Integrated Model for Simulation and Regulation of Basin Water Resources Considering Water Quantity and Quality and Its Application

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This article is well structured, easily understood and scientifically sound. This article proposes an integrated model for the simulation and regulation of water resources considering water quantity and quality and its application shows adaptability from river basin perspective. Some comments are listed as follow for minor revision.

1. The statement of the lack of water quality consideration in allocation requires further discussion(covering lines 99-116) since such consideration has become common. The paragraph should be rearranged as a certain part instead of an entire paragraph.
2. In the2.1 “Hydraulic network under dualistic water cycle”, this content description is too complex and should be further simplified.
3. In order to enhance the logic clues, 2.4 “solution methods” are encouraged to simplify and distribute into 2.3 "Model objective and constraints ".
4. In 3.2 “water demand”, the title does not quite match the content. It is more proper to rearrange the section as “data preprocessing”
5. Adding some research shortcomings and prospects to the last lines in 5 “Conclusion”.

Author Response

1. Summary Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and revised part has been marked in blue in the re-submitted files. 2. Point-by-point response to Comments and Suggestions for Authors Comments 1: The statement of the lack of water quality consideration in allocation requires further discussion (covering lines 99-116) since such consideration has become common. The paragraph should be rearranged as a certain part instead of an entire paragraph. Response 1: Thank you for your suggestion. The paragraph has been rearranged as a certain part in the introduction. The specific revisions are as follows. “In recent years, the structure of the water cycle has dualistically evolved due to the intensification of human water use, and consequently the discharge of pollutant loads from water use has a negative impact on the river water quality. Water resources regulation in consideration of the water quantity and quality is an important technical measure to realize the allocation of water resources and the control of water pollution in a basin (Wang et al.,2016). In order to improve their feasibility, it is very important to fully reflect the three cordons of China’s water resources management in water resources regulation. Therefore, we establish a basin-scale water resources simulation and regulation model which comprehensively considers the interactions between water quantity and quality. Meanwhile, the model objective function is expanded to fully reflect the requirement of water resources management in China. This study can help decision-makers formulate water resources regulation schemes from river basin perspective, especially in dry years. The main contents of this paper are organized as follows…….” Comments 2: In the 2.1 “Hydraulic network under dualistic water cycle”, this content description is too complex and should be further simplified. Response 2: Thank you for your good comment and suggestion. The description of hydraulic network has been further simplified from about 720 words in the first draft to about 430 words. In the revised draft, the focus is on highlighting the network relationships of water resources system. The specific revisions are as follows. “To effectively describe the basin-level dualistic water cycle, the hydraulic network of the water resources system should be constructed and topologized by point, line and area elements, as shown in Table 1. Area elements are composed of three kinds of units (i.e. water supply units, drainage units, water use units). They include many point elements, such as water sources, drainage outlets, and water users. Specifically, water supply units consist of river-type unit and reservoir-type unit, whereas river-type units include pumping works and diversion works. Large- and middle-sized reservoirs are considered to be independent reservoir-type units while ponds and small-sized reservoirs should be aggregated as several reservoir-type units for simplification of calculation due to their large number. According to water consumption and pollution loads discharge or not, water use units consist of instream water use unit and off-stream water use unit, which includes water users of living, industry, irrigation, and so on. Point elements are conceptualized and categorized successively from upstream to downstream, and they are interconnected by line elements, such as networks of natural rivers or artificial channels. Table 1 A conceptualized diagram of elements and processes of the water resources system, as shown in Fig.1, is established to reflect the directed correlation between all elements in the form of point, line, and area elements. In Fig.1, the water demands of off-stream water use units usually consist of living, industrial, irrigation and environmental demands, which can generally be supplied from reservoirs or rivers by use of diversion works or pumping works, and even groundwater. After being used by off-stream water use units, part of the water