PROJECT

Surveying the Ōhau Canal

Meridian Energy

Waitaki Valley, New Zealand

Location

Waitaki Valley, New Zealand

SECTOR

Infrastructure & Commercial

PROJECT SCALE

Critical Hydroelectric Infrastructure

Fox Environmental supported Meridian Energy in assessing the condition of a critical section of the Waitaki Hydroelectric Scheme—New Zealand’s largest hydroelectric power system, generating around 16% of the country’s electricity. By combining advanced hydrographic surveying, UAV technology and integrated spatial analysis, we delivered an accurate understanding of canal performance while allowing power generation to continue uninterrupted.

What the client needed

Maintaining the integrity of the Waitaki canals is essential to the long-term reliability of one of New Zealand’s most important infrastructure assets. The rock-armoured canals require ongoing monitoring to identify erosion, sediment build-up and any deterioration that could compromise performance.

The challenge

Surveying the canal presented several challenges. The canal remained operational throughout the project, requiring surveys to be undertaken with the waterway at full capacity. Access was constrained by bridges and salmon farm infrastructure, winter conditions demanded enhanced safety measures, and all equipment needed to operate without risk to the hydroelectric system.

How we helped

Fox Environmental surveyed approximately 2.4 kilometres of canal using both the BathyCat and Jettec unmanned surface vessels. The BathyCat was utilised during lower flow conditions, while the jet-powered Jettec enabled accurate surveying in faster-moving water. Both vessels remained tethered throughout operations to ensure safe deployment.

Despite reduced underwater visibility caused by glacial sediment, sonar mapping combined with UAV-derived LiDAR and aerial imagery enabled the creation of a detailed digital model of the canal and surrounding infrastructure, including the salmon farm rafts.

The completed 3D model was aligned with Meridian’s original design cross-sections, allowing potential areas of erosion and material accumulation to be accurately identified.

The outcome

The project delivered:

A high-accuracy, geo-referenced model of the canal.
Identification of areas requiring further inspection or maintenance.
Improved understanding of the influence of salmon farm infrastructure on canal performance.
Reliable information to support informed, cost-effective asset management decisions.

The clarity and quality of the final deliverables provided Meridian with confidence in both the findings and the recommended next steps. The project demonstrates Fox Environmental’s ability to combine innovative technology with practical engineering expertise to solve complex infrastructure challenges safely and efficiently.