I marvel at the engineering it takes to make an urban area work even some of the time. We walk around a lot and enjoy watching construction jobs happening and seeing just how much is involved in planning and no doubt jury rigging/problem solving along the way. There is one just getting off the ground that is an entire city block and it's fascinating to me, and I had not even pondered what they do with the rain which now will fall on roof tops.
We don't have that many streams of any size (until you get 3-4 miles out). The urban area in on a divide, a crest between the Gulf and Atlantic. I'm sure that provides some elevation change that is helpful. And the ground is largely granite 5 feet down.