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Te Puru flood protection scheme design report

TR 2013/42
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Report: TR 2013/42

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 Te Puru to reduce the flood hazard from the Te Puru Stream, 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
  • Agreed levels of service
  • Operation and maintenance
  • Flood hazard assessment
  • Residual flood risk
  • Planning controls, and
  • Scheme review.

Read or download the report

Te Puru flood protection scheme design report [PDF, 26 MB]

Contents
  Executive summary iii
1 Introduction 1
1.1 Background 1
1.2 Scope of report 1
2 Catchment overview 2
2.1 Catchment description 2
2.2 Te Puru Stream 3
2.3 Flooding issues 5
3 Hydrological assessment 8
3.1 Technical information 8
3.2 Catchment characteristics 9
3.3 Rainfall 9
3.4 Flow estimates 10
3.5 Hydrograph 11
4 Hydraulic model development 11
4.1 Introduction 11
4.2 MIKE-21 model 12
4.2.1 Model inputs 12
4.2.2 Model location 12
4.2.3 Model validation 13
4.2.4 MIKE-21 model assumptions and limitations 13
4.3 MIKE-11 model 14
4.3.1 Model inputs 14
4.3.2 Model location 14
4.3.3 Model validation 15
4.3.4 Bridge upgrade 15
4.3.5 Design models 15
4.3.6 MIKE-11 model assumptions and limitations 16
4.3.7 Peer review 16
5 Flood protection scheme 17
5.1 Scheme history 17
5.2 Scheme evolution 17
5.3 River and catchment works 18
5.4 Channel improvements 19
5.4.1 Background 19
5.4.2 Design details 19
5.5 Flood defences 20
5.5.1 Main scheme 20
5.5.2 Flood wall extension 21
5.5.3 Spillway 23
5.5.4 Floodgates 24
5.6 SH25 bridge upgrade 24
5.6.1 Pre-scheme SH25 bridge 24
5.6.2 Bridge design 25
5.6.3 Reduced freeboard 25
5.7 Future works 25
6 Agreed levels of service 26
7 Operation and maintenance 27
8 Flood hazard assessment 29
8.1 River flood hazard classification 29
8.2 River flood hazard map 30
9 Residual flood risk 32
10 Planning controls 33
11 Scheme review 34
12 References 35
  Appendix 1: NZTA’s bridge design assessment 37
  Appendix 2: WRC’s bridge model 51
  Appendix 3: Erosion protection design details 55
  Appendix 4: Flood protection scheme design details 58
  Appendix 5: Secondary overland flowpath arrangement 89
  Appendix 6: Bridge upgrade design drawings 92
  Appendix 7: As-built survey 97