Circulation and Sediment Dynamics

Abstract

Fjords, by their nature of being overdeepened basins, contain large volumes of saline water, which if protected by a sill, may lie almost stagnant (Fig. 4.1A). Exchange between the outer shelf waters and these protected deeper fjord waters tends to be intermittent. Estuarine circulation is common to many fjords, although its presence is seasonally regulated. Confined to a thin interval of the upper water column, the freshwater plume provides an important influence on the dispersal of dissolved and particulate matter. When the influx of fresh water is low or absent, sediment distribution may be strongly modified by wave or tidal mixing. Beneath the zone of estuarine circulation, there may exist larger, less-dynamic circulation cells that can be poorly coupled to the surface layer. The dynamics of polar fjords are further influenced by the effects of sea ice, icebergs, and tidewater glaciers. Chapter 4, then, sets out to discuss fjord circulation in relation to the dispersal, deposition, and resuspension of sediments.