Expert urges updates to infrastructure and reduction in emissions to avoid extreme flooding

Dr Ashish Sharma, a University of New South Wales (UNSW) researcher and professor, is well versed in hydroclimatology; the study of climate's influence upon waters on land.

He has co-authored a new study indicating probable maximum flood events will significantly increase over next 80 years.

When designing a dam, engineers accommodate the largest flood event that could reasonably be expected to occur at a particular location, known as the probable maximum flood (PMF). To get that data, they must first calculate the greatest depth of rainfall meteorologically possible over that area in a certain amount of time, which is called the probable maximum precipitation (PMP).

"The point is conclusive ... probable maximum precipitation, which is the upper limit of rainfall, is increasing by 38 per cent by the end of the century," Dr Sharma said.

Last week ACM editors across Western NSW - including the Central Western Daily - wrote an open letter to Canberra demanding a conversation that centres around better preparedness and protection from weather extremes for regional NSW be had.

That preparedness includes increased infrastructure, but dams, some of the costliest infrastructure in the world and the life of remote townships, are at risk of being compromised, the experts predict.

When rain filled up Wyangala Dam earlier this month, spill gates were opened and biblical volumes of water released and inundated towns like Forbes. The devastation, for many, was a sign our dams needed to be upgraded to avoid future flooding events.

"Water supply dams which store significant volumes of water behind them. You just don't want to pass that risk to community because the consequences of a dam failure are catastrophic, we can't allow it," Dr Sharma said.

"Our study is basically saying that the changes that are happening are very much because of climate change, which is part of the problem."

When it comes to La Nina, the wet phase of the El Nino Southern Oscillation weather pattern, it is not an unfamiliar phenomenon in Australia. Historically, we have experienced the cycle every three to five years.

While these patterns are familiar, their consequences are getting worse because the earth is heating up, Dr Sharma claims.

Dr Sharma says when temperatures go up, they complicate the weather in two ways; increasing evaporation and moisture retention.

"Higher temperatures mean they dry up the soil, but at the same time, if you've had wet conditions like three La Nina years in a row, then the rains have been so high that dryness in the soil is not an issue, because it's completely saturated and soaked ...," Dr Sharma said.

"Normally, [rain] would fall on dry soil and would kind of cancel out. But unfortunately, right now... when rainfall events occur they are heavier and essentially you're having these extremes that are much bigger."

Intervals of wet weather patterns and dry weather patterns have led to flooding and droughts in the past. Dr Sharma believes these events are only going to become more extreme in the future unless we do something about the climate emergency.

"[Expect] big changes in the severity of both floods and droughts as the climate warms up," he said.

The goalposts for the safety of riverside communities and bushfire-prone areas are shifting, and Dr Sharma says Australia needs to adapt its strategy.

There is already some infrastructure in place to protect vulnerable communities from such disasters like storm water drains, levees, and canals. However, the professor of hydrology in environmental engineering believes they must be updated to prepare for future weather conditions.

"I believe the right thing to do is revisit the adequacy of the existing infrastructure, see if they can be tweaked or changed, altered to provide that extra level of safety," he said.

Equally important is widespread acknowledgement of the common driver of these events; higher greenhouse gas emissions.

"I know that [reducing] greenhouse gas emissions is not going to make any difference in a year or two, but in the long run, it is the real solution," Dr Sharma said.

He also points to extreme events occurring in other parts of the world like dire reports of droughts in China, Korea, and Switzerland as well as the Hoover Dam drying up in the United States.

"If you think about it, it's all part of the same problem, and the problem is not La Nina not the El Nino, it's climate change," he said.

WHAT DO YOU THINK? We've made it a whole lot easier for you to have your say. Our new comment platform requires only one log-in to access articles and to join the discussion on the Central Western Daily website. Find out how to register so you can enjoy civil, friendly and engaging discussions. Sign up for a subscription here.