Accurate sediment volume data and bathymetric maps for councils and infrastructure managers — without divers, draining, or disruption.
Stormwater retention ponds, detention basins and treatment ponds are critical public infrastructure — but they fill with sediment over time, quietly losing the capacity they were designed to provide.
MĀKI surveys these assets using compact autonomous surface vessels (USVs) equipped with sonar and RTK GPS. The USV navigates a grid pattern across the pond surface, collecting depth measurements that are processed into detailed bathymetric maps and sediment volume reports.
No divers. No pumping. No disruption to pond operations. Just accurate, actionable data to support your asset management decisions.
Stormwater and treatment ponds often contain contaminated water. Our autonomous USV eliminates the safety and biosafety risks of sending divers into unknown or hazardous conditions.
Surveys are conducted with the pond at normal operating level. Sonar maps through the water column to the pond floor — saving the cost and disruption of dewatering.
RTK GPS and high-resolution sonar produce accurate sediment volume calculations that hold up to scrutiny — useful for procurement, reporting, and consent compliance.
Our compact USV launches from the bank — no crane, no barge, no support vessel required. Multiple ponds can be surveyed in a single day visit.
Reports are structured for asset management systems, long-term maintenance planning, and clear communication to elected members and the public.
Establish a baseline, then repeat surveys to calculate sediment accumulation rates — predicting when desludging is needed before capacity becomes an issue.
MĀKI surveys a wide range of water-filled infrastructure across New Zealand. If it holds water and there is a management question about what is on the bottom, we can survey it.
Stormwater infrastructure is out of sight, often out of mind — until it fails. Common consequences of under-monitored stormwater and treatment ponds include:
Regular bathymetric monitoring allows councils to manage these assets proactively — planning maintenance on their schedule, not in response to failure.
1. Pre-survey planning. We review the pond's design drawings (if available), set up a survey grid, and confirm access. Most surveys are booked 1–2 weeks out.
2. On-site survey. A MĀKI operator launches the USV from the bank. The vessel autonomously follows the survey grid, collecting sonar depth data and GPS positions across the full pond area. Typical small-to-medium ponds take 1–3 hours to survey.
3. Data processing. Raw sonar data is cleaned, georeferenced and processed into a point cloud. Volume calculations compare current depths against design drawings or a reference surface.
4. Report delivery. You receive a PDF condition report, georeferenced bathymetric map, cross-section profiles and data files. Turnaround is typically 5–10 business days after the survey.
Yes. MĀKI surveys are conducted at normal operating water level. The sonar system mounted on the USV measures depth through the water column — no dewatering required. This eliminates pumping costs and avoids any disruption to the pond's stormwater or treatment function.
Most councils survey stormwater ponds every 3–7 years, or after significant storm events. MĀKI recommends an initial baseline survey to document current conditions, followed by periodic repeat surveys to calculate sediment accumulation rates. This enables accurate prediction of when desludging is required — avoiding both premature and overdue dredging.
MĀKI's compact USV is suited to ponds from around 500 m² up to large reservoirs. For very small or confined ponds, we can discuss whether manual depth-profiling is a practical alternative. For large water bodies, multiple survey runs can be merged into a single dataset.
If you can provide original design drawings or as-built plans, these are used to calculate current versus design volume. If drawings are not available, we establish a relative reference surface from the current survey and use repeat surveys to track change over time.
A typical stormwater retention pond or detention basin takes 1–3 hours on-site for the physical survey, depending on pond size and complexity. Report delivery is typically 5–10 business days after the survey date.
MĀKI is based in the Waikato and operates nationally across New Zealand. We have worked with regional councils and territorial authorities across the North Island and are available to travel for survey projects anywhere in the country.
Advancements in Bathymetry Mapping for Efficient Settling Pond Management — how bathymetry mapping is changing the way settling pond owners manage their assets.
All MĀKI Services — full list of environmental monitoring, mapping and survey services across New Zealand.
Get in touch to discuss your pond, receive a quote, or find out more about what a MĀKI survey can tell you.
Get a quote View all services