Laserfiche WebLink
APPENDIX 9-5-2 (Cont.) <br /> Soil Interpretations <br /> FOOTNOTES <br /> 10 I Factor: This value indicates the relative amount of soil that can be expected to erode, through wind influence, in Tons-Per-Acre-Per-Year (T/AC/YR). It <br /> is related to the Wind erodibility Group number and the percent of dry soil aggregates greater than 0.84 mm in diameter. Values are taken from USDA-SCS, <br /> May 1981, Wyoming Soil Procedures Guide, pg. 35. <br /> 11 K Factor: This value indicates the relative susceptibility of a surface soil to water erosion. Values may range from .00 to .70. Higher K values <br /> indicate higher erosion susceptibility. Soils with K factor over about 0.40 are generally considered to be highly susceptible to water erosion. It should <br /> be noted that the K factor is primarily derived from physical characteristics of the soil, and does not reflect other soil erosion factors such as <br /> management practices, precipitation, or length and steepness of slope. <br /> Low Erodibility: .20 or less; Moderate Erodibility: .21 - .40; High Erodibility: greater than .40 <br /> 12 Hydrologic Group Classification of Soils: Hydrologic soil groups are used in watershed planning to estimate runoff from rainfall. Soil properties arc, <br /> considered that influence the minimum rate of infiltration obtained for a bare soil after prolonged wetting. These properties are: depth of seasonally <br /> high water table, intake rate and permeability after prolonged wetting, and depth to a very slowly permeable layer. The influence of ground cover is <br /> � treated independently - not in hydrologic soil groupings. <br /> The soils have been classified into four groups, A through D. The individual classifications are taken from the most current official soil series "Form 5" <br /> sheets, as summarized in "Erosion Factors and Hydrologic Group for Soils of Montana", October 3, 1981, and a similarly named and dated publication for <br /> Wyoming. Statements in parentheses following the definitions may be helpful to soil scientists wishing to place soils into hydrologic groups using the <br /> soil classification system. <br /> A. (Low runoff potential). Soils have high (rapid) infiltration rates even when thoroughly wetted and consist chiefly of deep, well to excessively <br /> drained sands or gravels. These soils have a high rate of water transmission. (Includes Psamments except those in Lithic, Aquic, and Aquodic <br /> subgroups; soils in Grossarenic subgroups of Undults and Udalfs, and soils in Arenic subgroups of Udults and Udalfs except those in clayey or fine <br /> families). <br /> CD <br /> B. (Moderately low runoff potential). Soils have moderate infiltration rates when thoroughly wetted and consist chiefly of moderately deep to deep, <br /> Co moderately well to well drained soils with moderately fine to moderately coarse textures with moderately slow to moderately rapid permeability. These <br /> osoils have a high rate of water transmission. (Soils other than those in groups A, C, or D). <br /> Co <br /> w <br />