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Scientific Investigations Report 2014–5048

Prepared in cooperation with the San Antonio River Authority and the Texas Water Development Board

Sediment Characteristics in the San Antonio River Basin Downstream From San Antonio, Texas, and at a Site on the Guadalupe River Downstream from the San Antonio River Basin, 1966–2013

By Cassi L. Crow, J. Ryan Banta, and Stephen P. Opsahl

Thumbnail of and link to report PDF (1.54 MB)Abstract

San Antonio and surrounding municipalities in Bexar County, Texas, are in a rapidly urbanizing region in the San Antonio River Basin. The U.S. Geological Survey, in cooperation with the San Antonio River Authority and the Texas Water Development Board, compiled historical sediment data collected between 1996 and 2004 and collected suspended-sediment and bedload samples over a range of hydrologic conditions in the San Antonio River Basin downstream from San Antonio, Tex., and at a site on the Guadalupe River downstream from the San Antonio River Basin during 2011–13. In the suspended-sediment samples collected during 2011–13, an average of about 94 percent of the particles was less than 0.0625 millimeter (silt and clay sized particles); the 50 samples for which a complete sediment-size analysis was performed indicated that an average of about 69 percent of the particles was less than 0.002 millimeter. In the bedload samples collected during 2011–13, an average of 51 percent of sediment particles was sand-sized particles in the 0.25–0.5 millimeter-size range. In general, the loads calculated from the samples indicated that bedload typically composed less than 1 percent of the total sediment load. A least-squares log-linear regression was developed between suspended-sediment concentration and instantaneous streamflow and was used to estimate daily mean suspended-sediment loads based on daily mean streamflow. The daily mean suspended-sediment loads computed for each of the sites indicated that during 2011–12, the majority of the suspended-sediment loads originated upstream from the streamflow-gaging station on the San Antonio River near Elmendorf, Tex. A linear regression relation was developed between turbidity and suspended-sediment concentration data collected at the San Antonio River near Elmendorf site because the high-resolution data can facilitate understanding of the complex suspended-sediment dynamics over time and throughout the river basin.

First posted April 22, 2014

For additional information, contact:
Director, Texas Water Science Center
U.S. Geological Survey
1505 Ferguson Lane
Austin, Texas 78754–4501
http://tx.usgs.gov/

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Suggested citation:

Crow, C.L., Banta, J.R., and Opsahl, S.P., 2014, Sediment characteristics in the San Antonio River Basin downstream from San Antonio, Texas, and at a site on the Guadalupe River downstream from the San Antonio River Basin, 1966–2013: U.S. Geological Survey Scientific Investigations Report 2014–5048, 33 p., http://dx.doi.org/10.3133/sir20145048.

ISSN 2328-031X (print)
ISSN 2328-0328 (online)



Contents

Abstract

Introduction

Methods

Sediment Characteristics

Sediment Loads

Summary

References Cited

Appendix 1. Streamflow, suspended-sediment concentrations, and instantaneous suspended-sediment loads at the sample collection sites in the San Antonio River Basin downstream from San Antonio, Texas, and at a site on the Guadalupe River downstream from the San Antonio River Basin, including data prior to 2011.

Appendix 2. Daily mean streamflow and estimated suspended-sediment loads at sample collection sites in San Antonio River Basin downstream from San Antonio, Texas, and at a site on the Guadalupe River downstream from the San Antonio River Basin, 2011–12.

Appendix 3. Daily mean turbidity at U.S. Geological Survey station 08181800 San Antonio River near Elmendorf, Texas (SAR Elmendorf), 2010–13.


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