1. Stream Stability and Sediment Transport Environmental Hydrology Lecture 21

2. Geomorphic work expressed in channel characteristics Winooski Falls, Photo by Jim Westphalen Channel dimensions (cross-section) Channel profile (longitudinal view) Channel pattern (plan view)

3. Channel Pattern Meandering StreamBraided Stream Plan (aerial) view of channel geometry Ward & Trimble, Fig 6.10

4. Channel Pattern Sinuosity (S) = L c / L v where L c = channel length L v = valley length

5. Helical flow induces meander formation Cut banks

6. Meander Geometry Ward & Trimble, Fig 6.11

7. How do these concepts scale? Graphic from A. Ward

8. How do these concepts scale? Ward & Trimble, Fig 6.15 “Hydraulic Geometry” of stream channels

9. Sediment Transport Upper White River, Vermont Photo courtesy K. Donna

10. Stream Load

11. Estimating Suspended Load Export Source: V. Axelsson, Uppsala Univ.,Sweden

12. Estimating Bedload Transport Mean boundary shear stress (  o )  o =  g R S Where:  = density of water g = gravitational constant R = hydraulic radius S = bed slope =  R S  = specific weight of water

13. Estimating Bedload Transport Tractive Force (T) T  =  d S Where:  = specific weight of water (kg/m 3 ) d = flow depth (m) S = water surface slope (m/m)

14. Estimating Bedload Transport Particle size at incipient motion (d*) d*  = c T Where: T = tractive force (kg/m 2 ) c = conversion factor [ f(T) ] d* = particle size (cm)

15. Estimating bedload transport T  =  d S d*  = c T

16. Channel Migration Upper White River basin, Vermont Figure courtesy K. Donna

17. 1990 1975 Date of photography Negative scale Daily mean Discharge 1 (cfs) Oct. 16, 19391:31,680178 July 19, 19561:15,840805 July 1, 19751:15,840415 Sept. 5, 19821:12,000162 May 3, 19901:15,8401220 1 Refers to mean daily discharge recorded at USGS Station #01144000 on the date that air photos were taken. From: Kathleen Donna, Assessing Channel Change on the Upper White River, Vermont University of Vermont, M.A. Thesis, Dept of Geography, 2002

18. Reach 3 Reach 4