Changes Since the Last FIRM (CSLF) dataset helps communities understand changes to their flood maps by identifying areas of floodplain and flood zone changes that have occurred since the previous flood map study.
Why do flood risks change?
Urban development
Removal of vegetation
Grading of the land
Constructed drainage networks
Flood mitigation projects
Changes of predicted storm surge elevations
More advanced modeling techniques
Better topographic data used in modeling
CSLF provides a large amount of information that can be used to enhance floodplain management activities. It is a great tool to assist communities in understanding changes to the flood maps. This is very useful to identify areas of impacts and where outreach could help facilitate a better understanding of the changes among a community’s citizens. Many communities see great benefit in sending notifications to citizens of upcoming changes to the Flood Insurance Rate Maps. Thus, explaining how the flood risk is changing, what options are available, and promoting the purchase or retention of flood insurance. Another benefit of CSFL is that it provides the ability for communities to quickly identify which structures are now at risk that were previously unidentified. CSLF is also extremely helpful in the identification of areas that will be subject to an appeal period—allowing communities to perform focused outreach efforts.