Floodplain Change Analysis using GIS


The Village of Oak Brook is currently reviewing the proposed flood
insurance rate map (FIRM) for the new 100 year flood plain. The last
time the FIRM was updated was in 2004 and it is necessary to review and
prepare for any changes that may occur within the boundaries provided by
the County. In order to get an idea of what properties and homes will
be added or removed from the floodplain, it is important to do in depth
analysis and comparisons of the 2004 FIRM to the proposed 2012 FIRM. It
was determined by Village engineers that the best method to do so would
be to use GIS to perform spatial analysis on both boundaries and their
intersecting buildings and properties.

The first step to analyzing the change was to obtain both the 2004
boundary and the proposed 2012 boundary in GIS format and figure out
which buildings and properties each boundary intersected. By using the
County provided property identification number (PIN), we were able to
compare what has changed from 2004 to 2012. We were then able to join
this information to the zoning layer in order to determine the type of
buildings and properties that are within each floodplain. This
information has proved quite valuable to the Village when determining
which areas of the proposed floodplain need to be objected to before
being made official. Without GIS this type of spatial analysis would be
virtually impossible, and certainly couldn’t be performed in the time
frame and with the limited personnel the Village was able to commit to.