Modeling the Physical Nexus across Water Supply, Wastewater Management and Hydropower Generation Sectors in River–Reservoir Systems
Round 1
Reviewer 1 Report
Reviewer`s notes
1. In chapter Introduction in last paragraph, should put a detailed aim of the work with giving what new work brings,
2. In the paper there are editing errors regarding units, eg. lines 239 - mg/l and N3H-N. It should be thoroughly checked and improved throughout the work.
3. The work should describe in detail the correlation relationships (Pearson's linear relationship), which are shown in Figure 5.
4. The work should describe in detail the correlation relationships (Pearson's linear relationship), which is shown in Figure 6.
5. The work should describe in detail the correlation relationships (Pearson's linear relationship), which are shown in Figure 7.
6. Chapter 4.3. Discussion is not a discussion, but rather a summary or conclusion. This chapter should be abolished. However, more information from other publications should be included in the description of the results obtained and this will be the right discussion.
General note:
The work is interesting and it contains an interesting practical problem. However, the work requires supplementing with the notes in points 1 to 6.
Author Response
1. In chapter Introduction in last paragraph, should put a detailed aim of the work with giving what new work brings, Response: it has been presented the aim of our paper and the new work brings in the last paragraph of the introduction part. Thanks. 2. In the paper there are editing errors regarding units, eg. lines 239 - mg/l and N3H-N. It should be thoroughly checked and improved throughout the work. Response: Checked and revised. Thanks. 3. The work should describe in detail the correlation relationships (Pearson's linear relationship), which are shown in Figure 5. 4. The work should describe in detail the correlation relationships (Pearson's linear relationship), which is shown in Figure 6. 5. The work should describe in detail the correlation relationships (Pearson's linear relationship), which are shown in Figure 7. Response: all of the Pearson correlation coefficients of the relationship lines in Figure 7 are around -1 value. Thanks. 6. Chapter 4.3. Discussion is not a discussion, but rather a summary or conclusion. This chapter should be abolished. However, more information from other publications should be included in the description of the results obtained and this will be the right discussion. Response: thanks for your suggestion. But we think this part will be useful for readers to understand more clearly about our results research. As what is the discussion, I fully agree what is your understanding. But there is not a general agreement on this issue. We insist to keep this part. Thanks. General note: The work is interesting and it contains an interesting practical problem. However, the work requires supplementing with the notes in points 1 to 6. Response: thanks again for your hard and careful work on our paper. we do think your comments is not only helpful in improving this paper but also beneficial to our research in the future. Thanks.
Reviewer 2 Report
Refer attached file.
Comments for author File: 
Comments.docx
Author Response
The paper provides new kind of work on finding nexus on Water supply-Water Quality- Hydropower generation. I have a few observations Comment 1: Why did not authors consider the DO level of water as a prime water quality indicator? Response: DO is a very important indicator of water quality. “Since the biochemical oxygen demand (BOD5) and ammonia as nitrogen (NH3-N) indicators in allowable wastewater are considered as a measure of water-organic pollutants” in waste water management. BOD5 and NH3-N are the most concerned indicator for the water planning and management in practice. Thanks. Comment 2: Authors considered most dry condition flow (99%) and dry condition (75%). It could have been better if analysis correspond to critical period and average flow period. Response: The percentage of water supply is very small in study area. The most dry condition flow (99%) and dry condition (75%) are often taken as the input for the water resources allocation and operation. From the proposing proper adaptive measures to the water shortages, the effectiveness of the measures should be more than that under the average flow period. Therefore, the extreme dry condition flows are adopted in our study. Thanks. Comment 3: When water supply is increased, decrease in hydropower generation. This happens the water released for water supply is unable to utilize for power generation. What does prevent in the system that utilizing this water for power generation? Response: it is absolutely right that utilizing supplied water for power generation can be found some place. The cascaded reservoirs are often found in a whole river basin, the water released for water supply is unable to utilize at lease for one reservoir for power generation. Our case study is an illustrative example for river-reservoir system. we have also explained that “This can be done by taking the input in our example as the output of another river-reservoir system in the upstream, or taking the output in our example as the input of another system in the downstream.” Thanks. Comment 4: In the result and discussion, the identified results on effects of boundary conditions on the nexus. It may be tabulated as considered boundary conditions vs its effect on the considered nexus. Response: it’s a very good suggestion. As the nexuses are formed by the data series, the table is not the best choice to show the nexus. And the figures to illustrate the effects of boundary conditions on the nexus are also acceptable. Thanks. Comment 5: It will be better if variation in outflow water quality with respect to inflow water quality is presented under different water supply level and further it shall be related with hydropower production. Response: it is a very good suggestion. The purpose of our paper is to propose a framework of physical nexus across water supply, wastewater management and hydropower generation sectors. There should be different conditions that impacts on the physical nexus. The effects of main factors have been analyzed in our paper, variation in outflow water quality with respect to inflow water quality can also be attributed to the water quality conditions. Thanks. Comment 6: What is the inherent governing equation between water quality and hydropower generation? Response: it is very good question. The target of the water quality protection in the downstream of the reservoir will impact the hydropower generation. As the water level in the reservoir is also an input to the hydropower generation equation and the water level is fluctuated by the series of releasing water, and then the amount of water releasing to diluting waste water in the downstream will be influence the water level in the reservoir and its hydropower generation. Thanks. Comment 7: “Since the environmental flow is not separated from the water for hydropower generation, it was only reduced by approximately 50 million kw•h (0.9% of the hydropower generation without water supply) in the study area, even if the amount of supplied water is assumed to increase to 10 times as much as water demand in 2030.” Please check the correctness of this sentence. I am unable to understand what exactly you want to convey to the reader with respect to the problem that you are addressing. Response: As the amount of water demand for society and economic development is small comparing the water inflow in our study area, the nexus between water supply and hydropower generation can be used for assuring water supply at very small cost of hydropower generation. So the contradiction between hydropower generation and water supply is not irreconcilable. Thanks.