An Assessment of Collector-Drainage Water and Groundwater—An Application of CCME WQI Model
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
An Assessment of Collector-Drainage Water and Groundwater –An Application of CCME WQI Model
Abstract
According to Victor Ernest Shelford’s “Law of Tolerance”, organisms within ecosystems thrive optimally when environmental conditions are favorable.
In reference to the above statement, this abstract should be rewritten. It does not explicitly state the objectives, results and implications of the study. It is also characterized with different fonts from the publication template provided
Introduction
Much as the authors have tried to compile the background of the study, this introduction is fairly written and needs tightening of the message. This should be done by demonstrating further the gaps in literature of the main problem statement. Secondly, the authors should avoid using short paragraphs.
According to the 2015 FAO report,…. In reference to this statement, the citation style should follow the accepted journal style.
In this section, the authors should demonstrate the objectives and implication of this study to science
Methods
Study area description – The authors should refer to the journal guidelines instead of referring the writing to the thesis objectives
Calculation of SAR. In this section, the authors should refer to the journal citation style instead of using footnotes
- What was the justification to use data from 2021 and 2023? And why these parameters
- Which standard was followed to analyse laboratory data? Remove unnecessary appreciation of the department in the paper and shift to the acknowledgement section
- Page 5, line 142 – which FAO standard is this and for which year?
Results and Discussion
- Based on the presentation of results and discussion, I propose that the authors should separate between the result and discussion sections
- The discussion section of this paper is very weak and therefore, the authors should present new findings from the results
General comment
- Much as the data in the manuscript is publishable, the authors need to restructure the paper to meet international standards
Comments for author File: 
Comments.pdf
The quality of English is moderate and requires further improvement
Author Response
Cover Letter
Nilufar Rajabova
PhD Student, National University of Uzbekistan named after Mirzo Ulugbek
Tashkent, Uzbekistan
Email: ni.rajabova@nuu.uz
Phones: +998 93 203 75 32, +998 50 120 75 32
Dear Reviewer,
We are pleased to submit our manuscript titled ‘An Assessment of Collector-Drainage Water and
Groundwater – An Application of CCME WQI Model’ (ID: water - 3520276) for your consideration.
We appreciate the valuable feedback provided by the reviewers of the Water journal to improve the
quality of our manuscript and to correct its shortcomings. We have carefully reviewed all comments and
revised the manuscript accordingly. Below, we respond to each comment point by point.
1. We have changed the title of the article, in consultation with our team, from ‘An Assessment of
Collector-Drainage Water and Groundwater – An Application of CCME WQI Model’ to ‘An
Assessment of Collector-Drainage Water and Groundwater In the Amudarya Region of
Karakalpakstan – An Application of the CCME WQI Model’.
We decided to change the title to align the title with the content of the full article.
2. We have decided, in consultation with our team, to add one author to our article, namely the fifth
author. The reason is that we did not have enough time to fix the article in a timely manner. For
this reason, we have decided to add an author to the article.
3. By the first review, we made the following changes to the 'abstract' of the article:
Abstract
According to Victor Ernest Shelford’s ‘Law of Tolerance,’ organisms within ecosystems thrive optimally
when environmental conditions are favorable. Applying this principle to ecosystems and agro
ecosystems facing water scarcity or environmental challenges can significantly enhance their
productivity. In these ecosystems, phytocenosis adjusts its conditions by utilizing water with varying
salinity levels. Moreover, establishing optimal drinking water conditions for human populations within
an ecosystem can help mitigate future negative succession processes.
The purpose of this study is to evaluate the quality of two distinct water sources in the Amudarya district
of the Republic of Karakalpakstan, Uzbekistan: collector-drainage water and groundwater at depths of 10
to 25 meters.
The research is highly relevant in the context of climate change, as improper management of water
salinity, particularly collector-drainage water, may exacerbate soil salinization and degrade drinking
water quality.
The primary methodology of the study is as follows: The Food and Agriculture Organization of the
United Nations (FAO) standard for collector-drainage water was applied, and the water quality index
was assessed using the CCME WQI model.
