Scouring of Replenished Sediment through Reservoir Flood Discharge Affects Suspended Sediment Concentrations at Downstream River Water Intake

Round 1

Reviewer 1 Report

The total storage capacity of important reservoirs in the world has been decreasing in the past and recent years by the lack of effective regional sediment management practices and planning.

Sediment accumulation in a reservoir reduces his water capacity and the sediment transport through downstream river; that have a considerable influence on the sustainability of any water supplies plans from the reservoirs, increases channel erosion, and affects the downstream ecosystems by lacking of usual and important sedimentation in many areas. Are evident effects on downstream river channels including the loss of farming, riverbank instability, and other channel morphology changes.  

This article shows some interesting lines of modelling the circulation and transfer of sediment in critical areas to control, to improve or optimize, the local actuation plans to solve that important problems. The replenishment of sediments method adopted is the disposing sediments dredged from reservoir with higher critical scour velocity to control the both fine and coarse sediments.

The model of velocity of sediment transport show the values in the replenishment candidate areas and the flow in main channel at different levels. The physical model, developed as mimic the scouring process and replenishment of sediments downstream. The model show that the concentration reduction ratio was approximately 90% in the sediment in replenishment area, with top concentration of 6600 mg/L, matching more or less the limit of 6000 (Bansin Water Treatment Plant). This replenishment must be considered in many similar problems.

The work is interesting for many reservoir areas worldwide.

Must be correct any erratum, i.e. : (m3/L) in place of (mg/L).

Must be revise the text to correct any similar error highlighting some details... (through hydraulic) (sic)...

In addition I suggest to the authors adapt the conclusions to the need concretion and clearness in the explanation of mean values or limit values, in the references on significance of modeled parameters.

  

 

Author Response

Comment 1: The total storage capacity of important reservoirs in the world has been decreasing in the past and recent years by the lack of effective regional sediment management practices and planning.

 

Sediment accumulation in a reservoir reduces his water capacity and the sediment transport through downstream river; that have a considerable influence on the sustainability of any water supplies plans from the reservoirs, increases channel erosion, and affects the downstream ecosystems by lacking of usual and important sedimentation in many areas. Are evident effects on downstream river channels including the loss of farming, riverbank instability, and other channel morphology changes. 

 

This article shows some interesting lines of modelling the circulation and transfer of sediment in critical areas to control, to improve or optimize, the local actuation plans to solve that important problems. The replenishment of sediments method adopted is the disposing sediments dredged from reservoir with higher critical scour velocity to control the both fine and coarse sediments.

 

The model of velocity of sediment transport show the values in the replenishment candidate areas and the flow in main channel at different levels. The physical model, developed as mimic the scouring process and replenishment of sediments downstream. The model show that the concentration reduction ratio was approximately 90% in the sediment in replenishment area, with top concentration of 6600 mg/L, matching more or less the limit of 6000 (Bansin Water Treatment Plant). This replenishment must be considered in many similar problems.

 

The work is interesting for many reservoir areas worldwide.

Response: Thanks for your comments and encouragement.

 

Comment 2: Must be correct any erratum, i.e.  (m3/L) in place of (mg/L).

Response: (m3/L) is revised to mg/L in page 17 Line 482 and page 19 Line 557.

 

Comment 3: Must be revise the text to correct any similar error highlighting some details... (through hydraulic) (sic)...

Response: Error highlighting is corrected from Lines 134 to 135, from Lines 177 to 178, Line 224, Line 231, from Lines 313 to 317, from Lines 326 to 327, from Lines 382 to 392, Figure 11, Table 2, Line 420, from Lines 423 to 424, from Lines 428 to 431, Line 438, from Lines 441 to 443, line 456, from Lines 494 to 497, from Lines 499 to 501, and Line 528.

 

Comment 4: In addition I suggest to the authors adapt the conclusions to the need concretion and clearness in the explanation of mean values or limit values, in the references on significance of modelled parameters.

Response: We would like to thank the reviewer.  According to the reviewer’s comment, the suggested values of two important parameters (  and ) for modelling the cohesive sediment transport are added in the revised manuscript. In general, the critical shear stresses of deposition and erosion differ in various study areas. However, they can be obtained through the experimental results with samples collected near the study reach. Fortunately, Liu et al. (2002) [18] have investigated the relationship between critical shear stress for erosion and sediment dry density in Tanshui River of Taiwan (including Shihmen reservoir). Therefore, suggested values (  = 0.1 Nm^-2 and  =  0.05 Nm^-2) from previous work by Liu et al. (2002) [18] are used in the model simulation. Pleased see the revised manuscript in Lines 173~176 of the revised manuscript.

Author Response File: Author Response.docx

Reviewer 2 Report

General:

Citations were noted by Author and year. In References section, citations were ordered alphabetically. In References sections citations must be ordered as they appear in the paper and in the paper, it must be referred by number: [1], [2], etc.

Avoid using bold letters, verify fonts Format, verify paragraphs Format, left align “where”.

Lines 137-141: Larger fonts used.

Lines 157-186: Review variables size, align left “where”, avoid to use equations in line with text (Lines 166, 173, 174, 176, 178)

Lines 280-296: Paragraphs are with Line spacing: Double.

Author Response

Comment 1: Citations were noted by Author and year. In References section, citations were ordered alphabetically. In References sections citations must be ordered as they appear in the paper and in the paper, it must be referred by number: [1], [2], etc.

Response 1: The references citations are referred by numbers.

 

Comment 2: Avoid using bold letters, verify fonts Format, verify paragraphs Format, left align “where”.

Response 2: The bold letters are corrected from Lines 134 to 135, from Lines 177 to 178, Line 224, Line 231, from Lines 313 to 317, from Lines 326 to 327, from Lines 382 to 392, Figure 11, Table 2, Line 420, from Lines 423 to 424, from Lines 428 to 431, Line 438, from Lines 441 to 443, line 456, from Lines 494 to 497, from Lines 499 to 501, and Line 528.

 

Comment 3: Lines 137-141: Larger fonts used.

Response 3: The large fonts are revised.

 

Comment 4: Lines 157-186: Review variables size, align left “where”, avoid to use equations in line with text (Lines 166, 173, 174, 176, 178)

Response 4: Equations in Lines 166, 173, 174, 176 and 178 are replaced to eq. (3), eq. (5), eq. (6) and eq. (7), respectively.

 

Comment 5: Lines 280-296: Paragraphs are with Line spacing: Double. 


Response 5: The line spacing is revised.

Author Response File: Author Response.docx