Floodplain hazard management assessment

ORC has recently completed a study to better understand and adapt to or manage floodplain hazards such as flooding and erosion.

The report by Damwatch Engineering Ltd focuses on management of three areas where floodplain hazards - flooding or erosion – may impact on the community or infrastructure in the head of Lake Wakatipu area;

  1. The lower Rees River and Glenorchy township
  2. The Dart floodplain and Kinloch access
  3. The Rees floodplain and the Rees bridge


The report

Floodplain hazard management report

The report identifies a range of potential hazard management interventions, and reviews the key benefits and constraints of those approaches.

These report does not give decisions or recommendations for a specific action. It is an information resource to help inform both the councils and the community as we together work to decide how to respond to these natural hazard challenges.

For each of the focus areas, the report includes tables discussing the engineering or river management interventions identified as possible approaches for management of floodplain hazards.

These assessments also included reviewing river management and engineered suggestions by community members as possible approaches for managing the flood hazard in the Rees River, Dart River and Glenorchy area.

They key report findings are presented as Tables 4.1, 5.1 and 6.1 of the Damwatch report. Each of these tables provides a summary of the potential intervention approach, and lists the key constraints which may be challenges in implementing that type of intervention.

Here is just one example.

Table 4.1 extract example Damwatch reportExample extract from Table 4.1 of the Damwatch report to show how assessment findings are laid out.

We welcome your feedback on the information in this report, please get in touch by email headofthelake@orc.govt.nz

Please let us know;

  • If you think this report has missed anything?
  • Do you have any questions, or is any information unclear?
  • Do you agree with the expert assessments – if not, why not?
  • Which of the approaches discussed in the report do you think should be investigated further – and why?

A similar consultant assessment of possible hazard management approaches for liquefaction and lateral spreading hazards is also underway.

This assessment will be a high-level overview of potential mitigation approaches for the liquefaction and lateral spreading hazards at Glenorchy, designed to provide information to help consider the following questions;

  • What mitigation is technically feasible for the liquefaction and lateral spreading hazards at Glenorchy township
  • What would be benefits of each mitigation approach, and what would they achieve?
  • What would be the indicative costs and key constraints to implementation of any of these approaches




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