Mapping Resources

Floodplain Maps Online

  • View the Flood Hazard Layers in the interactive Maine Floodplain Online Map application. Map sections can be printed and/or saved as PDF documents. Different orthophoto layers can be turned on/off also.

  • The Digital Flood Insurance Rate Maps (DFIRM) are also available for download in PDF format. Use the Maine Floodplain PDF Maps application to access the PDF maps. Zoom to your area of interest and then click on the map for a link to that area's DFIRM PDF file.

  • The FEMA Map Service Center is an excellent source of information for most of your mapping needs. The home page has a helpful index of commonly requested services and some specific links are provided below.
    • Effective Date for Floodplain Maps (alphabetical listing)
    • Online access to Maine Floodplain Maps
    • Check for changes to floodplain maps
    • Flood Insurance Rate Studies (FIS) provide the basis for establishing floodplains. The FIS has several sections but most importantly it details:
      • The study area
      • Engineering methods used to determine base flood elevations
      • Exhibits showing flood profiles
      • Tables showing floodway data, summary of discharges and still water elevations, etc.

Floodplain Mapping Modernization

Converting floodplain maps to a digital format is one more step towards FEMA’s goal to acquire better more accurate mapping. It does not address all the flaws in existing maps. However it will make the maps easier to change in the future and reduce the costs of printing new maps in the long term. Processing Maine’s floodplain maps to a digital format for distribution in electronic media and made available on the internet will increase availability to more people than ever before. The first counties to be remapped into a completely digital format are Oxford, Kennebec, Androscoggin, Cumberland and York

Additional county specific mapping modernization data will be posted here shortly.

Challenges to Good Floodplain Mapping

Good Elevation Data

Floodplains are called that because they tend to be wide and relatively flat. When the river floods it spreads out and inundates a large area. Depth of water is measured in feet and may be as much as 30 feet above the normal high water mark of the river or stream. So when mapping a floodplain it is important to be able to determine land elevations very accurately.

The problem here in Maine is that for most of the State elevation data has not been remapped since the 1920’s when the United States Geological Survey completed a nation wide survey to determine elevations. Most of the maps show topographic elevations in 10 or 20 foot increments. Consequently it is impossible to delineate floodplain boundaries that generally fall within a range of a few feet accurately.

Cost

The process of creating completely new Floodplain maps is incredibly costly, time consuming and complex. Google Earth and other similar programs lure you into the impression that it is mere childs play to create simple easy to use maps.

Creating new digital floodplain maps is neither simple nor easy. Even the shortened process of upgrading existing floodplain maps to overlay new ortho-photo base maps is an expensive time consuming process that requires a significant amount of time and effort. Even with the increased funding FEMA has received for upgrading the nation's floodplain maps it is insufficient to correct all the known shortcomings.

This process requires building new maps with several layers of information and integrating huge databases of supporting documentation. Each layer must be registered to the new base map and go through a rigorous quality analysis and control process to ensure that the databases have been accurately compiled, before it is stored on the FEMA mapping information platform. In addition because the various layers of information are mapped at different scales each layer must be electronically manipulated to fit as closely as possible to the base map.

Just this relatively simple process will cost over $2,000 per flood map panel. With over 1800 map panels in Maine, the total cost of just converting to digital would be over 3.5 million dollars. This does not include any additional funding for new topography, hydraulic, hydrological analysis or re-delineation of floodplain boundaries. Early estimates of costs for new high resolution topographical data alone come in at approximately 5 million dollars and completing new hydrological and hydraulic data to cover areas that have been mapped with only approximate studies have not been estimated with any degree of accuracy but would undoubtedly run into the millions of dollars also.

More accurate floodplain maps will be hard to come by until high resolution topography can obtained.

If you would like to learn more about estimating mapping values FEMA publishes a Blue Book that establishes values of products provided by outside agencies that can be used in developing floodplain maps.