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Scientific Investigations Report 2012–5003

Prepared in cooperation with the Bureau of Reclamation

Statistical Relations of Salt and Selenium Loads to Geospatial Characteristics of Corresponding Subbasins of the Colorado and Gunnison Rivers in Colorado

By Kenneth J. Leib, Joshua I. Linard, and Cory A. Williams

Thumbnail of and link to report PDF (6.85 MB)Abstract

Elevated loads of salt and selenium can impair the quality of water for both anthropogenic and natural uses. Understanding the environmental processes controlling how salt and selenium are introduced to streams is critical to managing and mitigating the effects of elevated loads. Dominant relations between salt and selenium loads and environmental characteristics can be established by using geospatial data. The U.S. Geological Survey, in cooperation with the Bureau of Reclamation, investigated statistical relations between seasonal salt or selenium loads emanating from the Upper Colorado River Basin and geospatial data. Salt and selenium loads measured during the irrigation and nonirrigation seasons were related to geospatial variables for 168 subbasins within the Gunnison and Colorado River Basins. These geospatial variables represented subbasin characteristics of the physical environment, precipitation, geology, land use, and the irrigation network. All subbasin variables with units of area had statistically significant relations with load. The few variables that were not in units of area but were statistically significant helped to identify types of geospatial data that might influence salt and selenium loading. Following a stepwise approach, combinations of these statistically significant variables were used to develop multiple linear regression models. The models can be used to help prioritize areas where salt and selenium control projects might be most effective.

First posted June 29, 2012

For additional information contact:
Center Director, Colorado Water Science Center
U.S. Geological Survey
Box 25046, Mail Stop 415
Denver, CO 80225
http://co.water.usgs.gov

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Suggested citation:

Leib, K.J., Linard, J.I., and Williams, C.A., 2012, Statistical relations of salt and selenium loads to geospatial characteristics of corresponding subbasins of the Colorado and Gunnison Rivers in Colorado: U.S. Geological Survey Scientific Investigations Report 2012–5003, 31 p.



Contents

Abstract

Introduction

Methods

Relation of Salt and Selenium Loads to Geospatial Characteristics

Summary

References Cited

Appendix A. Relation between Seasonal Salt Loads and Individual Geospatial Variables—Results of Simple Linear Regression Analysis of Seasonal Salt Loads

Appendix B. Relation between Seasonal Selenium Loads and Individual Geospatial Variables—Results of Simple Linear Regression Analysis of Seasonal Selenium Loads


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