Research on Spatial Difference, Distribution Dynamics and Influencing Factors of Urban Water-Use Efficiency in the Yellow River Basin

Round 1

Reviewer 1 Report

The manuscript of the article “Research on Spatial Difference, Distribution Dynamics and Influencing Factors of Urban Water Use Efficiency in the Yellow River Basin” presents an analysis on the factors that influence the urban water use efficiency in the Yellow River Basin. The well-known spatial Durbin model have been used with Gini coefficient, Kernel density estimation and Markov chain to analyze the statistical data.

The content of this work falls within the scopes of the journal. However, it is not easy for readers to follow the flow of the paper.

This paper is interesting in my point of view and my recommendation is to make a minor revision before publication in sustainability.

Some comments are as follows:

1.   Abstract:

The results were presented in the “boring” way for readers!

“…. The results show that 11 the overall urban water use efficiency of the Yellow River Basin shows a fluctuating upward trend 12 and a significant spatial imbalance pattern. Hypervariable density and intraregional differences 13 constitute the main source of whole regional differences; the dynamic evolution characteristics of 14 urban water use efficiency distribution in different regions are different, and spatial factors have a 15 non-negligible impact; the urbanization process and population density spatial spillover effects are 16 negative in the state of spatial interaction; the spillover effect of industrial structure upgrading is 17 positive; The direct and spillover effects of openness are both positive; The direct effect of water use 18 structure is positive…”

Please present with some explanation and comments.

 

2.   Introduction:

o   information provided from Lines 29 to 32 to prove that “The Yellow River Basin is a water-scarce basin” should be cited.

“…. The Yellow River Basin is a water-scarce basin, and our country’s per capita freshwater 28 resources are only 1/4 of the world average, while the Yellow River basin per capita is only 29 27% of the national average in China. It is responsible for 12% of country’s population, 30 13% of food production and water supply tasks for cities along the river with 2% of coun-31 try’s river runoff”.

 

o   A map of the study area should be added.

o   the 2^nd paragraph is very long (Line 49 … Urban water use efficiency…. To Line 125 …. in the Yellow River Basin”. Please divide it into 2-3 paragraphs based on the contents.

o   the objective of this study from Line 110 to Line 125 should be short and concise.

3.   Research Methods, Index Selection and Data Sources

o   Lines 143 – 145: “……………due to lack of data in the municipal district, industrial wastewater is approximately replaced by the city's caliber……”. The authors should provide which data source was used to estimate the wastewater using the city’s caliber.

o   Eq. (5): I suggest adding more explanation for the parameters in the equation such as d, b, q, …

o   I could not find the data used for the analysis in this section. It is mentioned by the authors that data was taken from the China Urban Statistical Yearbook, etc., I suggest that a Table describe the data and data sources should be added if it is possible.

o   In Section 2.2. Dagum Gini coefficient and its decomposition, why the cities were grouped according to the upper, middle and lower reaches of the Yellow River Basin? Please explain and insert the map of study area accordingly.

4.   Empirical Results and Analysis

o   Table 3: The Wald test, LR test and Hausman test were mentioned to explain the results in Table 3. The roles of these tests should be presented first in Section 2.5. Spatial Durbin Model. Elaboration is needed.

o   It is very difficult to read Table 1 without any highlighted numbers for discussion (peak, trend, ….). Please use graphs to present the results for easier understanding where possible.

o   the paragraph is very long (Line 238 … The results of the SE-U-SBM …. To Line 286…………….  are 0.020 and 22.04% respectively”. Please divide it into 2 paragraphs based on the contents.

o   Axis titles should be added to Figure 1. Colored presentation is preferable.

o   This section presents many tables and only one figure was shown. My suggestion is more figures should be presented here in order to clarify the results specially to support the discussions on the spatial relationship between the upper-, middle- and lower- reaches of the basin.

o   It is very difficult to read Table 2 and Table 4 without any highlighted numbers for discussion (peak, trend, ….). Please use graphs to present the results for easier understanding where possible.

