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Coromandel flood protection scheme design report

TR 2013/45
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Report: TR 2013/45

Author: Megan Wood (Wainui Consulting Limited)

About this report

The purpose of this design report is to provide a summary of the works that have been undertaken at Coromandel town to reduce the flood hazard from the Karaka and Whangarahi streams, including the rationale behind the scheme development, the agreed levels of service, the design details, as built information, the operation and maintenance requirements of the scheme, the residual flood risk and the scheme review requirements.

The design report includes the following sections:

  • Catchment overview
  • Hydrological assessment
  • Hydraulic model development
  • Flood protection scheme
  • Future works
  • Agreed levels of service
  • Operation and maintenance
  • Flood hazard assessment
  • Residual flood risk
  • Planning controls, and
  • Scheme review.

Read or download the report

Coromandel flood protection scheme design report [PDF, 3.6 MB]

Contents
  Executive summary vii
1 Introduction 1
1.1 Background 1
1.2 Scope of report 1
2 Catchment overview 2
 2.1 Catchment description 2
 2.2 Whangarahi and Karaka Streams 3 
 2.3 Flooding issues 5
 3 Hydrological assessment 9
 3.1 Technical information 9
 3.2 Catchment characteristics 9
 3.3 Rainfall 11
 3.4 Flow estimates 11
 3.5 Hydrograph 13
 4 Hydraulic model development 14
 4.1 Introduction 14
 4.2 Model inputs 14
4.3 Design models 15
4.4 Model validation 15
4.5 Model assumptions and limitations 15
4.6 Peer review 16
5 Flood protection scheme 17
5.1 Long-term vision 17
5.2 Scheme evolution 18
5.3 Channel improvements 20
5.4 Albert Street properties 22
5.5 Flood defences 23
6 Future works 26
6.1 Outstanding scheme components 26
6.2 Managing the existing scenario 27
7 Agreed levels of service 39
8 Operation and maintenance 30
9 Flood hazard assessment 32
9.1 River flood hazard classification 32
9.2 River flood hazard map 33
10 Residual flood risk 35
11 Planning controls 36
12 Scheme review 37
13 References 38
  Appendix 1: Peer review of hydraulic model 39
  Appendix 2: Flood defences design 47
  Appendix 3: As-built survey 55