Revised Wind Erosion Equation

Abstract

The Revised Wind Erosion Equation (RWEQ) was developed at the request of the Natural Resource Conservation Service to replace the Wind Erosion Equation (WEQ). RWEQ incorporates new technology developed since WEQ was published in 1965. While the basic inputs are the same for the two equations, the form of the input data is considerably different. RWEQ can estimate erosion each day or for 365 days. Multi-year crop rotation systems can be input into RWEQ and modifications to the management system can be made to evaluate the most desirable farming system for each land manager. j{WEQ is based on the assu~ption that the wind has a limited capacity to transport eroded material. As clean wind blows over an erodible surface, soil material will be emitted from the surface, The emission process will accelerate due to abrasive soil material accumulation as wind passes over the erodible soil. Initially the ability of the soil to emit eroded material will limit the increase in material being transported by the wind. As the wind approaches its maximum transport" capacity. it is the ability of the wind to carry additional material that will limit increases in transport. This process has been observed, measured and is modeled in RWEQ. The technology in RWEQ emphasizes that to effectively control wind erosion and minimize land damage efficient wind erosion control practices must be in place over the entire field. When erosion does occur, soil losses are greatest within a few tens of meters of the upwind boundary. Measured annual soil losses at Crown Point. Indiana, were 31.21 kg m-2 , WEQ technology estimated 0.00 kg m-2 erosion, and RWEQ estimated 25.24 kg m-2 erosion. With the RWEQ technology. land managers can be confident that they can plan erosion control systems for their farmlands that will be effective. In addition, the wind barrier routine, hill effects, and field length equations will estimate erosion within the field and the quantity of material that will be leaving the downwind field boundary.