The Zoning Office frequently receives questions regarding whether a property is in the floodplain and/or if there are places on the property where structures can be constructed outside of the floodplain. The Flood Insurance Rate Maps (published by FEMA) show the boundaries of the 100-year floodplain and will often show a specific elevation (i.e. 500' above sea level). Utilizing existing GIS data layers (aerial photography and contour maps) can be very helpful in showing the boundaries of the floodplain on a specific piece of property.

 

The following map is an example of how GIS data layers are used in this process.

 

zoning

 

Let's say that a request came in to the Zoning Office asking if the Lawndale cemetery is outside of the 100-year floodplain. Review of the paper copy Flood Insurance Rate maps will show that the 100-year floodplain elevation is 592' in the vicinity of the cemetery. With this elevation it is possible to use the two GIS data layers (aerial photography and contour maps) to show, what, if any, land is above the 100-year floodplain.

 

Looking at the above map, you will see that there is a long, dark line that wraps around the cemetery. This line is the 600 foot elevation line. The other lines represent one (1) foot contours or changes in elevation. Moving away from the 600' elevation down to Kickapoo Creek we find elevations of 595' and 585'. Since we know that the 100-year floodplain elevation is 592' then it is possible to see that that the cemetery is outside of the 100-year floodplain because the elevation around the cemetery is approximately 600'.