Julia Poska| November 16, 2018

Houston can partially blame the unprecedented flooding it experienced during Hurricane Harvey last year on its skyline. A new study co-authored by Gabriele Villarini, associate professor of civil and environmental engineering and director of IIHR-Hydroscience and Engineering at the University of Iowa, found that Houston’s topography exacerbated Harvey’s rainfall.

Researchers obtained data on rainfall and water discharge in Houston during the storm from various national agencies, and compared it to a computer model that simulated the same storm with a twist. In the model, the city of Houston was replaced with undeveloped farm fields to calculate the built environment’s effect on the storm’s behavior.

The analysis concluded that urban development in the Houston area increased the likelihood of intense fooding 21 times during that particular storm. In other words, if Houston were really an expanse of farmland instead of a city, less rain would have fallen.

“The buildings stop the air from being able to move forward, away from the ocean,” co-author Gabriel Vecchi from Princeton told NPR. “They sort of stop the air in that general area, and the air has nowhere to go but around the buildings, or up.”

Vecchi said when tall buildings push air farther upwards, the amount of atmospheric water vapor that condenses into rain increases. Houston’s skyline not only stalled the storm, but squeezed more rain out of it.