The Canadian Council of Ministers of the Environment (CCME) model was adapted to assess
groundwater quality using Uzbekistan's national drinking water quality standards.
The results of two years of collected data, i.e., 2021 and 2023, show that the collector-drainage water
quality index has limited potential for use as secondary water for irrigation of sensitive crops and has
been classified as "poor".
As a result, salinity increased by 8.33% by 2023. In contrast, groundwater quality was rated as ‘Fair’ in
2021, showing slight deterioration by 2023.
The study highlights the need for using organic fertilizers in agriculture to protect drinking water quality,
improve crop yields, and promote soil health while reducing reliance on chemical inputs. Furthermore,
adopting WQI models under changing climatic conditions can improve agricultural productivity,
enhance groundwater quality, and provide better environmental monitoring systems.
4. We have revised the 'introduction' section based on the suggestions and comments made in the
'first review' and have stated it as follows:
1. Introduction
The quality of water resources in Central Asian countries is primarily influenced by geological, abiotic
factors such as rainfall, and anthropogenic activities, particularly agriculture. In several regions within
this vast ecosystem, the scarcity of water resources necessitates continuous monitoring and protection of
surface and groundwater. Groundwater, often found at depths of 10-25 meters in arid ecosystems, plays a
critical role in supporting the adaptation of living organisms [1-9]. Given that Central Asia is
predominantly an agricultural region, the rational use and improved condition of water and soil
resources demand constant observation. For instance, approximately 70% of irrigated land in Uzbekistan
is affected by salinity, which poses a significant challenge for sustainable agricultural practices [10-17].
Previous research highlights that soil salinity has escalated, partly due to the use of groundwater for
irrigation in agricultural lands [18, 19, 10, 12, 20, 21].
In 2008, 17.4% of a total of 743.5 thousand hectares of land, and 27.5% of 1,182.9 thousand hectares in
2010, were affected by high groundwater levels, with the water table rising to within 1-2 meters of the soil
surface. This issue is often exacerbated when groundwater seepage occurs near the surface [7, 22-24].
In 2023, the State Committee for Land Resources, Geodesy, Cartography, and State Cadastres of
Uzbekistan reported that 46.6% of irrigated land was saline, with 2.5% classified as strongly saline, 13.3%
as moderately saline, and 30% as slightly saline.
The salinity and mineral content of the studied water bodies - collector-drainage waters and groundwater
at a depth of 10-25 meters - are increasing, primarily due to anthropogenic factors, namely agricultural
activities [6, 10, 16].
The Ministry of Water Management of Uzbekistan (MoWR) also reported that in 2023, the Amudarya
district of the Republic of Karakalpakstan had a total of 39,515 hectares of irrigated land, with 70.6%
classified as saline. This area included 2.5% highly saline land, 35% moderately saline cropland, and
33.1% slightly saline land.
In this ecosystem, the proximity of groundwater, Quaternary deposits, and agricultural practices are key
factors influencing the mineralization of underground drinking water. Significant amounts of salt
accumulate in the upper soil layers due to evaporation caused by seepage waters, resulting in severe
salinization of soil resources. This process is further aggravated by the crystallization of salts on the soil
surface, primarily driven by sodium (Na⁺) ions, which impede water infiltration [25, 10-17, 26].
The Quaternary deposits in the Amudarya delta, consisting of sand and soil, allow for easy surface water
transfer, further contributing to the salinization problem [11-15].
Improper management of open drains in agricultural landscapes can raise groundwater levels, leading to
secondary salinization of cultivated areas. Groundwater resources in Uzbekistan have decreased by 40%
between 1965 and 2002 due to overuse, and in the arid western and southern regions, groundwater
consumption has exceeded sustainable limits. This overexploitation has exacerbated water scarcity in
these regions, a problem that persists today [10, 12-15].
Additionally, the discharge of collector-drainage waters into river ecosystems, combined with the misuse
of chemicals in agriculture, has further degraded groundwater quality [24, 17].
