Interaction of Tidal Inlets in a Multi-inlet Bay System: A Case Study Along the Central Gulf Coast of Florida

Abstract

Changes in the morphology of individual tidal inlets on sandy coasts are influenced by tides, waves, winds and longshore currents. In a multi-inlet bay system, however, a change in the configuration of one inlet can affect hydraulics throughout the bay and can influence the stability of adjacent inlets. This study presents a means of quantifying the degree of interaction between multiple inlets on a low-energy, microtidal coast by applying a two-dimensional hydrodynamic model to the inlet-bay system. The study area was Boca Ciega Bay along the Gulf coast of Florida. The investigation assessed the interaction between John's Pass and Blind Pass.

The study consists of analysis of the morphological history of the study area, a field investigation, construction of a numerical hydraulic model, and analysis of historical and predictive simulations. A two-dimensional hydraulic model was constructed and calibrated to spring and neap tidal conditions and verified for post-dredging conditions two years later. The bay tidal prism and portion serviced by each inlet was determined from model output and field data. Predictive and historical simulations were made to investigate how changes in bay or inlet morphology affect the hydraulic environment of the system. Results indicate traditional stability analyses alone may be inadequate for characterizing the behavior of multi-inlet bay systems because the morphological development of an inlet is influenced by factors that affect the tidal-prism distribution of the bay. The change in prism fed by each inlet and the subsequent hydraulic response of the pass may be quantified through model analysis.