The Revised Universal Soil Loss Equation (RUSLE) provides conservationists with a tried and tested method for selecting the best conservation plans for controlling soil erosion. Soil erosion by water continues to be a major problem affecting croplands, rangelands, and forests, landfills, military training grounds, mined and reclaimed land, and construction sites. In developing this erosion prediction technology, ARS scientists provided conservationists with a planning guide for selecting a land-use practice with a predicted soil loss that is lower than the acceptable limit. This limit is usually referred to as the soil-loss-tolerance value. The widely used RUSLE is considered to be the best erosion prediction technology available for conservation planning at the local field office level. As a consequence, RUSLE has been implemented by the USDA's Natural Resources Conservation Service throughout its field office system. It has been routinely used by local NRCS conservationists to help farmers and other land users protect and preserve the landscape and associated soils for years of future productive use. This erosion prediction technology has also been used by many public and private organizations to assist in conservation planning so as to ensure that the land is used in ways that prevent excessive erosion, provide for the land's long-term maintenance as a natural resource, and protect downstream areas from excessive sedimentation and degradation of water quality.

National Sedimentation Laboratory, Oxford, MS
Keith C. McGregor, (662) 232–2972, mcgregor@sedlab.olemiss.edu

To rehabilitate and revitalize thousands of U.S. earthen dams, scientists will need to rely on more than 60 years of ARS hydraulic engineering research, expertise, and databases. Today, many of the dams no longer work efficiently and need repairs. Many of these 10,000 flood-control structures, constructed with the assistance of USDA, were designed with a 50-year service life. Unlike dams along rivers, these protect the nation's watersheds. Many serve as municipal water supplies; prevent floods; provide water for irrigation, recreation, fish and wildlife habitats, and groundwater recharge; and improve water quality. Yearly, they provide Americans with more than $800 million in benefits. Over the next 10 years, more than 1,000 earthen dams will need significant repairs and modification. ARS and USDA's Natural Resources Conservation Service are developing technologies for rehabilitating and revitalizing the dams, and software for applying the technologies to solve engineering problems. The software program, called SITES, combines the principles of geology, hydrology, soil science, and physics to predict the performance of vegetated earth spillways used in these structures. It will be used to predict how an earthen spillway will perform and to evaluate its potential for failure. Future versions will incorporate current research to predict the damage that results from embankment overtopping.

Hydraulic Engineering Research Laboratory, Stillwater, OK
Darrel M. Temple, (405) 624–4135, ext. 226, dtemple@pswcrl.ars.usda.gov