal heights, wave height) in order to assess the likelihood of a storm surge resulting. 3 Investigate the direction, and speed of predicted winds and estimate how long the high winds are predicted to last. Take more care when a weather system is producing winds coming from a north to easterly direction.
It should be noted that exceptionally high tide levels can occur because of the combination of spring tide, low barometric pressure, and wind set up even without rainfall occurring.
Events with resultant sea levels up to 1.8 m RL (Moturiki Datum) are not uncommon and problems are not expected with these events. Of concern, are events which exceed 2.0 m RL (Moturiki Datum) at lower estuary sites, particularly if accompanied by strong wave action.
14.12 Bay of Plenty coastal areas of concern
Some BOPRC assets are vulnerable to extreme sea levels associated with some coastal events. Areas where problems may arise include:
Lower Whakatāne River stopbanks Lower Rangitāiki River stopbanks Lower Tarawera River stopbanks Rangitāiki Plains drainage Kaituna Plains drainage Kaituna Wetland culverts Maketu Estuary stopbanks, Singletons Drain area Maketu Estuary diversion gates at Ford Road Maketu residential area Tauranga Harbour especially Judea industrial area Little Waihi
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Flooding of the lower levels of the Rangitāiki Plains is sensitive to coastal processes, particularly since the earthquake of 2 March 1987. The earthquake lowered many hectares of land to the extent that a considerable portion of the Plains are now below mean sea level. Many parts of the Rangitāiki Plains are drained by managed pumping systems which can be overwhelmed during significant flooding and/or coastal events.
14.13 Post event data collection
Because of the rarity of these coastal events and the value of the data that can be gained from them, it is important that inspections and measurements be made of the sensitive areas as soon as possible. The data should be compiled into a storm surge report to document the event for future reference.
There are several components of storm surge that will provide information about the significance of a storm event and most of these we are able to monitor. These include:
Astronomical tidal height. Barometric setup. Wind setup. Wave heights also play a key role in the amount of wave run-up experienced on the coastline. Specific data collection triggers include the following: . Advice from Peter Blackwood indicates it is worth surveying high water marks and debris levels whenever the Ōhiwa/Moturiki recorders register anything above RL 1.5-1.6 m Moturiki Datum. . Collect surveyed water levels whenever a pressure system has passed through the Bay of Plenty that produced an unusually low/high storm component, be that wind speed, barometric pressure (say <980 mb), wave height (above 10-12 m). A judgement call will need to be made. . If the Data Services Team are carrying out their coastal surveys request them to record high water/debris levels at each of their coastal cross sections. . When collecting debris/high water marks try, where possible, to collect information from the same location as data has been collected in the past (especially within estuaries/harbours). This will enable more accurate comparisons of storm events to be made in the future. Maps are shown below outlining possible data collection locations within the Tauranga and Ōhiwa Harbours. For details on historic open coast sites, see Graeme O’Rourke and/or the Coastal Profiles folder (blue). Data Services use Pukehina Wave Buoy information to determine when data collection is required and usually send their team out to survey the coastal profiles if wave heights reach 10 m or above. Due to its distance offshore, the wave buoy is not always a direct indicator of wave height at the coastline, however, if waves do reach the 10 m wave height, it is recommended that investigation of other storm components e.g. height of wave run-up locally and tidal elevations at recorders, be carried out briefly in order to identify if more data collection is required.
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Bay of Plenty Regional Council Flood Warning Manual 11
Appendices
Appendix 1 – Flood Warning Guide 3
Appendix 2 – Standard Operating Procedures 5
Appendix 3 – Notes page 13
Appendix 4 – Lake Matahina Flood Management Plan 15
Appendix 5 – Flood Warning Manual Improvement Plan 17
Appendix 6 – Acronyms 19
Appendix 7 – References 21
Appendix 8 – Useful links 23
Appendix 9 – Flood Room Resources 25
Appendix 10 – Flood equipment list: Rivers and Drainage 27
Appendix 11 – Inter Council Memorandum for assistance 29
Appendix 12 – Flood Team contact list 31
Appendix 13 – Emergency Support Contact Details 33
Appendix 14 – CDEM contacts 35
Appendix 15 – Radio station contacts 37
Appendix 16 – Essential contacts 39
Appendix 17 – Contractor and equipment contacts 45
Appendix 18 – RT Call Signs 53
Bay of Plenty Regional Council Flood Warning Manual 1
Appendix 1 – Flood Warning Guide
Bay of Plenty Regional Council Flood Warning Manual 3
Appendix 2 – Standard Operating Procedures
SOP FM 01 Flood Room Set Up Page 6 SOP FM 02 Flood Room – Phone Set Up Page 9 SOP FM 03 Flood Room - RT Protocols Page 11 SOP FM 04 Flood Room (Logistics Monthly) Checklist * Obj ID A113979 SOP FM 05 Flood Manager Monthly Checklist* Obj ID A134331 SOP FM 06 Flood Manager Pager Page 12 SOP FM 07 Not currently allocated SOP FM 08 Not currently allocated SOP FM 09 Flood Forecasting Monthly Checklist* Obj ID A134330
*Objective reference only, these checklists are not held in this manual.
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SOP FM 01 Flood Room – Set up Version 3 Updated : 30 May 2016 The Flood Manager has the responsibility to activate the Flood Room during a flood event. Set up of the Flood Room may be done by the Flood Manager or by the Logistics staff.
The Flood Manager will have started their own Flood Log noting all messages and actions prior to any activation. Flood warnings will have been actioned if any trigger levels have been exceeded.
Flood Room set up:
1 Activate the phones in the Flood Room. Refer to SOP FM 02. 0800 884 881 – extensions 9845 (main flood phone), 9848 and 9849
Test that the phones are working correctly by calling the extensions. Check that the voicemail message plays clearly.
If activating during business hours, advise reception staff to forward any flood related calls to extension 9845.
Note: if ext 9845 is engaged, an incoming call will be diverted to ext 9848, if that phone is engaged, the call diverts to ext 9849.
2 If no TNZ flood warning messages have been sent out, send out a test message to ensure the system is working correctly. www.tnz.co.nz Log in: [email protected] Password: Floodteam123
3 If activating outside of standard business hours. Notify security and the duty property staff that the Flood Room has been activated.
Nutech Security (07 578 8233), Note: if required the password is CHUBB.
Duty property staff 0800 884 881, extension 9428. Any problems with the alarm, notify the BOPRC Property Team Leader 027 801 4400.
After hours: After 8:00 pm weekdays, weekends and public holidays, the door alarm has a two hour time out and reset function, entering your PIN will deactivate the alarm for an additional two hour period.
4 Turn on the TV screen No.1, this is linked to the laptop on docking station No. 1.
5 Turn on TV screen No. 2, this can be linked to the flood modelling computer or docking station No. 2. The HDMI cable can be plugged straight into the PC but the adaptor (attached to docking station No. 2) must be used to connect to the docking station.
