Estimates of the transport through the East River, New York

The hydrodynamic characteristics of the East River, New York, which connects Long Island Sound to New York Harbor, have been investigated via a high-resolution, topographically conformal and orthogonal curvilinear grid together with high-quality acoustic Doppler current profiler measurements. The objective is to determine the volume flux of water through this important water body. The model was calibrated and validated through comparisons with measured salinities, water levels, current velocities, and data-based estimates of volume flux. Detailed statistical analyses demonstrated that both the tidal and meteorological bands spanning inverse frequencies between 3 hours and 5 days were well simulated by the model. The climatological band (inverse frequencies greater than 5 days) did not exhibit uniformly good agreement because of the paucity of salinity and temperature measurements available for use as model forcing functions. Results from an 18-month (1988 to 1989) simulation indicate that the net long-term flux of water is directed out of Long Island Sound and toward New York Harbor. The total rate was found to be about 310 m3 s−1. At the eastern end of the East River near its confluence with Long Island Sound, the net flow was distinctly two-layered with flows of about 260 m3 s−1 directed toward the sound in the surface layer and flows of approximately 570 m3 s−1 in the bottom layer directed toward New York Harbor. There appeared to be a 100 m3 s−1 monthly variation about the mean transport at the eastern end. However, on shorter timescales the transport reversed direction for days at a time.