Tidal Inlets

Definition: An tidal inlet is a channel, maintained by tidal flow, connecting the ocean with a bay, lagoon or marsh and tidal creek system. Tidal inlets typically cut through shore-parallel barriers and spits.

Tidal Deltas

Definition: An accumulation of sediment on the shoreward or oceanward side of an inlet (figure 1).

Figure 1. Flood and ebb tidal deltas are deposited on the shoreward and oceanward side of an inlet (mesotidal/mixed energy). Channels occupied by the ebb and flood tidal flows are shown by light and dark blue arrows respectively. Redrawn from USAC EM 110-2-1810 figure 4-15. The flood ramp throat and main ebb channel form the inlet throat, the deepest portion of the channel. Sand moved into the inlet by waves and flood currents are either deposited on the flood tidal delta or circulated back out to the ebb tidal delta. Waves reorganize sediment in a series of swash bars which eventually migrate and attach to the ends of the barrier. Typically the down drift end receives the most sediment.

Types of tidal deltas

Ebb tidal deltas:

Flood tidal delta:


Online Sites

Lindley Hanson/email /Gls214
Department of Geological Sciences, Salem State College, Salem, MA
last modified 11/25/03