6 Turn on the RT. Broadcast a message over Channel 1 (Voice Whale), 3 (Voice Edge) and 19 (Voice Rot) to notify staff that the Flood Room has been activated and who the Duty Flood Manager is.
All stations, all stations this is Flood Base. The Flood Room has been activated at (insert time) the Duty Flood Manager is (insert name). Please use your RTs when appropriate and ensure that any critical information is provided to the Flood Manager or the support staff in the Flood Room as it comes to hand. Flood Base listening.
Repeat the message after 10 minutes.
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7 Initiate a status board. For information for all the major river level, refer to step 8. The Flood Manager will provide instructions for the additional information they required on the status board.
8 Open HydroTel™ from Application Launcher – User name Engineer and Password River
Select the Reports tab at the top of the navigation tree on the left. From drop down menu, select Site Summary (SQL), the report will be automatically generated. To print, right mouse click on the report and send to printer. Use this information to populate the whiteboard.
Time of the report. River level and is it increasing or decreasing + or –. Tide times - Tauranga, Whakatāne and Ōpōtiki high tide information is available on the internet.
The status board information should be kept up to date throughout the event.
9 Send out flood warnings to pre-determined groups as directed by the Flood Manager or as trigger levels are exceeded. Refer to Part 5 of the Flood Warning Message Guide for further information.
10 Print out any Sitreps and media releases. Place on the designated clip boards.
11 Set up flood event folder in Objective if the Flood Manager hasn’t already done so.
Flood event location in Objective
Hazard and Maritime Management/Hazard and Risk Management and Mitigation/Flood Hazard & Flood Management/Flood Management, Forecasting and Monitoring/Flood Managers Record
Flood events by year
Figure:1 Flood event Objective location
Set up a new folder in Objective for the flood event documentation, Objective reference fA304096, (Hazard and Maritime Management).
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General notes:
1 Use the RT to convey messages to all the staff in the field. The RT provides situational awareness for all staff responding during a flood event.
2 During significant events, reception staff should be kept up-to-date with relevant information so they are aware of what is happening and can pass clear information on to the public if necessary.
3 Supplementary information is kept in the Flood Room Information Folder. 4 A selection of printed maps are available for use during a flood event. 5 News broadcasts are worth listening to for situational awareness. There is a radio in the Flood Room and TV screen 1 is equipped with Freeview TV.
Back up electricity supply 6 The generator servicing BOPRC Toroa Street server room in the depot, will provide backup electricity to all the Toroa Street buildings in the event of a power cut. It will automatically shut down when the electricity comes back on.
7 The generator outside the West Wing link of the Quay Street building (south side) maintains power to the whole Quay Street BOPRC building. The West Wing is not covered by this power back up circuit. During a power cut, start up and shut down is automatic.
8 An emergency electrical kit is available for providing power to the Engineers office.
9 Should all power to Quay Street be cut off, the IT systems will stay on line for about half an hour, using battery backup. Contact the ICT Operations Team Leader on 029 368 9214 or Chief Information Officer on 021 667 310.
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SOP FM 02 Flood Room – Phone set up Version 3 Updated: 30 May 2016
To set the phones to ring
(Activation setting - During a flood event)
0800 884 881 – extensions 9845 (main flood phone), 9848 and 9849
On each phone dial the following:
543 Wait for voicemail to answer – this will say Do Not Disturb.
Enter return time of 1700 followed by the # key
Enter the number of days you will be at location as 8 followed by the # key
This will stop the phone calls going directly to voicemail until 5:00 pm, eight days from when the setting is done (the phones will ring). NOTE: This is counter intuitive as it is opposite to how you normally set the deskphones.
To clear voicemail messages
Dial 51 Ext 9845 Pin 99845 Ext 9848 Pin 99848 Ext 9849 Pin 99849 Clear messages Hang up
To divert the phones to voicemail and paging system
(Standard setting – Non flood event time)
On each phone do the following:
Dial 541 (wait until the voicemail answers and tells you “office selected your presence has now been set” then hang up. There should be an arrow showing at the top righthand side of the screen.
This will divert all calls to voicemail. Any messages left on the phone from that point on will trigger a page to the Duty Flood Manager.
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SOP FM 03 Flood Room – RT protocols Version 2 Updated: 1 March 2015
Flood event use
All call-sign numbers are preceded by the word ‘Regional’. Be concise, think about what you want to say before talking. Wait your turn. Ensure you hang up the microphone after you finish with the radio telephone.
Standard Call Initiation:
Receiving persons call-sign followed by the call-sign of the person initiating the call, i.e.“Regional 65 this is Flood Base over”.
Standard Initiation Receipt: Receiving persons call-sign followed by ‘receiving’, i.e. “Regional 65, receiving”.
Standard Discussion Closure: Concisely deliver your message followed by ’over’, i.e. “I’ll be returning at 15 hundred over”.
Standard Call Closure: Initiator of call sequence closes by stating their call sign followed by ‘out’, i.e. “Flood Base out”.
RT call signs can be found in contact section. Call signs are reassigned as people leave or new positions are created. The list in the contact section may not be the latest version.
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SOP FM 06 Flood Manager - Flood Duty Pager Version 4 Updated: 5 May 2016
Pager notification generated from the afterhours flood phone calls.
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Appendix 3 – Notes page
The notes page should be used for comments, to add context, provide history to additions or deletions made to the Flood Warning Manual.
A1 The comment regarding calibration is valid as at 01 August 2013. Once the two staff gauges have been read and calibrated during a flood event, the text in section 8.4 should be updated.
A2 Ensure the field kit is restocked after use and any amendments made to the Flood Warning Manual, once the first thorough monitoring has been undertaken.
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Appendix 4 – Lake Matahina Flood Management Plan
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Appendix 5 – Flood Warning Manual Improvement Plan
Overview
The purpose of the Improvement Plan is to identify areas of improvement in the Bay of Plenty Regional Council Flood Warning Manual and general response during a flood event. This includes:
The Flood Warning Message Guide contains a separate improvement plan relating to flood warning groups and issuing flood warnings. Standard operating procedures should be developed further to ensure all routine tasks have been covered. All the rating curves in this manual need to be reviewed and updated. The Kaituna and Whakatāne rating curves have been flagged to change because of modelling underway by the engineers. Data from unknown sources needs to be confirmed, updated or removed if out of date or irrelevant. There is information in the manual that has been noted as source unknown. Reviews and debriefs should be standardised and the process documented. Pre-arranged and instantaneous volunteers during a flood event need to have an agreed documented process to manage these situations safely in the future. Bay of Plenty CDEM Group will provide a standard operating procedure for this. Flood Management GIS layer should be set up and added to the maintenance schedule. Waioeka River flooding mapping to be updated. Analysis of the Rangitāiki River rate of rise during a flood should be undertaken, to provide a guideline for the four hour window before the Rangitāiki Floodway starts to spill. Refer to Rangitāiki at Te Teko staff gauge prompter page. Dam break analysis and flood mapping should be investigated and resulting information included in the Flood Warning Manual. Review and possible inclusion of data for the Rotorua area. In particular, the Utuhina and Ngongotaha Streams.
