Flood plain areas a no go? Anything to look for on the elevation profile?

Hi everybody, I am in the market to buy a house in Houston for the first time after renting for just over a year. A few of the properties that I have seen and liked, I am finding are just on the edge of 100-year flood plain. One of them is actually 1/3 100 year and 2/3 500 year.

My question is, what is the likelihood that either of these properties would flood? Should I consider them if they are literally on the edge, or would you completely advise to stay away from a property remotely close or on a flood plain?

Thanks in advance for your responses/advice.