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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #382220
Research Project: Long-term Management of Water Resources in the Central Mississippi River Basin

Location: Cropping Systems and Water Quality Research

Title: Incorporating a precipitation factor into the Soil Vulnerability Index Classification

Author
item PHUNG, QUANG - University Of Missouri
item THOMPSON, ALLEN - University Of Missouri
item Baffaut, Claire

Submitted to: International Soil and Water Conservation Conference
Publication Type: Abstract Only
Publication Acceptance Date: 3/17/2021
Publication Date: 7/26/2021
Citation: Phung, Q., Thompson, A., Baffaut, C. 2021. Incorporating a precipitation factor into the Soil Vulnerability Index Classification [abstract]. 76th International Soil and Water Conservation Society Annual Conference, July 26-28, 2021, virtual. Available: https://www.swcs.org/events/past-events/past-annual-conferences/2021-annual-conference/

Interpretive Summary:

Technical Abstract: The Soil Vulnerability Index (SVI) developed by NRCS uses widely available inputs from the SSURGO database to classify agricultural land into four levels of vulnerability to sediment and nutrient losses: low, moderate, moderately high, and high. However, previous work has identified inconsistencies of vulnerability assessment across the United States, possibly because neither precipitation amount nor intensity are included in the SVI. Therefore, the objective of this research was to evaluate if inclusion of annual or seasonal rainfall characteristics can improve the ability of the runoff component of SVI to assess vulnerability to runoff and sediment yield. The study included six Conservation Effects Assessment Project (CEAP) watersheds in Ohio, Missouri, Mississippi, Georgia, Maryland, and Pennsylvania, selected for their range of rainfall characteristics. Sediment yields within each studied watershed were simulated using the Soil and Water Assessment Tool (SWAT) or the Annualized Agricultural Non-Point Source Pollution Model (AnnAGNPS) using precipitation data from 1985 to 2014 from all watersheds. The Universal Soil Loss Equation (USLE) R-factor is one means to describe the effect of rainfall on sheet and rill erosion. Annual R-factors, which ranged from 189 to 390, were compared with the simulated sediment yields. Preliminary results indicated that the SVI classification of fields in each watershed could shift to more or less vulnerability due to changes in precipitation characteristics. The coefficient of determination (r2) between R-factors and sediment yields ranged between 0.50 and 0.97, with most values greater than 0.7. This study will discuss how R-factors help explain the shift in SVI classification caused by differences in precipitation.