Australian authorities must plan for more severe floods, experts have warned, amid concern that the management of the Townsville Ross River dam contributed to extensive flooding when a massive amount of water was released downstream.

The decision to open the floodgates when the dam water level reached 43m was based on a 2012 study that warned doing so could cause more extensive property damage during the most extreme flooding events.

The dam’s spillway gates were fully opened late on Sunday night, just before the dam level peaked at 42.97m, and in line with a current management plan. About 1,900 cubic metres of water a second gushed into the Ross River and ultimately into low-lying Townsville suburbs, where residents had to be evacuated.

The Queensland premier, Annastacia Palaszczuk, said on Monday the floodgates had to be opened “to make sure the water had somewhere to go”.

Some residents have expressed anger that water was allowed to build for so long, rather than be released more steadily during the previous week of continued heavy monsoonal rain.

The Northern Water Management study, commissioned by the Townsville council in 2012, underscores the almost impossible nature of such policy decisions; saving homes on one flood scenario, causing more extensive damage in another.

The previous trigger for the Ross River Dam floodgates to be fully opened was 41.75m. Modelling for a one in 100-year flood scenario under the previous trigger predicted 960 properties in Townsville would be flood affected. The 2012 study concluded that by delaying the trigger to fully open the spillway to the current level of 43m, only 90 properties would be affected by a once in a century flood event.

But the same modelling showed that, during even more extreme floods, delaying the opening of the gates would result in flooding at a larger number of properties. In the event of a one in 1,000-year flood, 3,120 homes would be affected. The number is about 600 more than predicted under the previous management plan for Ross River Dam.

Based on the rate of water coming from the dam spillway on Sunday night, about 1,900 cubic metres a second, the study rated this week’s unprecedented monsoonal rainfall as comparable to about a one in 1,000 year flood.

Australian National University professor Jamie Pittock said authorities in Australia typically made planning and flood management decisions based on the “one in 100” year designation. Elsewhere, in Europe and the United States, contingencies are made for more extreme natural disasters.

“We’re creating trouble by not planning for those [extremes],” Pittock said. “With climate change, the recurrent interval of large floods are increasing. What today is the one in 100 year flood, in five years time it could well be the one in 50-year flood.”

Pittock said the need to spill water from Ross River Dam highlighted the limits of using dams for flood control.

“Flood control dams will only ever be able to capture small and medium-sized floods. At some point the empty space behind the dam wall builds up,” he said. “Studies show that flood control dams lull people living downstream into a false sense of security.

“Then accidentally, or deliberately, development occurs in the floodplain. Queensland is a particularly egregious place for building stuff in dumb places. Flood-prone land is often the cheapest land, so unless you’ve got a strong planning regime local government ends up putting things like childcare and schools there ... so you end up exacerbating the risk to the whole community.”

Townsville residents told Guardian Australia on Tuesday they believed more water should have been released progressively from the dam, rather than allowed to build over a week of heavy rainfall.

“How about the fact they didn’t do it gradually over the whole time like they should have, and they’re celebrating when they should have been in panic mode,” Idalia resident Leah Kim said. “We didn’t get flooded by the rain alone, we got flooded when those waters came down.”