Three-Dimensional Hydrodynamic Model of New York Harbor Region

Abstract

Three-dimensional simulations of estuarine circulation in the New York Harbor complex, Long Island Sound, and the New York Bight have been conducted using the Estuarine, Coastal and Ocean Model (ECOM) within the framework of a single grid system. The model grid is curvilinear and orthogonal, with resolution from 100 m in rivers to about 50 km in the bight. The model forcing functions consist of (1) meteorological data; (2) water level elevation and temperature and salinity fields along the open boundary; and (3) freshwater inflows from 30 rivers, 110 wastewater treatment plants, and 268 point sources from combined sewer overflows and surface runoffs. Because the goal of this study is to maximize, to the extent possible, the predictive skill of the modeling system, the motivation for and a detailed description of the construction of these boundary forcing functions are presented. Two 12-month periods are considered: (1) October 1988 to September 1989 for model calibration; and (2) October 1994 to September 1995 for model validation. For model calibration, the results are compared with water levels at 14 stations, currents at six stations, and temperature and salinity at 35 stations. Model validation is accomplished using data from an extensive hydrodynamic monitoring program. Mean errors in predicted elevations and currents are less than 10% and 15%, respectively. Correlation coefficients for salinity and temperature are as high as 0.86 and 1.0, respectively. The level of skill shown by these statistical measures suggests that the model is capable of describing the entire spectrum of time scales for the computed quantities, from the semidiurnal to the annual scales.