Consequently, clean underground water used for drinking purposes in regions such as Bukhara,
Khorezm, and the Republic of Karakalpakstan no longer meets GOST standards for potable water [18, 22,
10-13, 15].
Increased soil salinity severely degrades soil quality and reduces crop productivity. The rise in salinity,
particularly during the crop growing season, delays yields and decreases agricultural output [1, 3, 11].
Soil salinity has become a major environmental issue in Central Asia, severely impacting agriculture and
soil quality. The area of saline soils in the region covers almost 91.5 million hectares. The most severe
cases of the problem occur in the south of the Republic of Kazakhstan, the Republics of Uzbekistan and
Turkmenistan. This increase in salinity is largely due to the drying up of the Aral Sea and unsustainable
agricultural irrigation practices. These factors have led to a rise in salt accumulation in the soil, reducing
soil fertility and crop yields, which threatens food security in the region. Addressing this issue requires
sustainable farming and water management strategies to prevent further degradation [27, 28, 10].
On a global scale, soil salinity has rendered 20% of irrigated land across more than 100 countries
unusable, with this figure continuing to rise due to climate change [15, 29].
This study focuses on the collector-drainage waters and underground drinking water affected by salt
washing practices in agricultural fields within the agrocenoses of the Republic of Karakalpakstan.
The two main research objects identified in the study, namely the first object - collector-drainage water
and the second object - groundwater, are located in the Amudarya region in the southern part of
Karakalpakstan, Uzbekistan.
The Amudarya district is located in the southwestern part of Uzbekistan, covering an area of 1,020 square
kilometers. The climate is sharply continental, characterized by significant temperature variations
between winter and summer. In January, the average temperature drops to between -16°C and −20°C,
while in July, it rises to between 27°C and 32°C. The annual precipitation is very low and averages 100
110 mm. This causes the formation of dry climatic conditions in this region. Geographically, the district is
situated at 39°13'30″ north latitude and 64°41'02″ east longitude *30+.
The region experiences highly variable climatic conditions and is primarily focused on agricultural
production. A large amount of cotton and wheat is grown in the agrocenoses. Given these conditions,
there is a constant need to wash away the salts that accumulate in the upper layers of the soil.
1.1. Aims and Objectives of the Study
The main aim of this study is to assess the water quality index of surface and groundwater in the
Amudarya region of the Republic of Karakalpakstan. The objectives of the study are as follows:
1. To evaluate the salinity levels of collector-drainage and groundwater.
2. To analyze the changes in water quality during the phenological phases of agro-cenoses.
3. Assessment of water quality of two research sites according to FAO and WHO standards using the
CCME WQI model;
4. Develop recommendations based on the results of the research.
1.2. Statement of problem
The Amudarya region of Karakapakstan is experiencing significant challenges with water quality in both
collector-drainage water and groundwater, which are critical for agricultural productivity and safe
drinking water. However, there is insufficient understanding of the current status and trends of water
quality in this region, particularly under the impacts of irrigation practices, climatic variations, and
chemical inputs. The existing water quality data lacks comprehensive analysis using standard models,
making it difficult to accurately assess and manage water quality. This study aims to apply the Canadian
Council of Ministers of the Environment Water Quality Index (CCME WQI) model to assess the water
quality of collector-drainage water and groundwater, providing a clear understanding of their status,
identifying critical pollutants, and suggesting sustainable management practices.
1.3. Justification for the study
The Amudarya region of Karakalpakstan is a critical agricultural zone heavily dependent on collector
drainage water and groundwater for irrigation. However, the increasing use of chemical fertilizers,
climate variability, and inefficient irrigation practices have raised concerns about the quality of these
water sources. Given that water quality is directly linked to crop productivity, human health, and
ecological sustainability, it is essential to have a clear understanding of its current status.
While water quality monitoring is conducted in the region, the available data is often scattered, lacks
standardization, and provides limited insight into the overall water quality. The application of the
Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) model in this
study is justified as it provides a standardized, comprehensive, and easily interpretable assessment of
water quality.
