A Multiply-connected channel model of tides and tidal currents in Puget Sound, Washington and a comparison with updated observations

Tides and tidal transports within Puget Sound have been calculated using a model in which the Sound is represented by 79 channels connected at 43 junctions. Linearized equations of motion were used to determine channel cross-sectionally averaged quantities for the principal tidal constituents ~. Ki' S2' N2• 0 1, Pi' MJ. For the M2 tide the amplitudes and phases at the entrances to the Sound and the friction coefficients in the channels were adjusted to bring observed and modeled tidal distributions into best agreement; for other constituents. only the tidal amplitudes and phases at the entrances were adjusted. Data from 47 tide stations in Puget Sound were used for fitting model parameters. Tidal amplitudes and phases match observations with an average difference of less than 1 em and 2' respectively for each of the constituents indicated. Transport values from the model were subsequently compared to transports calculated from currents measured on four sections across the Sound at both ~ and KI frequencies. Tidal transports at the ~ frequency match the transports calculated from the data with average difference of less than 3% for amplitude and 4.3' for phase. The model was also used to calculate cross-sectionally averaged tidal currents. tidal prisms, and tidal dissipation rates for the composite tide and for constituents. As an example of those results, the composite tide and the~ and KI constituents have tidal prisms of 7.69.4.74 and 3.73 km 3 and dissipation rates of 733. 528 and 78 MW. respectively.