Looking down the Waihou River to its distal end in the Firth of Thames, New Zeland, the system is river dominated, meaning that the majority of sediments carried by the Waihou River from inland New Zealand are deposited at its mouth. Over time, the accumulation of sediments has formed a broad, flat tidal delta that is a dominant feature in the South East region of the Firth of Thames.
The survey of the Waihou River Tidal Delta at the Southeastern corner of the Firth of Thames was one of the largest surveys undertaken by ASR Ltd. A 4000 m x 7000 m box including very shallow/intertidal areas was surveyed by a single point bathymetry system at 50 m spacing at a speed of approximately 10 km/hr. 560 km of data was recorded for a total 200,000 data points (not including some areas not covered by LIDAR) over a period of 13 days. Problems encountered include difficult access, strong tidal currents, surface and subsurface obstructions, extremely shallow water (less than 0.5 m) and cold, wintry conditions.
The most satisfying aspect being that against these challenges, the survey was completed on time, within budget and delivered high quality data. This kind of data falls between what LIDAR and expensive multi-beam systems can collect.