This study will not only identify the current status of water quality but also highlight the major pollutants
affecting it and propose sustainable management practices. Such information is critical for policymakers,
water resource managers, and local farmers to ensure the sustainable use of water resources in the
Amudarya region.
1.4. Research questions
1. What is the current quality of collector-drainage water and groundwater in the Amudarya region
of Karakalpakstan based on the CCME WQI model?
2. What are the main pollutants affecting the quality of these water sources?
3. How do seasonal variations and agricultural practice influence the water quality of collector
drainage water and groundwater?
4.
What sustainable water management practices can be recommended based on the assessment
findings?
1.5. Research significance
Water quality is a critical aspect of environmental sustainability, human health, and agricultural
productivity. In regions dependent on irrigation, such as the Amudarya region of Karakalpakstan,
understanding water quality dynamics is essential due to the heavy reliance on surface and groundwater
resources for agricultural practices. Collector-drainage water, primarily derived from irrigation activities,
and groundwater are the two primary water sources in this region. However, both sources face
significant threats from significant threats from salinity, nutrient contamination, and chemical residues
resulting from intensive agricultural practices.
Despite the importance of these water resources, there is insufficient understanding of their current status
and trends, particularly under the impact of irrigation, climate variability, and the use of chemical inputs.
Conventional water quality monitoring often provides fragmented data, making it difficult to assess the
overall health of these water bodies and develop effective management strategies.
To address this gap, this study applies the Canadian Council of Ministers of the Environment Water
Quality Index (CCME WQI) model to assess the water quality of collector-drainage water and
groundwater in the Amudarya region. The CCME WQI model offers a standardized approach to
evaluating water quality by incorporating multiple parameters into a single, easy-to-interpret index.
Through this approach, this study aims to provide a clear understanding of the current water quality
status, identify critical pollutants, and recommend sustainable water management practices to ensure the
long-term viability of water resources in the region.
5. The following amendments have been made to the Methodological section and its paragraphs:
2. Materials and methods
2.1. Studying area and Laboratory methods
Naturally, the quality of collector-drainage water is often very poor. This is because such water is
primarily used in agriculture to improve the soil conditions of crop fields through the ‘salt-washing
method’ by farmers or local populations. At times, when there is a shortage of surface water for
irrigation, this water is typically used as an alternative. However, before using it, it is crucial to assess the
water quality. Based on this assessment, measures to improve the water quality are then implemented.
This study covers two years, 2021 and 2023. Since the results of groundwater samples collected in 2022
were almost the same as those in 2021, the data for this year 2022 were excluded. In order to clearly
distinguish significant differences between the annual groundwater sample data in the statistical analysis,
the data for this year 2022 were not included in this study. To make the annual data of the two facilities
the same, the data for collector-drainage water in 2022 were also not included.
Field studies were conducted to study the water composition of the two sites. In addition, data from the
district sanitation and land reclamation departments were also used to collect sufficient data.
Collector-drainage water samples were taken monthly from a pond located in the area and analyzed in
the Reclamation Expedition Laboratory and the Sanitary Hygiene Laboratory. Water samples were taken
horizontally from the pond using special devices with grippers. 1-liter glass bottles were used to collect
water samples. Groundwater samples were collected from a total of 12 observation wells located in the
area. Water samples were taken vertically from the wells. 1-liter sterilized plastic bottles were used to
collect samples. The map shown in Figure 1 below shows the geographical location of the Amudarya
district and the two study sites from which water samples were taken.
The research was used laboratory analysis data on a total of 9 quality indicators of the collector-drainage
water (EC, НСО₃⁻, Cl⁻, SO₄²⁻, Ca²⁺, Mg²⁺, Na⁺, SAR, SAR (EC)).
Water quality was analyzed for a total of 9 physico-chemical indicators of groundwater (TH, Cl⁻, SO₄²⁻,
TDS, F⁻, Fe²⁺, NO₃⁻, Cu²⁺, pH). These indicators in the composition of the two types of water are important
in determining the overall quality of the water.