 

5.   Conclusions and Discussion

o   Lines 485 – 491: “Based on the basic water …, and deeply implement the most stringent water management system, strictly implement the three red lines of … and use water to determine production”. Clarification should be made on this conclusion since I could not find the results that support this conclusion.

o   Discussion should go first and then conclusions. Please conclude to the points of the study objective.

6.   General:

There are typos in the MS and some parentheses seems wrong (e.g. lines 219-221). Please review the format.

Many paragraphs are too long. Please divide them.

Author Response

Dear reviewer:

Thank you for your comments and suggestions. We have revised the paper and made the following reply:

Comments and Suggestions for Authors

The manuscript of the article “Research on Spatial Difference, Distribution Dynamics and Influencing Factors of Urban Water Use Efficiency in the Yellow River Basin” presents an analysis on the factors that influence the urban water use efficiency in the Yellow River Basin. The well-known spatial Durbin model have been used with Gini coefficient, Kernel density estimation and Markov chain to analyze the statistical data.

The content of this work falls within the scopes of the journal. However, it is not easy for readers to follow the flow of the paper.

This paper is interesting in my point of view and my recommendation is to make a minor revision before publication in sustainability.

Thank the reviewer for the affirmation of the topic and basic content.

Some comments are as follows:

1. Abstract:

The results were presented in the “boring” way for readers!

“…. The results show that 11 the overall urban water use efficiency of the Yellow River Basin shows a fluctuating upward trend 12 and a significant spatial imbalance pattern. Hypervariable density and intraregional differences 13 constitute the main source of whole regional differences; the dynamic evolution characteristics of 14 urban water use efficiency distribution in different regions are different, and spatial factors have a 15 non-negligible impact; the urbanization process and population density spatial spillover effects are 16 negative in the state of spatial interaction; the spillover effect of industrial structure upgrading is 17 positive; The direct and spillover effects of openness are both positive; The direct effect of water use 18 structure is positive…”

Please present with some explanation and comments.

Thanks to the reviewer’s criticism, we restated the abstract, also added corresponding explanations and comments. Please refer to the revised version for details.

2. Introduction:

o   information provided from Lines 29 to 32 to prove that “The Yellow River Basin is a water-scarce basin” should be cited.

Thanks to the reviewer’s criticism, we deleted the sentence. In the revised version, “China’s per capita freshwater resources are only 1/4 of the world average, while the Yellow River basin per capita is only 27% of the national average in China” can depict the characteristics of water shortage in the Yellow River basin.

“…. The Yellow River Basin is a water-scarce basin, and our country’s per capita freshwater 28 resources are only 1/4 of the world average, while the Yellow River basin per capita is only 29 27% of the national average in China. It is responsible for 12% of country’s population, 30 13% of food production and water supply tasks for cities along the river with 2% of coun-31 try’s river runoff”.

We changed it to the following:

China’s per capita freshwater resources are only 1/4 of the world average, while the Yellow River basin per capita is only 27% of the national average in China.

    “It is responsible for 12% of country’s population, 13% of food production and water supply tasks for cities along the river with 2% of country’s river runoff” comes from “Summary of Comprehensive Planning of the Yellow River Basin (2012-2030) [N]. Yellow River News, March 21, 2013 (2)”.  The data is relatively old, so we delete it.

o   A map of the study area should be added.

Thanks for the reminder. We added a map of the study area.

 

Figure1. The study area of Yellow River Basin

o   the 2^nd paragraph is very long (Line 49 … Urban water use efficiency…. To Line 125 …. in the Yellow River Basin”. Please divide it into 2-3 paragraphs based on the contents.

Thanks for the reminder. We divided this part into three paragraphs.

o   the objective of this study from Line 110 to Line 125 should be short and concise.

Thanks for the reminder. We have reduced the length of this part.