used by the living and industrial sectors is reused through sewage treatment works, then the remaining parts with pollutant loads are returned to the drainage units, while excess water for agricultural and environmental demands is returned to the drainage units. The drainage water and pollutant load from off-stream water use units reenter the river, affecting the process of the natural water cycle. For instream water use units, there are mainly the ecological flow demand of the section behind the dam and the interface sections between administrative districts. Ac-cording to the network relationships, the sum of the outflow amounts of the upstream water supply units and the return water amounts of the drainage units constitutes the inflow amounts of the downstream water supply units. The relationships between the inbound and out-bound water amounts, supply and drainage amounts, and water consumption and storage amount of each unit are connected based on a water balance, while also reflecting the migration and transformation path of the pollution load in the basin water resources system. Figure 1” Comments 3: In order to enhance the logic clues, 2.4 “solution methods” are encouraged to simplify and distribute into 2.3 "Model objective and constraints ". Response 3: Thank you for your suggestion. In the revised draft, the description of solution methods has been simplified from about 440 words in the first draft to about 220 words. Meanwhile, the section has distributed into 2.3 "Model objective and constraints ". See the revised draft for details. Comments 4: In 3.2 “water demand”, the title does not quite match the content. It is more proper to rearrange the section as “data preprocessing”. Response 4: Thank you for your good suggestion. The title has been revised as “data preprocessing”, which consists of two parts in the first draft: “data” in section 3.1 and section 3.2. Meanwhile, the two paragraphs in section 3.2 in the first draft has been rearrange into one paragraph in section 3.2 in the revised draft. The specific revisions are as follows. “3.2. Data and its preprocessing The dataset used in this study included five types of geographical diversions, so-cio-economic statistics, water supply projects, water use statistics, and meteorological and hydrological data. Basin geographical diversions of the county and township were obtained from the Jiangxi Bureau of Surveying, Mapping, and Geoinformation. Basin socio-economic statistics of the population, the gross domestic product (GDP), and the irrigation area were extracted from the Statistical Yearbooks of Pingxiang, Yichun, Xinyu and Ji’an in 2018. The characteristic value and operational rules of water supply projects were from the Hydrological Yearbook of Jiangxi Province in 2018. Basin water data on the water supply, water use, and water consumption were derived from the Water Resources Bulletin of Pingxiang, Yichun, Xinyu and Ji’an in 2018. Available long-term daily data from 13 precipitation stations, two evaporation stations, and one hydrologic station from 1980 to 2018 were obtained from the Hydrological Monitoring Centre of Jiangxi Province. In addition, the operation data of Jiangkou Reservoir over the years were from the Operation Manual of Jiangkou Reservoir, compiled by the Sanhe Jiangkou Hydraulic Power Plant in Jiangxi Province. All data shown in Table 2 were of good quality and were checked for quality control by corresponding agencies. Table 2 Based on the rainfall of 13 precipitation stations around the basin, the 10-day run-off at the basin outlet was simulated using the VWBM model from 1980 to 2019. The average annual runoff was 6.15 billion m3 in the basin over 40 years, in which the run-off from April 2018 to March 2019 was 4.79 billion m3. Furthermore, the runoff hydro-logical frequency in 2018 was about 90% based on the frequency analysis, and the pe-riod from April 2018 to March 2019 was chosen as the duration for this study according to the periodicity of reservoir operations and farmland irrigation. The water demands of the living sector were calculated according to the population and norm of living water use, while the industrial water demand was computed from the industrial added value and norm of industrial water intake. The water demands over 10-days were di-vided evenly throughout the year for the living, off-stream environmental and indus-trial demands. However, the water demand of farmland irrigation was evaluated based on the effective irrigation area and irrigation water quota, which was determined by crop intermittent irrigation scheduling and effective rainfall during the crop growth period. Therefore, the water demands of the various sectors, i.e., living, industrial, ag-ricultural, ecological and environmental sectors, in each water use unit were calculated for 10 days from April 2018 to March 2019. “ Comments 5: Adding some research shortcomings and prospects to the last lines in 5 “Conclusion”. Response 5: Thank you for your good comment and suggestion. Some research shortcomings and prospects has been added in the Section 5 in the revised draft. The specific revisions are as follows. “Basin water resources allocation system is mainly composed of large- and mid-dle-sized reservoirs in series or in