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Indiana Department of Natural Resources

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Water > Surface Water > Hydrologic / Hydraulic Models & Assessments > General Guidelines for the Hydrologic-Hydraulic Assessment General Guidelines for the Hydrologic-Hydraulic Assessment

-General Guidelines for the Hydrologic-Hydraulic Assessment of Floodplains in Indiana was created to assist the floodplain management community in establishing base flood elevations and floodway limits and in evaluating projects in accordance with the Indiana Flood Control Act and the National Flood Insurance Program. The guidelines detail methods acceptable to both the Indiana Department of Natural Resources (IDNR) and the Federal Emergency Management Agency (FEMA) with respect to hydrologic and hydraulic modeling and floodplain mapping. Also included in this guide are recommendations on presenting results of a floodplain study and other useful reference material.

Web links featured in the report

Click on a chapter heading below to reveal links.

Chapter 1: Introduction
Chapter 2: Obtaining a Floodplain Determination for a Minor Site Assessment
Chapter 2.5: Non-modeling Assessment Approaches Used by the IDNR
Chapter 3: Overview of the Process for Performing a Detailed Floodplain Analysis
Chapter 4: Mapping Standards and Methods
Chapter 5: Surveying Standards and Methods
Chapter 6: Researching and Evaluating Existing Models
Chapter 7: Guidelines for determining peak discharges
Chapter 8: Guidelines for Hydraulic Modeling Using HEC-RAS
Chapter 9: Guidelines for Alternate Hydraulic Models
Chapter 10: Presentation of Modeling Results

Indiana Floodplain Mapping Quick Links

  • The Indiana Floodplain Information Portal
    Launch INFIP, an interactive floodplain mapping tool, which includes address searching and eFARA, the Division of Water’s on-line floodplain analysis submittal tools.  INFIP also now includes the “Best Available Data” layer, showing up to date floodplain mapping information.
  • FEMA Map Service Center
    View and download official FEMA floodplain mapping products, including Flood Insurance Rate Maps, Flood Insurance Studies, Letters of Map Change (LOMA, LOMR-F, LOMR) FIRM database information, and preliminary and historic mapping products.
  • The Indiana Hydrology and Hydraulics Model Library
    View and download previous hydrologic and hydraulic models developed for Flood Insurance Studies, Construction in a Floodway applications, Floodplain Analysis / Regulatory Assessment (FARA), and others.
  • The General Guidelines for the Hydrologic-Hydraulic Assessment of Floodplains in Indiana 
    Technical guidance documents for developing floodplain modeling for submittal to the Division of Water.  Also includes external links to other modeling information.
  • NOAA Atlas 14 Point Precipitation Frequency Estimates
    Estimates of rainfall depths and distributions for various return periods throughout the state.
  • The Indiana Peak Indiana Peak Discharge Determination System
    Launch IPDDS, the Division of Water’s hydrologic computation system.  Includes directions on how to submit information to the Division for approval. 
  • The Indiana DNR HEC-RAS Geometric Data Tool
    This tool uses the State of Indiana’s LiDAR dataset, along with the National Hydrography Dataset, to create a Geometric Input file for HEC-RAS, the Corps of Engineers hydraulic modeling program.
  • Fluvial Erosion Hazards in Indiana
    The Fluvial Erosion Hazards portal features mapping of approximate areas of stream migration for communities to better manage river corridors. The setbacks vary based on the stream’s recent migration history (mobile or non-mobile).
  • Non Levee Embankments in Indiana
    The Non-Levee Embankment project is a joint effort between The Indiana Silver Jackets, The Polis Center, IMAGIS/Indy GIS, INDNR and SIU Geography. The purpose of the project is to identify non-levee embankments (NLE) utilizing LiDAR and geoprocessing techniques. NLE are elevated linear features adjacent to waterways and within the floodplain.
  • USGS Flood Inundation Mapper
    The Flood Inundation Mapper shows estimates of flood inundation areas based on USGS stream gage information. Areas are shown based on gage height, allowing users to view the approximate limits of a flood based on a reported gage reading.
  • Floodplain Management & Homeowner Information
    More information regarding floodplain management with respect to both insurance and construction.
  • Indiana DNR Basin Teams and ESC contact information
    Contact information for the ESC section managers.
  • Frequently Asked Questions
    Answers regarding floodplain maps and flood insurance.
  • InDNR Spatial Data website
    Download spatial data related to floodplain mapping.