Location: National Soil Erosion ResearchTitle: Status of process-based prediction technology for use in soil conservation planning activities in the United States
Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2018
Publication Date: 10/31/2018
Citation: Flanagan, D.C., Frankenberger, J.R., Srivastava, A., Huang, C. 2018. Status of process-based prediction technology for use in soil conservation planning activities in the United States. In: The 11th International Symposium on Agriculture and the Environment (AgroEnviron 2018), October 14-18, 2018, Nanjing, China. p. 11-14.
Technical Abstract: The United States Department of Agriculture (USDA) has been developing erosion prediction technologies since the 1940’s, in order to determine the rates of soil loss in different locations, on different soils and slopes, and under various management practices. Over 10,000 plot years of runoff and soil loss data from 35 Soil Conservation Experiment Stations (Gilley and Flanagan, 2007) were used as the basis for development of the Universal Soil Loss Equation (USLE) by Wischmeier and Smith (1978). The USLE is a purely empirical equation, composed of 6 factors (erosivity, erodibility, slope length, slope steepness, cropping/management, conservation practice) determined from statistical analyses of the observed plot erosion data. Since 1985, USDA has been developing a process-based model to replace USLE. The Water Erosion Prediction Project (WEPP) model contains science and equations representing fundamental processes of hydrology, flow hydraulics, soil detachment by raindrops and flowing water, sediment transport, and sediment deposition. It also simulates important related processes including plant growth, residue decomposition, soil disturbance and residue burial by tillage, residue management (addition, removal, etc.), climate generation, and irrigation (Flanagan et al., 2000; Flanagan et al., 2007). The validated WEPP model for application to hillslope profiles and small watersheds was first publicly released in 1995, along with a rudimentary DOS-based user interface. Since that time substantial additional work has been done to both the science model as well as in user interface development. WEPP updates have typically been released every 2-5 years. In 1999 a Windows interface was released that made application of WEPP much easier. The USDA Forest Service has developed web-based interfaces especially for forest roads and disturbed regions, and uses WEPP extensively to assess erosion risks from areas that have experienced wildfires. In 2013, NRCS began a cooperative effort with the USDA Agricultural Research Service (ARS) to develop the necessary interfaces and updated databases so they could implement WEPP in their field offices for conservation planning on hillslopes and small field watersheds. Activities during the past 5 years have included updating of the nationwide climate database with 40-years of temporally-consistent station data from 1974-2013, a new web-based interface (Figures 1-3) designed based on NRCS input and feedback, ability within the new interface to draw from thousands of existing NRCS land management operations and rotations, ability to utilize PRISM climate grid information, and testing and updating of plant growth and residue decomposition parameters for the wide range of crops used in NRCS conservation planning. NRCS regional and state agronomists are currently testing the initial web-based interface for hillslope profile runoff and erosion predictions, and the agency expects to implement WEPP in its field offices for use in conservation planning by the end of 2018. Additionally, a small field/watershed interface for WEPP is under development that will provide model simulation results for user defined watersheds or trapezoidal field areas. Watershed simulations will allow prediction of erosion from ephemeral gullies or effect of grassed waterways at controlling soil losses, as well as the effects of impoundments on reducing sediment losses.