Tidal energy fluxes and dissipation in the Chesapeake Bay

Abstract

Tidal energy flux and dissipation in the Chesapeake Bay are examined using a three-dimensional baroclinic model. The model currents are validated by a comparison with observed tidal current ellipses collected during previous field surveys. The model elevations are validated against sea-level records collected at tidal gauges. The baroclinic model produces more accurate predictions for sea-level heights and tidal currents than the tidal models which do not consider the effects of stratification. The averaged rms differences between the observed and modeled surface elevations are 3.4 cm for the M 2 constituent and 0.7 cm for the K 1 constituent. The averaged rms differences between the observed and modeled tidal current ellipses are 2.6, 2.1 cm s −1, 5.1° and 21.7° for the semi-major, semi-minor axes, inclination and phase of the ellipses, respectively. The total amount of tidal energy flux entering the Bay mouth is found to be 188 MW, 88% of which is associated with the M 2 component. Dissipation of tidal energy is highly non-uniform in the Chesapeake Bay. 40% of the energy dissipation occurs in four topographic hotspots: the Bay mouth region around the headland of Delmarva Peninsula, the region near the Rappahannock sill, the constriction near the Bay Bridge and the constriction north of Baltimore.