Here in Winnipeg on the flat prairie, any new housing developments must be built with water retention ponds. In a sudden heavy rain or sudden spring thaw that the storm sewers can't cope with, the ponds fill with water instead of basements. They can drain through the storm sewers at their leisure. We also have the occasional swale - a low-lying park or playground - that can absorb a sudden large run-off. While both take up space - meaning less taxes - they increase the property values of the houses along them - meaning more taxes.Vrede too wrote: ↑Mon Aug 28, 2017 11:30 amDramatic before-and-after images show Houston underwater
And of course the ground around houses must be a bit higher than street level. Streets and the outer edges of yards can fill with water, but the basements don't. I experienced this at my house in Mitchell during spring runoff.
I watched a show about a major city in Asia that gets hit by hurricanes. They also had a major problem with traffic getting in and out of downtown. So they solved both problems with a "Big Dig" style traffic tunnel. In a hurricane it's closed to traffic and acts as a giant storm sewer, draining the downtown to a river miles away.
While many of the Houston images are heartbreaking, some of the images are impressive. Some of those flooded freeways are much lower than ground level. This helps with noise abatement, but it looks like water retention was part of the plan. I've also seen aerial photo of completely flooded streets - surrounding green lawns and houses above water level. Someone's been planning ahead and doing it right.