Flow Services

ASL has been measuring flow in oceans and rivers since its inception in 1978. Early projects used rotor & vane type instruments but these have largely given way to acoustic instruments such as TRDI Acoustic Doppler Current Profilers (ADCP). ASL manufactures an Acoustic Scintillation Flow Meter (ASFM) that is primarily used for open channel flow and hydroelectric dam intake flow measurements. Following are various project applications that ASL has been involved in.

Technical Papers

River/Stream Flow and Discharge

Doppler Current Profilers, particularly the TRDI ADCPs with Bottom-Track, are ideal for flow and discharge measurement in open channels such as streams and rivers. ASL owns and operates various frequency ADCPs such as the 2 MHz StreamPro for up to 4 m depth, the 1200 kHz ADCP for up to about 15 m depth, and the 600 kHz ADCP for up to about 50 m depth.

StreamPro ADCP for shallow water
discharge measurements

Marine Terminals

Terminal design often requires a flow survey. Maximum flow speeds are important, as well as the flow direction which often affects the berth alignment. Often wave height and direction measurements are also required.

Current and wave distribution at
planned marine terminal site

Oil and Gas

Offshore drilling and production operations generally require measurements of the current profile, often in real-time. This may necessitate deployment of ADCPs both at surface (hard wired) as well as on the bottom (acoustic modem linked). Oil spill modelling may require flow measurements to validate the model.

ADCP and IPS deployments off
production platforms

Hydroelectric Dams

ASL manufactures the Acoustic Scintillation Flow Meter (ASFM) used primarily for measurement of flow into hydroelectric intakes. The computed discharge is used for index testing. Flow measurements are also often required for evaluation of the effect of any dam construction or modification. ASL conducted downstream flow mapping, augmented by numerical modelling , to determine the effect if any that expansion of several hydroelectric dams would have on downstream sturgeon habitat.

ADCP measured flow (red) versus
numerical model (blue)

Cable Laying and Pipeline

A vessel-mounted ADCP is often used during cable laying operations to provide real-time current profile data. This helps plan activities and can be particularly useful in coastal areas where surface currents are not necessarily representative of those at depth.

ADCP deployment to measure currents
Streamlined Underwater Buoyancy Systems (SUBS) are being used to mount downward looking ADCPs to measure currents in Cook Inlet Alaska. These SUBS greatly reduces variability caused by mooring movement in dynamic flow regimes.
Deployment of SUBS at Cook Inlet

Tidal Energy

One of the main criteria for evaluation of potential tidal energy sites is the current speed. ASL has been involved in several site evaluation projects such as Race Rocks, Victoria, and others near Campbell River. Flow measurements are often augmented by numerical modelling.

ADCP current profiler at site of tidal
turbine near Race Rocks, Victoria.

Environmental Impacts

Flow surveys are often required in order to fulfill Environmental Impact assessment requirements. One example is marine outfalls. Current profile measurements at the proposed outfall site are often used to evaluate the diffusion and flushing characteristics of the outfall and the receiving marine environment.

ADCP deployment to measure currents

Climate Research

Climate changes are occurring most rapidly in the Arctic Ocean. ASL products, and related services, are being used by major research organizations in North America, Europe and Asia for scientific studies to understand and predict the changing climate through the century. Long-term measurements of the Arctic Ocean fluxes of sea ice and water masses are being made with ASL's Ice Profiler, Acoustic Doppler Current Profilers (ADCP) and other instruments. ASL provides research studies of Arctic climate change to its industry and environment assessment customers on regional climate change within the Arctic Ocean.

Arctic instrument deployment