coolum yandina catchment mapMajor Towns: Doonan, Valdora

Subcatchment Area: 11 860 Ha

Rainfall: 1675 mm/yr (Valdora)

Major Land Uses:

  • Native Vegetation –5835 Ha (50%)
  • Beef Cattle – 1430 (12%)

The low hills of the Yandina Creek headwaters are populated by open forests of Blackbutt (Eucalyptus pilularis) and Grey Gum (Eucalyptus propinqua) on the crests and upper to mid slopes. The same landform in the upper Doonan Creek catchment is populated by Scribbly Gum (Eucalyptus racemosa) and Bloodwood (Corymbia sp.), which gives way to Banksia and Tea-tree shrub land on the lower slopes.

The riparian areas of both creeks are populated by remnants of Forest Red Gum (Eucalyptus tereticornis) open forests and fringing areas of rain forest species.  This landform is also populated by large areas and numerous fragments of Tea-tree (Melaleuca quinquenervia) wetlands and Wallum Heath. The largest areas of vegetation occur in the Doonan Creek catchment, which flows into an area of extensive wetlands located on the upper floodplain, and in the riparian areas of Coolum Creek.
Toward the confluence with the Maroochy estuary, small areas of Grey Mangroves (Avicennia marina), and rainforest appear along the margins of the river.

Yandina Creek floodplain showing aquaculture.

Yandina Creek floodplain showing aquaculture.

Incorporating Coolum, Yandina and Doonan Creeks, this large subcatchment drains the northeastern quarter of the Maroochy River Catchment. These creeks rise in the Eumundi Range, which is the eastern end of the Blackall Range after it turns toward the coast to form the northern boundary of the Maroochy Catchment. The western boundary is formed by the Ninderry Range, and offshoot of the Blackall Range. A small, unnamed line of hills running north south from the Eumundi Range separates Yandina and Doonan Creeks. Once clear of this obstacle, they confluence to form Coolum Creek, which flows into the Maroochy River Estuary.

The headwaters of Yandina Creek rise in low undulating hills composed of soil derived from Rhyolite and Andesite, a formation that also forms Ninderry Range, and the line of low hills that separate Yandina and Doonan Creeks. Doonan creek arises in undulating rises formed of sandstone.

In their upper catchments, both creeks form a narrow alluvial area immediately adjacent to the creek lines consisting of undifferentiated freshwater sediments mixed with colluvial material from the surrounding hills. These are discontinuous initially, but quickly coalesce in continuous floodplain formations.

vegetation in a tributary of Doonan Creek

vegetation in a tributary of Doonan Creek

Both creeks form a wide flood plain after exiting the confines of the low hills in which they arise, at about the tidal limit, upstream of the confluence that forms Coolum creek.

This floodplain is formed on Holocene and Pleistocene sand deposits, and is nearly level, and entirely below the 5m ASL contour. It is on this floodplain that the confluence of Yandina and Doonan Creeks forms Coolum creek, which drains into the Maroochy estuary.