Investigation of the Hydroelectric Development Potential of Nonpowered Dams: A Case Study of the Buyuk Menderes River Basin
Round 1
Reviewer 1 Report
After my review, I have questioned it what the scientific conclusion/conclusions are. In other words, the scientific conclusion should be included at the last section of the text. What is the scientific conclusion of this study. It is not well defined.
Author Response
Response to Reviewer 1 for water-2150181
“Investigation of Hydroelectric Development Potential of Non-Powered Dams: A Case Study of Buyuk Menderes River Basin”
Thank you for your comments and an opportunity to address the comments by the reviewers. We provide a point-by-point response to their comments below.
Reviewer 1, Comments to the Author:
After my review, I have questioned it what the scientific conclusion/conclusions are. In other words, the scientific conclusion should be included at the last section of the text. What is the scientific conclusion of this study. It is not well defined.
Author Response
We thank Reviewer 1 for their comment.
Author Action
We have updated the conclusion part. We have moved some statements in this section to the discussion section and have rewritten the conclusion in a more understandable. We have also included a recommendation section to give light on future work.
Author Response File: 
Author Response.docx
Reviewer 2 Report
See comments attached.
A very interesting paper.
Minor comments only.
Comments for author File: 
Comments.pdf
Author Response
Response to Reviewer 2 for water-2150181
“Investigation of Hydroelectric Development Potential of Non-Powered Dams: A Case Study of Buyuk Menderes River Basin”
Thank you for your comments and an opportunity to address the comments by the reviewers. We provide a point-by-point response to their comments below.
Reviewer 2, Comments to the Author:
I enjoyed studying the manuscript. It is well-written and duly illustrated. It is moreover novel, with high practical and economic value. Minor comments only.
Author Response
We thank Reviewer 2 for their comment. We have followed their valuable suggestions and requests to improve the manuscript, as listed below.
Reviewer 2, Issue 1
Line 28 CO2
Author Response
We thank Reviewer 2 for their comment.
Author Action
Corrected as CO2 .
Reviewer 2, Issue 2
Figures 2 Y-axis = m³ (instead of m3)
Author Response
We thank Reviewer 2 for their comment.
Author Action
Figure 2 has been redrawn.
Reviewer 2, Issue 3
Figures 3 and 4 Y-axis GWh (instead of GWH)
Author Response
We thank Reviewer 2 for their comment.
Author Action
Figure 3 and Figure 4 have been updated.
Reviewer 2, Issue 4
The Discussion is very appropriate
Author Response
We thank Reviewer 2 for their comment.
Reviewer 2, Issue 5
Conclusions are long (and somewhat descriptive + repeating facts already stressed in the Discussion).
Author Response
We thank Reviewer 2 for their comment. We agree that this chapter is long.
Author Action
We have updated the conclusion part. We moved some expressions in this section to the discussion section and summarized it as much as possible.
Author Response File: Author Response.docx
Reviewer 3 Report
Review report is attached in a file.
Comments for author File: Comments.pdf
Author Response
Response to Reviewer 3 for water-2150181
“Investigation of Hydroelectric Development Potential of Non-Powered Dams: A Case Study of Buyuk Menderes River Basin”
Thank you for your comments and an opportunity to address the comments by the reviewers. We provide a point-by-point response to their comments below.
Reviewer 3, Comments to the Author, Issue 1
The sentence is unclear "The results from the energy simulation revealed that 11 dams without electricity generation facilities have a total energy output of 38.7 GWh with a total capacity of 4.42 MW." Do you mean: "The results from the energy simulation revealed that 11 dams have potential of total energy output of 38.7 GWh with a total capacity of 4.42 MW?" What is LCOE and NPV?
Author Response
We thank Reviewer 3 for the comment and their suggestions for improvement. The results of this study show that the annual average hydropower generation potential and installed capacity for the selected 11 NPDs to be 38.7 GWh / year and 4.4 MW, respectively.
