[lukeschlather]

I don't think it's accurate to say we only have 150 years of data. We only have about 150 years of data collected in real time by humans, but we have plenty of other data. (Soil/rock strata,core samples, tree rings, etc.)

In some ways the geological and archeological evidence is more trustworthy than the evidence we've written down in the past century or two.

[jessaustin]

Do floods show up on the "geological and archaeological" records? Sure we can say that 50M yrs ago there was an ocean here, but that's a different statement than "in the last 1000 yrs there have been 14 floods that reached this height above the river".

[throwawayjava]

Big ones absolutely do. I'm not sure how small floods can get before the answer is no. IMNAG.

[enraged_camel]

No, it's not so simple either. If 200 years ago there wasn't a city there, then any kind of soil/rock strata, core samples, tree rings etc. likely won't show flooding, and therefore won't be representative of flood risk today.

Houston is a concrete jungle, which significantly increases the risk of flooding compared to even a decade ago.