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Now: Fri, Jan 28 2022 Current Version: RHEM v2.4


RHEM engine version used in this interface: rhem_v2.3.exe

RHEM Model Technical Documentation

RHEM Parameter Estimation Equations

RHEM Parameter File Descriptions

RHEM Executable

Download the latest version of the RHEM executable:

In order to run the RHEM executable, the following files are needed:
  • .RUN - description of the files needed to perform the run
  • .PAR - the input parameter file
  • .PRE - the storm file create for the selected climate station

Source Code

RHEM-related Github repositories

NAL Ag Data Commons

RHEM Web Tool dataset entry on Ag Data Commons:

Related Publications

International Climate Stations

We have been working on expanding the coverage of the RHEM Web Tool (interface).  You now have the ability to use international climate stations.  In the “Climate Station” panel, you will see a tab for “International” stations. At the moment, we are providing 4 climate stations from Jordan.   Our intent is to include more stations from around the world.  If you are interested in contributing additional stations to the RHEM interface, please let us know. 

The workflow to add new stations would be as follows:

  1. You send us a PAR file (description on the format of the CLIGEN .PAR file can be found here: https://www.ars.usda.gov/midwest-area/west-lafayette-in/national-soil-erosion-research/docs/wepp/cligen
  2. We run CLIGEN with your PAR file
  3. The new CLIGEN output is added to our RHEM interface as a new climate station
If you are unable to create a PAR file but you have rainfall records, or if you need assistance, don’t hesitate to contacts us for assistance

Related Projects

RHEM Batch Script

This script is able to run RHEM in batch mode based on the RHEM Model-as-a-Service (MaaS) using the Cloud Services Innovation Platform (CSIP). More inormation about MaaS and CSIP can be read in this publication. This functionality enables you to run RHEM with multiple scenarios in batch format using a Python script. In order for you to run RHEM in batch mode, you are required to have:

  1. An internet-enabled computer
  2. Python 3
  3. pip or conda (Python package installers)
  4. Spredsheet editing software (Excel, OpenOffice, Google Sheets, etc.)

The workflow to run the script:

  1. Download the script, the template spreadsheet, and the requirements.txt file (this is used to install required Python packages) from this location: https://github.com/ARS-SWRC/rhem_batch_csip
  2. Install the Python dependencies (from the requirements.txt file)
  3. Populate the Excel spreadsheet with the scenarios you would like to run
  4. Run the Python script
  5. After the Python script finishes running, the results will be saved to the same spreadsheet and the parameter files and summary outputs from RHEM will be saved in an output folder

RHEM Web Tool Versions Documentation

Version: 2.4

  • Climate Station panel:Added a new "International All" tab which includes a list of international stations.  This option runs the RHEM engine using the CSIP web service. This publications describes the creation of input parameters used to run CLIGEN to create the list of international stations: https://doi.org/10.5194/essd-13-435-2021
  • Climate Station panel:Added a new "CLIGrid " tab to run the RHEM engine using the coupled RHEM and CLIGEN with PRISM CSIP web services.
  • Scenario Comparison report:
    • Both Annual Average Graphs and Return Frequency Graphs now include the numeric scales in the y-axis.
    • A new "Change chart colors" link is available above the Scenario Inputs table.  This will change the colors of the graphs and the table headers with the scenario names. 
  • Risk Assessment report:
    • The probability values on the "Probability of Occurrence (yearly soil losses)" graphic appeared distorted when the probability of occurrence ranges were very low.  The annotations in the graphic have been changed to show all probability of occurrence labels in their own vertical space. 
    • The x-axis scenario labels now include both the scenario names and the scenario indices (e.g. Scenario 1, Scenario 2, etc)
  • Ke Equations Update: The equations for estimating the effective hydraulic conductivity (Ke) for Sand, Loamy Sand, Silty Clay, and Clay were updated to agree with the saturated hydraulic conductivity (Ks) 25% percentile values reported by Rawls et al. (1998). For Silty Clay Loam, we used the saturated hydraulic conductivity value reported by Stone et al. (1992). To test the model, we used ground cover and foliar canopy cover from NRI and BLM rangeland on-site data collected in 17 western states and soil texture information from SoilGrids and gSSURGO. The output showed a reduction of runoff and soil loss, which is a good empirical fit to observed behavior.
  • RHEM Batch Script:A Python script with a corresponding Excel spreadsheet (to define inputs) is available in the case the user would like to run RHEM scenarios in batch format.  The script and workbook have been updated to pull return frequency results from each RHEM run. 