We sincerely appreciate your time and consideration. Please let us know if any further revisions are
needed.
Best regards,
Nilufar Rajabova
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe article entitled "An Assessment of Collector-Drainage Water and Groundwater–An Application of CCME WQI Model” written by Rajabova et al. investigates the quality assessment of two distinct water sources in the Amu Darya district of the Republic of Karakalpakstan, Uzbekistan: collector-drainage water and groundwater at depths varying between 10 and 20 meters. Water quality analysis was conducted using the Canadian Council of Ministers of the Environment Water Quality Index, where it was adapted to the specific conditions of Uzbekistan. In addition to water quality issues due to soil salinization problems, the research results were also related to the climate change impacts, and the potential to improve agricultural productivity, water quality and environmental monitoring systems.
In general, the study demonstrates an interesting study on water quality analysis with detailed assessments on the adaptation of Water Quality Index in the region. The methods are appropriate and results are reasonable. Results are demonstrated with clear illustrations and tables. Regarding the English language, some minor corrections might be necessary. Some modifications are required as detailed below.
Some specific comments:
- The main goal and focus of the study needs to be mentioned at the end of the Introduction part. Also, the scientific contribution needs to be stated very clearly based on what has been reported in the literature and explaining the gap the study fills beyond what has been accomplished so far.
- Line 97: the reason or justification behind selecting the two primary study sites (referred to as Object 1 and Object 2) may need to be stated.
- Lines 99-100: the details on the procedure for taking groundwater samples need to be mentioned.
-Lines 109-110: the details on analytical measurement of the water quality parameters (including instrument type, model) needs to be mentioned.
- Lines 155-168: the details on the procedure for converting ion concentrations to milliequivalents per liter (mEq/L) may not be necessary, as it is straightforward and therefore citation to an appropriate reference might be sufficient.
- The materials and methods section needs to incorporate appropriate references
- Lines 309-310: Some explanation on the reason for why TDS and TH among other indicators showed the most increasing trend can be provided.
Comments on the Quality of English LanguageSome minor modifications in English language is required.
Author Response
Cover Letter
Nilufar Rajabova
PhD Student, National University of Uzbekistan named after Mirzo Ulugbek
Tashkent, Uzbekistan
Email: ni.rajabova@nuu.uz
Phones: +998 93 203 75 32, +998 50 120 75 32
Dear Reviewer,
We sincerely thank you for your valuable time and constructive comments regarding our manuscript
entitled ‘An Assessment of Collector-Drainage Water and Groundwater –An Application of CCME WQI
Model’. Your suggestions have been extremely helpful in improving the quality and clarity of our paper.
Below, we provide a point-by-point response to each of your comments and indicate the corresponding
changes made in the revised manuscript.
1. Taking into account the suggestions and comments made in the ‘Second Review’, the following
changes were made to the introduction of the manuscript:
1. Introduction
The quality of water resources in Central Asian countries is primarily influenced by geological, abiotic
factors such as rainfall, and anthropogenic activities, particularly agriculture. In several regions within
this vast ecosystem, the scarcity of water resources necessitates continuous monitoring and protection of
surface and groundwater. Groundwater, often found at depths of 10-25 meters in arid ecosystems, plays a
critical role in supporting the adaptation of living organisms [1-9]. Given that Central Asia is
predominantly an agricultural region, the rational use and improved condition of water and soil
resources demand constant observation. For instance, approximately 70% of irrigated land in Uzbekistan
is affected by salinity, which poses a significant challenge for sustainable agricultural practices [10-17].
Previous research highlights that soil salinity has escalated, partly due to the use of groundwater for
irrigation in agricultural lands [18, 19, 10, 12, 20, 21].
In 2008, 17.4% of a total of 743.5 thousand hectares of land, and 27.5% of 1,182.9 thousand hectares in
2010, were affected by high groundwater levels, with the water table rising to within 1-2 meters of the soil
surface. This issue is often exacerbated when groundwater seepage occurs near the surface [7, 22-24].
