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ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Watershed Physical Processes Research » Research » Publications at this Location » Publication #196629
Title: REGEM: THE REVISED EPHEMERAL GULLY EROSION MODEL

Author
item GORDON, LEE - UNIVERSITY AT BUFFALO
item BENNETT, SEAN - UNIVERSITY AT BUFFALO
item Bingner, Ronald - Ron
item THEURER, FRED - USDA, NRCS
item Alonso, Carlos

Submitted to: Federal Interagency Sedimentation Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/4/2006
Publication Date: 4/4/2006
Citation: Gordon, L., Bennett, S.J., Bingner, R.L., Theurer, F., Alonso, C.V. 2006. REGEM: The revised ephemeral gully erosion model. In: Proceedings of the 8th Federal Interagency Sedimentation Conference, April 2-6 2006, Reno, Nevada. CDROM.

Interpretive Summary: Ephemeral gullies serve as effective links transferring sediment and associated agrichemicals from upland areas to stream channels. Current erosion prediction technologies often require the exact topographic location of an ephemeral gully to be known, which greatly limits the application of such models. Technology has been developed in this study that incorporates state-of-the-art ephemeral gully science within watershed models. This includes the scour that is produced below ephemeral gully headcuts and the rate that the headcuts move up into the agricultural fields after rainfall events. Sediment that is eroded within the ephemeral gully is routed downstream within fields where the watershed model integrates all other sediment sources within a field, such as from sheet and rill erosion, and then combined with any other contributions including from channels to move the sediment to the watershed outlet. Ephemeral gully processes included within a watershed model also provides a tool that can determine the effect of conservation management practices and changing soil conditions on the development ephemeral gully erosion. This technology allows a more accurate and physically based examination of sediment sources in agricultural watersheds, providing tools necessary to effectively manage the Nation’s water and soil resources.

Technical Abstract: Ephemeral gullies serve as effective links transferring sediment and associated agrichemicals from upland areas to stream channels. Current erosion prediction technologies often require the exact topographic position (the length) of an ephemeral gully a priori, which greatly limits the utility of such models. The Revised Ephemeral Gully Erosion Model has been developed as a rational approach to predict ephemeral gully erosion and development. REGEM incorporates analytic formulations for plunge pool erosion and headcut retreat within single or multiple storm events in unsteady, spatially-varied flow at the sub-cell scale. The model employs sediment continuity equations for five soil particle-size classes to predict gully evolution and transport capacity. Event-based simulations demonstrate the model’s utility for predicting the initial development of an ephemeral gully channel, while continuous simulations allow the channel to evolve over multiple runoff events accounting for seasonal variations in management operations and soil conditions. REGEM currently functions as a stand alone tool, but it has now been integrated as an additional module within the Annualized Agricultural Non-Point Source (AnnAGNPS) suite of watershed modeling tools developed by the USDA. REGEM allows a more accurate and physically based examination of sediment sources in agricultural catchments, providing practitioners the tools necessary to effectively manage the Nation’s water and soil resources.