the hinterland, from beaches, and from spits and cheniers
(Semeniuk, 1983). Freshwater seepage can manifest as
discharge along the upper tidal flat surface as surface
flows, springs, or as subterranean flow along appropriate
stratigraphic conduits or sheets (Semeniuk, 1983;
Cresswell, 2000; Semeniuk et al., 2011).
Tidal flats in an estuarine environment
Tidal flats occur in different and varied geomorphic and
sedimentologic settings within an estuary. The main
settings are platforms bordering the margins of estuaries,
tidal parts of flood-tidal deltas, tidal parts of intraestuarine riverine deltas, the crests and flanks of middleof-estuary shoals, and the protected lagoons leeward of
spits. Figure 4 diagrammatically shows the locations of
tidal flats within an idealized estuary.
The platforms bordering the margins of estuaries, since
they can occur continuously or discontinuously along the
whole length of an estuary, can traverse salinity fields from
marine (at seaward parts of an estuary) to brackish or even
freshwater (at riverine parts of an estuary). In terms of
Tidal Flat, Figure 4 Diagram showing the typical geomorphic and sedimentologic location of tidal flats within an idealized estuary.
668
TIDAL FLAT