How trees are important tools when it comes to storm runoff

137.8 million trees in San Antonio are helping to fight storm water

Trees do more than just provide shade, as they take in carbon dioxide to clean our air and keep our city cool. They also help combat storm water.

SAN ANTONIO – The recent IPCC climate report says we can expect more severe weather in our future, from severe drought to more intense sporadic rain in San Antonio.

But one thing that can help us in both of these events are our trees.

Trees do more than just provide shade, as they take in carbon dioxide to clean our air and keep our city cool. They also help combat storm water.

“The important thing about trees and to some extent any kind of vegetation is that it helps absorb water as opposed to letting the water run off of an impermeable surface like concrete or pavement,” Sean Sublette, a meteorologist with Climate Central said.

And the deeper the root system the better, Sublette said.

“So the more trees you have typically will have more absorbent soils nearby. And, of course, you have the structures themselves, which all will take in water. They act as something that is going to absorb water compared to something like payment, which allows water just to run right off into streams, creeks, sewers, that kind of thing.”

By absorbing rainwater, reducing erosion, and creating more permeable soils, trees save nearly 400 billion gallons of stormwater runoff in the continental U.S. each year, according to Climate Central.

Climate Central used the U.S. Forest Service i-Tree tool to quantify trees’ carbon storage, storm runoff avoided, and air pollution absorbed.

In San Antonio, we have about 137.8 million trees according to Texas A&M Forest Service My City’s Trees web application.

Climate Central estimates that the number of trees in San Antonio remove 17.7 million tons of carbon dioxide equivalent, absorb 290 million pounds of air pollution and fight off 2,751 gallons of storm runoff.

Some scientists believe that number of storm water absorbed by millions of trees in the area can even be greater in Bexar County.

Sublette said San Antonio is in a good spot when it comes to the amount of trees helping us out.

Compared to some places outside of San Antonio, it looks pretty good actually, but it can always be better, but San Antonio is in a pretty good spot, especially compared to North Texas and West Texas, which doesn’t typically have as many trees around,” Sublette said.

However, when it comes to severe flooding, especially in areas by our creek beds and rivers, Sublette said no amount of trees can really prevent flooding from occurring.

“If you have very, very heavy rain, no amount of trees keep the flooding down, but it does decrease the risk of flooding, small stream flooding and ultimately larger flooding as well, Sublette said. “The more vegetation you have around and the fewer impermeable surfaces you have.”

The San Antonio International Airport has recorded 23.27 inches of rain in our city since January 1, according to KSAT’s meteorology team. That’s 2.60 inches above average.

About the Authors:

Sarah Acosta is a weekend Good Morning San Antonio anchor and a general assignments reporter at KSAT12. She joined the news team in April 2018 as a morning reporter for GMSA and is a native South Texan.

Azian Bermea is a photojournalist at KSAT.