2012 Annual Report
1a.Objectives (from AD-416):
1) Improve and extend the Wind Erosion Prediction System (WEPS) model and.
2) integrate WEPS with the National Soil Erosion Research Lab (NSERL) Water Erosion Prediction Program (WEPP) model to consolidate research resources for the two models and to improve the ease of simulating both wind and water erosion.
1b.Approach (from AD-416):
1. a) Extend WEPS beyond the current homogenous simulation area approach to improve simulation of field-scale variability by: i) further modularizing the erosion science code, ii) adding sub-field capability, iii) refining WEPS gridding algorithms, and iv) adding landscape terrain effects to WEPS; b) improve model inputs and science for WEPS through: i) updating weather, ii) adding crop competition and improved crop growth, iii) adding seasonal wind barrier porosity variability, and iv) improving soil and vegetation measurements with laser distance techniques; c) extend WEPS to additional soil types (i.e., organic dominated soils) and treatments (i.e., applied biosolids); and d) modify WEPS for application to special problems (i.e., regional air quality modeling, add PM2.5 emission, batch mode for WEPS, develop a single-event model); and e) publish the WEPS technical document.
2. Utilize common science and interface code for WEPP and WEPS to: a) provide common runoff and evaporation processes between the two models; b) provide common “winter processes” (simulation of freezing, thawing, freeze-drying processes); c) add water erosion specific input (hillslope length, slope, etc.) and output (water erosion, runoff, etc.) to the current standalone WEPS interface; d) address restrictions to simulating a homogeneous region represented by a single soil with common management practices applied to the entire field; and e) provide the necessary inputs to represent water erosion specific practices, such as terraces, artificial drainage, etc. to the user interface.
The Wind Erosion Prediction System (WEPS) model is a critical component of the USDA strategy to reduce particulate emissions from cultivated agricultural lands. An update release of WEPS (version 1.2.9) was provided to NRCS in October 2011 and an updated database in July 2012. ARS scientists at Manhattan, KS continue to improve the WEPS model and provide technical support including more maintainable computer code allowing expansion to complex fields and regional simulations. An improved weather generator was developed and will be incorporated into WEPS. WEPS has been modified for use as part of a dust warning system and two manuscripts have been submitted for publication on using WEPS to predict regional dispersion of soil particulate emissions.
Collaborative field research by an ARS scientist from Manhattan, KS and University scientists in Florida and Michigan was initiated to determine the effects of organic dominated soil properties, climate, and management on soil wind erodibility properties over time. Field sites were sampled and analysis performed for the first year of the two year study.
Collaborative research between ARS, Manhattan, KS and graduate students from Kansas State University studied the effects of crop residue removal for bioenergy on wind erosion potential. Field wind erodibility measurements were made at nine locations in Kansas. After entering the field measurements into WEPS, the potential effects on wind erosion of plant residue removal for bio-energy will be determined.
Three chapters were completed for an upcoming USDA Agricultural Handbook: WEPS Technical Documentation. In addition, six publications related to this project were submitted to peer-reviewed journals.
Reviews of methodologies available for vegetative barrier assessment showed that conventional methods like photogrammetry are low-cost but they provide a less accurate assessment of tree porosity and are limited to two-dimensional representations of vegetative barriers. Laser-based protocols for determining tree porosities are beneficial in terms of providing complex parameters (especially three-dimensional representations) that are never achievable using conventional methods but are limited by equipment cost and training. Numerical simulations of barrier effects have been initiated and will be validated using field test results for determining optimal barrier characteristics.
Wind tunnel measurements of abrasion energy. Growing plants help control wind erosion by reducing the wind speed at the soil surface and by trapping a portion of the eroding soil particles. However, few data exist on the effects of plant height and density on wind erosion. ARS researchers in Manhattan, KS used a wind tunnel study to determine the abrasion energies experienced by standing wheat plants (simulated with split plastic straws). Shorter plants (~6 inches) deflected particles upward so that more abrasion energy was experienced higher on the plants compared to taller plants (~9 inches) where there was a steady decrease in abrasion energy further up on the plants. Also, taller plants and higher plant densities reduced wind speeds at the soil surface and thus reduced the amount of soil that can be dislodged to cause abrasion. These results provide essential information for conservation planners and wind erosion researchers to design optimal conservation systems with the most appropriate plant population densities for erosion control for expected wind speeds.
Boac, J.M., Casada, M., Maghirang, R.G., Harner, III, J.P. 2012. 3-D and quasi-2-D discrete element modeling of grain commingling in a bucket elevator boot system. Transactions of the ASABE. 55(2):659-672.