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*Determine the most erodible soil at a site. Soils with silt and fine or very fine sand are highly erodible. [https://www.youtube.com/watch?v=fufeaLBLGlk See this Youtube]. | *Determine the most erodible soil at a site. Soils with silt and fine or very fine sand are highly erodible. [https://www.youtube.com/watch?v=fufeaLBLGlk See this Youtube]. | ||
*Identify the soil structure. General erodibility is Platy > Massive > Blocky > Aggregated. You likely will not encounter columnar structure. Granular structure varies. Fine and very fine sands are granular but highly erosive, while medium to coarse sands are less erosive. Certain practices at a site may change the structure, especially soils with appreciable amounts of clay. See adjacent image. | *Identify the soil structure. General erodibility is Platy > Massive > Blocky > Aggregated. You likely will not encounter columnar structure. Granular structure varies. Fine and very fine sands are granular but highly erosive, while medium to coarse sands are less erosive. Certain practices at a site may change the structure, especially soils with appreciable amounts of clay. See adjacent image. | ||
+ | *Examine the soil for organic matter content. Organic matter imparts a black color to soil. Organic matter binds soil and reduces the risk of erosion. | ||
+ | *If subsoils are exposed, this might increase erodibility since subsoils generally lack organic matter and disturbance may destroy the soil structure. | ||
+ | *Determine if rills and gullies are starting to form. These can lead to significant soil losses. | ||
+ | |||
+ | ==Suggested references and links== | ||
+ | *[https://stormwater.pca.state.mn.us/index.php?title=General_principles_for_erosion_prevention_and_sediment_control_at_construction_sites_in_Minnesota Soil Erodibility On Construction Areas] | ||
+ | *[https://dnr.wi.gov/news/input/documents/guidance/SoilLossGuidance.pdf Wisconsin Construction Site Soil Loss and Sediment Discharge Calculation Guidance] | ||
+ | *[https://stormwater.pca.state.mn.us/index.php?title=Soils_and_geology Soil surveys and other resources] | ||
+ | *[https://dec.vermont.gov/sites/dec/files/wsm/stormwater/docs/StormwaterConstructionDischargePermits/sw_9020_Erodibility_ Guidance.pdf Vermont Soil Erodibility Evaluation for General Permit 3-9020 Stormwater Runoff From Construction Activities] | ||
+ | *[https://mepas.pnnl.gov/mepas/formulations/source_term/5_0/5_32/5_32.html#targetText=The%20soil%20erodibility%20factor%20(K,transport%20by%20rainfall%20and%20runoff. Soil erodibility factor] | ||
+ | *[[General principles for erosion prevention and sediment control at construction sites in Minnesota]] | ||
+ | *[[Erosion prevention practices]] | ||
+ | *[[Sediment control practices]] |
Erodibility describes or is a measure of the inherent resistance of geologic materials (soils and rocks) to erosion. Highly erodible geologic materials are readily displaced and transported by water. This page provides basic information about soil erodibility.
There are four types of soil erosion.
The Universal Soil Loss Equation (USLE) and it's update, the Revised Universal Soil Loss Equation (RUSLE) are used to predict sheet and rill erosion. These equations do not apply to gully erosion and dispersive soils. The annual soil loss, in tons per acre, is given by the following formula.
Annual soil loss = R * K * LS * C * P
where
RUSLE factors are observable in the field and fairly simple to derive. The R and K variables are generally out of the hands of the construction site operator. Slope (S) and slope length (L) can sometimes be managed or impacted during the design phase of project development. Two RUSLE variables which can be controlled at active construction sites – the cover and practices factors (i.e., variables C and P) – are the focus of the erosion prevention measures. Erosion prevention practices, which mostly include soil preparation, vegetation, and the application of a mulch, blanket, mat, or other cover on bare soil, are the easiest, cheapest, and most effective approach for addressing runoff from construction sites. Sediment control – settling soil particles from temporarily ponded runoff water or filtering it using silt fencing or other materials – is more difficult, more expensive, and requires much more maintenance.
For more information on the USLE and RUSLE, see the following.
Soil erodibility ( K ) is the intrinsic susceptibility of a soil to erosion by runoff and raindrop impact. In general, the following affect K. See adjacent table.