Mesotidal

Mesotidal is a term used in coastal and estuarine hydrology to describe tides with moderate tidal ranges. In the standard global scheme, mesotidal regimes have spring tidal ranges typically between about 2 and 4 meters, measured as the difference between mean high water and mean low water. This places mesotidal coasts between microtidal (<2 m) and macrotidal (>4 m) regions. The actual range on a given coast can vary with seasons, local bathymetry, shoreline geometry, and tidal constituents.

Tidal behavior is governed by astronomical forcing (the moon and sun) and how coastlines and basins reflect and dissipate tidal energy. Mesotidal areas often experience semidiurnal tides (two high tides per day) or mixed semidiurnal patterns, and tidal amplitudes may be amplified in estuaries and bays that resonate with local depths.

Ecological and sedimentary processes in mesotidal zones are shaped by the regular but moderate rise and fall. Moderate tides drive tide-driven circulation, mixing, and nutrient exchange, facilitating salt marshes, tidal flats, and wetlands in suitable climates. Sediment transport and deposition can form mudflats and channel networks; salinity intrusion in river mouths depends on the balance of freshwater inflow and tidal forcing.

Engineering and coastal management considerations in mesotidal regions include navigation channel maintenance, flood risk assessment, and habitat conservation. Because tidal range sits between microtidal and macrotidal extremes, mesotidal estuaries often exhibit intermediate planforms and estuarine dynamics, with greater variability across different locations.