Discharge and current profiles under the ice

In 2004 SonTek developed, in conjunction with Environment Canada, a new methodology for measuring current flow under ice cover. Mini-Acoustic Doppler Profilers (ADP) were deployed from above the ice cover and water velocity data were collected with SonTek´s new Stationary Measurement Software. These initial field tests were made on the Mackenzie River at Fort Simpson, North West Territories, Canada. The original field site was chosen for its demanding environment conditions. At Fort Simpson, the Mackenzie River was over 1 km wide, with approximately thick 1 m of fast ice, areas with up to 80 cm of frazzle ice and currents of about 1 m/s. Temperatures dropped to below -20°C during part of the February field tests. A full set of Mini-ADPs (3.0 MHz, 1.5 MHz and PC-ADP) were utilized at various locations to generate velocity profiles from the water-ice boundary layer to the bottom boundary layer. SonTek´s Stationary Software was used to stitch various velocity profiles into a single discharge summary. Further refinements to the methodology and software have been ongoing in Canada and Asia. In March 2005 data was collected from a new field location at Heihe, Heilongjiang province in Northern China. The Heilongjiang River borders northern China and Siberia. It was about 700 m wide, with a maximum velocity of about 0.7 m/s and a total flow in winter of approximately 600 m³/s. In spring, the flow rates increase and the maximum velocities can get to 2 m/s.