USE OF CURRENT METERS FOR CONTINUOUS MEASUREMENT OF FLOWS IN LARGE RIVERS

Flows in the unregulated Great Lakes connecting channels, the St. Clair and Detroit Rivers, are normally determined using mathematical flow models with calibration based on periodic discharge measurements taken during the open-water seasons. Consequently, the calculated flows normally exhibit good accuracy during ice-free periods, but may contain large errors during winter months with extensive ice cover. The St. Clair River is particularly prone to large ice jams because of practically unlimited ice flow supply provided by Lake Huron and an extensive river delta that retards the passage of these ice flows. This study describes the experimental results of continuous flow measurements using electromagnetic (EM) current meters and an acoustic Doppler current profiler (ADCP) meter during 1983-1985 period. A record ice jam in the St. Clair River occurred in April 1984 and provided an excellent opportunity for testing the current meter program. Verification of current meter results was provided by flows transferred from the Detroit River, which was ice-free and permitted accurate flow simulation.