From the WEPS 1.5 User Manual17
The Wind Erosion Equation (WEQ) was first published in 1965 by Woodruff and Siddoway. For years, WEQ has represented the most comprehensive and widely used model in the world for estimating soil loss by wind from agricultural fields. WEQ uses five factors to calculate the erodibility of a given soil.
The equation for WEQ is:
E= f(I,K,C,L,V)
where E is the average soil loss (tons/acre/year), I is the soil erodibility, K is the soil ridge roughness, C is the climatic factor, L is the field length along the prevailing wind erosion direction, and V is the vegetative factor.
WEQ is largely empirical in nature and was derived from nearly 20 years of field and laboratory studies by scientists at the United States Department of Agriculture Agricultural Research Service (ARS) Wind Erosion Research Unit.18-21 Many improvements were made to WEQ over the next 30 years. The limitations of adapting WEQ to many problems and environments, as well as advancements in wind erosion science and computer technology, led to the USDA Natural Resources Conservation Service (NRCS) requesting that ARS develop a replacement for WEQ.22
References
17. Content from: The Wind Erosion Prediction System: WEPS 1.5 User Manual. Fort Collins, Colorado, USA: USDA-ARS Rangeland Resources & Systems Research Unit; 2016. See original text for full citations.
18. Chepil WS. Soil Conditions That Influence Wind Erosion. US Dept. of Agriculture; 1958.
19. Chepil WS. Wind erodibility of farm fields. J Soil Water Conserv. 1959;14(5):214-219.
20. Chepil WS. Conversion of Relative Field Erodibility to Annual Soil Loss by Wind 1. Soil Sci Soc Am J. 1960;24(2):143-145. doi:10.2136/sssaj1960.03615995002400020022x
21. Chepil WS, Woodruff NP. Estimation of wind erodibility of farm fields, USDA Prod. Res Rep. 1959;(25).
22. Hagen LJ. A wind erosion prediction system to meet user needs. J Soil Water Conserv. 1991;46(2):106-111.