Q&AZ: Does gravel landscape negatively impact the urban heat island effect in Arizona?

By Nick Sanchez
Published: Sunday, August 7, 2022 - 4:56pm
Updated: Sunday, August 7, 2022 - 5:27pm

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Q&AZ is supported in part by Abrazo Health

A Phoenix yard featuring mostly gravel and rocks
A Phoenix yard featuring mostly gravel and rocks.

In an effort to conserve water during the long-term drought, residents around the Southwest are tearing out their grass and opting for desert landscaping — also called hardscape — that primarily features gravel.

Through KJZZ’s Q&AZ project, a listener asked: Does hardscape contribute negatively to the urban heat island effect? 

Natural grass is more effective at cooling than hardscapes because it cools through evaporating water. But gravel is one of the cooler alternatives for a water-conscious landscape. 

Ariane Middel is an urban climatologist with Arizona State University. 

"The gravel is not as bad as, say, your asphalt parking lots because it has all these little air pockets and gaps," Middel said. "So at night, it actually cools down quicker than your parking lot or your sidewalk." 

As a pervious surface, gravel can allow water to seep down to the soil below better than asphalt or concrete.

Middel advises residents not to swap out their grass for artificial turf, another popular alternative, because its temperatures run hotter than asphalt on average.

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