How Wet Will My Pony Get? Understanding Flood Maps, Flood Plains and Floodways.

In the wake of the Hurricane Harvey disaster I thought it would be a good time to demystify Flood Maps.  “Ugh this sounds soo boring.”  I’m not going to lie, this is pretty dry stuff, but you might be interested to know, there are lots of horse pastures in flood zones.  “Wait, are you telling me that if we have a flood, Fluffy Pony could get flooded and drown?”  Yep.

Hopefully I have your attention.  “But I don’t own the property so how can I find out anything about flood stuff?”  Great question!  Did you know that flood maps are public records?  That means anyone can look at them and find out where properties will flood.  FEMA may be a bad guy to some people but they have made things pretty easy.  A good place to start is the FEMA website.  There is a lot of helpful information on their website including definitions to the terms you see and flood maps.

 

So let’s go over a few terms.

Floodway – These areas are designed to flow with water, that’s right, flow with current, anytime a creek or river overflows.  Basically these get hit first, they are made to take flood waters and help move it along to try and avoid filling floodplain areas.  Most places will not allow you to build new structures in a floodway, although people have been known to build without permits and sometimes buildings that were already there before it became floodway are allowed to stay.  

100 year Floodplain (1% chance of flooding every year)- The description can be deceiving, you may think that this area will only flood once every 100 years.  Sorry my friend, what it means is that you have a 1% chance of flooding every year.  So that means if it rains 100 times a year, there is a chance you will flood once.  In places like Houston, 100 times a year is a bit of a stretch so let’s say we get 25 good rains a year (not counting those little drippy rains we get in the afternoons).  If you have 25 good rains a year then you in theory could flood once every 4 years.

500 year Floodplain (0.2% chance of flooding every year) – Similar to the 100 year flood plain but less of a chance.  This is a 0.2% chance of flooding every year.  So if we go with 25 good rains a year, then you may flood once every 20 years.

1000 year Floodplain (0.1% chance of flooding every year) – This is a new one thanks to Hurricane Harvey, it works similarly to the other Floodplains so with 25 rains a year it could flood every 40 years.

Note: These are assumptions above, this does not mean that if you move into a 100 year floodplain that you will flood every 4 years.  It depends on how many rain events you get in a year and this is all probability, much like gambling, you have a chance to win, you also have a chance to lose, it all depends on the statistics and the odds.

So to find your nearest floodplain/floodway, try the FEMA interactive map.  Type in your address, barn address, the address of your BFF, or the address of your arch nemesis, and hit search.  Click on the “View Web Map” Icon.  Or skip that and go directly to this link which will take you to the maps and then you can sign in with your Facebook account or whatever you have available.  It will take you to a map similar to google maps.  It may look really confusing at first but give it a second to load, then click on “Basemap” in the upper left of the map, that will give you options I personally like the “Imagery Hybrid” map, it’s a satellite map with flood maps overlaid on top.  You can see if your back pasture is in a floodplain or if your indoor arena is in a floodway.  Hopefully your indoor is not in a floodway, it will wash all of your nice footing out and create huge holes in the ground from running water.  If you look at the purple area below, you will see a race track, that is the farm that I was at when it flooded waist deep.  

Yep, that was almost completely in a floodway (the area with the red hatch lines), and let me tell you, it flooded in a big way.  Even the back corner of the property is in a 100 year floodplain (teal/green area), and the road itself to get to the property is in all of those including the 500 year floodplain (yellow/orange/tan area).

If you have access to google earth, or another way to find elevation:  Another trick to find out what your odds are, find the nearest flood area, find the elevation around the floodway/floodplain, then compare it to the elevation of your property.  In flat places like Houston, a foot or two can make a big difference.

So the question is, how wet will your pony get?  Well if you have 1″ of water in the 500 year flood plain, then a 100 year flood plain would have about 2-3′ of water in it, then the floodway can have 5′-7′ or more depending on the depth of the creek.  At one location near the EE farm, it is about 15′ from the deepest part of the creek to the top of the water if its a 500 year flood with only 1″ of water in the 500 year flood so Fluffy pony will be swimming!

If you are in the Houston area, this website can help you during a rain event.  It will tell you how much rain the creek near you has gotten.  Click on the “More Information” it will give you info on that particular creek.

Below I have chosen one of the creeks still flooded from Harvey.  Click on the “Stream Elevation” tab to get all the details.

As you can see this creek is out of its banks.  But at what point are you in the floodway, 100 year Floodplain, 500 year Floodplain?  Well scroll down my friends and all will be known to you.

The 10 year and 50 year flood plain are pretty much considered floodway.  Currently this creek is just above the 500 year floodplain, so in this case if your horse is in a 500 year floodplain pasture, he would have water on his hooves, if he is in a 100 year flood plain pasture he would be belly/chest deep, your pony might be swimming.  If your pasture is in the floodway, your horses would be swimming or close to it and your ponies would be swimming for sure.  If you don’t live in the Houston Area, you may have a similar site to help you, especially if you are in a flood prone, highly populated area.

Note: The above is just to provide perspective, this provides no guarantees that your property will or will not flood.  This is merely to provide education to help you prepare for future disasters.  If you are in a flood prone area, it is always better to evacuate and not need to than to be stuck, better safe than sorry.