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Soil Survey Manual - Table 3-10

Index surface runoff classes based on slope gradient and saturated hydraulic conductivity

Slope Gradient Saturated Hydraulic Conductivity Class a, b
Pct. Very High High Mod. High Mod. Low Low Very Low
Concave c N N N N N N
<1 N N N L M H
1 to 5 N LV L M H HV
5 to 10 LV L M H HV HV
10 to 20 LV L M H HV HV
≥20 L M H HV HV HV
a. Abbreviations: Negligible-N; Very Low-LV; Low-L; Medium- M; High-H; and Very High-HV.

b. Consult Table 3-7 for definitions. Assumes that the lowest value for the soil occurs above 1/2 m. If the lowest value occurs 1/2 to 1 m, then reduce runoff by one class (medium to slow, for example). If it occurs >1 m, then use the lowest saturated hydraulic conductivity < 1 m.

c. Areas from which no or very little water escapes by flow over the ground surface.