Flow of Water in the Passages of Passamaquoddy Bay Measured by the Electromagnetic Method

Abstract

Water transports in the passages connecting Passamaquoddy Bay and the Bay of Fundy were measured by the electrical potential differences induced in the water moving across the earth's magnetic field. A phase difference between the transports in Letite and Western Passages was observed, slack water occurring later in Western Passage by 15 to 60 minutes. Variation of the transport with time for each passage was studied. A marked harmonic content was found, particularly of the second and third harmonics with periods six (6.2) and four (4.1) hours, and was evaluated by harmonic analysis.The harmonic component content of the tidal current transports in the Saint Croix Estuary was found to be in close agreement with that of the observed tidal heights at St. Andrews, N.B. The harmonic content of the transports in Letite Passage and in Western Passage was related to hydraulic or frictional tidal flow and to shallow-water tides respectively. Currents in Letite Passage found at anchor Sta. 51 and deduced from the square root of the head measured by tide staffs were consistent in form and phase with data from the electrode voltages.A small residual transport from Passamaquoddy Bay through Western Passage was inferred with some uncertainty.