<P> Most salt marshes have a low topography with low elevations but a vast wide area , making them hugely popular for human populations . Salt marshes are located among different landforms based on their physical and geomorphological settings . Such marsh landforms include deltaic marshes , estuarine , back - barrier , open coast , embayments and drowned - valley marshes . Deltaic marshes are associated with large rivers where many occur in Southern Europe such as the Camargue , France in the Rhone delta or the Ebro delta in Spain . They are also extensive within the rivers of the Mississippi Delta in the United States . In New Zealand , most salt marshes occur at the head of estuaries in areas where there is little wave action and high sedimentation . Such marshes are located in Awhitu Regional Park in Auckland , the Manawatu Estuary , and the Avon - Heathcote Estuary in Christchurch . Back - barrier marshes are sensitive to the reshaping of barriers in the landward side of which they have been formed . They are common along much of the eastern coast of the United States and the Frisian Islands . Large , shallow coastal embayments can hold salt marshes with examples including Morecambe Bay and Portsmouth in Britain and the Bay of Fundy in North America . </P>
where are salt marshes located in the us
rivers of the Mississippi Delta much of the eastern coast