Interaction of Tidal and Fluvial Processes in the Transition Zone of the Santee River, SC, USA

摘要

This study was conducted in the freshwater reach of the Santee River approximately 55±4 km from the mouth, a transition zone from a fluvial to an estuarine tidal regime. The dataset comprises bathymetric surveys, current profile and bottom pressure measurements at two locations, and time series of discharge. Our data indicate that the transition zone is characterized by strong tidal dissipation and distinctive channel geometry. Tidal dissipation is evident in the rapid decrease of the M_2 amplitude to the mean along-channel velocity ratio from 2.1 to 0.9 over a ～6-km distance. Channel cross-sectional area in the transition zone converges at a higher rate than both upstream and downstream while channel depth reveals threefold variations in the form of adjacent shoals and deeps. We hypothesize that the enhanced tidal dissipation is at the same time a cause and a result of strongly convergent bathymetry in the transition zone.