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  Services » Publications » Technical reports - by year » TR200212

Waikato and Waipa rivers flood event 6-16 July 2002

Report:TR 2002/12
Author: Adam Munro

Abstract

This report examines the key aspects of the “Waikato Waipa Rivers Flood Event of 6-16 July 2002”. It has been produced as part of Waikato Regional Council's internal reporting requirements.

The report provides a comprehensive overview of the flood event that resulted in very high river levels in the western and southern parts of the region as a result of heavy and persistent rain in the six weeks prior to the main event. The has been taken to pull together a wide range of information findings from both internal and external sources, including:

  • Hydrological data (rainfall totals and river levels)
  • Flood Management Strategies
  • Waikato Regional Council (WRC) Response
  • Key decision points

Waikato and Waipa Rivers flood event 6-16 July 2002
(1321 kb, 188 seconds to download, 56k modem)  

Table of Contents

1 Introduction 1
2 Hydrological Information 1
  2.1 Rainfall 1
  2.2 Severe Weather Warnings (SWW) 2
  2.3 River Level and Flow Information 2
3 Flood Warnings 3
4 Community Gate Operations 3
  4.1 Gate Open/Closure Times 4
5 The Waikato Hydro System 4
  5.1 Lake Taupo Management 7
  5.2 Karapiro Outflows 7
6 Flood Management Strategies Adopted 8
7 Environment Waikato’s Response 9
8 Flood Scheme Performance 10
  8.1 Background 10
  8.2 The Scheme Design 10
  8.3 River and Protection Scheme Performance 11
  8.4 Flood Profiles 12
    8.4.1 Flood Event 1998 12
    8.4.2 Flood Event 2002 13
    8.4.3 Performance 13
    8.4.4 Comments 13
  8.5 Remedial Works 13
    8.5.1 Waikato District Assets 13
    8.5.2 Franklin District Assets 13
    8.5.3 Environment Waikato Assets 13
  8.6 Costs and Funding 14
  8.7 Approximate Areas Inundated 14
  8.8 Summary of River and Protection Scheme Performance 14
  8.9 Operational Improvements 15
    8.9.1 Flood Warning Network Review 15
    8.9.2 Comments by area 15
9 Summary of Impacts 18
10 Local Initiatives 18
11 Where to from here 19
12 Summary and Conclusions 19
Appendix A: Severe Weather Warnings 21
Appendix B: Media Releases 26
  Flood Team Ready for Wet Weekend 26
  More Rain Predicted for Soaked Waikato 26
  Flood Teams Gear Up for Another Wet Week 27
  Flood Team Watches River Over Night 27
  More Rain Worries Flood Managers 28
  Council Makes Use of Weather Break 28
  Council Moves Water as River Peaks Drop 29
  Flood Scheme Holding as More Rain Looms 29
  Uncertain Forecast for Weekend Rain 30
  Heavy Rain A Concern for Mercer, Coromandel 31
  Fine Weather Gives Break for Flooded Waikato 31
Appendix C: TPD Diversion Matrix (guideline only) 33
  Factor 33
  Key criteria 33
  Rising/falling 33
  Options 33
  Maximum 33
  Average 33
Appendix D: Waikato and Waipa River Flood Profiles 34
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