Spring/Summer 2014 | By Donald Radcliffe
Over the last several decades, Wisconsin has seen an increase in extreme weather and variability, and these conditions are likely to become more common in the years ahead. Scientists in the Nelson Institute Center for Climatic Research (CCR) project a sharp rise in average annual temperatures in coming decades – somewhere between 4 and 9 degrees Fahrenheit – spawning more frequent and intense storms, droughts and heat waves.
These trends will challenge cities throughout the state. Sally Kefer, a land use specialist with the Wisconsin Department of Natural Resources (DNR), is helping Wisconsin communities adapt.
“Climate change adaptation is really about sustainability and building community resiliency,” says Kefer, a member of the Wisconsin Initiative on Climate Change Impacts (WICCI), a collaborative effort between DNR, the Nelson Institute and a number of affiliate organizations. “We’ve already seen extreme weather changes cause damage to expensive infrastructure and homes.”
A few communities have moved forward with adaptation efforts. One example is La Crosse, where Kefer led a recent study funded by the Association of State and Territorial Health Officials.
The project began in 2012, when more than 50 La Crosse community leaders met with CCR scientists and WICCI staff for a daylong workshop to discuss climate change science, potential changes and risks associated with climate change, and strategies to prepare for those changes.
“We asked people to share their experiences of extreme weather events,” says Kefer. “I think that’s very effective for helping a community to think through the impacts. It shows that we aren’t only projecting fancy models.”
La Crosse is a city of 50,000 people sandwiched between a series of bluffs and the Mississippi River. Its geography makes it vulnerable to flooding, so more and larger storm events, combined with a projected increase in winter rainfall, means that La Crosse will see increasing risk as the climate warms. The community has already experienced flooding in new areas.
At the 2012 workshop, Kefer and her team directed the conversation toward how to proactively address flooding risks, rather than dealing with destruction of property and infrastructure after the fact. Due to limitations in the city’s stormwater system, the cheapest option appeared to be increasing infiltration of rainwater.
Because cities are so heavily paved, the rate at which water can trickle into the soil is limited. Planners use small planted areas (called bioretention cells), openings for trees, rain gardens, and boulevard-style green strips between road lanes to help absorb stormwater.
Permeable pavement is another solution that can be used in parking lots, alleyways and residential streets to boost infiltration and reduce runoff. The Environmental Protection Agency ran a model of permeable pavement use in La Crosse and showed that installation in key locations could mean the difference between a post-storm disaster, with three weeks of standing water in the streets, and an inconvenience, with a few inches of standing water remaining for less than two days.
Flooding isn’t the only issue brought on by climate change. Kefer says adaptation involves a number of infrastructure decisions, including which street trees to plant. The tree species that thrive today won’t necessarily survive 50 years from now.
The spread of the emerald ash borer, an invasive insect expected to wipe out most of La Crosse’s ash trees, makes this a pressing issue. As foresters plan to replace the ash trees, they’ll need to consider climate change.
“Ecologically, we’ll start looking more like Tennessee and Kentucky,” Kefer explains, noting that tulip poplar and other warmer-climate trees are likely to be more common in Wisconsin’s future.
As extreme weather events and the resulting risks to public health increase, city leaders will also need to map out their most vulnerable populations and make constituents aware of locations that can serve as tornado shelters or heat refuges.
After the WICCI workshop in La Crosse, community leaders have been following through. The city has implemented more green infrastructure and a green streets ordinance that calls for more boulevard-type roadways, newly planted trees and shaded bike lanes, more places for people to gather, and, as a result, increased safety.
Kefer hopes LaCrosse and other Wisconsin communities will continue implementing climate change adaptation measures, providing safety and stability for residents across the state.
Record-shattering rainstorms that hit west-central Wisconsin in June 2008 caused catastrophic damage, including the televised failure of an earthen dam containing Lake Delton. The week-long rain barrage flooded 810 square miles, swamped sewage treatment plants and contaminated wells.
These events prompted UW-Madison researchers to ask: What if that same downpour had happened in Eau Claire, Madison, or any other location?
Answering that question becomes more crucial each year. Heavy rainstorms are on the rise in Wisconsin, according to scientists at the Nelson Institute Center for Climatic Research.
To enable communities to understand their vulnerabilities, Kenneth Potter, a UW-Madison professor of civil and environmental engineering and affiliate of the Nelson Institute, and David Liebl, a stormwater specialist with UW Cooperative Extension, have developed a new tool to help local decision makers see how their stormwater management systems would handle an enormous rain event. The computer simulation program can be used in conjunction with hydrologic models to determine what would happen if the 2008 storm had been centered over any region.
Potter and Liebl, who co-chair a stormwater working group for the Wisconsin Initiative on Climate Change Impacts, say this exercise can help infrastructure designers and managers understand the increasing risk of extreme events in a changing climate. It can also help update design and management tools, which currently rely on rainfall scenarios that do not account for rising temperatures, seasonal shifts and amounts of rainfall, and impacts toecosystems and property.
The innovative program allows local municipalities to test their stormwater management systems and infrastructure through simulation, using the real numbers of the Baraboo storm system.
“Being able to test our infrastructure against known damaging storms is very beneficial, especially since we can move the most intense point wherever we want to test,” says Jeremy Balousek, an engineer with Dane County’s Land and Water Resources Conservation Department, which is using the program. Read more about the storm simulation tool.
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