Since the early work of Lugo and Snedaker (1974), geomorphology has been used to organise
our understanding of the interactions between coastal wetlands and their habitats. Mangroves
and saltmarshes respond to hydrological and geomorphic conditions in consistent
ways (Thorn et al. 1967; Woodroffe 1983), such that the relationships between hydrological
and geomorphic change can be used as a template to predict changing distributions of
mangrove and saltmarsh.
With the exception of Tasmania, where mangroves are absent, saltmarshes in Australia are
restricted to the upper intertidal environment, generally between the elevation of the mean
high tide, and the mean spring tide. The distribution of these environments within an estuary
or embayment is controlled by patterns of riverine and marine sedimentation, shaped by the
major hydrological drivers of river discharge and tidal propagation. The position of intertidal
flats within an estuary will also exert profound influences on water salinity, and provide a
major control over the suite of saltmarsh species present.