NB_450_21_1 - NB 450-21-1 TCH - Continuation of the Revised Universal Soil Loss Equation (RUSLE2) Model for Water Erosion
NB 450-21-1 TCH - Continuation of the Revised Universal Soil Loss Equation (RUSLE2) Model for Water Erosion
National Bulletin: 450-21-1 Date: December 14, 2020
Subject: TCH - Continuation of the Revised Universal Soil Loss Equation (RUSLE2) Model for Water Erosion


 
Purpose.   To notify States that RUSLE2 remains the official NRCS tool for predicting soil erosion by water.
 
Expiration Date.   December 30, 2021
 

Background.   In 2013, NRCS made a decision to replace RUSLE2 with the Water Erosion Prediction Project (WEPP) for predicting sheet and rill soil erosion. In order to fully implement that decision, a Federal Register Notice was required. In 2016, NRCS issued a public notice of intent to implement WEPP to replace RUSLE2 as erosion prediction technology for NRCS. Public notice of this decision was issued in a Federal Register notice (81 FR 81053, November 17, 2016). The final decision regarding RUSLE2 and WEPP was delayed in order to allow further time to compare the models and associated impacts. National Bulletin 450-18-5 revised the schedule for adoption of the Water Erosion Prediction Project (WEPP).

Several studies have been issued related to these tools, including:

• an impact analysis completed in Iowa in April 2019;
• an NRCS 2019 nationwide tool comparison study;
• development of an ARS Strategic Plan for Erosion Research and Model Development (completed by ARS in March 2020);
• and a model comparison study of RUSLE2 and WEPP in Illinois published by ARS on July 21, 2020.

NRCS has reviewed these studies, and appreciates the work and dedication put into these efforts. In review of these studies, NRCS has made the decision to maintain RUSLE2 as its official erosion control model.

 

Explanation.   NRCS, in conjunction with the Agricultural Research Service (ARS) will continue with soil erosion models evaluation, WEPP development and testing, and updates to soil erosion models as necessary. WEPP remains available for use in situations when WEPP functionality such as soil erosion risk statistics and soil hydrology will benefit conservation planning. Regional and State agronomists can assist planners with WEPP.

Distribution.  This directive is available on the NRCS Electronic Directives System Web site at http://policy.nrcs.usda.gov.

 
Contact.   For further information, contact Dr. Betsy Dierberger, National Agronomist, Ecological Sciences Division, by telephone at (202) 720-3783 or by email at betsy.dierberger@usda.gov.
 
 

 /s/

Diane Gelburd
Deputy Chief
Science and Technology
 
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