KEARNEY — A former aide to five governors — four in Nebraska and one in Wyoming — says the 2019 Nebraska floods are a reminder that prevention requires looking at weather history beyond lifetimes and even centuries.

“The 100-year flood metric can make people think that once you’ve had that, the rest of your life is on easy street,” said W. Don Nelson of Lincoln, even though the odds of a 100-year event are the same tomorrow as they were yesterday.

Nelson, who also was owner-publisher of Prairie Fire from 2007 to 2016, a monthly regional publication that described itself as “the progressive voice of the Great Plains,” spoke Monday in Kearney at the joint convention of the Nebraska State Irrigation and Nebraska Water Resources associations.

“All of us have the advantage of spending our lives in the ‘Goldilocks’ period,” he said, which hasn’t been too hot or too cold, “and people are wired to think mostly ‘in my time period.’”

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Nelson said that when he visits disaster restoration sites, he often hears someone say, “I’ve lived here for 50 years and this hasn’t happened before.”

He added that while geologists say Nebraska’s land mass is 1.2 billion-1.6 billion years old, nearly all agricultural and municipal data related to natural resources and major weather events have been gathered in the last 100 years.

Nelson said Nebraska has more miles of rivers and streams than any other state, which can be a blessing and a curse, as revealed during the 2019 floods.

His concerns include the pressure in many places to develop all habitable land and use nearly 100 percent of ag land, mixed water regulation messages, and the use of inadequate or outdated actuarial data and floodplain maps.

Nelson said Congress has created “a layer cake of regulation on the waters of the United States” with some laws having opposite purposes and outcomes. “Where you stand depends on where you sit,” he added, including whether river interests are upstream or downstream.

Also, there is no national flood insurance policy that is sustainable. “So, Nebraska pays for hurricane damage in Texas and other Gulf states,” Nelson said.

Changes in extreme weather events aren’t always reflected in actuarial numbers.

For example, he said that in the 35 years from 1980 to 2015, there was an average of five extreme weather events annually that exceeded $1 billion each in damages. In 2016-2018, there were 15 such annual events.

Hurricane Harvey, the late summer 2017 storm that targeted Texas and Louisiana, was seen as a once-in-2,000-years storm. Nelson said that ratio “collapsed” in 2017 to one-in-300 years and planners now have adjusted the actuarial table to one-in-100 years.

Similarly, tidal surges once seen every 1,000 years now are expected approximately every 30 years.

“The 100-year-flood isn’t very helpful anymore because it’s a movable concept,” Nelson said. His “what that tells us” list included:

- We must accept that climate change — whatever its cause — affects our weather.

- Weather will bring more frequent extremes and intense events.

- Many people falsely believe the Federal Emergency Management Agency is a rescue agency with a team of responders. “We’re all on our own for quite a bit of time. We have to make due with what we’ve got,” Nelson said.

- A better understanding is needed of water physics related to bank stabilization and disconnects of creeks from riverbeds.

Nelson said there has been a “failure of imagination” in disaster planning and mitigation, even as events never imagined continue to occur.

“How do we mitigate the pickle we find ourselves in, in many communities,” he said, with Nebraska’s settlement history filled with people who chose to live by watercourses.

On a recent trip between Lincoln and Rapid City, S.D., he passed through Winslow, Neb. The town of around 100 people on the Elkhorn River north of Fremont has flooded several times, including last March.

Nelson said Winslow is nearly abandoned now and reminds him of Niobrara, another flood-prone town that has been moved to higher ground twice.

He believes more communities will face such issues, at least to protect flood-threatened facilities such as municipal water systems and wastewater treatment plants. Such increasingly common threats require thinking about big picture flood mitigation, Nelson said.

He suggested getting past lifetime observation limitations by exploring paleoclimatology, the study of past climate that uses data from tree rings and ice cores to identify “eons ago” conditions on the Great Plains.

Nelson said Nebraskans can access many flood prevention planning resources from federal, state, local and university entities that have treasure troves of information, technologies and expertise.