3. Research Methods, Index Selection and Data Sources

o   Lines 143 – 145: “……………due to lack of data in the municipal district, industrial wastewater is approximately replaced by the city's caliber……”. The authors should provide which data source was used to estimate the wastewater using the city’s caliber.

Thanks for the reminder.

Wastewater is the content that must be considered when measuring urban water use efficiency. The research object of this paper is cities in the Yellow River Basin, not all municipal administrative districts. Due to the lack of accurate data on urban wastewater, we replace it with industrial wastewater in the municipal administrative district. We think that the industries in the Yellow River basin are mainly concentrated in cities, so the industrial wastewater in the municipal administrative district can largely represent the wastewater output of the city.

The data is from “China Urban Statistical Yearbook” and related provincial statistical yearbooks.

o   Eq. (5): I suggest adding more explanation for the parameters in the equation such as d, b, q, …

Thanks for the reminder. We added some explanation for the parameters in the equation.

o   I could not find the data used for the analysis in this section. It is mentioned by the authors that data was taken from the China Urban Statistical Yearbook, etc., I suggest that a Table describe the data and data sources should be added if it is possible.

Thank the reviewer. The following table is a descriptive analysis of variables. In order to save space, we did not put it in the text. The calculation method of each variable is in the text.

variables	min	max	mean	standard deviation
Urban water use efficiency	0.309	1.360	0.922	0.120
	0.044	1.499	0.343	0.229
	0.732	1.000	0.938	0.056
	0.000	7.151	1.194	1.287
	1.774	8.668	6.300	1.079
	0.000	106.667	5.567	11.142
	0.000	0.762	0.320	0.153

o   In Section 2.2. Dagum Gini coefficient and its decomposition, why the cities were grouped according to the upper, middle and lower reaches of the Yellow River Basin? Please explain and insert the map of study area accordingly.

Thank the reviewer. The Yellow River basin covers a vast area, and each part is quite different. It can be divided into upper, middle and lower reaches according to the natural environment and hydrological conditions of the area where the river flows. The spatial node cities are Hohhot where Hekou Town is located and Zhengzhou where Taohuayu is located. Since the dividing point is located in a specific city, we use words instead of maps to describe it.

4. Empirical Results and Analysis

o   Table 3: The Wald test, LR test and Hausman test were mentioned to explain the results in Table 3. The roles of these tests should be presented first in Section 2.5. Spatial Durbin Model. Elaboration is needed.

Thank the reviewer. “Wald test and LR test can be used to check whether the spatial Dubin model can be simplified into the spatial lag model and the spatial error model” was added in 2.5. Spatial Durbin Model.

o   It is very difficult to read Table 1 without any highlighted numbers for discussion (peak, trend, ….). Please use graphs to present the results for easier understanding where possible.

Dagum Gini coefficient and decomposition method were proposed by Dagum in 1997. This method makes up for the traditional Gini coefficient and Theil index. The limitation of the method has effectively solved the problem of overlapping sample data and the source of regional differences, so it has been widely used by many scholars. Table 1 further reports the overall difference of urban water use efficiency in the Yellow River basin from 2008 to 2018 calculated according to Dagum Gini coefficient and its decomposition method and the decomposition results of its subgroups.

As a nonparametric estimation method, kernel density estimation usually uses smooth peak function to fit sample data and continuous density curve to describe the distribution of random variables. It has the characteristics of strong robustness and weak model dependence, and is widely used in spatial imbalance analysis by many scholars. In general, the distribution, shape, ductility and other characteristics of random variables can be observed from the curve images obtained by kernel density estimation.

o   the paragraph is very long (Line 238 … The results of the SE-U-SBM …. To Line 286…………….  are 0.020 and 22.04% respectively”. Please divide it into 2 paragraphs based on the contents.

Thank the reviewer. We divided it into 2 paragraphs based on the contents.

• Axis titles should be added to Figure 1. Colored presentation is preferable.

