The Significance of Coastal Processes for Management of the River Murray Estuary

The tidal prism in the River Murray estuary has been reduced by over 85 percent since completion of the barrages in 1940 and regulation has diminished the rate and size of river flows through the estuary. Reduced fluvial flushing has emphasised the dominance of coastal processes at the river mouth. These are expressed in the accretion and stabilisation of a flood-tidal delta, the migration of the mouth, the erosion of Sir Richard Peninsula and the accumulation of new flood-tidal deltaic deposits. Inconclusive studies relating river flow to mouth migration indicate the importance of coastal processes such as littoral drift, tidal flux and sea state, particularly at times of low river flow, in explaining the position and morphology of the mouth. Previous management strategies have failed to consider coastal processes adequately.