From Houston Public Media:
What made last month’s flooding, especially in north Harris County, so bad?
Simple: a whole lot of rain says Mike Talbott, executive director of the Harris County Flood Control District.
“It has a lot to do with this phenomenal rainfall … people don’t want to talk about the rainfall,” Talbott tells News 88.7.
But people are talking about how other factors, besides the massive rainfall, may have made things worse. And one those people is a professor of geology at the University of Houston, Shuhab Khan.
“It’s making it worse,” says Khan.
What Professor Khan believes is making flooding worse in certain neighborhoods is a geological condition Houston and many cities suffer from and have for decades: subsidence. It’s where many acres of ground sink.
Historically in Harris County, subsidence has been worse in areas where over the decades, groundwater and oil and gas have been sucked out from under the ground, causing the land to sink by fractions of an inch a year, in some places by feet over many years.
Could it be that today, the ground that homes are built on is sinking in different places than it did decades ago and thus, could this make flooding worse in places where people say, “It never flooded like this before.”
When Professor Khan looked at maps showing where last month’s flooding damaged the most homes, those maps looked eerily similar to ones he’d drawn aspart of a study two years ago, maps showing where subsidence was happening in Harris County.
“Those are the areas that are areas that are subsiding very rapidly. North and northwest. It used to be Jersey Village. (Now) it’s moving northeastwards, north and northeast these days. But it is the same area where the flooding was,” Khan tells News 88.7.
Khan says one subsidence zone is drifting northeast towards the Woodlands and seems to be affected by fault lines that traverse the area. Khan is not saying that subsidence alone is why there’s flooding.
“Of course there would be flooding. But maybe not huge,” says Khan.
At the Flood Control District, Mike Talbott does not agree.
“It’s not subsidence,” Talbott told us. “It didn’t have any role in this event, it really was about the rainfall. This was phenomenal rainfall that caused some phenomenal flooding. “