The current and sea level variability in the Chesapeake and Delaware Canal

Abstract

Current and sea level observations in the Chesapeake and Delaware (C&D) Canal are used to examine the frequency‐dependent spatial distributions of tidal and subtidal variability along the canal. To first order of approximation, the C&D Canal is shown to be a linear system. A linearized, frequency‐dependent analytical model is developed to examine details in the tidal and subtidal variability along the canal, and results agree well with observations. The principal semidiurnal tides (M2) at the two ends of the canal are roughly in phase but differ substantially in amplitude. The amplitude of the M2 tide increases monotonically from the Chesapeake end of the canal toward the Delaware end. The amplitude of the M2 current is of the order 60 cm s−1, and it is higher in the western part of the canal than in the eastern part of the canal. The amplitudes of the principal diurnal tides (K1) at the two ends of the canal are much smaller than those for M2, but the K1 tides at the ends are nearly 180° out of phase with each other. The amplitude of the K1 tide decreases toward the interior of the canal from both ends. Relatively strong K1 current of the order 20 cm s−1 exists in the canal, and its amplitude shows only slight variation along the canal. There are substantial differences in the subtidal sea level fluctuations along the canal, resulting in strong subtidal currents which may exceed 70 cm s−1. The importance of the C&D Canal on the upper Delaware Bay is assessed by comparing the volume flux through the canal relative to that in the upper Delaware. It is shown that the influence of the canal on the Delaware depends strongly on the time scales involved. It appears that the C&D Canal is not important to the overall tidal response in upper Delaware Bay, but the subtidal volume flux through the canal must be included for a proper assessment of the dynamics of upper Delaware Bay at subtidal frequencies.