Numerical study in Delaware Inland Bays
Date
2006
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Publisher
University of Delaware
Abstract
The purpose of this study is to explore the physical transport and water quality in the Delaware Inland Bays through coupling two models: ECOMSED and RCA. ECOMSED is a fully integrated three-dimensional hydrodynamic model, and RCA is a general purpose water quality model. ☐ The Delaware Inland Bays, located in Sussex County, Delaware, consist of two interconnected shallow coastal lagoons, Indian River Bay and Rehoboth Bay. The Inland Bays are connected to the Atlantic Ocean via the Indian River Inlet and they are tidally flushed. The Inland Bays are typical shallow bar-built estuaries that play a significant ecological role due to their high primary and secondary productivity. ☐ The entire Inland Bays are the model domain, and a grid generation program, CoastGrid is used to generate the curvilinear grid. The grid has high resolution in the Bays, satisfying the resolution needed along the tortuous rivers. The coupled model systems have been set up, taking account of tidal elevation, freshwater discharges, wind stress, and water surface heat exchange. Also, reactions affecting dissolved oxygen are included in the water quality model, such as plant photosynthesis, respiration, and reaeration. A database of Delaware Inland Bays has been provided by DNREC to calibrate and verify the coupled models. The formatted database contains the available data in the Inland Bays. ☐ The coupled models are calibrated using a year long data set, then they are compared with another year’s data for verification. The calibrated models are capable of simulating the hourly tidal surface elevation at Rosedale Beach in Indian River well for the whole year, and the models are also able to reproduce the yearly variations well with the field measurements for salinity, temperature, and dissolved oxygen. ☐ The Inland Bays are dominated by the semi-diurnal tide, M2. The water temperature shows the expected seasonal variations in the entire Bays, while the salinity varies. The water in the upper and middle portions of the Indian River Bays is fresher than the water near the inlet, and the salinity in the Indian River Bay has larger diurnal oscillations than that in Rehoboth Bay. The DO shows large diurnal swings in summer and fall, and the simulations also reveal the super-saturation and near-anoxic conditions inside the Bays. ☐ The results generated from the coupled models are in reasonable agreement with the available data. It has been shown that numerical models are effective tools for simulating water quality in shallow waters.