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and simplification of SOPs Appendix 1 23/01/2015 2 Flood Warning Message Guide – Version 1, 18 October 2013 (A1684503) superseded by Version 2, 18 December 2014 (A2001882) 11/12/2015 2 Flood Warning Message Guide – Version 2, 18 December Part 15 2014 (A2001882) superceded by Version 2.1, December Flood 2015 (A2214804) Warning Groups 30/03/2016 3 Major updates include: Hours of work Part 2 Flood Forecasting updates Part 3 Name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 Bay of Plenty Regional Council Flood Warning Manual iii 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 Bay of Plenty Regional Council Flood Warning Manual v 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 vi Bay of Plenty Regional Council Flood Warning Manual 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