Erosion at Warp Speed?

Fifty to 100 years from now, rainstorms at some places in America may be more intense—and may be more frequent—some climate experts predict.

Among the expected consequences: significant increases in stormwater runoff and in the amount of soil that’s washed from fields, orchards, vineyards, grazinglands, and perhaps even from sloping backyards or hilly parklands near you.

That’s according to Mark A. Nearing, soil scientist and research leader at the Agricultural Research Service’s Southwest Watershed Research Center in Tucson, Arizona. In a series of studies reported over the past several years in the Journal of Soil and Water Conservation, Catena, and other scientific publications, Nearing and colleagues ran climate data from the past century through seven leading mathematical models. That yielded intriguing computer simulations of the potential soil-erosion punch that tomorrow’s thunderstorms might pack.

The projections for two watersheds—one in the southwestern United States and one in Europe—indicate that stormwater runoff at those locales could increase by 23 to 31 percent during this century. In turn, soil erosion could increase by 25 to 55 percent.

These worrisome estimates are based on an array of factors, including the presumption that the U.S. climate trends of the past 100 years—and farming practices—will continue along the same lines.

Another investigation, this one encompassing eight sites from Oregon to Georgia, indicated that stormwater runoff and soil erosion would increase in all but two of the venues, according to computer simulations from two of the models.

And results from still another investigation suggest that increases in soil erosion will outpace increases in rainfall. For every 1-percent increase in rainfall, there will be a 1.7-percent increase in soil erosion.

These findings and others are helping scientists get a better idea of the possible soil-erosion-related consequences of global climate change. From that foundation, they can develop ways to better protect vulnerable topsoil from the erosive power of tomorrow’s thunderstorms.—By Marcia Wood, Agricultural Research Service Information Staff.

Mark A. Nearing is with the USDA-ARS Southwest Watershed Research Center, 2000 E. Allen Rd., Tucson, AZ 85719; phone (520) 670-6481, ext. 152, fax (520) 670-5550.

"Erosion at Warp Speed?" was published in the September 2006 issue of Agricultural Research magazine.