Granted, Houston is flat low lying land but with all the contrete from building and building and building there is no soil left for the rains and water to soak into so the flooding will only get worse over time.
That's a pretty general statement.
I live by The Woodlands, which is woods and land, and we had flooding, too.
The problem is that the overall region has what is essentially a clay-based soil that doesn't absorb much rain, unlike, say, Florida which is limestone and very porous.
This is the reason that SE Texas floods; the soil can't absorb the water the way that other regions can.
Furthermore, we have the Brazos River, the San Jacinto River, and the Trinity River, which funnels the rainwater from upstate into the Houston area, which overflows the river banks as well as the bayous that feed off of them.
-PJ