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Burning Forests Impact Water Supplies

 

prescribed_fire_EVallery_Bugwood_5432804.jpgAfter a wildland fire burns away vegetation, rivers may rise. This could provide some relief for water supplies in drought-stricken areas, but there are trade-offs, according to a new study led by Center scientists and published in Nature Communications. “The bad news is that burned forests can cause water quality problems from soil erosion and sediment during flooding, immediately or long after the fires have occurred. This is especially problematic in watersheds that provide drinking water downstream,” explains research hydrologist Ge Sun. In the first nationwide study of wildland fire impacts on surface freshwater resources, researchers examined three decades of fire data along with climate and streamflow from 168 river basins. They found the most significant post-fire streamflow increases in the drier parts of the Lower Colorado Basin, in the Pacific Northwest, and in California. "The large scale of this study enabled us to determine that the annual river flow changed, and in most cases increased, when a fifth of the basin or more was burned by wildland fire,” says hydrologist Dennis Hallema, the study's lead author. In the southeastern United States, researchers found no significant change in streamflow after prescribed burns, which typically take place over smaller areas and burn less hot. Results from the study, which was funded by the Joint Fire Science Program, can help land managers design mitigation strategies to suit local climate, watershed characteristics, and wildland fire conditions. Read more about the study in news releases from Nature Communications, the Southern Research Station, and Oregon State University, and listen to an interview on Phoenix-based KJZZ radio...

Pictured: In the Southeast, low intensity prescribed fires on smaller areas did not show appreciable streamflow increase for large watersheds. Photo by Erich Vallery, USDA Forest Service, Bugwood.org.

 

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