BOAMBEE HEAD OUTFALL

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Physical Environment

Landscape

Boambee Head appears to be a seaward outcrop of Brooklana formation rocks which consist of siliceous argillite, slate and rarer siliceous greywacke (Geological Series Sheet SH 56 – 10 & 11). To the south is Sawtell Beach and to the north is the entrance to Boambee Creek and then Boambee Beach.

Bathymetry & Substrate

Water depth at the point of discharge is about 1.5m at mean high tide. At low tide the pipe outlet is exposed (MHL387 1984, MHL693 1994).

Currents, Winds and Waves

Studies indicate:-

• nearfield dilution is dependent on wave action (MHL769 1997).

• on most occasions effluent would spread within the surf zone between the discharge and the rocks within the swash zone approximately 100m to the south (MHL693 1994).

• in most cases effluent would travel offshore from this area in a weak to strong ‘rip’ current.

• in a typically easterly swell the effluent would be held against the shore by wave action and only travel offshore during lulls between wave sets.

• effluent moving offshore would be influenced by a combination of wave induced longshore drift and wind driven currents.

• during south-east to south-west winds and south-east swell effluent would travel north against the rocks.

• during north-east winds and easterly swell effluent would move south along the beach in the swash zone.

Outfall Site

Barnacles

Oysters

Boambee

(Boam_5) Last updated May 2000