As many of you know, FEMA tightened their flood zone policies and broadened their maps after Hurricane Katrina. This creates a double edged sword for homeowners. First, there is now a bigger likelihood that their property may fall into a flood zone and, if it does, flood insurance is costly.
When you are buying land or a home, even in town, always check with the county/city. I have my clients do an insurability test. To do that, call your local insurance agent, give them the address and they will be able to tell if it needs flood insurance. However, in our area, land without a home on it often does not have an address.
What to look for visually. Is the land near a creek? If the slope is steep near the creek, the map won't go so far out. I have seen a parcel of land over a mile from a creek because the elevation was similar. Are their washes or arroyos nearby? Are you downhill from a lake/reservoir? What about in town in a relatively flat area? I have seen blocks of homes in the flood zone because of a wash running through town over 1/2 mile away. Another area of town was in the flood zone because of heavy rain runoff going through that area.
Help from the county/city. Every city/county has a flood map. You can just go in and ask to see it.
Above all, make sure you get a good Realtor that can help point you in the right direction to determine flood zones of any property you are looking at.
On your own.
I found my place with the help of the FEMA map. You first need to have google earth (http://earth.google.com/) on your computer before you do this.
I downloaded the google earth map overlay, FEMA_NFHL_v3.0.kmz. When you double click on that link it will open google earth with the FEMA map overlays. The elevation of our building site is 6500'.
We had a creek on one side of where we wanted to build and a cliff on the other so, as you can see, we were really close. Of course, we verified with the county and site engineer. We recommend you do not do this on your own but this tool is a good starting place. Just enter your address once you get the google map overlay downloaded.