Marine Geophysical and Hydrographic Surveys: ASI Marine Underwater Mapping Services
ASI Marine’s underwater mapping services employs a combination of hydrographic, marine geophysical, and visual inspection techniques to conduct thorough underwater investigations. Using a combination of geophysical mapping and charting technology, ASI Marine is able to locate the submerged surface features and targets in question, addressed by clients. These findings are measured and mapped with precision accuracy in real-time. ASI Marine’s in-house certified hydrographers, cartographers and graphic specialists produce detailed technical reports (hardcopy and GIS compatible formats) utilizing geophysical data acquired during the underwater investigations allowing clients to make informed decisions for asset management and/or engineering purposes.
ASI Marine’s personnel have both domestic and international experience with over 40 years of providing geophysical services. This, combined with ASI Marine’s extensive inventory of the latest geophysical equipment, enables us to provide a broad range of techniques to conduct any underwater investigation.
The suite of marine geophysical services available include:
- Marine geophysical surveys utilizing side scan sonar, sub-bottom profiling, bathymetry and positioning
- Geological investigations
- Habitat mapping and archaeological surveys
- Underwater search, survey and recovery
- Dredging surveys and volumetric determination
- Sonar profiling/imaging surveys
- Open-water remotely operated vehicle (ROV) inspections
- Integrated navigation and positioning services
- Cable and pipeline inspections
- Unmanned survey vessel (USV) inspections
Technologies used for ASI Marine Geophysical and Hydrographic Services include:
- Single-beam and Multi-beam Bathymetry – provides precise water depth measurements allowing generation of 2D and 3D underwater mapping.
- Side Scan Sonar Surveys – provides an acoustic “aerial photo-like” 2D image of the seabed/riverbed/reservoir bed.
- Water Current Data Collection – Acoustic Current Doppler Profiler (ADCP) Deployments. Provides high accuracy current profiling data and complete water column sampling. By using for four transducers, the direction of the water particles can be determined as well as their velocity.
- ROV Deployment – Underwater sonar and video collection. Can be used for sample collection and small underwater tasks.
- Navigation and Positioning Services – Differential Global Positioning Systems (DGPS) – real-time kinematic (RTK) centimetre accuracy systems as well as sub-metre accuracy systems depending on the requirement.
- Marine Magnetometer Surveys – used to detect ferrous metals on or under the seabed/riverbed/resevoirbed.
- Sub-bottom Profiling – Industry standard technique for the collection of data concerning shallow geological and sedimentary conditions below the seabed/riverbed/resevoirbed providing valuable insight into the nature of the sub-bottom.
- Sediment Sampling – Dependent on the bottom type and water depth, a drop core sampler or a grab sampler (e.g., Ponal sampler) can be used. Samples can then be analyzed for contamination, grain size analysis and geotechnical properties.
Benefits of Sonar Surveys:
- Remote target identification
- Monitoring of silt and debris accumulation, scour and erosion in hazardous conditions
- Observation of collapse or undercutting occurrences enabling corrective action
- Remote measurement of infrastructure
- Power generation providers (hydro, thermal, and nuclear sectors)
- Private sector companies
- Engineering consulting firms