maroochy estuary mapMajor Towns: Maroochydore

Subcatchment Area: 12 040 Ha

Rainfall: 1680 mm/yr (Yandina)

Major Land Uses:

  • Native Vegetation – 3000 Ha
  • Residential – 2100 Ha
  • Sugar cane – no longer grown as a   major crop…

Remnant native vegetation covers approximately one quarter of the subcatchment area, the majority of this is on freehold land not in reserves. As this entire subcatchment is tidal, the riparian vegetation is dominated by mangrove communities of Grey Mangrove (Avicennia marina) and Orange Mangrove (Bruguiera gymnorrhiza) and saline herbland of rushes (Juncus sp.) and salt grasses (Sporobolus sp.).

The coastal areas away from the riparian zone are populated by frontal dune scrub. The main species are Brown Salwood (Acacia aulacocarpa) and Coast Banksia (Banksia integrifolia); this is interspersed with areas of open and closed Wallum heath populated by Wallum Banksia (Banksia aemula), Swamp Banksia (Banksia robur) and Grass Tree (Xanthorrhoea australis). This gives way to Eucalyptus – Melaleuca – Lophostemon grassy woodland, which occurs on the floodplain areas away from the river channel. The low lying areas and drainage lines subject to short-lived periodic inundation support pure stands of Broad Leaved Tea Tree (Melaleauca quinquenervia). The areas of higher elevation support open woodlands of Forest Red Gum (Eucalyptus tereticornis), Broad Leaved Tea Tree, and Swamp Box (Lophostemon suaveolens).

The upper slopes and crests of the low hills bounding the subcatchment support open forests of Blackbutt (Eucalyptus pilularis) interspersed with pockets of gallery forest and Piccabeen Palms (Archontophoenix cunninghamiana).

maroochy estuary

maroochy estuary

Comprising the tidal section of the Maroochy River, the Maroochy Estuary begins at the confluence of the North and South arms of the Maroochy River, and drains into the South Pacific Ocean at Maroochydore.

For its entire length, the Maroochy Estuary is tidal, and drains at a low angle through Quaternary alluvium of gravel, sand, silt and clay forming a level to slightly undulating but narrow floodplain that is initially constricted by steep, low hills. This opens out and becomes quite extensive once the river leaves the low hills. The channel begins to widen at this point, with several channel islands occurring.

Near the mouth, the landform changes into coastal sand dunes of Holocene wind blown sand, Pleistocene tidal sand, and saline muds which are deposited around the shoreline of the river.

Hire boats on the beach at Maroochydore

Hire boats on the beach at Maroochydore

The lower reaches of the estuary are a highly complex and dynamic system of channels, sand banks, intertidal shoals and sand bars. Two islands, Goat and Channel, divide the estuary into two channels, north and south. The river mouth is migratory, moving north and south according to the prevailing coastal conditions, and cyclonic and flood events