Experts say expect more floods, more often

Heavy rains caused flooding on Oahu, April 2018. Credit: KHON

Expect more heavy rain, more often, and get ready for even worse from named storms and hurricanes. That’s what experts warn, and they say our infrastructure needs to change to keep up.

Steven Businger, SOEST Atmospheric Sciences Department (ATMO) professor and chair, has seen big storms and floods come and go. He says what used to be rare is becoming more frequent — and all the engineering to withstand it needs to be rethought.

“For those people who were flooded, this past weekend, I feel sorry for them but they can expect that to happen again in the next five years,” Businger said. “There will be another flood. I would say that’s the return period for a storm like this.

It used to be every 10 years, he says.

“We don’t generally design things for a 100 year return period but I think we should. We should start doing that because these floods, unusual floods are becoming more common,” he explains. Why? “The sea surface temperature is warming with climate change, and warmer sea surface leads to a larger amount of water vapor. It pushes water vapor into the air and so the result is storms that produce heavier rain, and that’s been shown all over the world that’s happening.”

“But a much bigger problem is a hurricane,” Businger adds, “because then you’re going to have the flash floods plus the high winds plus the storm surge. If we don’t harden our infrastructure for the possibility of having a hurricane hit Honolulu, then I think we’re doing our society a disservice.”

Read more about it and watch the video at KHON.

Update 04-19-18: Read more about the unpredictability of storms this size in Honolulu Civil Beat, with quotes from ATMO’s Steven Businger and Pao-Shin Chu.