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Indiana Department of Natural Resources

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

Indiana Floodplain Mapping Quick Links

FAQFrequently Asked Questions:  Answers regarding floodplain maps and flood insurance.

Prelim MapsPreliminary Digital Flood Insurance Rate Maps:  View and download preliminary Digital Flood Insurance Rate Maps issued by FEMA and IDNR.  If you received a letter from IDNR regarding changes to the floodplain status of a property, click here to view maps.

General guidelinesGeneral Guidelines for the Hydrologic-Hydraulic Assessment of Floodplains in Indiana:  Technical guidance documents for developing floodplain modeling.  Also includes external links to other modeling information.

Floodplain managementFloodplain Management: More information regarding floodplain management with respect to both insurance and construction.

Floodplain PortalIndiana 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 program.  If you received a letter from IDNR regarding changes to the floodplain status of a property, click here to enter an address and view floodplain information.

Indiana Peak Discharge Determination SystemIndiana 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 (under construction). 

The Indiana Hydrology and Hydraulics Model LibraryNEW! 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), others.

ContactESC Contact Information:  Contact information for the ESC section managers.

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