Collecting Sonar Data for the Slough Restoration Project

By Ken Jones

Recently, Ken Jones and Dan Tonsmeire were out boating on the East River, St. Marks River and the Apalachicola River collecting sonar data. Ken Jones explains why.

Apalachicola River at Four Tree Cutoff

As part of the Slough Restoration Project, we need to accurately characterize the distribution of the flows through distributaries, including the East River, one of our restoration sites. This is done via a hydrodynamic model. We use sonar data to provide location and water depth to describe the channels within the model boundaries.  Models are great tools in describing the physical nature of a complicated hydraulic system.

The timing and quantity of freshwater flowing into Apalachicola Bay from the Apalachicola River are key to the health of the organisms that live in the estuary. The main stem of the river flows into Apalachicola Bay at the bridge near the City of Apalachicola. However, the river is bifurcated starting about 14 miles upstream where the East River takes a small percentage of the flow, and also about 11 miles upstream where the St. Marks River strips a significant amount of the total flow from the main stem. The St. Marks River then distributes the Apalachicola flows back to the East River through the East River Cutoff and into the Little St. Marks.

This complicated interaction between these three channels and the tides distribute a large amount of total flow from the river into East Bay between Blounts Bay to the southern end at the John Gorrie Bridge. It is only with this tool can we define this interaction.

East Bay has long been recognized as the most productive portion of the estuarine systems and this productivity is directly related to the delivery of freshwater through these distributaries. As part of the Slough Restoration Project, we will be removing sediment from the upper reaches of East River which will return this part of the distributary system to its natural state. Increasing flow will presumably increase the delivery of freshwater and essential nutrients into the northernmost and most productive sections of East Bay. Our model will test our hypothesis by telling us how much benefit we can expect to see from our project.

Ken Jones is the Project Manager and Principal Engineer of Apalachicola Riverkeeper’s Slough Restoration Project. This multi-year project is funded by the National Fish and Wildlife Foundation’s Gulf Environmental Benefit Fund.

Douglas Slough, Spiders Cut and the East River are project sites. Sign up for email updates here.

from recent sonar data

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