Thank the reviewer, we processed the axis to avoid affecting the key lines. After color comparison, we still tend to retain the non color images.

o   This section presents many tables and only one figure was shown. My suggestion is more figures should be presented here in order to clarify the results specially to support the discussions on the spatial relationship between the upper-, middle- and lower- reaches of the basin.

o   It is very difficult to read Table 2 and Table 4 without any highlighted numbers for discussion (peak, trend, ….). Please use graphs to present the results for easier understanding where possible.

Thank the reviewer. We add words to the text for the research results in Table 2 and Table 4.

5. Conclusions and Discussion

o   Lines 485 – 491: “Based on the basic water …, and deeply implement the most stringent water management system, strictly implement the three red lines of … and use water to determine production”. Clarification should be made on this conclusion since I could not find the results that support this conclusion.

Thank the reviewer. According to the research, improving urban water use efficiency requires improving the "expected" output of existing water resources input on the one hand, and reducing the "unexpected" output of water resources input on the other. Therefore, it is very necessary to thoroughly implement the strictest water management system, strictly implement the three red lines of water resources development and utilization control, water use efficiency control and water function area restriction on sewage collection. The three red lines better fit the connotation of water resources utilization efficiency, and are the content that must be paid attention to to to to improve urban water use efficiency in the Yellow River basin.

o   Discussion should go first and then conclusions. Please conclude to the points of the study objective.

Thank the reviewer. We optimized the research conclusion and discussion. The discussion part is mainly about countermeasures and suggestions, which we still tend to put behind the brief conclusion.

6. General:

There are typos in the MS and some parentheses seems wrong (e.g. lines 219-221). Please review the format.

Thank the reviewer. We made changes and checked the full text format.

Many paragraphs are too long. Please divide them.

Thank the reviewer. We divided some long paragraphs.

Author Response File: Author Response.pdf

Reviewer 2 Report

This study presents quantitative analysis results about the spatial distribution and imbalance pattern of water efficiency in Yellow River Basin. The object of the research, methods, results and discussion were well organized to present the results of the research. There are minor comments that would improve the understanding of the manuscript as bellow.

 

1.   If it is possible, including text or map about the definition of the regions analyzed in the manuscript (e.g. us-stream, mid-stream, down-stream) would improve understanding of the readers.

 

2. Also, if it is possible, including brief discussion using the definition or map of the analyzed regions may provide better understanding about the characteristics of water use.

 

3.   The abbreviations of model names would be defined when they are firstly mentioned (i.e. line 67 DEA-U-SBM, SE-U-SBM etc.)

Author Response

Dear reviewer:

Thank you for your comments and suggestions. We have revised the paper and made the following reply:

Comments and Suggestions for Authors

This study presents quantitative analysis results about the spatial distribution and imbalance pattern of water efficiency in Yellow River Basin. The object of the research, methods, results and discussion were well organized to present the results of the research. There are minor comments that would improve the understanding of the manuscript as bellow.

Thank the reviewers for their affirmation of the topic and basic content.

1. If it is possible, including text or map about the definition of the regions analyzed in the manuscript (e.g. us-stream, mid-stream, down-stream) would improve understanding of the readers.

Thanks for the reminder from the reviewer. We added a map of the study area. But the spatial node cities are Hohhot where Hekou Town is located and Zhengzhou where Taohuayu is located. Since the dividing point is located in a specific city, we use words instead of maps to describe it.

Figure1. The study area of Yellow River Basin

2. Also, if it is possible, including brief discussion using the definition or map of the analyzed regions may provide better understanding about the characteristics of water use.

Thanks for the reminder from the reviewer. We use words instead of maps to describe the characteristics of water use because of spatial node cities are located in a specific cities.

3. The abbreviations of model names would be defined when they are firstly mentioned (i.e. line 67 DEA-U-SBM, SE-U-SBM etc.)

Thanks for the reminder.  DEA-U-SBM means Data envelopment analysis-slack based measure with undesirable outputs, SE-U-SBM means  super efficiency-slack based measure with undesirable outputs. As the full name is longer, we still prefer to use abbreviations.

Author Response File: Author Response.pdf