An understanding of the interrelationships between field length, soil transport and average soil loss is extremely important to understanding the wind erosion mechanics imbedded in RWEQ.
The transport equation used in RWEQ, describes the quantity of soil
RWEQ requires: weather data; soil texture or soil properties; field size, shape, and orientation; slope length and gradient of hills; dates of planting, tillage, or harvest; crops and yields; amounts of flat and/or standing residues; growing crop canopies; height, density, spacing, and orientation of barriers or shelterbelts; and amount and rate at which irrigation water is applied.
The RWEQ program uses the management inputs of tillage or irrigation with the weather data to degrade soil surface roughness and decompose surface residues.
Otherwise, RWEQ computes erodible fraction from soil physical and chemical properties (Fryrear et al.
In RWEQ, the soil crust factor is included whenever there is 12.
All methods have advantages and disadvantages, but because of its simplicity and application to field conditions the chain method is used in RWEQ.
In RWEQ the effect of irrigation is considered equivalent to rainfall regardless of the method used to apply the irrigation water.
RWEQ uses crop height at harvest, harvest height, and decomposition coefficients to partition residue mass into standing and flat pools.
To verify the transport Equation (1) used in RWEQ, field measurements of transport quantity were collected from the 51 erosion periods at 22 sites, listed in Table 1.
The weather data from each site/period were summarized and used in RWEQ to estimate soil loss for the measurement period.