parallel, and the water supply relationship and scheduling rules are complicated. The regulation problem of water resources is char-acterized by multi-objectives, multi-constraints and multi-stages. Numerical simula-tion can be used to effectively improve the level of regional water supply security. Some model such as WEAP, MIKE Basin with friendly interface and efficient operation have been applied in many basin water resources regulation. The multi-water source joint allocation model of Xiong’an New Area was established by using WEAP, and ra-tionally utilized Xiong’an reservoir to achieve the adjustment of abundance and drought, which could meet the water shortage plan of the dry year in 2035[41]. the water resources allocation of the Guangdong-Hong Kong-Macao Greater Bay Area was constructed based on the WEAP, and the results showed that some regions could improve their water satisfaction by about 10% to 15% considering the priority order of water use in regions and industries [42]. Based on the industrial water demands as well as guarantee rate requirements, optimizing the water supply rules or scheduling order of reservoirs can not only play the role of joint compensation of water projects, but also improve the rationality and feasibility of the water resource allocation process. How-ever, it has implemented the three cordons system of water resources management since 2012 in China, which can make more reasonable regulation in most areas. There-fore, the basin-scale water resources simulation and regulation model considering the water quantity and quality was established in this study, highlighting the requirement of water resources management through the model objective function. Through its ap-plication in the Yuanhe River Basin, it was found that the model exhibited good per-formance in the regulation of water resources constrained by the requirements of the cordons of the total water use and pollution load limits. There are two conclusions as follow. (1) Based on point, line, and area elements, a topological hydraulic network of the water resources system was expanded to clearly map the relationships between vari-ous units, such as water supply units, drainage units, and water use units. Based on the basin hydraulic network relationship, the model can simulate the regulation process of water resources considering the impact of water use on the instream quality and qual-ity restrictions on the water supply. The water amount and quality in the river could be simulated at the same time to provide a water quality judgement for the water sup-plies of different sectors. Meanwhile, by employing a water and pollutant load balance method, the processes of water supply, water consumption, and discharge of water us-ers were objectively formulated to achieve the mutual feedback coupling with the wa-ter quantity and its quality. In addition, as important water supply projects, the opera-tion process and their effect of large- and middle-sized reservoirs can be provided to guide actual management. (2) In the Yuanhe River Basin, a water resources system was conceptualized with 57 off-stream units and 23 instream units as water use units as well as 62 river-type units and 17 reservoir-type units as water supply units, where the drainage units and river-type water supply units were consistent. Under the three cordons of China’s wa-ter resources management, the combination of a reduction of the water supply and pollutant loads can be considered to set candidate schemes based on the basin’s actual situation. By minimizing the objective function, the water demands of the living, in-dustrial, and agricultural sectors decreased by 4, 9, and 13%, respectively, and the COD and NH3-N concentrations decreased by 13 and 15%, respectively, for the se-lected scheme. The model results showed that the water shortage was 212 million m3 with a rate of 13.5%, and the loads of COD and NH3-N were 29,100 tons and 0.26 mil-lion tons, respectively. The regulation result of the selected scheme can satisfy the cor-dons of the total water use and the pollution load limits in the basin. In general, the model has the potential to support basin water resources allocation considering the water quantity and quality under new complex requirements faced by the three cordons of water resources management in China. Thus, there are two limita-tions of the model. Firstly, an important premise of the model is the "static hypothesis", that is, the water quantity and quality in the calculated water resources system change slowly, and better results can be obtained in the analysis of basins with large spatial scales and longtime steps, but there is still a problem of cumulative error caused by the time difference of drainage. Secondly, the actual engineering layout is very complicat-ed, and the simplification in hydraulic network will be obvious differences in some plain water network areas, which would lead to unreasonable results. In the future, it is necessary to use AI technology and deep learning to supplement the limitation of the model as presented above. In addition, combined with short-term runoff forecast, roll-ing regulation schemes of the model can effectively enhance the effectiveness of basin water resources management in practice.”

