tidestends

Tidestends is a term used in coastal geomorphology to describe the systematic tendency for tidal currents and water levels to exhibit a consistent alongshore orientation over tidal cycles, producing a net directional bias in sediment transport and shoreline morphodynamics. The concept emphasizes that tides do not distribute energy equally in all directions; estuaries and embayed coastlines can show persistent alongshore components due to resonant tidal modes and bathymetric steering. The term is not widely standardized and appears primarily in specialized coastal engineering literature; some authors relate tidestends to tidal asymmetry and residual circulation patterns.

In mechanisms, tidestends arise when coastal geometry, such as tapering coastlines or headlands, modifies the distribution of tidal energy; the primary tidal constituents like M2 and S2 interact with shelf gradients to generate residual alongshore flows; wind forcing and freshwater input can reinforce or oppose these tendencies. Detection uses time series of current velocities, water levels, and shoreline positions, often via ADCPs and harmonic analysis, to identify a persistent alongshore component.

Applications include predicting long-term sediment transport directions, planning dredging and inlet management, and assessing shoreline evolution under sea-level rise and climate scenarios. Limitations include regional variability and the influence of seasonality and weather events.

See also: tidal current, tidal asymmetry, sediment transport, coastal geomorphology, amphidromic system.