Using geographic information systems and remote sensing to map rangeland salinity source areas, Upper San Rafael River, Utah

This study used geographical information systems (GIS), remotely-sensed spectral data, electromagnetic induction (EMI) surveys, and solute analysis to identify salinity sources in upland and alluvial areas of the San Rafael Swell. Separate spectral models were developed to identify soils with natric or gypsic properties. Ground-truthing procedures revealed an overall accuracy of 80%. Apparent electroconductivity (ECa) and saturated paste conductivity (ECe) values for alluvial soils were analyzed by a weighted coefficients method. With this method, the ECa/EC e relationship produced r2 values from 0.45 to 0.94. The ECa values were interpolated to produce EC a contour maps. Interpretations of ECa maps and upland soil properties suggest salinity concentrations in alluvial areas are a function of upland soil properties, watershed size, and geology. Solute analyses of alluvial and upland soils suggest the salt composition and concentration of alluvial soils reflect the upland soils and geologies to which they are hydrologically linked.