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript constructed a basin simulation and regulation model of water resources considering the water quantity and quality and applied it to the Yuanhe River basin to provide further instructions on regional water resource management. The workload is all right, and the figures and text format are mostly well-organized. My opinion is minor revision. Comments are listed as follow:

1. Introduction is too long which lacks clear logic in some paragraph and could be further refined. Some sentences are not clear, such as Lines 120 to 124, the authors should indicate the study's problem statement clearly?

2. The minimum acceptable values for living, industrial, agricultural, together with ecological and environmental sectors are determined without proper introductions in lines 331-333.

3. The study area does not show widely concerned issues and distinctive regional characteristics relating to water resource management, which should be further refined and improved to reflect its applicability.

4. Why are the runoff and reservoir inflow calibration and validation periods chosen differently? Why is the calibration period (1980-2006) not including the simulation period (1980-2019) in runoff simulation? 

5. Give the appropriate explanation about the calculation of the water shortage rate in the section "Distribution of water shortage rate"

6. The author is suggested to unify the format of references.

Comments on the Quality of English Language

The English writing can be further improved to meet the requirements of a scientific paper.

Author Response

1. Summary Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and revised part has been marked in blue in the re-submitted files. 2. Point-by-point response to Comments and Suggestions for Authors Comments 1: Introduction is too long which lacks clear logic in some paragraph and could be further refined. Some sentences are not clear, such as Lines 120 to 124, the authors should indicate the study's problem statement clearly? Response 1: Thank you for your good comment. The logic of the introduction has been adjusted for highlight study’s problem, especially in the last three paragraphs in the first draft. And words of the introduction further refined from about 1268 in the first draft to about 948. In China, it has implemented the three cordons system of water resources management since 2012, which can make more reasonable regulation of water resources in most areas of China. As for the study’s problem, considering the water quantity and quality, the basin-scale water resources simulation and regulation model has been established, highlighting the requirement of water resources management through the model objective function. The specific revisions in the introduction are as follows. “…… Water projects including diversion and pumping works, ponds and reservoirs are the key-carriers in basin water resources system. Water resources regulation that is organically linked with project scheduling has attracted more attention, which usually includes two stages: water resources allocation and water project scheduling (Wang et al., 2021). The effective combination of water project scheduling and water resources allocation is an important demand for the water resources utilization under the perfect distribution of water projects, especially large- and middle-sized reservoirs (Wang et al.,2020). Through the scheduling of water projects, underground water exploitation and water use behavior, basin water resources regulation can be aimed at making the spatiotemporal distribution of water resources adapt to the economic needs of society and the ecological and environmental requirements as much as possible. Wang et al. (2019) proposed an optimization-simulation method that takes into consideration engineering measures, including water transfer projects, reservoirs, diversion and pumping works. Aiming at realizing the coupling of the water resources allocation with the operational process of hydraulic projects, You et al. (2018) established a model through the construction of an integrated framework for water transfer projects and the local water resources system. You et al. (2021) proposed a two-layer structure ecological operation model for the integrated ecological operation to combine water exploitation and the operation of hydraulic facilities. The operation rules of specific reservoirs were optimized based on the inflow and water supply provided by the upper layer model, which were then utilized in a second-layer model for reservoir operation. In recent years, the structure of the water cycle has dualistically evolved due to the intensification of human water use, and consequently the discharge of pollutant loads from water use has a negative impact on the river water quality. Water resources regulation in consideration of the water quantity and quality is an important technical measure to realize the allocation of water resources and the control of water pollu-tion in a basin (Wang et al.,2016). In order to improve their feasibility, it is very important to fully reflect the three cordons of China’s water resources management in water resources regulation. Therefore, we establish a basin-scale water resources simulation and regulation model which comprehensively considers the interactions between water quantity and quality. Meanwhile, the model objective function is expanded to fully reflect the requirement of water resources management in China. This study can help decision-makers formulate water resources regulation schemes from river basin perspective, especially in dry years. The main contents of this paper are organized as follows. Section 2 describes the methods, including hydraulic network structure, integrated modeling with an objective, constraints, and solution methods. Then, the application of this method in the Yuanhe River Basin, including study area, data preprocessing, and basin network are presented in Section 3. Next, model calibration and validation, different regulation schemes, the selected scheme regulation results are analyzed in Section 4. Finally, the main conclusions of this study are summarized in Section 5.” Comments 2: The minimum acceptable values for living, industrial, agricultural, together with ecological and environmental sectors are determined without proper introductions in lines 331-333. Response 2: Thank you for your good comment. During the extreme drought period, some sectors are allowed to experience water shortage for some time in the engineering design and management in China. According to the importance of the