SKENNARS HEAD OUTFALL

Click the photograph for a enlarged view

Physical Environment

Landscape

The ocean foreshores in the vicinity of the Skennars Head ocean outfall are dominated by rocky headlands of moderate relief (approximately 40m ASL). The headlands are comprised of columnar basalt (Lismore Formation basalt – Tweed Heads Geological Series Sheet SH 56-3) and characterized by a steep cliff face. At the base of the cliff is a relatively narrow rock platform. 

Immediately north of the outfall site is Little Boulder Beach, which is composed of basalt boulders. At the northern extremity of Little Boulder Beach is a relatively wide, low gradient rock platform (Iron Peg). Further to the north is Boulder Beach, which also consists of basalt boulders. South of Skennars Head the coastal cliffs continue for some 500m. Beyond this zone is the Sharps Beach embayment which is a sandy beach system. 

Bathymetry & Substrate

Water depth in the vicinity of the ocean outfall is less than 2m to a distance of 40m from the coast. Gradients to the 10m ISLW depth are low at less than 3%.

Currents, Winds and Waves

Studies (Sinclair Knight 1991, PWD 1991) indicate:-

• northbound currents 36% of the time

• southbound currents 56% of the time

• westbound currents 8% of the time

• under northerly winds (~8m/s) effluent moves south

• under south to south-easterly winds effluent is driven northwards past Iron Peg and seaward

• under north-easterly winds effluent moves south and towards the coast

• under westerly winds the plume advances offshore
  

• moderate to high energy wind waves

Outfall Site

Outfall Site

Skennars Head

(Sken_5) Last updated May 2000