Determining the Sources of Fine-Grained Sediment Using the Sediment Source Assessment Tool (Sed_SAT)

Open-File Report 2017-1062

Prepared in cooperation with the U.S. Environmental Protection Agency
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A sound understanding of sources contributing to instream sediment flux in a watershed is important when developing total maximum daily load (TMDL) management strategies designed to reduce suspended sediment in streams. Sediment fingerprinting and sediment budget approaches are two techniques that, when used jointly, can qualify and quantify the major sources of sediment in a given watershed. The sediment fingerprinting approach uses trace element concentrations from samples in known potential source areas to determine a clear signature of each potential source. A mixing model is then used to determine the relative source contribution to the target suspended sediment samples.

The computational steps required to apportion sediment for each target sample are quite involved and time intensive, a problem the Sediment Source Assessment Tool (Sed_SAT) addresses. Sed_SAT is a user-friendly statistical model that guides the user through the necessary steps in order to quantify the relative contributions of sediment sources in a given watershed. The model is written using the statistical software R (R Core Team, 2016b) and utilizes Microsoft Access® as a user interface but requires no prior knowledge of R or Microsoft Access® to successfully run the model successfully. Sed_SAT identifies outliers, corrects for differences in size and organic content in the source samples relative to the target samples, evaluates the conservative behavior of tracers used in fingerprinting by applying a “Bracket Test,” identifies tracers with the highest discriminatory power, and provides robust error analysis through a Monte Carlo simulation following the mixing model. Quantifying sediment source contributions using the sediment fingerprinting approach provides local, State, and Federal land management agencies with important information needed to implement effective strategies to reduce sediment. Sed_SAT is designed to assist these agencies in applying the sediment fingerprinting approach to quantify sediment sources in the sediment TMDL framework.

Suggested Citation

Gorman Sanisaca, L.E., Gellis, A.C., and Lorenz, D.L., 2017, Determining the sources of fine-grained sediment using the Sediment Source Assessment Tool (Sed_SAT): U.S. Geological Survey Open File Report 2017–1062, 104 p.,

ISSN: 2331-1258 (online)

Table of Contents

  • Acknowledgments 
  • Abstract 
  • Introduction
  • Navigating the Instruction Manual 
  • Downloading Sed_SAT
  • Getting Started
  • Preparing Data for Sed_SAT 
  • Navigating Sed_SAT 
  • Set PATHs 
  • R Packages
  • Import Data 
  • Imputation of Nondetects in Source Data
  • Target Dataset Data Test
  • Negatives and True Zeros 
  • Start Step 1: Test for Univariate Normal Distributions 
  • Start Step 2: Outlier Test 
  • Start Step 3: First Linear Regression 
  • Start Step 4: Second Linear Regression for Organic Content 
  • Start Step 5: Bracket Test
  • Start Step 6: Multivariate Normality Test 
  • Start Step 7: Forward Stepwise Linear Discriminant Function Analysis 
  • Start Step 8: Mixing Model and Error Analysis 
  • Export Data/Tables/Plots 
  • References
  • Appendix 1. Sed_SAT File Structure 
  • Appendix 2. Example Datasets
  • Appendix 3. Size and Organic Content Data
  • Appendix 4. SetPATHs Screen
  • Appendix 5. Information on R-Packages Used in Sed_SAT
  • Appendix 6. Stable Isotope Selection Screen 
  • Appendix 7. Import Data Screens
  • Appendix 8. Problems Found in the Data Testing Module
  • Appendix 9. Preparing for Imputation and Imputation Group Selection Screen
  • Appendix 10. Reporting Limits Import Screens
  • Appendix 11. Choosing Imputation Parameters Screen
  • Appendix 12. Imputation Results
  • Appendix 13. Defining Functions to Shift True Negatives and/or True Zeros Into Positive Space
  • Appendix 14. Step 1 Outputs
  • Appendix 15. Step 2 Output 
  • Appendix 16. Selecting Target Samples to Analyze
  • Appendix 17. Step 3 Output 
  • Appendix 18. Step 4 Output 
  • Appendix 19. Step 5 Output 
  • Appendix 20. Step 6 Output 
  • Appendix 21. Step 7 Output 
  • Appendix 22. Step 8 Output 
  • Appendix 23. Export Screens

Additional publication details

Publication type:
Publication Subtype:
USGS Numbered Series
Determining the Sources of Fine-Grained Sediment Using the Sediment Source Assessment Tool (Sed_SAT)
Series title:
Open-File Report
Series number:
Year Published:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Maryland Water Science Center
Report: viii, 104 p.; Application Site
Online Only (Y/N):
Additional Online Files (Y/N):