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Appendix 6 – Acronyms
List of acronyms used in the Flood Warning Manual.
Acronym Description AEP Annual Exceedance Probability AMP Asset Management Plan API Antecedent Precipitation Index BOPRC Bay of Plenty Regional Council CDEM Civil Defence and Emergency Management GNS Geological and Nuclear Sciences MCDEM Ministry for Civil Defence and Emergency Management NIWA National Institute of Water and Atmospheric Research ODC Ōpōtiki District Council ORC Old Rangitāiki Channel PPE Personal protective clothing PTWC Pacific Tsunami Warning Centre RC Regional Council RDC Rotorua District Council RT Radio telephone SH State Highway SITREP Situation report SOP Standard operating procedure TCC Tauranga City Council WDC Whakatāne District Council WBOPDC Western Bay of Plenty District Council
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Appendix 7 – References
New Zealand Resource Management Act 1991 (Reprint as at December 2009).
Ministry of Civil Defence and Emergency Management, the CDEM Act 2002.
Bay of Plenty Civil Defence Emergency Management Group Plan 2012 - 2017, Civil Defence Publication 2012/01, ISSN: 1175 8902 (Print), August 2012
TrustPower, Bay of Plenty Region Emergency Action Plan and Procedures Manual.
Environment Waikato, River flood monitoring and response in the Waikato Region 2001/2012. Volume 1 (background information).
Horizons Regional Council, Whanganui Flood Action Plan, June 2012.
Waioeka Otara
Towards a Waioeka Otara Floodplain Management Strategy, Review of the Current Flood Hazard and Existing Responses, P. Wallace, October 1999. Operations Report 99/05.
Preliminary Options Assessment for Waioeka Otara Floodplain Management, P. Wallace, March 2000. Operations Report 2000/01.
Waioeka Otara Floodplain Management Strategy, P. Wallace, September 2001. Operations Report 2001/04.
Waioeka Otara Rivers Scheme Rural Stopbanks, June 2002, P. Wallace, 2007.
Waioeka Otara Floodplain Management Plan, Woodlands Road Stopbank, P. Wallace, 2007.
Waioeka Otara Floodplain Management Plan – Woodlands Road Stopbank, P. Wallace, 2007. Operations Publication 2007/01.
Waioeka Otara Floodplain Management Strategy, 2007 Review P. Wallace, September 2008.
Whakatāne Tauranga
Hydraulic Modelling of the Whakatāne River Upstream of Tāneatua, P. West, August 2005. Operations Publication 2005/07.
Hydraulic Capacity Review of the Waimana River and Floodplain, I. Pak, January 2006. Operations Publication 2006/02.
Hydraulic Capacity Review of the Waioho Stream and Canal, I. Pak, October 2006. Operations Publication 2006/10.
Stopbank Breach Risk Assessment Whakatāne River, P. Wallace, March 2006.
Whakatāne Waimana Floodplain Management Strategy, Stage 1, Review of Current Flood Hazard from the Whakatāne Waimana Rivers and Existing Responses, R. Britton, January 2007.
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Whakatāne Waimana Floodplain Management Strategy, Stage 1, Review of Current Flood Hazard from the Whakatāne Waimana Rivers and Existing Responses, R. Britton, June 2008 (updated from January 2007). Operations Publication 2008/09.
Whakatāne Waimana Floodplain Management Strategy, Stage 2, R. Britton, June 2008. Operations Publication 2007/02.
Rangitāiki Tarawera
Review of Flood Carrying Capacity of the Rangitāiki River below Edgecumbe, P. Blackwood. Operations Report 2000/09.
Review of the Flood Carrying Capacity of the Tarawera River below State Highway 30, V. Arts April 2005. Operations Publication 2005/03.
Hydraulic Modelling of the Rangitāiki Plains Tarawera River to Rangitāiki River, P. Wallace, December 2006. Operations Publication 2006/06.
Rangitāiki Tarawera Floodplain Management Strategy, Stage 1, R. Britton, September 2008.
Rangitāiki Tarawera Floodplain Management Strategy, Stage 2 and 3, Draft Report, R. Britton, February 2011.
Flood Risk Assessment of the Rangitāiki Plains, R. Britton, February 2011.
TrustPower Flood Management Plan.
Kaituna
Kaituna River Major Scheme Hydraulic Review, M. Surman. Operations Report 2005/01.
Hydraulic Modelling of the Kaituna River – January 2009, P. Wallace.
Flood forecasting
The Unity Hydrograph as used for Flood Flow Forecasting in the Bay of Plenty Region, P. Herbst. Operations Report 2001/06.
A Regional Formula for the Estimation of Peak Floods in the Bay of Plenty Region, P. Herbst, December 2004. Operations Publication 2004/06.
Manual for Operation of the Flood Forecasting Model for the Lower Rangitāiki River developed by Technical Services, with details of the Calculation Procedure, P. Herbst, May 2005.
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Appendix 8 – Useful links
Objective references
Flood Warning Manual qA867 Corporate Support/Procedures and guidelines Flood management and event documentation qA1129 Hazard and Maritime Management/Hazard and Risk Management and Mitigation Map references
Catchment maps (1-6) GIS – 463211 River Schemes and Drainage Districts C2264 Flood Management Monitoring Network of the BOP region GIS 463210 Websites http://www.boprc.govt.nz/ http://monitoring.boprc.govt.nz/RainfallMap/ Weather http://www.metservice.com/national/home http://metconnect.co.nz MetService - Bay of Plenty Coastal Forecasts NZCity - Weather http://www.metvuw.com/
Marine http://www.metservice.com/marine/recreational-marine/bay-of-plenty Land Information New Zealand - Tidal Predictions
CDEM http://www.bopcivildefence.govt.nz/ http://www.civildefence.govt.nz/ GeoNet - geological hazard monitoring http://www.police.govt.nz/ http://www.fire.org.nz
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Radio stations
National Radio:http://www.radionz.co.nz/ 101.0 FM and 819 AM Whakatāne - 101.7 FM Rotorua – 1188 AM and 101.5 FM
Newstalk ZB:http://www.newstalkzb.co.nz/ Tauranga – 1008 AM Rotorua – 747 AM
Classic Hits: http://www.classichits.co.nz/ Tauranga and Eastern Bay of Plenty - 95.0 FM Rotorua - 97.5 FM and 90.9 FM
More FM:http://auckland.morefm.co.nz/ Tauranga - 93.4 FM Rotorua - 95.9 FM
Radio Live:http://www.radiolive.co.nz/ Tauranga – 1107 AM Whakatāne - 92.1 FM Rotorua – 1107 AM
1XX:http://www.1xx.co.nz/ 90.5 FM Whakatāne, Ōpōtiki, Kawerau and Edgecumbe - 93.0 FM Ohope Beach - 92.9 FM Te Puke – 1242 AM
Sunlive Website:http://www.sunlive.co.nz/
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Appendix 9 – Flood Room Resources
PC – two screens. Laptop. Phones – 0800 884 880 (DDI 0800 884 881) extensions 9845, 9848 and 9849. RT (back up batteries). Information folder. Bolts for Whakatāne River stoplogs. Radio. Large TV screen monitor x 2. General emergency kit: Torches, batteries, matches, candles, lantern and gas, soup, chocolate etc.
