Warning issued on our dams’ stability

AUSTRALIAN dams are set for more major influxes, with concerns about whether existing infrastructure is under threat from more consistent major flooding events.

New research from UNSW and Melbourne University has shown existing dams, due to climate change, are under greater risk than previously assumed, with the model which engineers use to calculate how much rain will fall not being updated for at least 20 years.

The research paper found the Probable Maximum Precipitation (PMP), a measure of the greatest amount of rainfall meteorologically possible over a certain amount of time, was set to increase by a considerable amount due to the warming climate.

An increasing PMP would also mean another measure, called a Probable Maximum Flood (PMF), would increase over time. If green policies are not implemented and carbon emissions remain high, the amount of rainfall falling over large dam locations could increase by 38 per cent across the next 80 years, the report found.

Even using the most conservative estimates regarding emissions and subsequent climate change, the modelling suggests an average increase in PMP of 13 per cent across Australia over the same period.

The consequences of dams being under unprecedented pressure from rainfall can be dire, according to UNSW Water research centre senior engineer and lead author of the paper Johan Visser.

“There are a lot of risks involved with dams given the amount of water they are holding back,” Mr Visser said.

“Some of the worst floods around the world were due to extreme storms overwhelming a dam, causing it to fail and release water downstream.”

“For each 1-degree Celsius rise in temperature, the atmosphere can hold approximately 7 per cent more water,” says Mr Visser.