In 2023, the State Committee for Land Resources, Geodesy, Cartography, and State Cadastres of
Uzbekistan reported that 46.6% of irrigated land was saline, with 2.5% classified as strongly saline, 13.3%
as moderately saline, and 30% as slightly saline.
The salinity and mineral content of the studied water bodies - collector-drainage waters and groundwater
at a depth of 10-25 meters - are increasing, primarily due to anthropogenic factors, namely agricultural
activities [6, 10, 16].
The Ministry of Water Management of Uzbekistan (MoWR) also reported that in 2023, the Amudarya
district of the Republic of Karakalpakstan had a total of 39,515 hectares of irrigated land, with 70.6%
classified as saline. This area included 2.5% highly saline land, 35% moderately saline cropland, and
33.1% slightly saline land.
In this ecosystem, the proximity of groundwater, Quaternary deposits, and agricultural practices are key
factors influencing the mineralization of underground drinking water. Significant amounts of salt
accumulate in the upper soil layers due to evaporation caused by seepage waters, resulting in severe
salinization of soil resources. This process is further aggravated by the crystallization of salts on the soil
surface, primarily driven by sodium (Na⁺) ions, which impede water infiltration [25, 10-17, 26].
The Quaternary deposits in the Amudarya delta, consisting of sand and soil, allow for easy surface water
transfer, further contributing to the salinization problem [11-15].
Improper management of open drains in agricultural landscapes can raise groundwater levels, leading to
secondary salinization of cultivated areas. Groundwater resources in Uzbekistan have decreased by 40%
between 1965 and 2002 due to overuse, and in the arid western and southern regions, groundwater
consumption has exceeded sustainable limits. This overexploitation has exacerbated water scarcity in
these regions, a problem that persists today [10, 12-15].
Additionally, the discharge of collector-drainage waters into river ecosystems, combined with the misuse
of chemicals in agriculture, has further degraded groundwater quality [24, 17].
Consequently, clean underground water used for drinking purposes in regions such as Bukhara,
Khorezm, and the Republic of Karakalpakstan no longer meets GOST standards for potable water [18, 22,
10-13, 15].
Increased soil salinity severely degrades soil quality and reduces crop productivity. The rise in salinity,
particularly during the crop growing season, delays yields and decreases agricultural output [1, 3, 11].
Soil salinity has become a major environmental issue in Central Asia, severely impacting agriculture and
soil quality. The area of saline soils in the region covers almost 91.5 million hectares. The most severe
cases of the problem occur in the south of the Republic of Kazakhstan, the Republics of Uzbekistan and
Turkmenistan. This increase in salinity is largely due to the drying up of the Aral Sea and unsustainable
agricultural irrigation practices. These factors have led to a rise in salt accumulation in the soil, reducing
soil fertility and crop yields, which threatens food security in the region. Addressing this issue requires
sustainable farming and water management strategies to prevent further degradation [27, 28, 10].
On a global scale, soil salinity has rendered 20% of irrigated land across more than 100 countries
unusable, with this figure continuing to rise due to climate change [15, 29].
This study focuses on the collector-drainage waters and underground drinking water affected by salt
washing practices in agricultural fields within the agrocenoses of the Republic of Karakalpakstan.
The two main research objects identified in the study, namely the first object - collector-drainage water
and the second object - groundwater, are located in the Amudarya region in the southern part of
Karakalpakstan, Uzbekistan.
The Amudarya district is located in the southwestern part of Uzbekistan, covering an area of 1,020 square
kilometers. The climate is sharply continental, characterized by significant temperature variations
between winter and summer. In January, the average temperature drops to between -16°C and −20°C,
while in July, it rises to between 27°C and 32°C. The annual precipitation is very low and averages 100
110 mm. This causes the formation of dry climatic conditions in this region. Geographically, the district is
situated at 39°13'30″ north latitude and 64°41'02″ east longitude *30+.