Electrical emergency kit: extension leads, power boards to run power to the Engineers office in the West Wing.
Note: The emergency kits should be checked after a flood event and restocked as necessary. Reference library. Various Maps.
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Appendix 10 – Flood equipment list: Rivers and Drainage
BOPRC Emergency Equipment List – Operations Updated June 2016 Items Description PT No. Person responsible Edgecumbe Depot Water harvesters McEwans PT 24 A Pawson / T Dunlop McEwans PT 24 A Pawson / T Dunlop McEwans PT 25 A Pawson / T Dunlop McEwans PT 81 A Pawson / T Dunlop McEwans PT 82 A Pawson / T Dunlop Mobile pumps Sykes Mobile Pump PT 58 A Pawson / T Dunlop Doda Flood Pumps 300, 400, 450 PT 120 A Pawson / T Dunlop Sykes Yakka Mobile – Quick PT 133 A Pawson / T Dunlop Response Trash Pump – Small PT 135 A Pawson / T Dunlop New Sykes Mobile Pump W618A PT166 A Pawson / T Dunlop Digger Bobcat 1.8T PT 178 A Pawson / T Dunlop Trucks Hino Hiab – Older V201 A Pawson / T Dunlop Hino Hiab – Recent PT 131 A Pawson / T Dunlop Stoplogs Te Rahu stoplogs A Pawson / T Dunlop Waioho stoplogs A Pawson / T Dunlop Tractors Massey Ferguson with loader PT 54 A Pawson / T Dunlop Case 95 HP PT171 A Pawson / T Dunlop Case – Blade and mower PT148 A Pawson / T Dunlop Tandem PT 102 A Pawson / T Dunlop Tandem braked PT 151 A Pawson / T Dunlop Prescott trailer PT 167 A Pawson / T Dunlop Generators Suzuki (Three held in town) PT 22 A Pawson / T Dunlop Elvis – Edgecumbe PT 44 A Pawson / T Dunlop Traffic control Various signage PT 111 Arthur Rangihika / T Dunlop Held at Kaituna Diggers Hyundai Digger (Long reach) PT 139 Jason Rive / A Rangihika Bobcat 323 digger PT152 Jason Rive / A Rangihika Tractor Massey Ferguson – Not Warranted PT 119 Jason Rive / A Rangihika Mobile pump Doda 350 Flood Pump x 2 PT 120 Jason Rive / A Rangihika Held at Ōpōtiki Trailer Tandem PT 78 Shaun Menzies / T Dunlop
Bay of Plenty Regional Council Flood Warning Manual 27
Appendix 11 – Inter Council Memorandum for Assistance
Bay of Plenty Regional Council Flood Warning Manual 29
Appendix 12 – Flood Team contact list
Work phone Home phone Cell phone Email address Flood PHONE EXT 9845 or 026 252 8438 FOR THE DUTY FLOOD MANAGER Managers Roger Waugh 0800 884 881 extn: 9519 07 312 5216 029 368 9519 [email protected] Mark Townsend 0800 884 881 extn: 9437 07 312 5673 027 222 0298 [email protected] Graeme O’Rourke 0800 884 881 extn: 9521 07 312 4689 021 190 9523 [email protected] Mark James 0800 884 881 extn: 9527 07 312 4906 021 190 1191 [email protected] Rivers & Bruce Crabbe 0800 884 881 extn: 9513 07 307 0825 021 756 032 [email protected] Drainage Manager Data EDS FLOOD PHONE 027 274 1149 Services Glenn Ellery 0800 884 881 extn: 9449 07 312 4657 021 288 9449 [email protected] Flood Duty Officers Lisa Bevan 0800 884 881 extn: 9432 027 379 5370 [email protected] Charl Naude 0800 884 881 extn 9421 027 517 7421 [email protected] Field Tony Dunlop 0800 884 881 extn: 9526 07 307 0773 021 933 879 Tony [email protected] Operations Wendy Walker 0800 884 881 extn: 3010 07 322 8281 027 359 1457 [email protected] Rivers and Drainage Arthur Rangihika 0800 884 881 extn: 3527 07 308 8254 021 676 112 [email protected] Edgecumbe Andrew Pawson 0800 884 881 extn: 3526 07 304 9237 021 958 834 [email protected] Depot Shaun Menzies 0800 884 881 extn: 3522 07 308 7003 027 704 8924 [email protected] Technical Ingrid Pak 0800 884 881 extn: 9523 07 308 5882 021 167 0095 [email protected] Support Katalin Maltai 0800 884 881 extn: 9586 - 027 765 4484 [email protected] (Flood Forecasters) Marnie Fornusek 0800 884 881 extn: 9516 021 132 8480 [email protected] Denjam Khadka 0800 884 881 extn 9529 027 886 0769 [email protected] Raoul Fernandes 0800 884 881 extn: 9525 021 151 6499 [email protected]
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Work phone Home phone Cell phone Email address Sue Southerwood N/A (Contractor) Peter West N/A (Contractor) 07 312 9742 022 049 9601 [email protected] Logistics Kirsty Brown 0800 884 881 extn: 9530 07 312 0417 027 357 5061 [email protected] Support Brydie Such 0800 884 881 extn: 9001 07 929 5722 021 025 92921 [email protected] Pam Crabbe 0800 884 881 extn: 9347 07 307 0825 021 145 4866 [email protected] Mel Pullar 0800 884 881 extn: 9401 07 308 2427 027 333 6750 [email protected] Jo Heath 0800 884 881 extn: 9572 07 304 8900 - [email protected] Karen Parcell 0800 884 881 extn: 9346 07 308 9056 021 310 430 [email protected] Wendy Walker 0800 884 881 extn 3010 029 222 3528 [email protected] Dana Thompson N/A (Contractor) 027 227 4242 [email protected] (COMMS) PIM DUTY NUMBER 027 440 9528 (Public Information Manager) ICT ICT Operations 029 368 9214 [email protected] Support Team Leader Chief Information 021 667 310 [email protected] Officer Property PROPERTY DUTY PHONE 0800 884 881 Ext. 9428 Rachael Burgess 0800 884 881 extn: 9428 027 801 4400 [email protected]
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Appendix 13 – Emergency Support Contact Details
New Zealand Transport Agency (NZTA)- State Highway and Bridge Emergency Phone Numbers New Zealand Transport Agency (NZTA) - Emergency phone number is 027 473 7766.
