Tidal height monitoring: Nerang entrance stabilisation

John Driver - Division of Marine and Ports, Department of Transport Qld , 01 October, 1990

The Nerang River flows to the sea through a broad shallow tidal estuary known
as The Broadwater and meets the ocean via an entrance channel between the
southern end of South Stradbroke Island and the Southport Spit.
Both the entrance and estuary are significant for recreational and commercial
reasons. The Broadwater provides safe navigation and anchorage for
recreational craft as well as numerous fishing vessels. Small craft regularly
cross the entrance bar to visit offshore fishing areas and reefs.

The Nerang River Entrance has had a history of instability and has migrated
steadily northwards under the influence of the longshore sand drift generated by
the waves and currents in the nearshore zone. (Estimated to be 500,000 cubic
metres nett per annum).

There is no accurate early history of the movements of the Nerang River.
However, at the turn of the century, the entrance was just north of the present
Jubilee Bridge. Since then, the entrance has migrated steadily
northwards at an average rate of between 20 and 40 metres per annum. This
northward migration has been associated with equivalent erosion of the southern
end of South Stradbroke Island. In addition, the channels through the entrance
have been variable in location and depth. This has often made navigation
hazardous and has contributed to a significant number of boating accidents over
the years.