sectors and their water shortage impact, the minimum acceptable value is set differently for living, industrial, agricultural and environmental sectors. In this study, According to Design standard for irrigation and drainage engineering (BG 50288-2018), Technical specification for water supply projects in towns and villages (GB/T 43824-2024) and so on, 95%, 90%, 85% and 85% are selected as the values for the living sector, the industrial sector, the agricultural sector and ecological and environmental sector, respectively. For simplicity, the specific revisions are as follows. “In fact, moderate water shortages in the living, industry, farmland irrigation and environmental sectors are acceptable when the basin is hit by a drought disaster. The optimal value of Sd in the different sectors is 100%, but the minimum acceptable value is set differently according to national relevant technical specification for water supply projects. In Poyang Lake, 95%, 90%, 85% and 85% are selected as the values for the living sector, the industrial sector, the agricultural sector and ecological and environmental sector, respectively. ……” Comments 3: The study area does not show widely concerned issues and distinctive regional characteristics relating to water resource management, which should be further refined and improved to reflect its applicability. Response 3: Thank you for your good suggestion. To show widely concerned issues and distinctive regional characteristics, the introduction about the study area has been further refined and improved to reflect its applicability. The Yuanhe River with developed social economy is a primary tributary of the Poyang Lake basin. In the basin, the water demand of industries is large, which leads to tensions between different water use sectors and areas in the dry season. In 2018, the water classes are Ⅳ or Ⅴ at Linjiafang in Luxi and Houcun in Fenyi in some months, and the water classes are the same at Tang-bian and Huxindao in Jiangkou Reservoir in most months. Therefore, the water quality is poor in some river sectors, which affects the local water intake. For simplicity, the specific revisions are as follows. “……According to the Environmental quality standards for surface water (GB3838-2002), the water classes are Ⅳ or Ⅴ at Linjiafang in Luxi and Houcun in Fenyi in some months in 2018, and the water classes are the same at Tangbian and Huxindao in Jiangkou Reservoir in most months. In the basin, the water demand of industries is large, which leads to tensions between different water use sectors and areas in the dry season. Moreover, the water quality is poor in some river sectors, which affects the local water intake. In the existing regulations, different projects generally supply water to certain sectors and areas, and the reservoirs that undertake water supply tasks do not give priority to instream ecological flow. The issue of water resources has become significant in Poyang Lake, affecting regional economic development and social sta-bility. The water use characteristics of Yuanhe River Basin are obvious, which can represent other basins of Poyang Lake.” Comments 4: Why are the runoff and reservoir inflow calibration and validation periods chosen differently? Why is the calibration period (1980-2006) not including the simulation period (1980-2019) in runoff simulation? Response 4: Thank you for your good comment. In the upper reaches, Shankouyan reservoir covered about 70% of areas of Luxi station has affected the data consistency of the station. Since the data series is long enough, the optimal values of the three parameters of VWBM can be obtained from the period of 1980-2006 as well. However, Shankouyan reservoir covers less than 5% of the basin and its impact on the water use is very small in the basin. The data period of 1980-2019 is more appropriate for model calibration and validation. Comments 5: Give the appropriate explanation about the calculation of the water shortage rate in the section "Distribution of water shortage rate" Response 5: Thank you for your good suggestion. In the section "Distribution of water shortage rate", the appropriate explanation about the water shortage rate are added. For simplicity, the specific revisions are as follows. “The spatial distribution of the water shortage rate of water use units in Yuanhe River Basin is shown in Fig. 12. The variation range of the water shortage rate was 9.7–28.8% with the average rate of 13.5%, where the largest and smallest water shortage rates were located in Xiacun and Wentang, respectively. There were 52 water use units in the basin accounting for 91.2% of the total units, and the water shortage rate was between 10 and 20%. The top four water use units with large rates were in Xiacun, Nanmiao, Baimu and Nanmu, with rates of 28.8, 24.9, 22.4, and 22.2%, respectively. Usually, the headwaters and tributaries are dominated by small projects while the midstream and downstream areas are controlled by large- and middle-sized projects in Yuanhe River Basin. Therefore, although the water demand was not very large in the areas, the units located in the headwaters or some tributaries still prone to water shortage due to no adequate water supply projects, such as water diversion and pumping works, ponds, reservoirs. However, there were large water demands in Luxi, Yichun, Fenyi and Xinyu in the main stream, which are areas with high social and economic development, but the water shortage rate was low at about 10.3% because of the large capacity of water supply projects and abundant transit water amount. As a result, the water shortage characteristics were certainly different after water resource regulation in the basin.” Comments 6: The author is suggested to unify the format of references. Response 6: Thank you for your good suggestion. The format of references has been modified. See the revised draft for details.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

I appreciate the authors for completing this work, but I have one major concern. The authors claim that the developed model in this article performs well in water resources management and has the potential to support basin water resources allocation, considering both water quantity and quality. However, there is no comparison between the advantages and limitations of the developed model and other water resources models (such as WEAP). Additionally, as a water resources management model, the authors must present the limitations of the model in discussion section. In addition, the answer to this question should be provided at the end of the introduction, focusing only on the novelty aspect.

