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ARS Home » Pacific West Area » Reno, Nevada » Great Basin Rangelands Research » Research » Publications at this Location » Publication #322969
Title: USDA internet tool to estimate runoff and soil loss on rangelands: rangelands hydrology and erosion model

Author
item Weltz, Mark
item NOUWAKPO, SAYJRO - University Of Nevada
item HERNANDEZ, MARIANO - University Of Arizona
item Nearing, Mark
item Stone, Jeffry
item Armendariz, Gerardo
item Pierson Jr, Frederick
item AL-HAMDAN, OSAMA - Texas A&M University
item Williams, Christopher - Jason
item SPAETH, KENNETH - Natural Resources Conservation Service (NRCS, USDA)
item WEI, HAIYAN - University Of Arizona
item Heilman, Philip - Phil
item Goodrich, David - Dave

Submitted to: The Progressive Rancher
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2015
Publication Date: 12/1/2015
Citation: Weltz, M.A., Nouwakpo, S.K., Hernandez, M., Nearing, M.A., Stone, J.J., Armendariz, G.A., Pierson, F.B., Al-Hamdan, O., Williams, C.J., Spaeth, K.F., Wei, H., Heilman, P., Goodrich, D.C. 2015. USDA internet tool to estimate runoff and soil loss on rangelands: rangelands hydrology and erosion model. The Progressive Rancher. 8:24-25.

Interpretive Summary: Rangelands are the most dominant land cover type in the United States (770 million acres) with approximately 53% of the nation’s rangelands owned and managed by the private sector, while approximately 43% are man¬aged by the federal government. Information on the type, extent, and spatial location of land degradation on rangelands is unknown as there is no systematic or coordinated national data-set on status or condition of rangelands for the United States. Therefore, developing tools for assessment of status and conditions of rangelands that address environmental process, such as soil erosion, is necessary for rangeland resource management. The challenge for rangeland soil erosion modeling is to aid land managers in defining thresholds of accelerated soil loss and assessing the risk of crossing those thresholds to avert land degradation. This requires the ability to identify an ecosystem’s vulnerability to extreme runoff events before changes in resources occur. The new physically based Rangeland Hydrology and Erosion Model (RHEM) has been developed by the USDA for assessing soil loss rates on rangelands that specifically assesses the risk of soil loss at hillslope scales. RHEM’s ability to predict runoff and soil erosion on saline soils was evaluated on 2 ecological sites in central Utah, U.S. To evaluate hydrologic response we used a rainfall simulator with rainfall rates applied as a 2yr, 10yr, 25yr, or 50yr rainfall return rate on dry soil. At each site 3 replications of the rainfall intensities were applied for a total of 12 plots. The RHEM model did an excellent job in predicting runoff at the 2 sites. RHEM predicted sediment yield reasonably well with no significant bias in the predicted sediment yield. A land management practice that alters vegetation has a direct impact on runoff and soil erosion. In general as vegetation increase soil erosion decreases. RHEM can be used to compare alternative states of vegetation and if conservation is warranted to reduce soil erosion on rangelands. RHEM provides a valuable tool for adaptive management and allows managers a means to quantify if rangeland restoration practices will reduce soil erosion rates and where on the landscape they should be placed for maximum effectiveness.

Technical Abstract: Rangelands are the most dominant land cover type in the United States (770 million acres) with approximately 53% of the nation’s rangelands owned and managed by the private sector, while approximately 43% are managed by the federal government. Information on the type, extent, and spatial location of land degradation on rangelands is unknown as there is no systematic or coordinated national data- set on status or condition of rangelands for the United States. Therefore, developing tools for assessment of status and conditions of rangelands that address environmental process, such as soil erosion, is critical for rangeland resource management. The challenge for rangeland soil erosion modeling is to aid land managers in defining thresholds of accelerated soil loss and assessing the risk of crossing those thresholds to avert land degradation. This requires the ability to identify an ecosystem’s vulnerability to extreme runoff events before changes in resources occur. The new physically based Rangeland Hydrology and Erosion Model (RHEM) has been developed by the USDA for assessing soil loss rates on rangelands that specifically assesses the risk of soil loss at local scales. RHEM’s ability to predict runoff and soil erosion on saline soils was evaluated on 2 ecological sites in central Utah, U.S. To evaluate hydrologic response we used a rainfall simulator. A single rainfall was applied to each plot as either a 2yr, 10yr, 25yr, or 50yr rainfall return rate on dry soil. At each site 3 replications of the rainfall intensities were applied for a total of 12 plots. The RHEM model did an excellent job in predicting runoff at the 2 sites (R2 0.90). RHEM predicted sediment yield reasonably well with no significant bias in the predicted sediment yield. Vegetation is the primary factor controllable by anthropogenic activity that influences surface runoff and soil erosion on rangelands. RHEM can be used to compare alternative states of vegetation and if conservation is warranted to reduce soil erosion on rangelands. RHEM provides a valuable tool for adaptive management and allows managers a means to quantify if rangeland restoration practices will reduce soil erosion rates and where on the landscape they should be placed for maximum effectiveness.