Wisconsin Geospatial News

Flood map modernization moving forward in Wisconsin

Floods are the nation’s most common and costly disaster posing a significant threat to life and property. Wisconsin ranks tenth in the nation in documented flood damages, where flooding has been the principal cause in 16 out of 24 Presidential Disaster Declarations in Wisconsin over the thirty-year period from 1971 through 2001.

To reduce the expense to the federal government related to flooding, Congress established the National Flood Insurance Program in 1968. This program guarantees flood insurance will be available to communities that agree to adopt land-use regulations so that new development will be reasonably protected from potential food damages, and so that businesses and homes lying within a floodplain will be eligible to buy flood insurance policies.

Map Modernization Program heightens need for revised flood mapping

Early in this decade, the Federal Emergency Management Agency (FEMA) developed the Flood Map Modernization Program designed to modernize flood mapping nationwide by 2008. To support Map Modernization, Congress in 2003 infused an additional $150 million (up from $50 million) annually into the National Flood Mapping Program.

The intended goal of the additional funding was to improve and update the woefully deficient existing flood maps. The manual cartographic processes and limited topographic information available in the 1970s and 1980s produced maps that are inadequate for the precise identification of flood hazard areas in communities, and for setting flood insurance rates. Nearly two-thirds of Wisconsin’s existing flood hazard maps are more than 10 years old, which reduces the accuracy and usefulness of these maps, particularly in areas where there is development pressure near rivers and lakes.

Over the past three years, the expanded federal funding for flood mapping has impacted Wisconsin. Nineteen of the state’s 72 counties have undergone a variety of revised mapping processes, with preliminary revised maps due for unveiling to the public this fall. Still, the increase in funding has not been sufficient to cover all of the needs in Wisconsin, and in most other states.

The catastrophic flooding following Hurricane Katrina last year demonstrated how ill-prepared we as a nation were to understand and respond to serious flooding events. Poor mapping contributes to this lack of understanding the impacts of flooding. Recently, many organizations and individuals, including the Association of State Floodplain Managers headquartered in Madison, have been leaning on Congress to appropriate even more money toward flood mapping. It appears that Congress may be on the verge of doing so. 

Congress set to enhance Map Modernization

Currently, both the House and Senate are considering reform and modernization appropriation bills, which if passed, will expand the specifications and content of flood maps. Some of the more notable proposed changes include the provision that flood maps identify all areas with a “500-year flood potential”, identify areas of residual risk located behind levees, dams, and man-made structures, and areas that could be inundated as a result of dam failure. The draft bills also specify that new ground elevations be collected utilizing the newest technologies, that data be collected on a watershed basis, that published maps be in a digital format, and that they be compliant to geospatial data standards as established by the Open Geospatial Consortium. The bills also propose to remove the requirement that states contribute 50% to the cost of the revised mapping.

DNR coordinates flood mapping in Wisconsin

Wisconsin law requires that communities enact floodplain zoning, and the statute holds the state responsible for ensuring that engineering and hydrologic studies are reasonable and accurate. Under this requirement, the WI Department of Natural Resources (DNR) has the responsibility for these assurances. Over the years, DNR has developed the technical staff expertise to manage flood map modernization and other water regulatory responsibilities. This includes 16 water management engineers working with hydrology, hydraulics, dam safety and water regulation permitting, and GIS staff to improve effectiveness and customer service.

DNR is about to release its map modernization plan for 2007. Working with FEMA, DNR plans to manage all aspects of the remapping work for eleven counties. At this time, six counties have been identified: Barron, Dodge, Oconto, Outagamie, Sauk and Rusk. An additional five counties will be selected at a later time. DNR will give highest priority to mapping counties who recently acquired detailed and comprehensive elevation data. All data and imagery used in the mapping process will be archived by FEMA.

For those mapping tasks requiring redefining and redrawing floodplain boundaries, DNR intends to contract with Wisconsin-based consulting firms. Overall, DNR will work with local communities, counties, regional planning commissions, and other agencies to coordinate activities and encourage sharing of resources.

For more information on Wisconsin Flood Mapping, contact Amanda Schwoegler at the DNR: (608) 267-7571.