Author: Tanya M. Beck

Publisher:

Published: 2019

Total Pages: 201

ISBN-13:

Tidal inlets on sandy shorelines separate barrier islands and serve as a conduit for transport of sand and water between embayments and oceans, seas, or other tidally influenced waterbodies. Tides and waves induce currents along the coastline that transport sediment across-shore and alongshore. Coastal managers must optimize barrier-inlet system stability while conserving limited sediment resources, and often base management decisions and engineering design upon geomorphic and numerical models that predict the morphological behavior of tidal inlets on short-to-medium timescales (years to decades). The overall goal of this study was threefold. First, to provide science-based practical guidance for regional sediment management in the vicinity of tidal inlets. Secondly, to enhance the understanding of the temporal and spatial scales of sediment pathways in these regions through numerical simulation of traced sediment transport. And, third, to combine these lessons learned in both regional sediment management and analysis of morphodynamic and sediment bypassing pathways with application to a common practical management practice of inlet shoal mining and adjacent beach placement. The temporal and spatial scales controlling the morphodynamics of barrier-inlet systems were reviewed within a regional sediment management context. Next, the application of regional sediment management methods to case studies of multiple barrier-inlet systems in West-Central Florida led to the development of a decision-support tool for regional sediment management (RSM) as applied to barrier-inlet systems. Connecting multiple barrier islands and inlets at appropriate spatio-temporal scales is critical in developing an appropriately scoped sediment management plan for a barrier-inlet system. Evaluating sediment bypassing capacity and overall inlet morphodynamics can better inform regional sand sharing along barrier-inlet coastlines; particularly where sediment resources are scarce and a close coupling between inlet dredging and beach placement is vital to long-term sustainable management. Continued sea-level rise and anthropogenic activities may intensify the need for investigating longer-term processes and expanding regional planning at a centennial timescale, and are acknowledged as challenging tasks for RSM studies going forward. A regionally focused, multi-inlet study was necessary to improve the management plans for the case study inlets (from north to south): Johns Pass, Blind Pass, Pass-a-Grille Inlet, and Bunces Pass. Key recommendations based on the case studies include: 1) allow the natural sediment bypassing to be re-established at Blind Pass inlet through reduced ebb-tidal delta mining, 2) reduce the interruption to sediment bypassing at Johns Pass and Pass-a-Grille inlets through an improved design of the dredged mining areas located along sediment bypassing pathways, 3) allow for continued natural sediment bypassing at Bunces Pass, and, 4) incorporate the cyclic sediment bypassing through swash-bar attachment into the management plan at Bunces Pass and adjacent barrier-islands. Similar systems in other regions may benefit from the lessons derived in this case study of an adaptively managed multi-inlet system.