Estuarine laterally averaged numerical dynamics: The development and testing of estuarine boundary conditions in the LARM code

The longitudinal and vertical hydrodynamics and transport in stratified waterbodies as formulated for the Corps of Engineers Laterally Averaged Reservoir Model (LARM) have been transformed to estuaries by development of appropriate boundary conditions. The resulting computational code Laterally Averaged Estuary Model (LAEM) is tested on the Potomac River estuary for a short period of time with intensive field data. The estuary problem was formulated in terms of spatially varying geometry, a time-varying tide height and salinity distribution at the mouth, and freshwater inflow. The LARM code was found to reproduce overall estuarine dynamics including tide heights, tide phase shifts, and salinity distributions. In addition, detailed time-varying vertical velocity profiles were produced to a high degree of resolution. Detailed results of the model including the distribution of vertical velocities and turbulent dispersion coefficients were compared to those expected for a coastal plain estuary with favorable agreement.