Type of Soil
The structure, density and size of a soil’s particles influences its likelihood of erosion.
Clay soils are the least erodible, sand and gravel the most.
soils have other problems: they are much faster to produce runoff due to poor infiltration, and this leads to the washing
of fine particles and the siltation of streams. Sand and gravel do not travel like clay.
Point: A soil dominant in clay that has silt, sand and/or organic matter.
Points: A sandy soil mixed with silt and organic matter.
Points: A clay soil with little or no organic matter.
Point: Sandy soils with little or no organic material. Loose and gravely rock.
and Type of Activity
Activity by animals and humans has a
large affect on likelihood of erosion. The more activity, the more erosion. Tunneling animals, such as gophers and ground
squirrels, are a threat to stability, more so if the fire has displaced their predators.
neglect drainage systems and improperly clear landscapes, and both increase chances of erosion greatly. But even walking on
a burnt landscape can slow its recovery; trampling lowers germinations rates, redistributes seeds, and crushes new seedlings.
o 1 Point: Animals and people walking on the site.
Points: Storm drains and gutters clogged. Tunneling and browsing animals lack predators and their populations are large.
o 4 Points: An area that was cleared sometime before the fire, and never
replanted, allowing shallow rooted opportunists to grow.
o 6 Points:
A barren landscape. Also, massive cuts into a hill and/or fill brought in on a slope.
A low temperature fire
can cleanse and waken a dynamic landscape. A high temperature will do just the opposite—not much survives 2,000 degrees.
Fire intensity not only affects a landscape’s rate of recovery, but also
the amount of repellency a soil has. Hotter fires produce more repellency. This test assumes a fairly hot fire, slow recovery,
and high repellency.
Roadways, sidewalks, driveways and parking lots can sometimes deposit their runoff on surrounding
properties. If your burnt landscape is receiving sheeting water, the risks of erosion are high.
Points: The site is not receiving sheeting water from nearby properties.
Points: The site is receiving sheeting water and it is flowing into the landscape.
Level of Risk
Between 6 - 13 points = Fairly Low Risk of Erosion
Between 14 - 20 points = Medium Risk of Erosion
Between 21 - 28 points = Fairly High Risk of Erosion
29 - 44 points = High Risk of Erosion
* This test was developed in February
1996, after the Vision Fire in Pt. Reyes and Inverness, October 1995. It was developed in partnership with Robert Crowell
of Cagwin and Dorward, a landscape architect and engineering firm in San Rafael, CA. This test is a fire-modified version
of the Universal Soil Loss Equation, a nationwide standard developed for farmers.