Although WEPS is designed to simulate rectangular field shapes, special field configurations such as circles or strip cropping can be simulated. By manipulating the field shape to represent a field with the same area and rotating the field along with any barriers many field shapes can be approximated.
Figure 1. Example of using sqare field shape to approximate a circle.
A circular field can be simulated using a square field of equal area. Figure 1 illustrates
how this would be visualized. Note that the yellow dashed circle is shown here to
illustrate the circular field and cannot be placed over the field within the WEPS
interface. For such fields, barriers should be added and the field rotated to best simulate
the actual field configuration.
Other field shapes can also be simulated with WEPS. A half circle can be represented
with a rectangle as illustrated in Figure 2. Figure 3 illustrates how an irregular field may
be visualized for a filed along a stream with filter strips along the North and East sides.
Figure 2. Example of using a rectangular field to simulate a half circle.
Figure 3. Example of using square field to simulate a field with a stream with buffers.
Figure 4. Example field layout for simulating strip cropping or grass barriers.
Fields managed for wind erosion control by strip cropping (non-contour, linear) are
simulated with each strip of unique management as anindividual rectangular field and
the erosion losses for each strip summed. For fields managed with grass strips, the fields are
simulated as individual strips with the appropriate barriers on either side. The erosion
loss from one section of the field is then multiplied by the number of strips to obtain the
soil loss for the entire field. Figure 4 illustrates a field layout for simulating
strip cropping or grass barriers.
WEPS 1.0 only allows tillage in one direction (e.g., Northwest/Southeast). In other words, multiple tillage directions such as where the operator tills parallel to each border of the field or a circular tillage pattern, cannot be simulated with WEPS 1.0. Observing the effects that tillage direction may have for the particular simulation may illustrate the need to alter tillage directions in the actual field to control wind erosion.