In Houston, certain neighborhoods flood but people don't drown. Underpasses are marked. And if there's a major storm, well, most of the bayous and creeks have flood zone clearances (if built up fairly recently) or notices. Avoid where it floods, not a problem.
Even Harvey was exceptional in the extent of the flooding, which pretty much just extended the usual flood zones much farther than expected. A lot of the city didn't flood at all. On my street the water didn't get over the 3-4" cement slope they call a "curb", much less up to the house or into it. Read the topo maps and you're safe.
Kerville and points west along the Guadalupe are known flood zones. Drained by a single river, a lot of the soil is underlain with limestone, which means no drainage. Even the Guadalupe has limestone for a lot of its course. (Somebody called the soil in the area 'caliche soil', which strikes me as wrong for the hill country--this is ancient limestone, not caliche, a heavily mineralized subsurface layer like you get in the Sonoran Desert due to rain dissolving minerals from the upper soil but the rain only soaks in a certain amount, year after year, for millennia ... The hill country's limestone will be karst in a million years.)
I might like visiting the area but if I camped there and I knew there was a chance of thunderstorms I'd steer well clear of being unconscious anywhere near the river or major streams. Again, the topo map is your friend. (With the ENSO in neutral, last I checked, the summer's climate's fairly unpredictable--some years it's real drought, other years bland, other years fairly wet. This is a fairly bland year, but in TX in summer sky-water is like in Arizona--you get it in storm cells. The one over Hunt County/Kerville stalled. This was real bad.)
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