Tidal variations of turbulence at a spring discharging to a tropical estuary

Abstract

AbstractMeasurements of velocity profiles and near‐bottom temperature and pressure were used to determine turbulence properties at a point‐source submarine groundwater discharge (brackish) in a tropical estuary. The turbulence properties estimated were Reynolds stress, turbulent kinetic energy production, and vertical eddy viscosity. Results showed a dominance of the zonal Reynolds stress component with maximum of 0.0025 m2 s−2 (2.5 Pa) at low tide. Turbulent kinetic energy production and vertical eddy viscosity values also reached maxima (0.98 W m−3 and ~10−1 m2 s−1, respectively) at low tides. Discharge of brackish water increased at low tides, relative to high tides, as indicated by vertical mean velocity and by mean velocity shear. These maxima were caused by decreasing hydrostatic pressure and likely increasing hydraulic head at the site of discharge. Increased turbulence at low tides was one order of magnitude larger than the turbulence caused elsewhere by tidal flows up to ~2.5 m s−1.