St. Augustine Inlet Research Paper

Looking at St. Augustine Inlet utilizing different models

Angela Antigua

Advanced Research Methods for Engineering

Introduction

Knowing the hydrology and hydrodynamics of an inlet is very beneficial to know when looking at various things in an ecosystem or establishment. From a biological aspect, the hydrology can affect phytoplankton biomass and composition in an estuary. From a coastal engineering aspect, knowing the hydrodynamics can help us better understand sediment transport. For this study, data from St. Augustine Inlet will be analyzed using various models such as CMS and ADCIRC. The ultimate goal for my thesis is to compare models to see which would suit best when looking at tidal inlets. St. Augustine Inlet is an important inlet

Augustine Inlet is a stabilized navigation channel located in north east Florida. St. Augustine Inlet is considered to be unique because it was relocated in the 1940s. It was located about 2-3 miles south of where it is today. It was relocated to allow a more navigable entrance for wartime activities1. The inlet has deposits on the interior of the bay and on the ebb shoal system. This is because the inlet is somewhat low and the north jetty is short.1

This 500-m-wide inlet connects the Atlantic Ocean to the Tolomato and Matanzas rivers . Although they are termed as rivers, they are actually coast parallel estuaries that feed a small tidal salt marsh.

This inlet is maintained by the U.S. Army Engineer District, Jacksonville as a deep-draft navigation channel. 3 Waves predominantly from the north east populate the St. Augustine Inlet. This creates a net southerly, longshore sediment transport 1. The wave climate is seasonal with wave energy usually the greatest during the winter season3. Winter seasons usually have subtropical frontal passages occurring every three to seven days3. Typically the wave heights during the passages average from 1.2 to 1.8 m with mean wave periods of 9-12 seconds. During summer months, waves average to 0.3-1.0 m with short mean wave periods at 5-8 seconds. 3 The tides range on the lower end of the mesotidal range at 6 to 13 ft. Spring high tidal ranges yield 6 ft and a mean value of 5

It is a product conducted at the U.S. Army Engineer Research and Development Center by the Coastal Inlets Research Program (CIRP). Surface elevation, flow velocity, sediment change and morphological change can all be calculated using the CMS.3

Modeling by Legault et al. has been used to determine a sediment budget for St. Augustine’s inlet. In order to determine the budget, they created a second report that needed to model the hydrodynamics in order to predict the amount of sediment that is transported.3 CMS has the ability to reproduce observed trends in ebb-tidal delta morphodynamics and changes in volume of notable morphologic features because of tide and hindcast waves. In order to calibrate the modeling system, CMS was used to reproduce observed water levels in the Tolomato-Matanzas estuary, the inlet’s current velocities and the ebb-tidal delta’s morphological change.