And my minor comments are as follows:

1- Figure 2 needs to be edited. Some relation missed, e.g. links for evaporation, return flow for agriculture to groundwater.

2- The manuscript needs revision. For example, equations should follow a consistent format. Additionally, the notation for alpha (α) and 'a' in Equations 2 and 4 should be standardized.

3- There seems to be excessive explanation, especially in the methodology section, which may not be necessary. 

4- A QQ plot would be more beneficial for visualizing the calibration and validation stages. I suggest using a QQ plot instead of (or in addition to) Figure 7.

Author Response

1. Summary Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and revised part has been marked in blue in the re-submitted files. 2. Point-by-point response to Comments and Suggestions for Authors Comments 1: The authors claim that the developed model in this article performs well in water resources management and has the potential to support basin water resources allocation, considering both water quantity and quality. However, there is no comparison between the advantages and limitations of the developed model and other water resources models (such as WEAP). Additionally, as a water resources management model, the authors must present the limitations of the model in discussion section. In addition, the answer to this question should be provided at the end of the introduction, focusing only on the novelty aspect. Response 1: Thank you for your good comment and suggestion. The model comparison about advantages and limitations have been added in the Section 5 in the revised draft. In addition, the answer has been provided at the end of the introduction to express the study novelty. The specific revisions are as follows. “5. Discussion and Conclusions Basin water resources allocation system is mainly composed of large- and mid-dle-sized reservoirs in series or in parallel, and the water supply relationship and scheduling rules are complicated. The regulation problem of water resources is char-acterized by multi-objectives, multi-constraints and multi-stages. Numerical simula-tion can be used to effectively improve the level of regional water supply security. Some model such as WEAP, MIKE Basin with friendly interface and efficient operation have been applied in many basin water resources regulation. The multi-water source joint allocation model of Xiong’an New Area was established by using WEAP, and ra-tionally utilized Xiong’an reservoir to achieve the adjustment of abundance and drought, which could meet the water shortage plan of the dry year in 2035[41]. the water resources allocation of the Guangdong-Hong Kong-Macao Greater Bay Area was constructed based on the WEAP, and the results showed that some regions could improve their water satisfaction by about 10% to 15% considering the priority order of water use in regions and industries [42]. Based on the industrial water demands as well as guarantee rate requirements, optimizing the water supply rules or scheduling order of reservoirs can not only play the role of joint compensation of water projects, but also improve the rationality and feasibility of the water resource allocation process. How-ever, it has implemented the three cordons system of water resources management since 2012 in China, which can make more reasonable regulation in most areas. There-fore, the basin-scale water resources simulation and regulation model considering the water quantity and quality was established in this study, highlighting the requirement of water resources management through the model objective function. Through its ap-plication in the Yuanhe River Basin, it was found that the model exhibited good per-formance in the regulation of water resources constrained by the requirements of the cordons of the total water use and pollution load limits. There are two conclusions as follow. (1) Based on point, line, and area elements, a topological hydraulic network of the water resources system was expanded to clearly map the relationships between vari-ous units, such as water supply units, drainage units, and water use units. Based on the basin hydraulic network relationship, the model can simulate the regulation process of water resources considering the impact of water use on the instream quality and qual-ity restrictions on the water supply. The water amount and quality in the river could be simulated at the same time to provide a water quality judgement for the water sup-plies of different sectors. Meanwhile, by employing a water and pollutant load balance method, the processes of water supply, water consumption, and discharge of water us-ers were objectively formulated to achieve the mutual feedback coupling with the wa-ter quantity and its quality. In addition, as important water supply projects, the opera-tion process and their effect of large- and middle-sized reservoirs can be provided to guide actual management. (2) In the Yuanhe River Basin, a water resources system was conceptualized with 57 off-stream units and 23 instream units as water use units as well as 62 river-type units and 17 reservoir-type units as water supply units, where the drainage units and river-type water supply units were consistent. Under the three cordons of China’s wa-ter resources management, the combination of a reduction of the water supply and pollutant loads can be considered to