Hydrodynamic modeling of residence, exposure, and flushing time response to riverine discharge in Mobile Bay, Alabama.

摘要

Measurements of hydrodynamic timescales (e.g. residence, exposure, and flushing time) generally describe the physical mass transport of particles within a water body. These measures' response and spatial variability to tides, riverine discharge, and local meteorology are investigated by performing Advanced Circulation 2-dimensional depth integrated model simulations of Mobile Bay, Alabama, a shallow, drowned river-valley estuary located on the northeastern coast of the Gulf of Mexico. Hydrodynamic model output is utilized by a Lagrangian particle tracking model to predict the trajectories of more than 30,000 discrete particles throughout the study area. Hydrodynamic timescales are estimated and analyzed based on these results. Spatially averaged timescales generally range between 4 and 130 days depending on the magnitude of riverine discharge and local meteorology. Synthesized results suggest average to excellent flushing throughout much of Mobile Bay, and relatively poor flushing along the eastern shoreline, the mid-section of Bon Secour Bay, and in some areas of the Mobile-Tensaw Delta.