Sedimentology Lecture #6 Class Exercise The Fenton River Exercise

Break out into 4 groups Look through these sediment transport slides to create a flow chart using different equations. You are not expected to complete the whole calculations in class. Focus on understanding the procedure. We will continue to work on this and other examples this afternoon. Submit your flow chart and answers via google doc and spread sheet with your afternoon exercise. Discussion: What information can these floodplain samples give us about past floods on the Fenton River?

Questions 1.What is the settling velocity of the coarse fraction (d95)? 2.What was the shear velocity of the transporting fluid? 3.What was the finest particle size that was transported as pure bedload? 4.What range of particle sizes were transported as incipiently suspended load? 5.Assume a drag coefficient Cd of What is your estimate of the depth-averaged velocity of the transporting flow in the river? 6.What is your estimate of boundary shear stress?

= Boundary shear stress = Shear velocity C d = hydraulic drag coefficient H = Flow Depth Boundary shear stress can be related to the mean flow velocity, by Relating  b to u

Key connections between solid and fluid phase Summary of Relationships between fluid and sediment Experimental Results: Pure Bedload:  b >  cr & w s /u * > 3 Incipient Suspension: 3 > w s /u * > 0.33 Full suspension: w s /u * ≤ 0.33

Empirical relationships: (Bagnold, 1941) For pure bedload For fully suspended load (Nino et al., 2003) (Smith, 1977) Reconstructing hydraulics from strata grain diameter (μm) Settling Velocity (m/s)

Workflo w (Smith, 1977) For modes of sediment transport associated with different grain sizes Velocity estimate for past floods Boundary shear stress estimate for past floods