The NZTA has a network contractor (Higgins) covering the state highways in the district council areas of Rotorua, Kawerau, Whakatane and Opotiki.
Higgins emergency phone is 027 444 0687.
The NZTA network contractor in the west (SHs in the WBOPDC and TCC areas) is Westlink. Westlink’s emergency phone number is 07 577 4680.
The NZTA bridge management consultant is BECAs, Andrew Ball 027 498 6718.
New Zealand Fire Service Mobile Command Centre If an alternative command centre is required:
Ring 111. Ask for Fire Service – Mobile Command Centre. Provide the NZFS the following details: . Address (where the vehicle will be set up for use by the Flood Team). . Bay of Plenty Regional Council contact person phone, number and email address. . Units are located in Tauranga, Hamilton and Gisborne.
Bay of Plenty Regional Council Flood Warning Manual 33
Bay of Plenty Regional Council Emergency Support Contact Details
Bay of Plenty Regional Council – Duty Property Officer
Duty property staff, 0800 884 881 extension 9428. Any problems with the alarm, notify the BOPRC Property Team Leader 027 801 4400.
ICT Support
Should all power to Quay Street be cut off, the IT systems will stay on line for about half an hour, using battery backup. Contact the ICT Operations Team Leader on on 029 368 9214 or Chief Information Officer on 021 667 310.
Harbour Master Duty officer
Tauranga Duty Officer 07 928 3385 Rotorua Duty Officer 07 921 3375 Whakatāne Duty Officer 07 308 8570
Geospatial Team
Contact phone number: 0800 884 881 extn 9247.
Email: [email protected]
34 Bay of Plenty Regional Council Flood Warning Manual
Appendix 14 – Civil Defence Emergency Management contacts
Name Work phone Cell phone Email address CDEM Group CDEM Group Duty Manager 027 519 4823 [email protected] Clinton Naude CDEM Manager 0800 884 881 extn: 8336 021 398 336 [email protected] Ōpōtiki ODC EOC Controller Aileen Lawrie 07 315 3030 021 819 342 [email protected] Alt Controller Barbara Dempsey 07 315 3030 027 7054775 [email protected] Whakatāne WDC EOC CDEM Duty Officer 027 704 8625 cd.duty@Whakatāne .govt.nz Controller Marty Grenfell (CE) 07 306 0502 027 215 6563 Marty.grenfell@Whakatāne .govt.nz Alt Controller David Bewley 07 306 0500 027 613 6244 davidb@Whakatāne .govt.nz Alt Controller Paula Chapman 07 306 0500 021 233 3970 paulac@Whakatāne .govt.nz Kawerau Kawerau District Council Chris Jensen 07 306 9009 0274782331 [email protected] Rotorua Rotorua District Council Duty CDEM 0274882181 [email protected] Linda Johnston 07 348 0192 (pager) 027 230 8705 [email protected] 07 348 4199 Jean-Paul Gaston – Controller 07 350 0162 027 655 4415 [email protected] Western Bay of Plenty CDEM Group Duty Manager 027 519 4823 Tauranga CDEM Group Duty Manager 027 519 4823 *Not all the CDEM controllers and alternative controllers are listed here that information is available from the CDEM Group Duty Manager.
Bay of Plenty Regional Council Flood Warning Manual 35
Appendix 15 – Radio station contacts
Contacts for all general advisory messages:
Contact number Fax number Email address Radio Bay of Plenty - 1XX 07 308 6239 07 307 1242 [email protected] Studio 07 306 1242 24 hour emergency contact Glenn Smith 021 244 9825 [email protected] Radio Live 0800 723 465 [email protected] Radio NZ 04 474 1999 [email protected] Radio NZ - Environment - Olivia Wix [email protected] Newstalk ZB 09 373 0000 [email protected] BOP Newstalk ZB 07 578 9139 [email protected] RNZ Rural 04 474 1999 [email protected] Sun Live and Weekend Sun 07 578 0030 07 571 1116 [email protected]
Bay of Plenty Regional Council Flood Warning Manual 37
Appendix 16 – Essential contacts
Contact number Fax number Email address ŌpōtikiDistrict Council 07 315 3030 07 315 7050 [email protected] Whakatāne District Council 07 306 0500 info@Whakatāne.govt.nz Kawerau District Council 07 306 9009 07 323 8072 [email protected] Tauranga City Council 07 577 7000 07 577 7193 [email protected] Western Bay of Plenty District Council 07 571 8008 / 0800 926 732 07 577 9820 [email protected]
Name Work phone Home phone Cell phone Fax number Email address Airport Control Towers Whakatāne 07 308 8397 Mount Maunganui 07 575 4144 Rotorua 07 345 5199 Awaiti-Omeheu Eveleens 07 304 9157 Floodgate Closures Platt Gow Trust 07 304 9591 AC and M Martin 07 304 9544 Steiner 07 304 8432 Nova All Electrical Faults/No Power 0800 500 710 (press 1) Whakatāne Office 07 306 2700 07 307 0922 Aniwhenua Power Station 07 366 4782 Fonterra Energy Centre 07 306 2718 (Edgecumbe Power Station) Commercial Manager: 07 306 2704 027 457 6303 [email protected] Chris Power Generation Mechanical Engineer: 07 306 2737 0274751468 [email protected] Gil Clark Generation Operations Engineer: 07 306 2706 0274750145 [email protected] Ken Dodson
Bay of Plenty Regional Council Flood Warning Manual 39