Version: 2.3 Update 5

  • Added a new checkbox and SAR input box to the Soil Texture panel for saline scanarios.
  • When a scenario is ran with this SAR value, a new row will appear in the Annual Averages table showing the "Salt Load".
  • RHEM v2.3 Update 5 now includes a new capacity for saline soils.

    The RHEM Web Tool has been updated with the capacity to account for the effect of saline soils on erosion and to provide estimates of salt loads associated with runoff and erosion events.

    The web interface now has an option under the Soil Texture Class tab. When checked, the user will be prompted to input the SAR (sodium adsorption ratio) value of the soil. If the box is not checked the model works as previously.

    Saline soils have greater erodibility and produce more erosion.  The equations used here to adjust the soil erodibility are based on the work of Nouwakpo et al., 2018. In addition, if the salinity option is active, the model will predict salt loads from the hillslope, also based on equations of Nouwakpo et al., 2018 on work done in the upper Colorado basin in Utah and Colorado. The salt load prediction is reported in the Annual Averages output table.

    Nouwakpo, S. K., Weltz, M. A., Arslan, A., Green, C. H., & Al-Hamdan, O. Z. (2018). Process-Based Modeling of Infiltration, Soil Loss, and Dissolved Solids on Saline and Sodic Soils. Transactions of the American Society of Agricultural and Biological Engineers ISSN 2151-0032 https://doi.org/10.13031/trans.12705

Version: 2.3 Update 4

  • Ability to export report graphics as SVG - this feature will enable users to export each of the report graphics in vector format (SVG). These files can later be transformed to other formats such as EPS or PDF using tools such as Adobe Illustrator or Inkscape. The report graphics will also be available for download as PNG images.
  • Added a "Yearly Totals" table to the return period table when running single scenarios - In addition to viewing the yearly maximum daily values for return frequency results, the user will now see yearly totals. Note that scenarios will have to be rerun in order for users to see this new section in their scenario results.
  • Added ability to define the order of the scenarios when running a scenario comparison. - This functionality is useful when the user needs to define a specific order of appearance for the scenario comparison report. This functionality is based on the selection order (click order) of the scenarios. An orange label (number) will appear next to each scenario selected.
  • Metric units in the output reports have been changed from tonne/ha to Mg/ha (4-3-2019)

Version: 2.3 Update 3

  • International climate stations are now supported. Users can submit CLIGEN .PAR files (with station statistics) to create a new climate station.
  • Slope length is defaulted to 50m (164ft). The slope length input box in the "Slope" panel has been removed.

Version: 2.3 Update 2

  • Slope length is now default to 50m (164ft).
  • The input parameter modification tool now allows the user to modify the LEN parameter (slope length).
  • Application has been scaled up allowing scenarios to run about 40% faster.

Version: 2.3 Update 1

  • This update provides a risk assessment (probability-based) approach to natural rangeland conditions erosion modeling, and provides the frequency of occurrence for each alternative scenario based on annual soil loss return levels.

Version: 2.3

  • New set of parameter estimation equations were developed to estimate the splash and sheet erodibility coefficient on natural rangeland conditions
  • Improvement to the rainfall disaggregation algorithm
  • In general, you may find that RHEM version 2.3 produces greater soil loss predictions than the previous version

Version: 2.2

  • New set of parameter estimation equations were developed for the Smith-Parlange infiltration equation
  • Minor adjustment done to the splash and sheet erodibility parameter estimation equation (11) and (12) described in Nearing et al. 2011 to account for an improved calibration factor and for better representing slope steepness
  • Erodibility coefficient Kω has been slightly increased to better represent concentrated flow erosion in undisturbed rangelands
  • Model version used to run scenarios can be seen in the scenarios listing

Version: 2.1

  • Multiply Kss for all cases by 1.3 in order to account for the bias in the log transformation (relative to Duan 1989)
  • Ability to rename scenarios through the scenarios list by clicking on scenario name
  • A graphical (PNG) report can be created from a scenario comparison
  • User account section added to control detailed output reports and manual input file modifications

Version: 2.0

  • A prototype next-generation version (version 2) of the Rangeland Decision Support System (RHEM) is under development.

Version: 1.2

  • Updated Kc and Tc.

Version: 1.1

  • Updated model equations.

Version: 1.0