Creating accurate terrain data is critical when it comes to understanding how rivers move, erode, and interact with the surrounding land. That’s why Gisborne District Council engaged us to deliver a combined UAV LiDAR and bathymetric survey across five key bridges and river channel sites throughout the Tairāwhiti region.

The aim was to generate a full terrain model that seamlessly captured both land and riverbed — giving council engineers a complete and continuous surface to work from for future planning, resilience assessments, and hydraulic modelling.

For the land-based component, our team deployed UAVs equipped with LiDAR sensors to capture high-density 3D data of the terrain above water. This method provided detailed topography, even through dense vegetation and over hard-to-reach areas. To complement the aerial data, we conducted bathymetric surveys using RTK GPS-mounted equipment on small watercraft. This allowed us to map the submerged sections of each river channel with precision, including variations in bed levels and flow paths.

At each of the five bridge locations, the two datasets — aerial LiDAR and bathymetric depth readings — were integrated into a single, geospatially aligned terrain model. The result: a high-resolution, site-specific surface that gives decision-makers exactly what they need to manage assets, assess flood risk, and design future works with confidence. Smart tech. Local knowledge. Seamless results. That’s how Onsite delivers insights where land and water meet.