To prioritize conservation planning efforts, much focus has been placed on identifying the most vulnerable areas of the landscape to sediment and/or nutrient loss. The Natural Resources Conservation Service (NRCS) has developed the Soil Vulnerability Index (SVI) to provide a straightforward approach to vulnerable area identification while minimizing accessibility issues associated with complicated models and input data.

The most significant soil properties for predicting the inherent vulnerability of soils to runoff and leaching were found to be hydrologic soil group, slope, and whole soil erodibility (or KW Factor). Using these commonly available soil parameters, soil map units can be readily classified into categories of High, Moderately High, Moderate, or Low vulnerability. These categories are applied to three dimensions of SVI: vulnerability to surface loss, vulnerability to subsurface loss on undrained soils, and vulnerability to subsurface loss on drained soils.

Improvements have been made to the initial SVI ruleset and have been incorporated into the ACPF toolbox. Soil taxonomic classification, soil parent material, and soil drainage class have been identified as additional soil parameters that are used to adjust vulnerability classes.

The ACPF provides two approaches for mapping SVI within a watershed:
1. Map unit–based SVI. Mirrors the current NRCS approach and utilizes gSSURGO soils data exclusively. SVI output is tied to the soil map unit.
2. Pixel-based SVI. Combines gSSURGO soils data with high-resolution topographic information available within the ACPF to produce a more spatially explicit SVI at a sub-map-unit scale. SVI output is tied to DEM resolution.