EXTREME MAKEOVER\ VIOLENT WEATHER PRECIPITATES REDESIGN OF INFRASTRUCTURE
- EXTREME MAKEOVER\ VIOLENT WEATHER PRECIPITATES REDESIGN OF
By Anita Weier Wednesday, June 18, 2008
The heavy rains, strong thunderstorms and fierce tornadoes that have
attacked the Midwest in recent weeks are a sign of the future, and
communities will have to adapt to more frequent occurrences of
extreme weather, experts say.
It could be an expensive process.
Ken Potter, a UW-Madison engineering professor who helped review the
New Orleans hurricane protection system after Hurricane Katrina, said
Wisconsin engineers will have to consider how to redesign structures
to prevent flooding and events such as the draining of Lake Delton
after extremely heavy rains.
Some reservoirs, dams, levees, roads and bridges as well as water,
sewer and stormwater systems will have to be rebuilt, and land use
and zoning will have to change, researchers say.
The design of sewer and water systems and stormwater detention ponds
was based on past rainfall statistics and will probably require
increases in capacity in the future, Potter said.
"Water control structures were based on what was known in the early
20th century. Much of our flood control and water structure was built
in the 1920s and 1930s. The effect of development also has to be
considered," Potter said.
"The past may not be a good indication of the future."
Though Potter and others stress that specific events such as recent
intense rains and tornadoes can't be linked directly to global
warming, those extreme weather events are consistent with
expectations due to a buildup of heat-trapping greenhouse gases. A
United Nations panel report on climate change compiled by hundreds of
scientists internationally predicted that extreme weather events --
such as heavy rain, heavy snow and heat waves -- will become more
"For the Great Lakes region, the proportion of precipitation falling
in extreme events has increased over the last 100 years" and is
expected to increase even more in the next century, said John
Magnuson, a UW-Madison emeritus professor who is an internationally
known lakes expert. Steve Vavrus, as assistant scientist at the
Nelson Institute for Environmental Studies at the university, found
that days of 1-inch, 2-inch and 3-inch precipitation spiked in
Madison during the current decade and that 1-inch precipitation days
have risen steadily in each decade since the 1960s.
But others, including Jonathan Martin, chair of the Department of
Atmospheric and Oceanic Sciences at UW-Madison, stress that weather
events are controlled by national-scale circulation patterns, and
that global warming effects can't be judged on a regional scale at
Martin and others note that air current patterns across the nation,
often influenced by temperatures in the Pacific Ocean and the amount
of moisture carried in currents from the west and south, influence
weather in Wisconsin.
Rusty Kapela, a meteorologist with the National Weather Service in
Sullivan, said seasons in Wisconsin that follow a "La Nina" time of
colder equatorial waters in the Pacific -- as is the case this year --
tend to have an above-average number of tornadoes.
"We average 20 tornadoes in each of the 10 warm seasons that follow
La Nina. This year we have had 16 so far," he said.
However, Todd Ambs, director of the water division for the state
Department of Natural Resources, noted the rainstorms that inundated
southern Wisconsin early this month fit in with frequent predictions
of extreme weather produced by climate change.
"I grew up in Michigan, and I don't recall big low pressure systems
just sitting over a region for days and dumping water," Ambs
said. "Everybody said when Vernon County got 16 inches in 24 hours
last August: a 100-year rain event. Now we had 11 inches in 24 hours.
Something is going on."
Potter said that although we don't know exactly what the future
climate will be, it would be prudent to proceed by protecting
Wisconsin from its greatest vulnerabilities, given the intensity of
rain in recent years.
"We have to be able to adjust," he said.\
HOW TO ADAPT\ Municipalities in Wisconsin will have to upgrade water-
related infrastructure -- including levees, sewer pipes and
wastewater treatment plants -- in anticipation of more frequent
downpours and floods, according to a 2003 report by the Union of
Concerned Scientists titled "Confronting Climate Change in the Great
Magnuson contributed to that report, which predicted that cities will
be subject to more extreme storms and floods, exacerbated by stream
channeling and more paved surfaces. The result will be greater
property damage, heavier burdens on emergency management, and
increased cleanup and rebuilding costs, unless changes are made.
Patrick Eagan, an engineering professor at UW-Madison who is an
expert in stormwater management and potential effects of climate
change, said good water management is the key to handling shifts of
normal weather patterns.
The more developed our landscape becomes, the more runoff we will
have, he said. So reducing runoff with rain gardens, porous pavement,
grass swales and green roofs will be important.
"If we have more runoff, our design standards for storm sewer systems
have to change. Our pipes and culverts are undersized," said Dick
Lathrop, a DNR scientist who is working with Magnuson in a new state
program planning how the state can adapt to climate change.
The Department of Transportation will have to look at vulnerable
situations where roads might be washed out, to prevent runoff from
eroding them, he added. Yet, the DOT can barely keep up with places
that are already damaged, according to Lathrop.
Smarter planning and zoning also will be essential.
For instance, topographic information about Lake Delton should have
been known, so people realized where water would go when the lake got
to a certain height, Potter said.
The lake broke through a county highway and headed to the Wisconsin
"Dams and reservoirs are designed to pass such events, and this dam
and reservoir could not," Potter said. "And this was not a maximum
flood that would involve rainfall of 20 inches."
State and federal regulations for high-hazard dams look at the whole
lake, not just a dam, he said.
"You don't let water spill out. You reinforce places where it might
go," Potter added. "Many dams and reservoirs have levees, and it
might have been a real cheap fix to put rip-rap there. That might
have been possible to do for tens of thousands of dollars. That would
not have cost nearly what it will cost to fix it."
It also might be logical to keep Lake Mendota at lower levels than
present in order to preserve wetlands and give the lake a bigger
storage capacity in case of bigger storms, Magnuson suggested.
Additionally, the whole notion of where you build also will have to
be considered, Eagan said.
"It makes no sense to build in floodplains where you get flooded over
and over again. It doesn't help the people and costs social money
that could be spent on other things," Eagan added.
A house in such an environment is a risk, he said.
The cost of bringing infrastructure up to higher standards that will
survive stronger weather will depend on how much is done and how far
the work goes.
"It depends on how good of shape it was in and how conservatively it
was designed," Potter said.
"It's expensive, but there has been discussion for a decade or more
that a lot of this has to be refurbished anyway, because
infrastructure is aging. For years we have shortchanged
infrastructure requirements. We have to do something, so the real
decision is how much we believe floods will increase and the results.
We should look at what is the most critical need and what is the most
When calculating the cost and standards of building, officials also
should consider the high cost of repairing or replacing a bridge,
road, dam or lake that fails, Potter warned.
Lee Sensenbrenner, a spokesman for Gov. Jim Doyle, said state
officials have their hands full at present working with the Federal
Emergency Management Agency to deal with current damages. They are
counting on federal funding to take care of much of the flood damage
to agriculture, homes and public infrastructure, so broad questions
about the future will have to wait.