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Grahams Creek flood protection scheme design report

TR 2018/09
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Report: TR 2018/09

Author: Ghassan Basheer

About this report

The purpose of this report is to document how key aspects of the Grahams Creek flood protection scheme in Tairua came into being and the level of flood protection it offers this community. Specifically the report provides an outline of the community demand for the scheme, community participation in defining the scheme parameters and levels of service, the scheme components and future requirements. It also describes the existing residual flood risks having constructed the flood protection works, to ensure that the beneficiaries of the scheme and local communities are aware of the scheme limitations. The operation and maintenance part of the report guides how the scheme will be maintained over time. A targeted rate is taken for maintenance (AM2175).  A targeted capital rate of c.$670,000 (AM2190) was also taken as well as opex costs from the Coromandel Zone budgets.  All costs were consulted on in Annual Plans.

 

Read or download the report

Grahams Creek flood protection scheme design report - Main [PDF, 2.7 MB]

Grahams Creek flood protection scheme design report - Appendix A part 1 [PDF, 7.7 MB]

Grahams Creek flood protection scheme design report - Appendix A part 2 [PDF, 3.1 MB]

Grahams Creek flood protection scheme design report - Appendix B [PDF, 3.2 MB] 

Grahams Creek flood protection scheme design report - Appendix C [PDF, 1.7 MB]

 

Contents
Abstract
Executive summary
1 Introduction
1.1 Catchment overview
1.1.1 Catchment description
1.1.2 Grahams Stream
1.1.3 Flooding issues
2 Hydrology
2.1 Peak flood flows
2.2 Flood volume and hydrograph shape
3 Hydraulic model parameters
3.1 Model bathymetry
3.2 Sea levels
3.3 Roughness
3.4 Boundary conditions
3.5 Model calibration
4 Community consultation
4.1 Scope of flood scheme works
4.2 Sign off to proceed
5 Agreed service levels
5.1 Right bank service level
5.2 Left bank service level
6 Technical design
6.1 Proposed flood alleviation components
6.2 Bridge capacity
6.3 Channel and floodway capacity
6.4 Culvert and floodgate
6.5 Stopbanks
6.6 Scheme Construction
6.7 Future works
7 Conclusions and recommendations
8 Flood hazard assessment
8.1 River flood hazard classification
8.2 River flood hazard map
8.2.1 Climate Change
9 Residual flood risk
10 Planning controls
11 Targeted Rating Classification
11.1 Direct and Indirect Benefit areas
12 Scheme review
  References/Bibliography