Name Work phone Home phone Cell phone Fax number Email address Generation Operations Manager: 07 306 2709 027 459 1757 [email protected] John Smyth Coastguard Coastguard Whakatāne 07 308 7110 BOP Harbour Master / Peter Buell 0800 884 881 027 519 3559 [email protected] Manager extn: 8411 Deputy Harbour Master Chris Isherwood 0800 884 881 021 649 819 [email protected] extn: 8418 Federated Farmers BOP President Rick Powdrell 07 573 7481 027 489 4075 [email protected] BOP Treasurer and chair of Derek Spratt 07 533 3764 027 482 0848 07 533 3764 [email protected] the BOP Rural Support Trust Katikati/Tauranga Chair Judy Treloar 07 544 8063 027 45333752 [email protected] Te Puke Chair Steve Bailey 07 573 7098 [email protected] Manawahe Chair Tim Mackintosh 07 322 1039 027 493 7312 [email protected] Whakatāne/Galatea/ John Howard 07 308 5084 [email protected] Tauranga Ōpōtiki In recess Generators NZ Generator (Steven Andrews) 07 574 2950 027 449 0490 [email protected] Helicopters Lakeland Helicopters 021 784 529 [email protected] Harbour City Helicopters Ltd 07 308 8551 027 243 0985 07 308 8101 [email protected] Mark Somerville Fonterra Edgecumbe Site 07 304 7000 07 304 7061 Energy Centre 24 hours 07 304 7001 – 1 - 4808 NIWA Rotorua (work hours) 07 346 1950 KiwiRail 24 hour Help Desk 09 488 6886 Duty Network Control Manager 04 498 2066 Network Control Manager 021 440 112 (Kawerau) Wellington 04 498 3006
40 Bay of Plenty Regional Council Flood Warning Manual
Name Work phone Home phone Cell phone Fax number Email address Bryon Briffault 027 492 4052 Andy Morris 027 284 8457 Gavin Smith 027 572 6116 Meteorological Office 04 470 0783 Maketu Diversion Closure Clem Tapsell 07 533 2327 Elaine Tapsell 07 533 2503 DOC Rotorua 07 349 7400 Police Edgecumbe 07 304 9004 Kawerau 07 323 1400 Mt Maunganui 07 575 3143 Murupara 07 366 1170 Ōpōtiki 07 315 1110 Rotorua 07 348 0099 Tāneatua 07 312 8070 Tauranga 07 577 4300 Te Puke (Kaituna area) 07 573 9147 Te Teko 07 322 8206 07 307 0873 Whakatāne 07 308 5255 Postmaster Waimana 07 312 3048 07 312 3046 (Bell and Hodgson: Agency) Ray Bell Raingauge Readers Wharawhara Water Treatment 0274978930 Plant Carter Holt Harvey (Tarawera @ 07 306 9050 Kawerau) TrustPower (Matahina Dam) 07 322 8014 NOVA (Aniwhenua Dam) 07 366 4782 07 306 2705 NOVA (Wheao Dam) 07 377 0372 John 027 432 5836
Bay of Plenty Regional Council Flood Warning Manual 41
Name Work phone Home phone Cell phone Fax number Email address Timberlands 07 343 1040 Tarawera, Omataroa, Galatea, Kāingaroa, Waiotapu, Tauhara Forest, Waimahia, Minginui Roading NZTA Duty Number 027 473 7766 Terry Boyle Mike Russell Higgins Duty Number 027 444 0687 NZTA network contractor – Rotorua, Kawerau, Whakatane & Opotiki Westlink Duty Number 07 577 4680 NZTA contractor – SH WBOPDC & TCC areas. NZTA Bridge Management 027 498 6718 BECAs Andrew Ball Whakatane Roading Opus Duty Phone 027 426 7373 Whakatane District Council Martin Taylor 027 254 5128 Aden Glynn 027 254 5128 Sand Bagging Assistance Federated Farmers Bruce Woods 07 322 8570 Scotty Muir (Galatea) 07 366 5666 Scottie McLeod 07 308 7731 Brian Power 07 308 4846 Glen Shaw 07 304 6063 07 3048236 Traffic and Crowd Legion of Frontiersman: 07 308 0928 Control Whakatāne Edgecumbe 07 304 9578 Maori Wardens 07 308 0936 Transpower Edgecumbe Substation 07 838 0677 021 443 144 Bob Combs (Station Manager)
42 Bay of Plenty Regional Council Flood Warning Manual
Name Work phone Home phone Cell phone Fax number Email address TrustPower Duty number – 24 hours 07 574 7958 Control Centre (Te Maunga) Kaituna Area Operations Centre 24 hrs 0800 878 787 (Tauranga) Generation 24 hrs 07 574 7958 07 574 4777 Matahina Dam 07 322 8014 07 322 8024 Head Office (Tauranga) 07 574 4800 07 574 7958 Generation 24 hrs 07 574 4888 extn: 777 Wheao Dam (Control Room) 07 575 2908 0274979215 0274979215 Power Lines: Western BOP 06 759 6565 Rotorua/Taupo 06 873 9397 Hydro Schemes (24 hr): Kaimai 07 574 4777 Wheao 07 574 4777 Matahina 07 574 4777 Waimana Area Te Waimana Kaaku Tribal 07 312 3700 [email protected] Executive Diane Ruru 07 312 3021 Waimana School Marie Tiopira 07 312 3038 Helen Te Waara 07 315 4611
Bay of Plenty Regional Council Flood Warning Manual 43
Appendix 17 – Contractor and equipment contacts
Contractors, pumps and equipment available for flood events *Panel Contractors Name of company Contact person Contact numbers Description Pumping equipment Rick Powdrell Te Puke – Federated Farmers 07 573 7481 027 489 4075 Hi Tech Irrigation Rob Sweet 07 889 7755 2 x AFIL 027 492 4046 1 x Doda Drain Tech Stu Munroe 07 308 4007 2 x 150 c Pelque pumps 027 274 7033 Hi-ab Selwood Pumps Steve Thorpe 09 526 9159 Mobile pumps – Various sizes 027 446 3489 Sykes New Zealand Steve Mercer 09 278 8300 Mobile pumps – Various sizes 021 833 565 Hire Pool Whakatāne 07 308 8821 6 x 6 Sykes pumps – Whakatāne Dave Rankin 027 497 7567 2 x super silence – 6’” Hire Pool Tauranga 07 543 0742 2 x 6” diesel -Normal 6” not silenced Jack (Tauranga) 027 587 8051 Hire Pool Mount Maunganui Adrian Penberthy 027 578 1803 Nation wide NB: Hire Pool and Hire Equip have (Mount Maunganui) 07 572 3436 12 x 100 mm pumps amalgamated 1.6.2013 On call phone no 027 235 0551 3 x 100mm high head pumps 23 x 150 mm pumps 1 x 200 mm pumps Suction 7 m x 7 m Delivery 20 m normal Selwood
Bay of Plenty Regional Council Flood Warning Manual 45
Contractors, pumps and equipment available for flood events *Panel Contractors Name of company Contact person Contact numbers Description Devon Hire New Zealand John Chapman 021 479 537 [email protected] Hartley’s Paul Hartley – Kawerau 07 323 7790 1 x 10” diesel 1 x 10” submersible plus generator Hawkes Bay Regional Council Dan Heaps 06 835 9200 0274 555 226 Email – [email protected] Hawkes Bay Regional Council Brendon Walker Operations 027 612 1555 Mobile pumps Environment Waikato Guy Russell [email protected] Roger Gee 07 856 7184 Fax 07 856 0551 Ian Saru 021 972 698 Peter Cowan 021 359 736 Ronny Gram 021 223 6713 Hauraki District Council Bruce Stephens ( Goldie) Email - [email protected] Water harvesters Fax 07 862 8607 07 862 8609 Western Bay Hire Ron Judd 027 220 9675 Te Puke 07 573 9671 Scotty McLeod Scotty – Local Farmer 027 490 5825 2 x Submersible pumps/One pump free standing Ginko Neville Loveridge 027494 6710
