THE ROLE OF SEVERE STORMS IN SOIL EROSION: A PROBLEM NEEDING CONSIDERATION

Authors: LARSON, WILLIAM - UNIVERSITY OF MINNESOTA; Lindstrom, Michael; SCHUMACHER, T - SOUTH DAKOTA STATE UNIV

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Soil erosion prediction equations have been developed for use in designing conservation management systems for cultivated fields. A key component of these prediction equations is long-term average rainfall patterns. In examination of soil erosion data from many location, we observed that soil erosion amounts were dominated by a few large, intense storms. This analysis suggests that using average rainfall patterns in soil erosion prediction equations may result in excessive soil erosion. As an alternative we suggest that additional safeguards should be built into conservation plans to accommodate conditions present during large, intense storms that occur at known frequencies. It would be impractical to design conservation systems to completely stop soil erosion from severe storms, but designing conservation practices to limit soil erosion at an acceptable level for a once in ten-year or once in twenty-year storm should be a reasonable goal. Obtaining this goal will allow development of conservation management practices acceptable by the farming community that protect natural resources.

Technical Abstract: Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE) were developed to predict long-term average erosion from cultivated fields for use in conservation planning. Both equations use long-term average precipitation patterns as the basis for describing erosivity. However, soil erosion losses are often dominated by a few storms sof high intensity and high precipitation amounts, which presents a possibl weakness in our design of conservation management systems. Examinations of soil erosion data from many location shows that when annual soil erosion amounts are ordered from the highest to the lowest over time, the resulting curve is exponential. The form of this curve illustrates the dominance of relatively rare events in the determination of long-term erosion averages. It is our thesis that additional safeguards should be built into conservation plans to accommodate conditions present during large, intense storms that occur at known frequencies. Designing conservation systems to eliminate soil erosion during severe storms may not be practical, designing conservation practices to limit soil erosion to T or 2T during a once in ten-year or once in twenty-year storm should be a reasonable objective.