How do the size and shape of a gulf affect its water properties?

The size and shape of a gulf significantly influence its water properties, primarily by determining the degree of isolation from the open ocean and the nature of internal circulation.1

• Isolation and Circulation: The ratio of a gulf's mouth width or cross-section to its total surface area or volume dictates how much it exchanges water with the ocean. A narrow mouth or the presence of a sill (a submarine ridge) restricts this exchange, which can lead to independent circulation patterns driven by local winds and river runoff. High sills, in particular, may cause stagnation and oxygen deficiency.1
• Salinity: In humid climates, river runoff can freshen gulf waters, leading to low salinity. Conversely, in arid zones, limited runoff combined with high evaporation results in significantly increased salinity.12
• Tides and Waves: Funnel-shaped gulfs often experience resonant tides, where the tidal range at the head is much greater than in the open ocean. Additionally, the shape and size of a gulf limit the penetration of open-ocean waves, causing local wave conditions to prevail.1
• Oscillations: Simple, isolated gulfs are prone to seiches—free oscillations triggered by atmospheric pressure changes or tectonic activity.1