River rating districts
Across Waitaha/Canterbury, flood protection and drainage works are carried out in dedicated rating districts. These works are called scheme works.
Some of these rating districts have liaison committees with voluntary community representatives to help our staff plan and prioritise scheme works.
Reporting is carried out via yearly district community meetings and a yearly asset condition summary that shows the condition of our assets and informs future planning for scheme works at a regional level.
We manage 58 river and drainage rating districts, each with scheme works on specific parts of rivers or drainage networks across Waitaha. It’s a big job and we need eyes and ears on the ground to help understand whether the current level of safety, security and resilience from flooding and erosion is being met, or if the district has adequate and appropriately resourced drainage network.
Large rating districts have dedicated liaison committees whereas for smaller schemes staff engage directly with all the ratepayers (no dedicated liaison committee as such).
District liaison committees
The purpose of each river or drainage rating district liaison committee is to liaise with Councillors and staff on matters relating to river control works and rating, and flood protection and flood plain management within the rating district.
Committees meet once a year, sometimes more depending on what scheme work is happening in their area. They provide advice and inform staff on the state of the river and the proposed works and budget for the coming year. They also have an influence on targeted rates set for each district and the timing of significant works but final decisions are made by Council.
While committees occasionally discuss matters such as incorporating amenity or biodiversity objectives into erosion protection works, or the influence of water takes on the river rating district works, those issues are not their primary focus.
River rating district meetings generally work on a three-year cadence:
Year one and two is where liaison committee members will meet to discuss current and proposed works, rating and funding, and asset management with staff. This provides an opportunity for committee members to bring feedback from the wider rating district/community for staff to consider where possible.
Year three is a public meeting where committee members are elected to represent the river rating district for the following three years. We encourage all river rating district ratepayers and adjacent communities to attend these meetings.
View events calendar for details on all of our river rating district meetings including date, time and venue.
Our river rating districts each have a work programme – these works are called scheme works.
Rating district information
A quarterly river operations report sets out what scheme works are planned across the region for the following three months.
See the latest three-monthly workplan for works across the districts on our current river works page.
Regional asset management
We also have a yearly asset condition summary that shows the condition of our assets and informs future planning for scheme works.
Asset condition is a measure of the physical state of the asset and is visually assessed by staff on an annual basis.
This information is critical to the management of the assets - maintaining the asset at minimum cost, maintaining the required level of service, forecast renewal requirements and prioritising works. The assets are inspected depending on the asset type and the importance of the asset, which means that not all assets are included in each annual summary.
We have several methods to monitor the condition of the rating district assets. We assess stopbanks, river fairways, river berms, and drains.
The asset condition summary explains the following types of condition assessment:
- Localised stopbank assessments, recording localised defects.
- Reach stopbank assessments, which summarise what risk a series of localised defects pose to a length (typically 3-5km) of stopbank.
- Fairway condition assessments, where the relative obstruction of the fairway is assessed by comparing to a design cleared fairway width.
- Berm condition assessments, where relative berm resistance to erosion is compared to a design or sufficient berm strength.
- Drain condition assessments, primarily assessing obstruction of drains.
Condition assessments are typically on a 1-5 scale, where 1 means excellent condition, 3 may be adequate or with minor deficiencies and 5 is very poor condition, or not fit for purpose.