Environmental Engineering FOURTH EDITION

240 ENVIRONMENTALENGINEERTNG

able 11-3. Vegetation Cover Factors (C) for Various Types of Ground Covef

Land use groups Examples Range of C values

Permanent vegetation

Established meadows

Small grains

Large-seeded legumes

Row crops

Fallow

0.0004-0.3

0.07-0.5

Protected woodland 0.0001-0.45

Prairie

Permanent pasture

Sodded orchard

Permanent meadow

Alfalfa

Clover

Fescue

Rye

Wheat

Barley

Oats

Soybeans

Cowpeas

Peanuts

Field peas

Cotton

Potatoes

Tobacco

Vegetables

Corn

Sorghum

Summer fallow 1 .o

Plowing-to-crop growth period

0.1-0.65

0.1-0.70

=Source: USEPA (1976), p. 59.

The USLE was developed by Agricultural Research Service (U.S. Department

of Agriculture) scientists W. Wischmeir and D. Smith in 1965 to predict soil loss in

agriculture regions. Because the original USLE was developed for agricultural land,

the equation factors are best defined for pastures and cropland. A newer version, the

Revised Universal Soil Loss Equation (RUSLE), is available as a computer model

from the U.S. Department of Agriculture (USDA) National Sedimentation Labora-

tory web site (http://www.sedlab.olemiss.edu/rusle). The RUSLE has been updated

to estimate soil loss wherever ground is broken, such as during construction or strip

mining, and is used to estimate soil erosion for a variety of soil management scenarios

including agricultural best management practices, mining and construction activities,

land reclamation projects, silvaculture activities, and residential storm water treatment

options. Used alone, the RUSLE projects relative changes in sediment yields if different

nonpoint source control technologies are designed and constructed. When integrated