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Tales of the Coast
Coastal Dynamics

Circulation and Drowned Valley Coasts

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.