Soil Erosion on the American River

1. Soil Erosion on the American River Brittany Tucker

2. American River http://www.frankbobbio.com/photogallery/Aerial/Folsom%20Lake%20&%20Lake%20Natoma/folsom_lake__lake_natoma_aerial.htm

3. Purpose • Erosion studies • provide scour depths • Scour depths determine the level a foundation must be dug to • Strong foundation is required to prevent major structural issues • Cracks • Breaks • Collapses

4. Data • Testing is performed at Texas A&M University • Erosion Function Apparatus (EFA) is used to determine erodibility level • Soil sample is placed in viewing window of water tunnel • Water is run over sample at set velocity • Amount of erosion is measured after pre-determined interval

5. Erodibility • Five levels of erosion • Level I: Very High Erodibility • Level II: High Erodibility • Level III: Medium Erodibility • Level IV: Low Erodibility • Level V: Very Low Erodibility • Level VI: Non-Erosive

6. Erodibility Graph

7. Analysis Method • 11 American River Samples Analyzed • Statistical data generated for 2 samples • Used all data as sample of American River Soil • Used data from each sample at 1 m/s flow rate

8. Total Sample The data generated in the table and the graph do not show any particular pattern.

9. Total Sample From the histogram it is difficult to determine whether the data is skewed or not because it is concentrated to the same area.

10. Fixed Flow Sample • Overall data was not statistically helpful • the data for a 1 m/s flow rate was analyzed • One data point was taken from each report • The point closest to 1 m/s flow rate

11. Fixed Flow Sample This data provides better grouping for such a broad analysis spectrum.

12. Fixed Flow Sample The fixed velocity case shows a normal distribution with the bulk of the samples being classified as medium erodibility.

13. Fixed Flow Sample To determine what the population mean erosion rate and standard deviation would be for a given flow velocity (1 m/s) would be, the equations below were used. With a confidence interval of 90% (α = .05), sample standard deviation (s) equal to 371.42 and sample size of 11. Assuming a normal distribution and using the t-distribution table the value of is equal to 1.812 The fact that Δμ is so close to μ is further proof that there needs to be further testing increase the number of data points for each test and that the data needs to be broken down in to more precise categories than the current erodibility levels

14. Conclusion • Majority of samples were of high or medium erodibility • Any structure built will require a deep scour level • Sample wills require additional points on a more precise scale • Fixed flow is a better sample for statistical analysis with a much lower variance • maintaining a similar conclusion to the large sample data

15. Back-Up

16. 2F-11-130 Block 1

17. Very High Erodibility I High Erodibility II Medium Erodibility III Low Erodibility IV Very Low Erodibility V Non-Erosive VI 2F-11-142U

18. 2F-11-155

19. Very High Erodibility I 2F-11-174U T3

20. High Erodibility II Medium Erodibility III Low Erodibility IV Very Low Erodibility V Non-Erosive VI 2F-11-175U Very High Erodibility I

21. Very High Erodibility I High Erodibility II  Medium Erodibility III Low Erodibility IV 2F-11-177U T4

22. 2F-11-179U T2 Medium Erodibility III Low Erodibility IV  Very Low Erodibility IV Non_Erosive VI

23. 2F-11-187

24. 2F-11-188

25. 2F-11-191

26. 2F-11-192