Coordinated Hazard Assessment and Mapping Program

Coordinated Hazard Assessment and Mapping Program

ASSESSING FLOOD HAZARDS IN ILLINOIS Floods are by far the most common natural disaster in Illinois, accounting for well over 90% of declared disasters. Flooding is also the most predictable natural hazard, yet Illinois citizens continue to suffer economic losses due to flooding. The first step to reduce economic and personal losses is to accurately identify where flooding is likely to occur. As a Federal Emergency Management Agency (FEMA) Cooperating Technical Partner (CTP), the Coordinated Hazard Assessment and Mapping Program (CHAMP) staff work with FEMA and the Illinois Department of Natural Resources, Office of Water Resources, to assess flood hazards and communicate flood risk. Between 2004 and 2013, CHAMP produced updated digital maps showing areas prone to flooding in 75 Illinois counties, and four additional countywide updates will be finalized by 2015. These Flood Insurance Rate Maps (FIRMs) show the areas nearly 12% of the state that have a 1% chance of inundation in any given year. Flooding potential requires continual reassessment, and FIRMs require continual updating with changing land use and climate and as better data become available. As of 2013, CHAMP has completed or has in progress updates for 14 counties in Illinois. Communities can use these maps to avoid putting citizens at risk by steering development away from high flood-risk areas and planning mitigation for built areas in identified floodplains. Engagement with community officials is ongoing throughout the study process and additional meetings are held to discuss proposed mapping updates and/or mitigation activities. The watershed data are updated for use by communities as projects progress.

STUDYING FLOOD HAZARDS The CHAMP team performs hydrologic and hydraulic studies to accurately determine flood hazards. These studies are conducted to meet state and federal standards for incorporation in the regulatory Flood Insurance Rate Maps. This work is performed for FEMA and under contract with communities or other agencies. The CHAMP team strives to provide the public with the most up-to-date flood hazard data on FEMA s FIRMs. CHAMP is committed to facilitating open communication with engineers, communities, and the public. A web page, Destined for DFIRMs, is maintained, showing the location of publicly funded studies (FEMA, state, local government). Engineers can consult this site to identify work in progress. illinoisfloodmaps.org/dfd.aspx

PROCESSING LOMR/CLOMR APPLICATIONS On September 1, 2010, the ISWS/CHAMP began reviewing applications for Letters of Map Revision (LOMR) and Conditional Letters of Map Revision (CLOMR) for non-levee revisions to the FIRMs as part of FEMAs LOMR Delegation Program. Currently, Illinois is one of only three statewide participants in the program. Through the LOMR Delegation Program, ISWS now has federal review authority of all non-levee MT-2 LOMR/CLOMR applications within the State of Illinois. Technical review of requests for map revisions by in-state staff provides a distinct advantage to engineers and developers in Illinois by offering consistent service from professionals ready to assist them throughout the process. Efficiencies in exchange of information about areas being studied are achieved through close coordination with program staff working on mapping studies and updates throughout Illinois all under one roof. H a n c o c k BOWEN «94 «61 AUGUSTA Williams Creek «101 This map illustrates stream reaches at risk for potential flooding that were not designated as Special Flood Hazard Areas (SFHAs) and were not shown on Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps as of July 1, 2007. Also shown are areas of Risk Class A (high), B (medium), and C (low) adopted by FEMA Region 5. Streams lacking a SFHA designation and draining more than one square mile in a Risk Class A area or draining more than 10 square miles in a Risk Class B or C area are shown with red lines. A table associated with this map lists streams with unmapped potential flood risk, their names, and the number of miles not within a Special Flood Hazard Area. µ 0 0.5 1 2 3 4 5 Miles Legend Streams without SFHAs Streams Municipal Boundaries County Boundaries Interstate Hwy US Highways State Routes Roads Risk Classes A - High Risk B - Medium Risk White Creek Ursa Creek Rock Creek Little Creek LIMA «96 LORAINE URSA «61 MENDON «96 24 172 COLUMBUS Mill Creek Pigeon Creek H oney Creek Tourneal Creek «57 «96 «336 PAYSON PLAINVILLE Thurman Creek Crooke d Neck Creek 24 «336 «104 QUINCY «104 South Fork Bear Creek COATSBURG CAMP POINT North Branch McKee Creek McKee Creek LIBERTY «61 «94 LA PRAIRIE A d a m s Grindstone Creek CLAYTON Walnut Fork Fishhook Creek Cedar Creek Missouri Creek South Fork Cedar Creek S c h u y l e r Missouri Creek TIMEWELL Littl e M McK ee Cr eek B r o w n issouri Creek Missouri Creek Dry Fork Streams Classified by Risk: Adams County, Illinois C C - Low Risk 72 36 P 36 i k e «72 106 Pigeon Creek nney Creek Beebe Creek BAYLIS IDENTIFYING UNMAPPED SPECIAL FLOOD HAZARD AREAS Some streams posing a flood hazard do not haved mapped floodplains. In order to communicate the risk of these areas, streams that have a potential flood risk for which Special Flood Hazard Areas (SFHAs) have not been mapped are identified for each Illinois county. CHAMP can conduct studies and prepare maps that meet FEMA standards for communities and counties that have unmapped SFHAs.