Author Action
The sentence between 7-9 lines is updated as follows:
“The results from the energy simulation revealed that the annual average hydropower generation potential and installed capacity for the selected 11 NPDs to be 38.7 GWh / year and 4.4 MW, respectively.”
Reviewer 3, Issue 2
It is unclear to the reviewer that the studies presented in lines 43 - 53 is relevant to the present study? Authors have not presented scientific literature on converting NPD for power generation and their advantages or consequences. It looks that authors write generic detail about NPD and previous work in this direction missing.
Author Response
We thank Reviewer 3 for the comment and their suggestions for improvement. There are few studies assessing the hydropower potential of retrofitting existing dams and reservoirs.
Author Action
The literature was reviewed, and all relevant studies were added. This part of the introduction has been updated again as follows:
“There are surprisingly few studies assessing the hydropower potential of retrofitting existing dams and reservoirs. Fjøsne and Bakken (2021) carried out a study in a basin in southern Spain and concluded that 5 out of 13 dams studied are economical feasible to be retrofitted. Al-Shnynat, N. (2018) identified a set of challenges by integrating a small hydropower plant at existing Mujib Dam, while Van Vuuren et al. (2011) investigated the potential in existing South African dams. There have also been some studies carried in the US investigating the potential of retrofitting, with encouraging outcomes (e.g. Hadjerioua et al., 2012).”
Reviewer 3, Issue 3
Unclear sentence: "This is the first study in the literature that deals with the on the and economic feasibility of hydroelectric retrofitting projects in Turkey."
Author Response
We thank Reviewer 3 for the comment and their suggestions for improvement. We agree that this sentence is unclear:
Author Action
The sentence between 98-99 lines is updated as follows:
“This is the first study assessing the technical and economical retrofitting potential in Turkey.”
Reviewer 3, Issue 4
Why authors selected crop coefficient (Kc), soil water content (SWC), deep water capacity (DWC), and runoff resistance (RRF) for the calibration? Authors should present the significance of these parameters over others.
Author Response
We thank Reviewer 3 for their comment. This section needs a clarification with a reference.
Author Action
The text in the related subsection has been updated to improve the clarity as follows.
“Regional calibration was done for all the catchments in this model. First, sensitivity analysis was performed for various calibration parameters to measure their influence on runoff volume changes for the sub-basins in the basin (Eryani et. al., 2022). The default values of these parameters in WEAP were increased and decreased by a percentage and the subsequent response in runoff volume changes were observed. The sensitivity of each parameter is measured by observing the absolute difference between the observed and simulated flow when each parameter is changed from its default value. The sensitivity was recorded as the ratio of the absolute difference between the observed and simulated flow when the default value of a parameter is changed, to, the absolute value between the observed and simulated flow when the parameter is at its default value. As a result of the sensitivity analysis, the main calibration parameters used for calibration were determined as crop coefficient (Kc), soil water content (SWC), deep water capacity (DWC) and flow resistance (RRF). Next, the model was switched to the catchment delineation mode to obtain an approximate understanding of the dominant land uses and elevation bands in the catchment.”
Reviewer 3, Issue 5
Authors should elaborate on why deviation for Curuksu, Dandalas catchments is high and what are the main causes for such large error?
Author Response
We thank Reviewer 3 for their comment. Actually, the deviation is not high. Simulated annual total flow values are within very good range (PBIAS < 10%) for each sub-basin at the time of calibration (Moriasi et al., 2007).
Author Action
In order to avoid misunderstanding, the following statement has been added to the text with reference.
“The simulated annual total flow values were within the very good range (PBIAS < 10 %) for each subbasin during calibration (Moriasi et. al., 2007).”
Reviewer 3, Issue 6
Figure 2 is not readable. Authors should improve the quality of the figure.
Author Response
We thank Reviewer 3 for their comment. We agree that the readability of these Figure 2 could be improved.
Author Action
Figure 2 has been redrawn.
Reviewer 3, Issue 7
What is Scenario 1 and Scenario 2?
