Spatial Variability of Hydrodynamic Timescales in a Broad and Shallow Estuary: Mobile Bay, Alabama

Abstract

ABSTRACT Webb, B.M. and Marr, C., 2016. Spatial variability of hydrodynamic timescales in a broad and shallow estuary: Mobile Bay, Alabama. Residence, exposure, and flushing times are examples of hydrodynamic timescales that describe the physical mass transport within a water body. The response and spatial variability of these measures to tides and discharge were investigated through hydrodynamic model simulations of Mobile Bay, Alabama using a two-dimensional depth-integrated circulation model coupled with a Lagrangian particle tracking model. Hydrodynamic timescales were estimated and analyzed using the particle tracking results. Flushing of the estuary was found to transition from tidally enhanced to river dominated for Q > 1715 m3 s−1. A simple power law regression was found to accurately represent the spatially averaged timescales (R2 > 0.99) for tidal and river forcing. Spatially averaged timescales generally ranged from 4 to 130 days, with large deviations related to particle initial position, magn...