A Risk Frontiers research trip to northern NSW flood-hit regions has found that “without exception” residents in all areas visited expressed alarm at the speed with which water levels rose and surprise at the ultimate height they reached.

“Residents expressed dissatisfaction with the limited frequency of warnings as waters rose quickly and perceived that peak heights had been underestimated,” the report by Steven George, Maxime Marin, Stuart Browning and Andrew Gissing says.

Risk Frontiers says the event has shown that house raising can afford people a false sense of security and result in people becoming trapped in extreme floods.

Key findings also include that building designs which integrate water resistant materials such as concrete and cement and tiles in favour of soft timbers, carpets and gyprock walls, prove far more resilient to flooding.

Caravan parks across the Northern Rivers suffered severe damage, as the event again highlighted the vulnerability of the parks and their residents to flooding.

“The long-held theory is that it should be possible to evacuate dwellings in caravan parks in a timely manner prior to flooding; however, many have evolved to be semi-permanent and fixed in place,” the report says.

Most areas experienced power and telecommunication failures of NBN, ADSL, mobile and landlines to some extent, with services often still out of action after two weeks.

Many people in South Lismore made the decision to remain in their homes, given the 2017 floods had not risen to the second level of Queenslander-style homes common around the town.

But some residents went to bed on Sunday February 27, only to wake in the early hours of the morning to find water in their second-story bedrooms.

“People reported being forced to take refuge in their roof cavities, with the speed of rising water preventing them from exiting homes via windows and doors,” the report says.

“There were also accounts of people dismantling roofs from inside to gain access to the roof to escape rising waters.”