Pittsburgh is unlikely to see the 20 inches of rainfall in two days that Houston experienced. But Kyle Siler-Evans, an engineer at the Rand Corporation, said the region’s hills and valleys present a different challenge.

“What that’s going to do is push flood water to the low lying points very quickly,” said Siler-Evans. “So you would tend to have much more localized flooding in a place like Pittsburgh, but potentially much more severe.”

Urban flooding is, I think, one of the most important issues this country is going to face over time, whether it’s tidal flooding in Miami or river flooding in Baltimore and Philadelphia or basement flooding in Chicago.

Rainwater runs from hilltops into valleys where it pools and starts to flood, Siler-Evans said. While there won’t be floods everywhere, he said homes in those valleys would be at highest risk, especially, those near the city's rivers.

“When we get a tenth of an inch of rainfall, somewhere in the system there is untreated sewage mixed with stormwater that overflows into the river,” said Siler-Evans. “In a typical year, we get 10 billion gallons of these sewer overflows.”

Read the full article on urban flooding by Tyler Polk at WESA