Tales of the Coast
Coastal Dynamics

Tidal currents and circulation affect drowned valley coasts when tidal current energy is greater than wave energy at the estuary mouth. Tide-dominated estuaries have a higher level of energy in the water movement than wave-dominated estuaries; therefore, sediment exhibits more mixing than in the latter type. There is also usually no bay-head delta, as tidal currents rework riverine sediments.

Barrier island
Source: National Park Service

Circulation and Drowned Valley Coasts

Estuarine Variability: Tidal-wave amplification is less likely to occur in irregular-shaped valleys, and these estuaries often become wave-dominated. In contrast, estuaries that have a funnel shape are more likely to be tide-dominated.