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Coastal Louisiana has always had a very dynamic geography. It has been fairly well established that conditions “on the ground” change rapidly enough that our primary risk-assessment tool (the Flood Insurance Rate Map) is inadequate for regulating development - especially development that should have a meaningful life expectancy. In addition to the adverse impacts of continued development that increases run-off and decreases flood storage capacity, absolute sea level rise, and disappearing wetlands, there is the more complicated issue of subsidence.

In this session the presenters will share information about rates of subsidence in Louisiana, the evidence of subsidence, factors influencing subsidence (including the ties to levees and drainage), and examples of possible long-term consequences. We will also show how collaboration between the LSU AgCenter and LSU Center for Geoinformatics has enhanced the University’s continuously operating GPS reference stations (CORS), improving the data used for flood risk forecasting and making the information and evidence of changing conditions more accessible to the people of Louisiana. This information, in combination with the Flood Insurance Rate Map, provides a more complete picture of future risk. Future risk is the risk to be mitigated. Thus “time” becomes the fourth dimension of mitigation planning.