Hundreds of thousands of people are under a blackout in Queensland, while flood warnings remain in place across New South Wales, after ex-Cyclone Alfred left a trail of destruction along Australia’s east coast.

Tropical Cyclone Alfred approaching, the Gold Coast's decades-old hidden rock wall acts as the city's line of defence against a surging ocean, according to an engineering expert.For about 50 years, the Queensland government has had a policy that meant seawalls must be constructed along the "A-Line".