46 Bay of Plenty Regional Council Flood Warning Manual
Contractors, pumps and equipment available for flood events *Panel Contractors Name of company Contact person Contact numbers Description Contractors with machinery *A and R Rust Alan Rust 0274 878 667 Awakeri. Heavy equipment and transporter. Beau Thompson Limited Beau Thompson 021 946 919 / 025 946 919 Whakatane. Trucks and excavators *Crowley Excavators Limited Craig Crowley 07 308 4408 Whakatane. Excavators and bulldozer. *Dovastons Agriculture Ltd Daniel Dovaston 0274 570 495 Te Puke. Heavy earthworks equipment. *Doug Gerrand Ltd Doug Gerrand Ltd 07 542 2410 / 0274 937 361 Te Puke. Excavators, grader, trucks and trailers. 0275 770 646 Downer NZ Limited Ian Simonsen 027 705 2724 EBOP. Heavy earthworks equipment. Jeff Tomblyn Awakeri 027 499 1382 *EBOP Plant Services Leigh Carter 07 308 0344 / 021 730 790 Whakatane. Excavators, trucks and trailers, bulldozer, large bobcat. Edwards Contracting Galatea Andrew Edwards 027 753 8428 Galatea. 12 and 20 T excavators, bulldozer and transporter. *Fulton Hogan Ltd Ivan 07 542 9010/027 454 7905 Tauranga. Quarry, heavy machinery and truck.s Warwick Knutson 027 430 1338 Gary Broadmore Gary Broadmore 07 308 8389 / 027 4497 4062 WhakataneTractors and tractor powered generator. G A and K A McRobbie Contracting Graeme McRobbie 07 322 8557 / 027 495 3513 Whakatane. Trucks and excavators. *Gorringes Ltd Andrew Gorringe 07 549 1075 / 0272959561 Katikati. Excavators, trucks and trailers. *Grant Farms Tom Grant 07 308 8259 / 027 496 0558 Whakatane. Truck and trailers, tractor and trailers and excavators, grader. *HEB Construction Ltd Chris Whitham 07 575 2325 / 0277 048 579 Tauranga. Heavy earthworks equipment. *Ice Construction Ian Shaw 07 542 3174 / 021 626 804 Tauranga. Heavy earthworks equipment. Industrial Traders Dave Fretwell 0274 976 6518 Kawerau. Hiab truck *JMC Tauranga Paul Francis 027 223 427 / 07 552 6141 Te Puke. Earthworks machinery.
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Contractors, pumps and equipment available for flood events *Panel Contractors Name of company Contact person Contact numbers Description *Josephs Earthmoving Matt Josephs Rotorua. Heavy earthworks machinery. *J Swap Craig Payne 0274 927 882 Whakatane and Te Puke. Heavy earthworks Awakeri Quarry equipment and rock supplies Kāingaroa Roading Jan Bolton 07 366 5635/027 472 7839 Galatea. Trucks/excavators and grader *Kiwiland Excavators Ltd Stan Keane 07 533 1958 / 027 2467397 Te Puke. Heavy earthowrks equipment. *Kiwi Land Developers Kym McIntosh 07 533 3063 / 027 4741589 Te Puke. Heavy earthowrks equipment. Murray Salt Contracting Brian 07 573 6673 / 07 573 6672 / 027 446 Te Puke. Heavy earthowrks equipment. 6546 Porter Hire Mount Maunganui Steve McIntyreRiver 07 575 6340 Mobile:027 492 2709 Heavy earthworks equipment dry hire Readfields Limited Bruce Read 027 497 3820 Te Puke. Excavators / trucks *R Mahy Contracting Richard Mahy 021 769 763 Whakatane. Earthworks machinery and rock supplies *Seger Roading Ltd Derek Maisey 07 3455 800 / 021 901 471 Rotorua. Heavy machinery. *Tracks Concrete 2002 Ltd Ken Young 027 494 6437 Whakatane. Trucks and excavators Bas (Kevin) Dodds 027 454 4741 Transfield Ken Knowlson 027171 8438 Tauranga and Whakatane. Earthworks machinery *Waiotahi Contractors – Ōpōtiki Spike Petersen 0274 797 280 Opotiki. Heavy earthworks equipment. Anthony Rudkin 0274 490 760 *Waiotahi Contractors - Whakatāne Graham Mills 07 308 8098 Whakatane. Heavy earthworks equipment. *WBE Construction Ltd. Harry Wilson 027 474 9813 Opotiki and Whaktane. T Heavy earthworks John Van den kirk Hoff 027485 4270 equipment and rock supplies *Woodward Contracting Ltd Dennis and Liz Woodward 07 573 9071 / 0274 972 550 Te Puke. Heavy earthworks equipment. Electrical contractors *Control Tech Karam De Lacey 07 315 8867 / 0274 993 944 Opotiki. Electrician
48 Bay of Plenty Regional Council Flood Warning Manual
Contractors, pumps and equipment available for flood events *Panel Contractors Name of company Contact person Contact numbers Description Jeff Enckevort 027 499 3944 ESP 07 308 9800 Brett Magee 027 443 3212 *WEC - Whakatāne Electrical Mike Jennings 07 308 0446 Electrician Contractors (24 hours) (for Kopeopeo and Thornton West Pump Station) Brian East 07 304 9470 / 027 274 0540 First choice for Rangitāiki Pumps, part of Whakatāne Electrical Contractors) *Milbank Industrial Electric Craig Milbank 07 323 7733 / 021 926 124 Whakatane. Electrician Electricity suppliers Bay of Plenty Electricity 0800 500 710 Horizon Energy 07 922 8800 – 0800 467 496 Engineering contractors Bay Fabricators 07 308 6557 *BW Engineering formerly Sisson Brian Windall 07 308 5596 Engineering and stop logs installations Engineering Whakatāne Hi Ab truck Eastern Bay Engineering Ltd Les Maynard 027 4921004 / 07 308 9797 Whakatāne.Engineering
*John Wilson Engineering Ltd John Wilson Edgecumbe. Engineering Morris Bros Engineering Robbie Morris 07 304 9892 Edgecumbe. Engineering Summit Engineering and 07 348 0464 Rotorua. Engineering Hydraulics Ltd *Opotiki Pumps and Irrigation Stephen Carter 07 315 5533 / 027 239 5212 Opotiki. Engineering *William Ross Engineering Ltd 07 323 8821 Manukorihi Drive Kawerau Ian Ross 027 454 0297 Engineering
