THREE-DIMENSIONAL MODELING OF HYDRODYNAMICS AND DISSOLVED OXYGEN TRANSPORT IN TONE RIVER ESTUARY

Abstract

 A three-dimensional hydrodynamic model for simulating estuarine dynamics has been developed. The model, called CIP-Soroban flow solver, has been specifically designed for reproducing the current and salinity fields in density-stratified water bodies with a free surface. It is based on the Constrained Interpolation Profile (CIP) scheme and the Soroban computational grid system. Simulations of the time-dependent current and salinity fields of the Tone River Estuary have been performed using this model. Two periods are used to examine the predictive capability of the model. The first was in August 1997, which produced extensive field data related to vertical profiles of salinity, which showed evident changes in salinity intrusion processes between spring and neap tides; and the second in August 2001, which produced sufficient data associated with continuous measurements of vertical profiles of velocity, which showed characteristic residual flows averaged over ten tidal cycles. The model is examined in detail to reveal its inherent capability of simulating the dynamic behavior of density flow in the Tone River Estuary. In these two periods, the measured salinity and velocity data are reproduced well by the 3-D model. After investigating the capability of the hydrodynamic model, the dissolved oxygen (DO) transport model is incorporated into the hydrodynamic model to study the role of density stratification and residence time of seawater at the onset and development of hypoxia. The results of a long-term simulation of 100 days show good agreement with the field data.