Coastal Systems

The coastline within the NAR has a generally linear north-south alignment, consisting of a range of beach types backed by low dunes, with intervening sand promontories or points, rocky headlands, and low to high cliffs. The sandy deposits are generally underlain by a limestone platform, and have variously formed dune fields, sandy plains, and mobile sand sheets. These sandy landforms are broken in some areas by high cliffs, headlands, alluvial floodplains, seasonal wetlands and lagoons, and cave systems. The popularity of both natural and artificial lookouts with local residents and visitors alike indicates that the land and seascapes over the region are a prized natural value and are important socially, culturally and economically (NACC, 2005).

The coastal environment faces pressures from urban settlement, as the majority of the population within the NAR is concentrated with the coastal areas. A good proportion of the coast, especially between Lancelin and Dongara, is contained in Nature Reserves and National Parks and managed by the Department of Parks and Wildlife. Other areas are managed to varying degrees by Local Government, a mix of organisations (e.g. Unallocated Crown Land), or by private landowners (NACC, 2005).

The NAR lies in two coastal regions including the Batavia Coast and Central Coast Region. The Batavia Coast occurs in the Geraldton Hills Interim Geographic Bioregion (IBRA) and is comprised of foredune vegetation including grasses and shrubs (Spinifex longifolius, Olearia axillaris, Aristea isotider and Scaevola crassifolia).

Areas with sand over sallow rock support quite dense acacia and banksia tall shrubland, with the distinctive smelling Acacia rostellifera and Melaleuca cardiophylla forming thickets on limestone ridges. Further inland the array of low and tall shrubs increases, with eucalypts and acacias prominent (NACC, 2005).

The whole Central Coast area lies in the Lesueur Sandplains IBRA subregion and Swan Plain Coastal IBRA subregion. In the Quindalup dunes, which occur from the southern extremity of the region north to Green Head, there are three plant communities from the beachfront, moving inland. A dense low shrubland in the swales and secondary dunes, and dense, tall shrubland further inland. The coastal wetlands and limestone areas support their own distinct vegetation communities. The coastal areas between Lancelin and Guilderton, and between Cliff Head and Illawong are an important area for limestone endemics (NACC, 2005).

Coastline Movements - Vegetation Lines, Sourced from DoT. View full page map.

The coastal lands are important for the conservation of heath-dwelling mammals, including dibblers and dunnarts. The Central Coast is rich in bird species, including marine and migratory species of seabirds. The heathlands are important as habitat for fairy-wrens and honeyeaters, and support other animals such as reptiles (NACC, 2005).

For more information on regional fauna, visit the biodiversity fauna page.

Estuaries are defined as semi-enclosed coastal water bodies that represent the mixing zone between

marine-derived saltwater and terrestrially derived freshwater. Tides, wind, waves and river flows are important physical processes that influence variations in estuary shape and ecology. Estuaries are often host to large amounts and a wide variety of plants, birds, crustacean and fish: fish production per unit area is probably higher than in any other natural water bodies (NACC, 2005).

The NAR estuaries tend to be small (a few kilometres in length) with low and seasonal rainfall in the catchments combining with the wave-dominated coast causing the mouths to be blocked by sandbars most of the year. Though tides continue to influence circulation when the bars are closed, limited exchange between estuaries and the open ocean means they are vulnerable to water quality impacts associated with increased nutrient, toxicant and sediment loads from the catchments (NACC, 2005).

Drawing on studies of the Moore, estuarine biodiversity is high: twenty-five species of fish are known to occur in the estuary and there are about 14 freshwater species in the Moore River and Gingin Brook. Relatively little is known about most of these estuaries, though the Moore is under significant pressure, and has therefore received a relatively large amount of research and management attention. Estuaries in the region are also significant for their social (e.g. recreation and Aboriginal heritage) and economic values (NACC, 2005).

There is evidence of Noongar and Yamaji people occupying various parts of the coast for extensive periods of time. Stone artefacts have been found in caves in the Jurien Bay region, and the area between Greenhead and Jurien Bay has the largest number of midden deposits in the Southwest Australia. Coastal dunes throughout the region were also used as burial sites, and skeletal remains have been exposed by dune blowouts. The mouths of rivers and estuaries tend to be particularly significant, especially Bowes River. Changes in tenure, management and development in the coastal zone should protect the environmental, cultural, spiritual and historic values of these areas (NACC, 2005).

Beach Photo Monitoring in the NAR

Click on the icons and tabs for more information. View full page map.

Go to the online Photo-viewer.

Photomon    For more information about Photomon, NACC’s photo monitoring App visit the NACC website.

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