Forest fires kill people and animals, destroy property, and can cost millions of dollars to fight. But they have an upside: They help relieve water shortages in the western United States.
That’s the conclusion of a study reported this week in Ecohydrology, which found that—between 1990 and 2008—trees lost to fires saved more than 76 billion liters of water that would have otherwise been lost through evaporation from leaves to the atmosphere. To study this “evapotranspiration,” hydrologists and ecologists used a combination of satellite data (the intensity of “green” indirectly indicates the amount of evapotranspiration going on) and tower-based measurements, which measure actual water loss from trees in forests in two California river basins.
For a century, forest managers have sought to prevent forest fires, and as a result, western forests are too dense for the local water supply and also are more susceptible to wildfires. Thinning forests by cutting down smaller trees or with controlled burns would reduce fire risk and would lead to more water in local rivers that could be used for power, irrigation, and other areas where water is needed, they note.