A new method of bathymetric surveying of stormwater ponds is saving time, increasing data quality and reducing health and safety risks for field staff. It involves driving a remote controlled Q-boat around stormwater ponds with an Acoustic Doppler Current Profiler (ADCP) and collecting accurate bathymetric and position data, which can be used for multiple purposes.
Auckland Council manages nearly 500 stormwater ponds across the Auckland region, so maintenance works do present a significant cost. To provide a means to prioritise pond maintenance, Pattle Delamore Partners (PDP) and Auckland Council are using this new methodology to calculate sediment accumulation volumes, comparing the ADCP results to as-built drawings of when the pond was built or last maintained. This information is useful to determine whether the stormwater pond is functioning efficiently, whether dredging maintenance is required, and where greatest sedimentation is occurring within the pond. The data can also provide an indication of dredging costs based on the sediment volume that requires removal.
There are numerous advantages that the Q-boat and ADCP methodology has over the traditional manual probe surveying method including: faster data collection; greater data accuracy; and reduced health and safety risks. In addition, comparative evidence between the two methods suggests that the manual probe surveying method may actually be compromising the integrity of the pond.
In this paper, the field techniques used to collect ADCP data and the post field data processing techniques will be explained, and the potential uses of data outputs explored. The benefits and shortfalls of this method compared to the manual probe surveying method will also be discussed with examples given.