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Contractors, pumps and equipment available for flood events *Panel Contractors Name of company Contact person Contact numbers Description Knowledgeable manpower available Federated Farmers Contacts Matt Gow 0274 744 065 Liaison with farmers etc Brian Power 0274 787 827 Robin Barkla 07 308 6520 Kaituna Liaison Person Richard Weld 0274 728 146 Liaison with landowners kaituna Phillips Contracting Josh Phillips 0275 873 551 Labour- tractors Paul McDowell Labour hire- pumps John Knebel Ōpōtiki John 07 3155 304 Labour unit Companies for sand supplies (Sand bagging) Allied Concrete Andy Horsburgh 027 224 7558 / 07 307 0317 Sand and concrete trucks Firth Concrete Ngature Pewhata 07 308 7029 Office Sand and concrete trucks Waiotahi Contractors Limited Spike Petersen Ōpōtiki 07 315 6580 / 027 479 7280 Sand and concrete trucks Firth Concrete Tauranga Willy Waters 027 471 2749 / 07 571 0162 Sand and concrete trucks Purchase of sacks for sand bagging Textile Bag and Sack Co Limited Auckland 09 629 0656 Fax Good service provided 09 629 0266 Phone
50 Bay of Plenty Regional Council Flood Warning Manual
Contractors, pumps and equipment available for flood events *Panel Contractors Name of company Contact person Contact numbers Description Rail iron/pipes/wire rope general engineering supplies Rope and Rail Andy Moir 021 934 457 Quarries Fulton Hogan – Matawai Sean McIntyre 027 681 8353 Fulton Hogan – Poplar Lane Daniel Topp 027 702 6126 Arthur Fulton 027 437 2379 Pukehou Quarry – Waiohau Rob Angus 027 289 8810 Otipa Quarry– Matahina Harry Wilson 027 278 5947 John Van den kirk Hoff 027 485 4270 A R Rust Contracting Alan Rust 027 487 8667 Ratahi Quarry– Waiotahi Earl Bunyan 027 492 4151 Contractors Graham Mills 027 494 5694 Awakeri Quarries – J Swap Craig Payne 027 492 7882 Bakkers Quarry – Pumice Alan Baker 027 449 7155
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Appendix 18 – RT Call Signs
Updated January 2016 – Refer to SAM for the latest list.
Bay of Plenty Regional Council Callsigns Key to Prefixes: ’Regional’ ’Bay of Plenty Civil Defence’ Student Mary-Anne 1 22 Reuben Fraser 43 Andy Bruere 64 Greg Corbett 200 Environmental Macleod Delivery Student Regulatory 2 Mark Townsend 23 David Paine 44 John Morris 65 Marnie Fornusek 201 & Customer Service Graeme Jessica Hunter Student Technical 3 Arthur Rangihika 24 45 Paul Futter 66 202 O’Rourke Smith Services 4 Daniel Batten 25 Tim Senior 46 Adrian Heays 67 Shane Grayling 203 Student Corporate 5 Andrew Pawson 26 Shaun Menzies 47 Dwayne McKay 68 Daryll Hall 204 Hamish Lass 6 Nancy Willems 27 Steve Pickles 48 Helen Creagh 69 Arch Delahunty 205 Angela Reade 7 Anaru Freeman 28 Stephen Park 49 Laboratory Ute 70 Ingrid Pak 206 Tanya Amaya 8 Donna Watchman 29 Paul Scholes 50 Amy Greaves 71 Terriann Payne 207 Steven Campbell 9 Stan August 30 Eddie Grogan 51 Diane Harvey 72 John Holst 208 Matthew Harrex 10 Jason Rive 31 Glenn Ellery 52 Sam Weiss 73 Pim De Monchy 209 Milly Farquar George (Hori) 11 Roger Waugh 32 Craig Putt 53 Shane Hona 74 210 Richard Mallinson Melbourne 12 Yves Denicourt 33 Craig Rowson 54 Karen Parcell 75 Shay Dean 211 Raoul Fernandes 13 Rochelle Carter 34 Brent Hutchby 55 Clinton Naude 76 Jo Cranswick 212 Katalin Maltai 14 Ken Tarboton 35 Lisa Bevan 56 Peter Buell 77 Mike Collins 213 Paul Bourton Malcolm Paul 15 Bruce Crabbe 36 57 78 Jason Laurent 214 Mike Caldwell Burningham Greenshields 16 Tony Dunlop 37 Charl Naude 58 Dale Williams 79 Lisa Naysmith 215 David Ede Penny 17 Rob Win 38 Braden Rowson 59 Wiki Mooney 80 216 Matt Liddicoat MacCormick 18 Brendon Taipeti 39 Rob Donald 60 Alby Osborne 81 Jon Edney 217 Andy Wills 19 Rick Knebel 40 Alastair Suren 61 Courtney Bell 82 Niroy Sumeran 218 Hamish Dean Reuben 20 Marcus Bloor 41 Janine Barber 62 83 Thomas Grant 219 John Paterson Hawtree 21 Charles Harley 42 Bruce Gardner 63 Chris McKay 84 Ross Powell 220 Mathilda Hasselman 85 Sam Stephens 221 Samantha Titze Bay of Plenty Regional Council Channels 86 Warwick Murray 222 Aydin Maxfield CHANNEL CHANNEL NAME DESCRIPTION 87 Chris Brewer 223 Natalie Miedema # 1 VOICE WHALE Coastal Transmissions 88 Simon Stokes 224 Jean McCauley George Kelly- 2 WHALE REV Coastal Reverse 89 Jill Owen 225 Waihirere 3 VOICE EDGE Inland Transmissions 90 David Marven 226 Amanda Death 4 EDGE REV Inland Reverse 91 Eykolina Benny 227 Craig Morris 5 TELEMETRY Telemetry Channel 92 Krystle Doney 228 Fraser Toulmin 6 TELEM REV Telemetry Reverse 93 Peter Vercoe 229 Gloria Oliver * Transmission Forbidden on CH 7 to CH 15 unless authorised 94 Marlene Bosch 230 Jono Meldrum * 7 NIWA NIWA Telemetry 95 Scott Mahupuku 231 Naomi Luckett * 8 NIWA REV NIWA Telemetry Reverse 96 Mark James 232 Jim Tetlow * 9 BOP Rptr ES75 CDEM Portable Repeater 97 Andrew Blayney 233 Meagan Edhouse * 10 BOP SX 1 ESX52 CDEM Simplex 1 98 Ryan Standen 234 Kaz Thompson Stephanie * 11 BOP SX 2 ESX77 CDEM Simplex 2 99 235 Jodie Rickard Bathgate * 12 CD 16 CDEM 16 100 236 * 13 CD 16 REV CDEM 16 Reverse 101 237 * 14 CD 6 CDEM 6 102 238 * 15 CD 6 REV CDEM 6 Reverse 103 239 19 VOICE ROT Rotorua Area Link Channel 104 240 20 SET TO SET Set to Set (Walkie Talkie) 105 241 Channels in italics are main Bay of Plenty Regional Council voice channels 106 242
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