Introduction

The Water Erosion Prediction Project (WEPP) model was developed by the USDA Agriculture Research Service (ARS) and Natural Resources Conservation Service (NRCS) along with university researchers 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 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 the WEPP user interface available through the Water Erosion Prediction Project web page then 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 and make changes that you expect will lead to reductions in rates of water erosion rates and are likely to recommend to the land owner or producer. For example, you can reduce tillage intensity, add a cover crop, use contouring, etc. 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 accomplish these tasks. Do so along with your responses to the following questions.

References