Author Response
We thank Reviewer 3 for their comment. Scenario 1 and scenario 2 are explained between lines 190 - 201 of the manuscript, before.
Reviewer 3, Issue 8
Although the capacity factor for Orenler dam is high, the potential for power generation is less than 1 GWh. Will this be really profitable? Because, there will be environmental impact, changes in the biological life, additional cost for power generating equipment, etc.
Author Response
We thank Reviewer 3 for their comment. Orenler dam potential for power production was determined by its technical specification and annual average outflow as displayed in Table 2. Orenler has a low annual outflow and that is why its energy output is below 1 GWh. The capacity factor as defined is the ratio of the WEAP simulated energy from Orenler to the Potential energy production derived from the technical specification of the Orenler dam. The scope of this study did not consider the sensitivity of the project profitability to quantified environmental impact, changes in biological life and future capital cost that may arise due to damages of dam or its structural components.
Reviewer 3, Issue 9
Cost of retrofitting has several flaws. Authors must present credible calculation steps otherwise the Table 4 has no scientific value.
Author Response
We thank Reviewer 3 for their comment. The capital cost components considered for the scope of this study was the penstock cost, turbine cost, complete electromechanical equipment including civil and transportation and the powerhouse cost. All of these costs were chosen from the NVE cost base for a small hydropower project and the chosen prices were subjected to the inflation rate from 2010 (year of publishing book with NVE curves) till 2022 to realize the current prices in 2022. Before the penstock diameter was selected for each dam, a penstock diameter vs cost optimization was run. Larger penstocks reduce the frictional head loss and its related head loss costs but are also expensive than penstocks with smaller diameter and high frictional head loss cost. Because the head loss and pipe cost are both related to the pipe diameter, the optimization is run to detect the diameter at which the optimal head loss cost and capital cost could be achieved. Reduction in head loss cost as a result of increasing the diameter of the pipe is noted as a benefit to the system. An increase in the pipe diameter leading to an increase in pipe cost is recorded as a cost to the system. The successive changes in the benefits and the costs for each change in diameter is recorded as delta benefit and delta cost respectively. The values of delta benefits and cost are plotted against their respective diameters on a graph and the point of intersection between the delta benefit and the delta costs is chosen as the optimal point because it is the point at which changes in benefits to the system equals the changes in cost to it. The diameter at the point of intersection is noted as the optimal diameter. Once the optimal diameter of the penstock is chosen, its cost can be obtained by inserting the value of the optimal diameter into the cost function from the chosen penstocks NVE curve. The head loss cost for each penstock is obtained from Manning’s equation and the electricity price while the formula for the pipe cost was retrieved from the NVE curves.
Operational cost included the main operation and maintenance cost (4%) and the income and natural resource tax(35%). At a rate of 5%, operational year of 49 years and an energy price of $ 0.09, the Net present value, internal rate of return and benefit cost ratio for the projects were obtained. With this scope of economic analysis Orenler had an NPV of 0.182 as shown in Table 5. This shows that Orenler is marginally profitable. If scope of cost components is changed and the costs related to changes in biological life is successfully quantified (monetarily) and added to the cost structure, there is a likelihood that like Tavas Yenidere and Yavaslar (shown in Table 5), Orenler will not be profitable.
The information about the cost of retrofitting and optimization are given in line 271-285.
Reviewer 3, Issue 10
Conclusion is too long. Authors should focus on main outcome instead of presenting a repeated summary of the results. Authors should also discuss the consequences on biological life by using/converting NPD to power production dam?
Author Response
We thank Reviewer 3 for their comment. We agree that this chapter is long. Consequences on biological life by converting/using NPD to electricity generation dam are not within the scope of this study.
Author Action
We have updated the conclusion part. We have moved some statements in this section to the discussion section and have rewritten the conclusion in a more understandable. We have also included a recommendation section to give light on future work.
Author Response File: Author Response.docx
Round 2
Reviewer 3 Report
The authors have addressed the comments.
Author Response
We thank Reviewer 3 for the comment and their suggestions for improvement.
