Techniques for Measuring and Analyzing Inlet Ebb-Shoal Evolution

This Coastal Engineering Technical Note CETN provides techniques to measure and analyze the evolution of ebb shoals associated with tidal inlets. Tidal inlets are one of the most dynamic features along a coastline. The complex temporal and spatial interactions of waves, tides, and longshore currents create and constantly modify the morphology and sedimentary structures found at tidal inlets. Quantification of the magnitudes, rates, and patterns of geomorphic change is central to sediment budget calculations, estimation of dredging requirements, and assessment of whether inlet changes have had a significant effect on adjacent beaches. Inlet shoals are also potential sources of sand for beach fill and sand bypass projects. Mining of these shoals can provide a local source of needed sand. These engineering activities will modify natural coastal processes and change the inlet sediment pathways and channel morphology. Engineering objectives at inlets providing a stable navigation channel and locating low-cost sand-borrow sources need to be met without adversely impacting the inlet or adjacent shorelines. Before new construction or modification of existing engineering begins, the historic evolution of the inlet and how engineering alternatives might modify the existing inlet morphodynamics should be understood.