Garden with Insight v1.0 Help: Soil patch next day functions: calculate today's wind erosion
Wind erosion calculation in this model is fairly complex and we won't
go into great detail here. There typically isn't much wind erosion on a small garden plot, so it has only a
small effect on the simulation.
Wind erosion does not occur if: 1) the option to calculate it is turned off, 2) the wind erosion acceleration
factor (a parameter) is zero, 3) there
is snow on the soil patch, or 4) the wind speed today was less than 7.5
meters per second.
If wind erosion does occur today, it is calculated in two steps. First, the potential amount of wind erosion is calculated by integrating wind erosion
over the course of the day using an assumed distribution of wind speed
over the day. The potential wind erosion depends on the mean
unsheltered travel distance of wind across the watershed (a long thin
watershed has more wind erosion than a square one), soil water content in the top soil layer (dryer soil = more wind erosion), and a soil patch parameter for
the mean size of soil particles (smaller particles are easier to blow away). Remember that each soil patch
in this simulation has its own watershed, as if it were in its own separate valley.
The potential wind erosion for today is reduced by multiplying it by
several factors that range from zero (no wind erosion) to one (no
reduction from the potential amount). The factors are as follows.
The soil erodibility
factor is based on the relative proportions of sand, silt and clay (the
soil texture). Roughly, the more sand the greater the wind erosion.
The surface roughness
factor has to do with the roughness of the surface of the soil. Soil ridges tend to protect the soil from
wind erosion, depending on which way the wind is blowing. The orientation of the soil patch is compared
to the wind direction for the day to determine sheltering or exposure of the soil to wind.
The vegetative cover
factor is based on the amount of live and dead plant matter on the soil. Soil cover tends to reduce
The coarse fragment
factor reduces wind erosion based on rocks in the surface soil layer.
EPIC Wind erosion