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Streams at Your Fingertips

Challenge

Access to mapping and updated modeling that result from Federal Emergency Management Agency (FEMA) and state projects benefit both the general public and the engineering community. However, for the non-technical user, locating property and determining food risk directly from the published Flood Insurance Rate Map (FIRM) can be difficult. For the technical user, obtaining the data and the models that helped develop the FIRMs can be time-consuming and labor-intensive. 

Solution

Located on the Indiana Department of Natural Resources’ (IDNR) website, www.floodmaps.in.gov, the Indiana Floodplain Information Portal (INFIP), the Indiana Peak Discharge Determination System (IPDDS), and the Indiana Hydrology and Hydraulics Model Library were created to provide easy, public access to data that was previously unavailable, difficult or time-consuming to obtain.

INFIP is a mapping application that provides floodplain information to help citizens determine flood risk. INFIP uses floodplain data from IDNR-approved resources and FEMA’s FIRMs to provide the most available, comprehensive coverage of floodplain information for the state. The IPDDS is a web-based resource for the engineering community that pulls data for analyses from U.S. Geological Survey (USGS) Streamstats and IDNR-studied stream sources and generates flood frequency discharge information for streams. The Indiana Hydrology and Hydraulics Model Library is an online resource that allows users to view and download available hydrology and hydraulic models for Indiana waterways. Several types of models are available by stream reach utilizing FEMA’s Coordinated Needs Management Strategy database. 

Outcome/Results

INFIP is an outreach tool for property owners and local officials that allows users to easily find and print floodplain mapping and Base Flood Elevations (BFE) information for a given location in Indiana. Using an innovative way to derive elevation data directly from the model, INFIP has over 1.66 million data points and 11,500 total miles of data along its mapped floodplain and expects this number to grow to over 2 million. Datasets are maintained through in-house expertise and a partnership with the Polis Center at Indiana University-Purdue University Indianapolis. Preliminary and effective data can be compared to show users the changes that have occurred in mapping when a new study is underway. Users also can receive written state verification of the BFE at a site or parcel through the automated electronic Floodplain Analysis Regulatory Assessment (eFARA) tool.

IDNR estimates flood-frequency peak discharges for the 1-percent-annual-chance flood event for its regulatory programs. To estimate the peak discharge, the IDNR had used several different computer programs developed internally. With the development of Streamstats by USGS, GIS technology and the internet, IDNR adapted these programs and made them accessible via the internet. The IPDDS allows a technical user to select a site, and receive a computation of watershed statistics based on Streamstats and historical DNR determinations. These data can be downloaded for further analyses. 

IDNR created an archive of all available H&H models in the state. This Indiana Hydrology and Hydraulics Model Library is searchable by stream reach. Before the library was created, requests for models were handled via email. Now models can be retrieved by users via a web-based self-service system. Available models include Flood Insurance Study, permitting, FARA, and FEMA regulatory models. 

Benefits

INFIP saves property owners time in locating parcels within the floodplain and helps them determine their BFE and flood risk easily. BFEs can be provided for both Zone A and Zone AE streams. (FEMA’s published FIRMs do not provide BFE information for Zone A flooding sources.) The eFARA process provides users with DNR verification of BFEs for Letter of Map Amendments and to satisfy local permitting requirements. This verification, previously done manually, is now automated. The resulting verification, confirmed by a technical analyst, generates BFEs and verification letters in a fraction of the time needed previously. IPDDS and the Indiana Hydrology and Hydraulics Model Library take data that were previously used primarily in-house and available by individual request and makes these data easily accessible through the internet for the benefit of the engineering community.

Ultimately, IDNR has found that when the general and technical community have access to information and the process is transparent, they can obtain the information they need and are more willing to support the program. 

Lessons Learned

Risk MAP Phases

Describe which Risk MAP phases were impacted by this project.

  • Data Development and Sharing
  • Risk Awareness and Mitigation Outreach 
  • NFIP Map Changes and Impacts Preliminary
  • Map Release and Mitigation 

Risk MAP Goals Advanced

Which Risk MAP goals were advanced through this project? 

  • Increasing Awareness 

When creating these on-line tools, there are many moving parts and connections to outside databases. Thoughtful, intentional design of these systems is required for success. What data are available, what systems can be integrated, how they tie into other systems that may or may not be online, and how the data will be maintained must all be considered. An endeavor like IDNR’s cannot be lightly entered into with the expectation that because datasets exist they can work well together. Much thought is needed to ensure the interconnectivity of different datasets. The funding for these projects was provided by the Indiana Office of Community and Rural Affairs (HUD disaster block grant funding), FEMA, and the Indiana Department of Natural Resources. Also, the Indiana Silver Jackets team was a valuable resource for technical support throughout development. 

Resources

Floodmaps.in.gov

Indiana Floodplain Information Portal

Indiana Peak Discharge Determination System (IPDDS)

Indiana Hydrology and Hydraulics Model Library  

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Last updated February 11, 2021