set candidate schemes based on the basin’s actual situation. By minimizing the objective function, the water demands of the living, in-dustrial, and agricultural sectors decreased by 4, 9, and 13%, respectively, and the COD and NH3-N concentrations decreased by 13 and 15%, respectively, for the se-lected scheme. The model results showed that the water shortage was 212 million m3 with a rate of 13.5%, and the loads of COD and NH3-N were 29,100 tons and 0.26 mil-lion tons, respectively. The regulation result of the selected scheme can satisfy the cor-dons of the total water use and the pollution load limits in the basin. In general, the model has the potential to support basin water resources allocation considering the water quantity and quality under new complex requirements faced by the three cordons of water resources management in China. Thus, there are two limita-tions of the model. Firstly, an important premise of the model is the "static hypothesis", that is, the water quantity and quality in the calculated water resources system change slowly, and better results can be obtained in the analysis of basins with large spatial scales and longtime steps, but there is still a problem of cumulative error caused by the time difference of drainage. Secondly, the actual engineering layout is very complicat-ed, and the simplification in hydraulic network will be obvious differences in some plain water network areas, which would lead to unreasonable results. In the future, it is necessary to use AI technology and deep learning to supplement the limitation of the model as presented above. In addition, combined with short-term runoff forecast, roll-ing regulation schemes of the model can effectively enhance the effectiveness of basin water resources management in practice.” “1. introduction …… In recent years, the structure of the water cycle has dualistically evolved due to the intensification of human water use, and consequently the discharge of pollutant loads from water use has a negative impact on the river water quality. Water resources regulation in consideration of the water quantity and quality is an important technical measure to realize the allocation of water resources and the control of water pol-lution in a basin[24]. In order to improve their feasibility, it is very important to fully reflect the three cordons of China’s water resources management in water resources regulation. Therefore, we establish a basin-scale water resources simulation and regulation model which comprehensively considers the interactions between water quantity and quality. Meanwhile, the model objective function is expanded to fully reflect the requirement of water resources management in China. This study can help decision-makers formulate water resources regula-tion schemes from river basin perspective, especially in dry years. The main contents of this paper are organized as follows. Section 2 de-scribes the methods, including hydraulic network structure, integrated modeling with an objective, constraints, and solution methods. Then, the application of this method in the Yuanhe River Basin, including study area, data preprocessing, and basin network are presented in Sec-tion 3. Next, model calibration and validation, different regulation schemes, the selected scheme regulation results are analyzed in Section 4. Finally, the main conclusions of this study are summarized in Section 5. ” Comments 2: Figure 2 needs to be edited. Some relation missed, e.g. links for evaporation, return flow for agriculture to groundwater. Response 2: Thank you for your good comment and suggestion. The Figure 2 has been edited and replaced in revised draft. The revised Figure is presented as follow. Figure 2. Coupling process of the dualistic water cycle in water resources regulation system. Comments 3: The manuscript needs revision. For example, equations should follow a consistent format. Additionally, the notation for alpha (α) and 'a' in Equations 2 and 4 should be standardized. Response 3: Thank you for your good comment and suggestion. the manuscript has been revised, especially uniform the equation format, including the notation for alpha in Equations 2 and 4. Comments 4: There seems to be excessive explanation, especially in the methodology section, which may not be necessary. Response 4: Thank you for your good comment and suggestion. The description of hydraulic network has been further simplified from about 720 words in the first draft to about 430 words. In the revised draft, the focus is on highlighting the network relationships of water resources system. In addition, the description of solution methods has been simplified from about 440 words in the first draft to about 220 words in the revised draft. Meanwhile, the section has distributed into 2.3 "Model objective and constraints ". See the revised draft for details. Comments 5: A QQ plot would be more beneficial for visualizing the calibration and validation stages. I suggest using a QQ plot instead of (or in addition to) Figure 7. Response 5: Thank you for your good suggestion. Two QQ plots for calibration and validation has been added to the Figure 7. The revised Figure is replaced in revised draft and presented as follow. Figure 7. Runoff series at Luxi station using VWMB from 1980 to 2006.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript, once edited, is suitable for publication in this journal.