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   Floods & Hurricanes
 Home>Family & Home>Hazards and Threats>Floods & Hurricanes>

Using interactive maps to find ground elevation

NOTE: A print version of information on this page can be downloaded from the Related Documents section, below.

Whether the threat is from the Mississippi River crest moving toward Louisiana or floods induced by local rain or storm surge, many people want to compare their ground elevation to a predicted flood elevation at their property.

The LSU AgCenter has two mapping services/sites that ANYONE can use to find ground elevation at ANY spot in Louisiana.

  • Both sites allow you to find a point by pan-and-click on the map or by entering a street address.
  • Both sites allow you to turn on a background aerial image to locate a specific building or property.
  • You can zoom in and out on either map, as well as pan the map in any direction.
  • Click with the mouse on either map to place a pin and see ground elevation value (along with other information about the point).
  • Both sites provide images with a resolution and precision that is more accurate than the flood modeling or forecasts shown on the maps. The location of flood boundaries is approximate and should be used only for estimating purposes. 

www.LSUAgCenter.com/floodmaps

This link takes you to the portal for Flood Insurance Rate Maps, which are used in the National Flood Insurance Program.

  • Click on the parish of your choice.
  • When the parish map opens, you can turn off the flood layers (uncheck the boxes in the upper right corner).
  • Enter an address and click on “find”
  • Turn on the “Hybrid” base map to activate the aerial imagery and really zero in on an individual structure.

LSUAgCenter.com/floodmaps is directly accessible from the LSU AgCenter home page; click on “Flood Maps” under Featured Links. Learn more about the flood maps and how to use them during flood emergencies.

http://maps.lsuagcenter.com/windspeed_elevation/

This link takes you to the LSU AgCenter Wind Speed and Elevation interactive map. kThe Windspeed_Elevation platform does not require you to select a parish before locating the property of interest.

  • Turn off the “Basic Wind Speed” layer (the on-off toggle is just above the legend).
  • Enter an address and click on “find”
  • Turn on the “Hybrid” base map to activate the aerial imagery and identify individual structures.

These systems have limitations, use with caution

  • The websites should not be relied upon to determine levee elevations. Due to the nature of the data, narrow features such as the crown of levees are difficult to represent accurately, and are only approximations. The local OEP should have information about current local levee elevations.
  • The flood elevation in the river, at the gauge, is not necessarily the elevation the water will be 100-yards or a few miles away from the gauge. The river elevations are of the water level in a very constrained environment. We hope local authorities and forecasters will attempt to predict the water surface elevation in specific locations, if the levees are breached or over-topped.

Stream gauges, readings that need to be adjusted when comparing to ground elevation

Predictions for flood water surface elevations are provided in Louisiana by the River Forecast Centers (RFCs) of the National Weather Service (NWS). Access that tool at www.srh.noaa.gov/lmrfc . NWS-RFCs have very few gauges where there are no rivers and streams, as is the case inside levee-surrounded areas like New Orleans, St. Bernard, urbanized Jefferson and parts of other southeast parishes.

Some gauges in Louisiana report water level elevations using a different vertical reference system than the reference system USGS uses when sending ground elevation to the mapping portals.

The following river stage gauges report water level elevations in the same vertical reference system that is used to provide ground elevations in our websites.

Mississippi River Gauges

      • Red River Landing
      • Baton Rouge
      • Donaldsonville
      • Reserve

Atchafalaya River Gauges

      • Simmesport
      • Melville
      • Butte LaRose
      • Morgan City

The following river stage gauges report water level elevations using a different vertical reference system than is used to provide ground elevations in our websites, and require a conversion factor to be added to the gauge reading to get a number that can be compared to the ground elevations provided in our system.

Mississippi River Gauges

      • Natchez - Add 17.3 feet to the gauge reading or predicted crest at that gauge
      • Vicksburg – Add 46.2 feet to the gauge reading or predicted crest at that gauge
Related Files
FilenameDescriptionFile Size
FloodRiskMaps_Hurricane_090211.pdf Online mapping tools for assessing risk during threats from rain, rising rivers or storm surge. 148.92 KB
Using+LSU+AgCenter+Interactive+Maps_doc.pdf Using LSU AgCenter Maps - Instructional flier for use offline 386.96 KB
Last Updated: 4/28/2012 7:38:56 AM
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