Development of environmental and oceanographic real-time assessment system for the near-shore environment

The coupling of real-time measurements and numerical models will be important in overcoming the challenges in environmental and oceanographic assessments in surface waters. Continuous monitoring will take advantage of current state-of-the-art in sensor development, remote sensing technology. The numerical modeling tools available exist in many different forms and varying levels of complexity from depth integrated one-dimensional (1-D) models to full three-dimensional (3-D) models. Common to all are the constraints and forcing required in driving the models. These include hydrodynamic and barometric information, which are relatively difficult to obtain given the time scale of the bio-chemical and physical processes governing the fate and transport of the constituents of interest. This study is focused on the development of a framework that couples real-time measurements and numerical simulation for tracking constituents in surface waters. The parameterization of the mixing and turbulent diffusion impacts the formulation of the constituent-transport governing equations to the extent that the numerical model is being driven by near real-time observations of hydrodynamic data and the consequent evaluation of model coefficients. The effects of shear-augmented diffusion processes in shallow embayment and near-shore waters are investigated in order to develop algorithms for obtaining a shear diffusion coefficient, Ke from shear-current measurements and turbulent diffusion-coefficient, Kz measured by the auto-correlation function, Rτ of the velocity time-series. Typically, the diffusion coefficients are measured through tracer experiments as determined by the time rate of change of the variance of a growing patch (K = ?? dσ2 /dt), which introduces the concept of diffusion length-scale (or time-scale). In this study, the dye-tracer experiment was used, not so much in the context of evaluation of a diffusion coefficient, but within a modeling framework to validate a numerical scheme driven by real-time hydrodynamic observations. Overall, the effect of shear-currents in shallow wind-driven estuaries is studied using a prototype bay typical of the Texas Gulf-coast. A numerical model was developed and used in testing these hypotheses through a series of dye-tracer experiments under varying meteorological conditions.