4.2: Water Erosion Prediction Project (WEPP)
- Page ID
- 28890
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Water Erosion Prediction Project (WEPP)
Learning Objectives
By the end of the laboratory exercise, you will have:
- Become familiar with the use and application of the WEPP model
- Run simulations in WEPP and showed proficiency in changing settings, changing a management template, saving and opening files, etc.
- Used the WEPP model to estimate the effects of implementing conservation practices on soil erosion
Acknowledgement and Recommended Reading
The Water Erosion Prediction Project (WEPP) was developed by researchers and staff members of the USDA-ARS, USDA-NRCS, and cooperating Land-Grant universities. The most recent iteration of the model is designed to be used as a web application and can be accessed on the USDA-NRCS WEPP web page (USDA-NRCS 2023). The current draft of the WEPP Web-Based NRCS User Guide (USDA-NRCS 2020) is available under the help menu of the WEPP web interface.
Materials
Materials required to complete this laboratory activity include the following:
- Soil cover and slope data from Soil Health Assessment Part I: Soil Cover, Slope, and Residue Breakdown
- Information about the crop rotation for your study site
- A computer with internet access
Introduction
The USDA Agriculture Research Service (ARS), Natural Resources Conservation Service (NRCS), and university researchers developed the Water Erosion Prediction Project (WEPP) model to predict soil erosion on individual slopes and small watersheds. The newest iteration of WEPP has or will replace RUSLE2 for soil erosion modeling. To gain a further understanding of how the model operates, read the draft of the Water Erosion Prediction Project (WEPP) Web-Based NRCS User Guide available through a link at the top of the help menu within the WEPP web interface.
Estimate Erosion Rates Under Existing Management Practices
For the assignment for this lab exercise, you will conduct a series of simulations for your study site. Follow the directions below, and refer to the user guide if you have any questions about how to perform one of the steps.
Access to the WEPP user interface available through the Water Erosion Prediction Project web page; complete the following steps for your study site.
Select the county where your study site is located, then use the WEPP Map feature to select the appropriate field. Select the map unit and map unit component for the simulation from within that field. Describe the slope steepness, length of slope, aspect, and shape. Then select the management template that most closely matches the practices used by the landowner or producer.
In the management screen, edit the operations, dates of operations, target yields, added residue, and any spray operations as needed. Save the management file (.man file) to your local directory (your computer’s hard drive or a USB flash drive). Now you are ready to run the simulation. Run the simulation and save it to History as the Benchmark Run. View and save the PDF Summary of the Run to your local directory.
Estimate Erosion Rates Under Alternative Management Practices
Now you are ready to conduct some simulations based on changes to land management. Reopen the management screen and make changes that should lead to reduced water erosion rates; these changes should be the ones you would likely recommend to the land owner or producer. For example, you could reduce tillage intensity, add a cover crop, or use contouring among other options. Save this modified Management file to your local directory (.man file). Run this simulation and save it to the History as Alternative 1. Save the Project Run (done on the Projects Screen) to your local directory.
Next you will repeat this process to simulate a second alternative (Alternative 2). Save the Project Run to your local directory as before.
You will submit your benchmark and alternative project files (.prg files) as evidence that you can do these tasks. Add your responses to the following questions.
Questions
- What were the average erosion rates for the Benchmark run and Alternative 1? Did the resulting change in erosion rate for Alternative 1 meet your expectations? Explain.
- Describe what you changed in your management from the Benchmark run to the Alternative 1 run.
- What were the average erosion rates for the Benchmark run and Alternative 2? Did the resulting change in erosion rate for Alternative 2 meet your expectations? Explain.
- Describe what you changed in your management from the Benchmark run to the Alternative 2 run.
- Considering your responses to Questions 1-4, what would you test next to further reduce the erosion rate? Explain your reasoning.
- Compare and contrast WEPP and the USLE. Specifically, what are the advantages of each model? What are some of the disadvantages of each model?
- What types of erosion are modeled using WEPP? (Hint: refer to the resources cited in the introduction)
References
USDA-NRCS. 2023. Water Erosion Prediction Project. https://www.nrcs.usda.gov/resources/tech-tools/water-erosion-prediction-project.