Or it needs to be emphasized that dropping 6 months of rain in 2 days over a large area is going to overwhelm any city planning. Houston isn't exactly a dry place. Take any Canadian town and drop 6 months of precipitation in liquid form on it and 120 miles upstream. The towns would be gone, this is actually pretty good. This is a 2000 year flood, computer models can't even simulate this, seriously they are breaking under the simulation.