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ARS Home » Pacific West Area » Reno, Nevada » Great Basin Rangelands Research » Research » Research Project #430841

Research Project: Risk Mapping Salt Mobilization and Transport Areas in Utah

Location: Great Basin Rangelands Research

Project Number: 2060-13610-003-07-A
Project Type: Cooperative Agreement

Start Date: Jun 1, 2016
End Date: May 31, 2019

Objective:
Research on the topic of dissolved-solids (salts) loading to streams from rangelands is needed for identifying Ecological Sites that have a high probability to transport salts to the Colorado River. This project would develop methodology to utilize NRCS - National Resources Inventory data with BLM – Assessment, Inventory, and Monitoring Strategy data to estimate the risk of soil loss and salinity loading at the scale of the hillslope for the day the sample was collected. The state of Utah would be used as a demonstration project to address data compatibility and complexity of combining these 2 different datasets. The project would develop a method to predict site vulnerability to soil loss and salt mobility and transport as a function of either ecological region or watershed depending on sample numbers in these two data sets. This project will provide BLM state-of-the-art capabilities for systematically assessing the risk of salt loading and soil erosion that can be annually updated as new data is collected. It would also provide BLM with a method to quantitatively track rangeland health and if it is improving, stable, or declining using soil erosion/salt loading as an index of sustainability as sites are resampled in future years. The technique can be replicated across BLM lands in the west providing a nationally consistent estimate of sediment and salt loading by region that is derived from BLM administrated lands.

Approach:
A new physically based model has been developed by the ARS for assessing soil loss rates on rangelands that specifically assesses the risk of soil loss at national, regional, and local scales. The Rangeland Hydrology and Erosion Model (RHEM) was developed exclusively from rangeland experiments and predicts runoff and soil loss at the scale of a hillslope and temporally at the scale of a single rainfall event. The RHEM model was designed to use simple and readily available data from NRCS National Resources Inventory (NRI) and BLM Assessment, Inventory, and Monitoring Strategy (AIMS). Model inputs are canopy and ground surface cover, slope,and soit texture that will be taken directly from NRI and AIMS data sources. Climate data will be generated with the CLIGEM model for 300 years of precipitation from the nearest weather station. Soil erosion will be estimated for 2, 10, 25, 50, and 100 year return period runoff events. Using currently available remotely sensed data (i.e., Landsat or Modis) develop technology and generate estimates of canopy cover by lifeform and ground surface cover by ecological site for state of Utah where salt loading is a concern. These estimates of cover will be cross validated with NRI and AIMES data and used to estimate runoff, soil loss, and Total Dissolved Solids with the RHEM model. Soil erosion will be estimated for each NRI and AIMS datapoint for the state of Utah where salt loading is a concern and aggragated into risk based categories of sustainability: sustainable (< 2.2 ton ha year), at risk (>2.2 to 4.5 ton ha year), and unsustainable > 4.5 ton ha year by either watershed or Omernick level IV Ecoregions depending on sample density within the 2 datasets. Develop a comphrensive training document to transfer technology to state and federal agencies for use in assessing health of rangelands as a function of soil loss.