REACHING OUT TO COMMUNITIES Through collaboration with state, local, and tribal entities, FEMA s Risk Mapping Assessment and Planning (Risk MAP) program provides quality data that increase public awareness and promote action that reduces risk to life and property. The ultimate goal is to reduce flood losses and break the cycle of disasters. CHAMP staff are pursing the Risk MAP goals in Illinois. FEMA s plan calls for ongoing engagement with state and local officials and watershed stakeholders through a series of meetings. The process begins with Discovery at a watershed level called the HUC 8 (hydrologic unit code). Available data are collected across the watershed and then a Discovery Meeting is held to discuss flood issues and technical data needs with communities that lie all or partially within the watershed. Local officials, floodplain managers, community engineers and planners, local development interest, watershed groups, and other stakeholders attend the meetings, provide additional information, and discuss flood issues, technical data needs, and the status of mitigation planning in the watershed. Watershed reports, maps, and data are posted at illinoisfloodmaps.org/ discovery.aspx. Additional outreach meetings to discuss new studies (Flood Risk Review Meetings) and to discuss mitigation options (Resilience Meetings) are conducted by CHAMP to help communities understand, prepare for, and mitigate flood risk.

APPLYING KNOWLEDGE OF FLOOD ISSUES TO RESEARCH CHAMP researchers apply the tools and knowledge acquired through preparing flood studies and working with communities to identify research needs. Research areas include trends in peak flows, impacts of urbanization, leveed areas, climate change impacts, and detailed hydrologic and hydraulic modeling. PRODUCING AND USING NON-REGULATORY DIGITAL PRODUCTS Detailed hydraulic studies have the potential to unlock a library of powerful digital mapping products. Using these models with high-resolution digital terrain models, digital depth grid data can be produced and used to display the depth of flooding for various frequency events (e.g. 10, 4, 2,1, and 0.2% frequency), the frequency of flooding at a given location in the floodplain, and/or the chance of inundation over a 30-year time period. When coupled with stream gage data and National Weather Service forecasts, the inundation areas for a given flood stage can be mapped. These data are shared with project stakeholders to make emergency management decisions and help mitigate flood risk. Another product being produced and delivered is a Changes Since Last Firm (CSLF) database. This database tracks the changes of Effective FIRM data and updated study information.

PREPARING NATURAL HAZARD MITIGATION PLANS A comprehensive Natural Hazard Mitigation Plan (NHMP) has proven to be an effective way to reduce or eliminate the risk to human life and property from natural hazards. Mitigation plans are the basis for FEMA funding for community projects that reduce exposure to flood losses. They provide valuable information and are enhanced when they include risk assessment determined by FEMA s HAZUS software, for which ISWS staff have specialized training. This powerful software couples current scientific and engineering knowledge with the latest Geographic Information Systems (GIS) technology to produce localized estimates of hazard-related damage and economic losses for buildings and infrastructure from earthquakes, hurricanes, and floods. Our HAZUS experts can prepare digital data, detailed maps, and reports of the potential impacts of natural hazards. The CHAMP team has worked with University of Illinois Extension providing Hazus data for mitigation planning in five counties. University of Illinois at Urbana-Champaign isws.illinois.edu 217-333-2210 2204 Griffith Drive Champaign, IL 61820 Climate and Atmospheric Science: 217-333-4535 Chemistry and Technology: 217-333-9321 Groundwater Science: 217-333-6800 Water Quality: 217-333-9544 Surface Water Hydrology and Hydraulics: 217-333-9544 Coordinated Hazard Assessment and Mapping Program: 217-333-9544 Water Resources Data and Information: 217-333-2210 National Atmospheric Deposition Program: 217-333-0887