Identification of Hydraulic Parameters Influencing the Hydraulic Erodibility of Spillway Flow Channels
Round 1
Reviewer 1 Report
The manuscript is much improved from the previous version I reviewed. It provides a good overview of the topic.
Author Response
Your various suggestions and comments have greatly contributed to the improvement of the content of this article.
Thank you.
Reviewer 2 Report
Identification of hydraulic parameters influencing the hydrau-2 lic erodibility of spillway flow channels
3.2. Average flow velocity in open channels
This paragraph is too long becouse it refer to basic hydraulics.
- Conclusion and future research directions
The authors should insert the part concerning Figure 12 in the previous paragraph i.e. Discussion, so reorganizing the conclusions
Author Response
Response to Reviewer 2 Comments
Q-1: 3.2. Average flow velocity in open channels
This paragraph is too long because it refer to basic hydraulics.
Response: We agree with the reviewer, but this addition was suggested by the other reviewer in the previous version. However, we tried to summarized some part of the paper.
Q-2: 5. Conclusion and future research directions
The authors should insert the part concerning Figure 12 in the previous paragraph i.e. Discussion, so reorganizing the conclusions
Response: Great comment, we've moved Figure 12 and part of the Conclusion to the Discussion and made some minor changes in the Conclusion.
Author Response File: 
Author Response.docx
Reviewer 3 Report
Identification of hydraulic parameters influencing the hydraulic erodibility of spillway flow channels
This paper reviewed carefully the rock mass erosion of dam spillways and modelling of erosion force based on a lot of previous studies. Also, discussing the results of existing works, authors pointed out future research directions.
The aims and conclusions were well written and this study includes interesting contents contributing to progress of this research area. So, I recommend this article to be published in Water after miner revision.
I hope authors to revise according to following my specific comments.
Specific remarks are listed below.
- Eq.(2): Sf means the differential of energy loss with streamwise direction, i.e., dH/dx. How dH/dx is measured or evaluated in the laboratory experiment?
- Eq.(3): Does Eq.(3) corresponds to Eq.(1)? I think that Eq.(3) mistakes sin_theta for cos_theta.
- Fig.7: Nezu & Rodi (1986) shows that upper limit of inner layer, in which velocity profile obey the log-law, is 20% of the water depth. You had better introduce their study.
Nezu, I. and Rodi, W. (1986) Open-channel flow measurements with a laser Doppler anemometer, J. Hydraulic Engineering., 112, 335-355.
4.Fig.7: Which is actual spill way flow classified to the smooth or rough boundary layer?
5.Eqs.(37) and (46)ig.2: P in (37) means a total power per unit area. In contrast, P in (46) means water pressure. They should be described in different variables.
Author Response
Response to Reviewer 3 Comments
This paper reviewed carefully the rock mass erosion of dam spillways and modelling of erosion force based on a lot of previous studies. Also, discussing the results of existing works, authors pointed out future research directions.
The aims and conclusions were well written and this study includes interesting contents contributing to progress of this research area. So, I recommend this article to be published in Water after miner revision.
I hope authors to revise according to following my specific comments.
Specific remarks are listed below.
Q-1: Eq.(2): Sf means the differential of energy loss with streamwise direction, i.e., dH/dx. How dH/dx is measured or evaluated in the laboratory experiment?
Response : There is an analytical solution obtained from Darcy’s experiment to determine Sf. And this solution is as follows:
, where is the energy loss by friction (in m) over a distance L; is determined as follows:
, where is the friction factor of Darcy and is the diameter of the pipe (m).
For channel flow, the diameter of the pipe ( ) is replaced by the effective diameter ( ). Assuming that corresponds to the hydraulic radius of a full pipe, is equal to .
And becomes:
NB: This equation is presented in section 3.2 (Eq. 19) of the article.
Q-2: Eq.(3): Does Eq.(3) corresponds to Eq.(1)? I think that Eq.(3) mistakes sin_theta for cos_theta.
Response : Eq. 3 is used as an alternative solution to Eq.1. That is, Eq.1 represents the average shear stress of the bottom surface of the channel. However, the actual stress at a specific point along a channel bottom can vary at any time (Pells 2016). As a result, the term shear velocity is used to account for the variability of the shear stress.
After checking, it appears that have not been confused. However, for a better understanding of the difference between Eq.1 and Eq.3 we bring the following justification.
Eq. 1 :
knowing : and
By substitutions in Eq.1 we get Eq.3.
Q-3: Fig.7: Nezu & Rodi (1986) shows that upper limit of inner layer, in which velocity profile obey the log-law, is 20% of the water depth. You had better introduce their study.
Nezu, I. and Rodi, W. (1986) Open-channel flow measurements with a laser Doppler anemometer, J. Hydraulic Engineering., 112, 335-355.
Response: According to the reviewer comment this reference is added to the paper, as well as a few sentences showing the importance and relevancy of this paper for a better understanding and applicability of the various laws related to the boundary layer theory, including the log law of the wall and the velocity defect law.
Q-4: Fig.7: Which is actual spill way flow classified to the smooth or rough boundary layer?
- According to Yen 2002, the inner law region (fig.7) below the transition zone is generally thin and it is difficult to measure velocity within it, especially when the roughness of the wall is large.
- According to Pells 2016, under the flow conditions considered for rough unlined spillways, the roughness elements may exceed the thickness of the boundary sublayer (fully turbulent flow) and the velocity profile is fully developed, that is, the thickness of the boundary layer is equal to the depth of the outflow.
This information added to the paper according to the reviewer comment.
Q-5: Eqs.(37) and (46)ig.2: P in (37) means a total power per unit area. In contrast, P in (46) means water pressure. They should be described in different variables.
Thanks for this remark, in Eq 46 the water pressure was represented by Pr.
Round 2
Reviewer 2 Report
The authors revised the paper, in particular the paragraphs concerning Discussion of the results and Conclusion. The paper can be accepted.
