Gilman Soil Series
USDA Code: CA0219
K-Factor
0.24
Soil Erodibility Factor
Texture Class
fine sandy loam
Drainage Class
well drained
About Gilman
Deep, well drained soils formed in alluvium from mixed sedimentary and metamorphic rock sources. Found on stream terraces and flood plains adjacent to major rivers at low to moderate elevations, slopes of 0 to 5 percent.
K factor values are sourced from the USDA Natural Resources Conservation Service (NRCS) SSURGO database.
Using Gilman in a RUSLE calculation
For a California construction project, use the soil K factor with rainfall erosivity, slope length and steepness, cover management, and support practice inputs. The K factor represents the soil erodibility portion of the model, so selecting the soil series that matches the site is important for defensible stormwater documentation.
In a SWPPP workflow, the practical question is not just what soil type is mapped near the project. It is whether the mapped series, K factor, and drainage assumptions match the site evidence well enough to support the RUSLE or RUSLE2 calculation.
California Distribution
Mapped along the Trinity River and its major tributaries in Trinity and Humboldt counties. Important riparian agricultural soil supporting vegetable production and pasture in river bottom areas.
Counties Where Found
Gilman soil FAQ
What is the K factor for Gilman soil?
Gilman has a listed K factor of 0.24 in the Rapid RUSLE soil directory. Confirm final values against project specific soil survey data before submitting permit documents.
Where is Gilman soil found in California?
Gilman is mapped in Humboldt, Mendocino, Trinity. County mapping is based on available soil series data and should be verified for the exact project location.
How is Gilman used in RUSLE erosion calculations?
Use the Gilman K factor as the soil erodibility input in RUSLE or RUSLE2, along with rainfall, slope, cover, and support practice factors for the site.
Calculate erosion risk with Gilman soil data
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