Leopold Center for Sustainable Agriculture

Flood workshop: What can be done for urban areas

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Wayne Petersen, urban conservationist for the Iowa Department of Agriculture and Land Stewardship, has a lot of ideas for slowing storm water runoff, factoring in water quality as well as quantity within Iowa’s urban locales. As new housing and cityscapes develop, he is pushing for management practices based on infiltration. Permeable pavement for roads and parking, ways to restore soil quality and bio-retention are three areas that need to be considered when developing neighborhoods, shopping areas and parking lots.

Iowa City mayor Regenia Bailey and director of planning and community development Jeff Davidson concur. They are revisiting the areas of Iowa City that were flooded to see how they can improve and, hopefully, prevent occurrences similar to what happened in their city this summer.

All presenters agreed that developing retail or residential areas within a flood plain is not good city planning. Damage from the flood included many homes and condos in several subdivisions, buildings throughout the University of Iowa campus as well as city recreation space. Iowa City officials are working with FEMA to buy out structures within the 100-year flood plain. They also are recommending flood proofing, which includes installation of flood doors, re-mountable flood walls, alarm systems and elevating mechanical, electrical and plumbing systems in structures located in the 100-year flood plain.

Even if all new development was designed to deal with higher amounts of rainfall, Petersen is aware that older neighborhoods also need alterations to help alleviate storm water runoff. He calls it “retrofitting the built world.”

There are things that can be done to lessen urban stormwater runoff including the installation of “green” streets and rain gardens, both of which have the ability to increase the landscape’s capacity to hold water and shed less runoff. Green streets include permeable concrete or asphalt or pavers with underlying gravel to aid in water retention and increase water absorption. Bio-retention cells are another way to retrofit existing parking areas and similar spaces. Bio-retention cells are areas around or within parking lots or along roadsides used to intercept, infiltrate and protect water quality.

Communities could be improved in the future if the planners and residents would consider their carbon footprint as well as their hydrological footprint, keep development out of flood plains and design for higher amounts of stormwater runoff.

Back to Leopold Letter Winter 2008