Revisions to Suspended-Sediment Concentration, Percent Smaller Than 0.063 Millimeter, and Instantaneous Suspended-Sediment Discharge Reported for a Cooperative Program Between the U.S. Geological Survey and the U.S. Army Corps of Engineers in the Lower Mississippi-Atchafalaya River Basin, October 1989 to February 2015

Scientific Investigations Report 2018-5147
Prepared in cooperation with the U.S. Army Corps of Engineers, New Orleans District
By: , and 

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Abstract

This report presents revised results for four parameters reported for suspended-sediment samples that were collected in the lower Mississippi-Atchafalaya River Basin as part of a cooperative program between the U.S. Army Corps of Engineers, Mississippi Valley Division, New Orleans District and the U.S. Geological Survey (USGS). The cooperative program has been active since 1973 at seven sites: two sites on the main stem of the Mississippi River, three sites on the Atchafalaya River, one site on the Old River Outflow Channel, and one site on the lower Red River above the confluence with the Old River Outflow Channel. The four parameters—suspended-sediment concentration, percent by mass of the sediment that passes through a 0.063-millimeter (US 230) sieve, instantaneous stream discharge, and instantaneous suspended-sediment discharge—reported for 2,895 samples have been modified to reflect the findings of a full review of the cooperative program, which was initiated by both agencies in January 2015. The revised results are for samples collected from October 1989 through February 2015. Ninety-four percent of the revised values for suspended-sediment concentration are lower than their corresponding original reported values, indicating that less suspended sediment moves through the lower Mississippi River system than was previously reported. For example, the median revised instantaneous suspended-sediment discharge at the Mississippi River at Tarbert Landing, Miss. (USGS station 07295100), was 315,000 short tons per day, compared to 378,000 short tons per day as originally reported. At the Atchafalaya River at Simmesport, La. (USGS station 07381490), the median revised suspended-sediment discharge was 105,000 short tons per day, compared to 143,000 short tons per day as originally reported. The systematic downward revision in instantaneous suspended-sediment discharge values was due to a systematic downward revision in the suspended fine (less than 0.063 millimeter) sediment concentration. The effect of the revision on the suspended-sand concentration and instantaneous suspended-sand discharge was weaker. Any model of sediment load or transport processes in the basin that uses data from the affected samples should be reevaluated on the basis of the revised results.

Suggested Citation

Norton, K.K., Olsen, L.D., Baumann, T.E., Simmons, L.B., Clark, A.P., Demcheck, D.K., and Johnson, M., 2019, Revisions to suspended-sediment concentration, percent smaller than 0.063 millimeter, and instantaneous suspended-sediment discharge reported for a cooperative program between the U.S. Geological Survey and the U.S. Army Corps of Engineers in the lower Mississippi-Atchafalaya River Basin, October 1989 to February 2015: U.S. Geological Survey Scientific Investigations Report 2018–5147, 232 p., https://doi.org/10.3133/sir20185147.

ISSN: 2328-0328 (online)

ISSN: 2328-031X (print)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Description of the Cooperative Program
  • Critical Review of Field, Laboratory, and Computational Protocols
  • Methods Used To Revise Results
  • Corrected SSC and Related Results
  • Critical Evaluation of Revised Results
  • Conclusions
  • References Cited
  • Appendix 1. U.S. Army Corps of Engineers (USACE) FORTRAN source code for modules used to process laboratory results and compute suspended-sediment load for a cooperative program between the U.S. Geological Survey and the USACE in the lower Mississippi-Atchafalaya River Basin from 1973 to February 2015
  • Appendix 2. Example laboratory data sheet used for recording laboratory results for a cooperative program between the U.S. Geological Survey and the U.S. Army Corps of Engineers in the lower Mississippi-Atchafalaya River Basin from 1973 to 2001, which also served as the basis for the Excel spreadsheet that was used from 2001 to February 2015
  • Appendix 3. Example 80-column text file (SED file) used as input to the U.S. Army Corps of Engineers (USACE) FORTRAN modules that computed suspended-sediment concentration, particle-size distribution, and suspended-sediment discharge for a cooperative program between the U.S. Geological Survey and the USACE in the lower Mississippi-Atchafalaya River Basin from 1973 to February 2015
  • Appendix 4. Corrected and original results for instantaneous stream discharge, suspended-sediment concentration, suspended-sediment percent smaller than 0.0625 millimeter, and suspended-sediment discharge for water samples collected from select sites in the lower Mississippi-Atchafalaya River Basin

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Revisions to suspended-sediment concentration, percent smaller than 0.063 millimeter, and instantaneous suspended-sediment discharge reported for a cooperative program between the U.S. Geological Survey and the U.S. Army Corps of Engineers in the lower Mississippi-Atchafalaya River Basin, October 1989 to February 2015
Series title Scientific Investigations Report
Series number 2018-5147
DOI 10.3133/sir20185147
Year Published 2019
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Lower Mississippi-Gulf Water Science Center
Description Report: x, 232 p.; Data Release
Country United States
Other Geospatial Lower Mississippi basin
Online Only (Y/N) N