Observation and simulation of winds and hydrodynamics in St. Johns and Nassau Rivers

SummaryWater surface elevations and daily flows are measured in the St. Johns and Nassau Rivers (north Florida) and reveal a storm event in mid-May 2009 and a sea level anomaly in June and July 2009. In an effort to reproduce these events, wind and tidally driven hydrodynamics are simulated from the deep ocean into the St. Johns and Nassau Rivers using a shallow water equations model. Calibration adjusts spatially distributed Manning’s roughness based on modeled-observed discharge. For validation, the model captures the regular tidal fluctuation as well as the hydrodynamic responses of the storm event in mid-May at the six water level gaging stations. At the flow gaging station, the model captures the ebb tendency of the tide as well as a strong perturbation (flood pulse) that occurs because of the storm event in mid-May.

► Winds, water levels, and daily flows are measured in St. Johns and Nassau Rivers.
► Winds and pressures are modeled at regional and local scales.
► Hydrodynamics are modeled as driven by tides, winds, and pressures.
► Manning’s roughness is calibrated for the river and wetlands.
► River flows are tidally ebb-dominant but strongly influenced by storms (winds).