Key Concepts in Geomorphology – ideas for revision
Chapter 6 – Channels
Please add your comments about how to improve Chapter 6 here.
8 thoughts on “Chapter 6 – Channels”
Page 197- Washload
Washload is considered as the particles smaller than 63 micro meters. It might be useful to mention the size of the washload particles beside the size of cobble, gravel, and sand for comparison.
Page 195- equation 6.7
This equation is the definition of non-dimensional shear stress (τ*) which is valid for any sediment grain size including gravel and sand. However in the context, it has been referred to for just gravel. Is there any reason for that constriction?
Page 194- Initial of transport
Equation 6.6
Again this relation is valid just for normal condition.
Also I would suggest to present the other famous term for initial of motion as “incipient motion’ because it is being widely used in technical papers and books. In that case, the reader would be familiar with both technical terms associated with the start of the motion
Page 187; discharge variability
The bankfull discharge is one of the most important indices in geomorphology. Although it has been described in this section, the measurement or estimation is not defined. Therefore, it might be a good idea to present a simple analytical approach to estimate bankfull discharge as
Plotting stage vs discharge and where there is an abrupt change in curve slope indicates the bankfull discharge
Page 182- Figure 6-1; Shear stress
The definition of the shear stress presented here as τ= ρ.g.d.s = γ.d.s is for ‘normal condition’ where the water surface profile is parallel to river bed, otherwise this formula is not applicable. It might be a good idea to highlight this assumption embedded in this formula.
In figure 6.4 and photo 6.11 (pgs 192-193) cutbank and point bar are both illustrated but the two illustrations don’t point to the same locations. While they both do point to cutbanks and point bars would aid in understanding if in the photo both of the features are illustrated on the same bend of the river as they are in the figure.
There is a typo on page 187. the sentence on calculating the Froude Number is a run on and should be split up. A photo of a graded stream would be helpful, especially one that can place a graded steam into the real world. An end of chapter question addition could be on defining a wetted width and also on the mechanisms that form potholes. I don’t understand the point of “at-a-station hydraulic geometry” and the associated photo (Figure 6.2) on page 187-8. If you could supply more sample figures of at-a-station hydraulic geometry it would help readers understand what it is.
Photo 6.16—That photo is too complex to convey the idea of a meandering channel to a beginner. A photo with a uniform less complex vegetative and topographic patterns would put the focus on the channel geometry.
University of Vermont
Page 197- Washload
Washload is considered as the particles smaller than 63 micro meters. It might be useful to mention the size of the washload particles beside the size of cobble, gravel, and sand for comparison.
Page 195- equation 6.7
This equation is the definition of non-dimensional shear stress (τ*) which is valid for any sediment grain size including gravel and sand. However in the context, it has been referred to for just gravel. Is there any reason for that constriction?
Page 194- Initial of transport
Equation 6.6
Again this relation is valid just for normal condition.
Also I would suggest to present the other famous term for initial of motion as “incipient motion’ because it is being widely used in technical papers and books. In that case, the reader would be familiar with both technical terms associated with the start of the motion
Page 187; discharge variability
The bankfull discharge is one of the most important indices in geomorphology. Although it has been described in this section, the measurement or estimation is not defined. Therefore, it might be a good idea to present a simple analytical approach to estimate bankfull discharge as
Plotting stage vs discharge and where there is an abrupt change in curve slope indicates the bankfull discharge
Page 182- Figure 6-1; Shear stress
The definition of the shear stress presented here as τ= ρ.g.d.s = γ.d.s is for ‘normal condition’ where the water surface profile is parallel to river bed, otherwise this formula is not applicable. It might be a good idea to highlight this assumption embedded in this formula.
In figure 6.4 and photo 6.11 (pgs 192-193) cutbank and point bar are both illustrated but the two illustrations don’t point to the same locations. While they both do point to cutbanks and point bars would aid in understanding if in the photo both of the features are illustrated on the same bend of the river as they are in the figure.
There is a typo on page 187. the sentence on calculating the Froude Number is a run on and should be split up. A photo of a graded stream would be helpful, especially one that can place a graded steam into the real world. An end of chapter question addition could be on defining a wetted width and also on the mechanisms that form potholes. I don’t understand the point of “at-a-station hydraulic geometry” and the associated photo (Figure 6.2) on page 187-8. If you could supply more sample figures of at-a-station hydraulic geometry it would help readers understand what it is.
Photo 6.16—That photo is too complex to convey the idea of a meandering channel to a beginner. A photo with a uniform less complex vegetative and topographic patterns would put the focus on the channel geometry.