Water: WARSSS
Calculate Sediment Yield for Baseline Existing Condition: Flow Related Sediment Yield
Prediction Level
Assessment
Steps
Hydrologic Relations1. USGS Regional Curves
2. Drainage Arearat
3. Field Calibration
4. Final Determination
Stream Morphology
5. Stream Classification
6. Dimensionless Ratios
Stability Analysis
7. Channel Stability
8. Bank Erosion Prediction
9. Bank Erosion Rates
Flow/Sediment Relations
Sediment Rating Curves
10. Flow Modifications
11. Dimensionless Flow
12. Bankfull Q & Sediment
13. Dimensionless SRCs
14. Bedload Rating
15. Flow Duration Curves
16. Flow-Related Yield
17. Flow-Related Increases
Supply Changes
18. Channel Changes
19. Bedload Transport
20. Hillslope Processes
21. Hillslope Sediment
22. Entrainment Calculation
Stability Consequences
23. Sed. Transport Changes
24. Aggradation Potential
25. Degradation
26. Enlargement
Summary Analysis
27. State Shift
28. Total Sediment
29. Departure Analysis
30. ID Loads by Category
This is accomplished by taking the converted dimensionless ratio flow-duration curve and multiplying increments/duration of time in days by the sediment yield associated with that flow. The computations for total annual suspended and bedload sediment yield are shown in Worksheet 24 (xls). Procedural steps for computations of the FLOWSED model are presented in Table 19.
FLOWSED is a model developed for the WARSSS objectives. It predicts annual suspended sediment and bedload sediment yield in tons/year. It utilizes both dimensionless suspended and bedload sediment rating curves by stream type/stability and regionalized dimensionless flow-duration curves. The suspended sediment dimensionless sediment rating curve used for FLOWSED is shown in Figure 56. The dimensionless bedload rating curve is shown in Figure 57 for "good" and "fair" stability stream types. An expanded data set involving measured suspended and bedload sediment rating curves were used to test significance between "poor" stability stream types from "good" and "fair" (Troendle, et al, 2001). Validation tests using one data point for bankfull discharge, bankfull suspended sediment and bankfull bedload sediment were used to predict sediment rating curves on independent data sets of the U.S.Geological Survey data in Wyoming, Idaho, Nevada, and Colorado. The resultant relationships depicting predicted versus observed values are shown in in Figure 58 (PDF, 75 kb, 1 p.), Figure 59 (PDF, 54 kb, 1 p.), Figure 60 (PDF, 59 kb, 1 p.) and Figure 61 (PDF, 50 kb, 1 p.). These predictions were made using the Pagosa Springs, Colorado data set in Figure 56 and Figure 57. The prediction of total annual sediment yield is accomplished by measuring the bankfull values of discharge (CFS), suspended sediment (mg/l) and bedload sediment (kg/s), then converting the dimensionless relation to dimensioned values in order to obtain the rating curves. |