Barnett & MacMurray Ltd (B&M) was commissioned by Northland Regional Council to formulate a concept for a Kaihu River flood management system.

This statement of the concept of a flood management scheme for the Kaihu Valley is intended to be circulated to stakeholders for comment. The principles underlying the concept are that it should be economically justifiable, environmentally sustainable, and should treat all parts of the valley fairly, so far as possible.

Report Table of Contents

1. Summary

2. Introduction

3. Historical background

4. Cost constraints

5. Sustainability constraints

6. Outline of the concept

7. Design floods

8. Principles for fair distribution of floodwaters

9. Calculating the flooding volume proportions

10. Design process to achieve fair distribution of floodwaters

11. Treatment of less floodprone areas

12. Management of river sediment load and floodplain sedimentation processes

13. Council’s and landowners’ roles in construction, maintenance and monitoring

14. Effect of the proposed scheme in large floods

15. Conclusions

16. References