The region experiences highly variable climatic conditions and is primarily focused on agricultural
production. A large amount of cotton and wheat is grown in the agrocenoses. Given these conditions,
there is a constant need to wash away the salts that accumulate in the upper layers of the soil.
1.1. Aims and Objectives of the Study
The main aim of this study is to assess the water quality index of surface and groundwater in the
Amudarya region of the Republic of Karakalpakstan. The objectives of the study are as follows:
1. To evaluate the salinity levels of collector-drainage and groundwater.
2. To analyze the changes in water quality during the phenological phases of agro-cenoses.
3. Assessment of water quality of two research sites according to FAO and WHO standards using the
CCME WQI model;
4. Develop recommendations based on the results of the research.
1.2. Statement of problem
The Amudarya region of Karakapakstan is experiencing significant challenges with water quality in both
collector-drainage water and groundwater, which are critical for agricultural productivity and safe
drinking water. However, there is insufficient understanding of the current status and trends of water
quality in this region, particularly under the impacts of irrigation practices, climatic variations, and
chemical inputs. The existing water quality data lacks comprehensive analysis using standard models,
making it difficult to accurately assess and manage water quality. This study aims to apply the Canadian
Council of Ministers of the Environment Water Quality Index (CCME WQI) model to assess the water
quality of collector-drainage water and groundwater, providing a clear understanding of their status,
identifying critical pollutants, and suggesting sustainable management practices.
1.3. Justification for the study
The Amudarya region of Karakalpakstan is a critical agricultural zone heavily dependent on collector
drainage water and groundwater for irrigation. However, the increasing use of chemical fertilizers,
climate variability, and inefficient irrigation practices have raised concerns about the quality of these
water sources. Given that water quality is directly linked to crop productivity, human health, and
ecological sustainability, it is essential to have a clear understanding of its current status.
While water quality monitoring is conducted in the region, the available data is often scattered, lacks
standardization, and provides limited insight into the overall water quality. The application of the
Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) model in this
study is justified as it provides a standardized, comprehensive, and easily interpretable assessment of
water quality.
This study will not only identify the current status of water quality but also highlight the major pollutants
affecting it and propose sustainable management practices. Such information is critical for policymakers,
water resource managers, and local farmers to ensure the sustainable use of water resources in the
Amudarya region.
1.4. Research questions
1. What is the current quality of collector-drainage water and groundwater in the Amudarya region
of Karakalpakstan based on the CCME WQI model?
2. What are the main pollutants affecting the quality of these water sources?
3. How do seasonal variations and agricultural practice influence the water quality of collector
drainage water and groundwater?
4.
What sustainable water management practices can be recommended based on the assessment
findings?
1.5. Research significance
Water quality is a critical aspect of environmental sustainability, human health, and agricultural
productivity. In regions dependent on irrigation, such as the Amudarya region of Karakalpakstan,
understanding water quality dynamics is essential due to the heavy reliance on surface and groundwater
resources for agricultural practices. Collector-drainage water, primarily derived from irrigation activities,
and groundwater are the two primary water sources in this region. However, both sources face
significant threats from significant threats from salinity, nutrient contamination, and chemical residues
resulting from intensive agricultural practices.
Despite the importance of these water resources, there is insufficient understanding of their current status
and trends, particularly under the impact of irrigation, climate variability, and the use of chemical inputs.
Conventional water quality monitoring often provides fragmented data, making it difficult to assess the
overall health of these water bodies and develop effective management strategies.
To address this gap, this study applies the Canadian Council of Ministers of the Environment Water
Quality Index (CCME WQI) model to assess the water quality of collector-drainage water and
groundwater in the Amudarya region. The CCME WQI model offers a standardized approach to
evaluating water quality by incorporating multiple parameters into a single, easy-to-interpret index.
Through this approach, this study aims to provide a clear understanding of the current water quality
status, identify critical pollutants, and recommend sustainable water management practices to ensure the
long-term viability of water resources in the region.
2. The process of collecting water samples is inherently complex and requires caution. The article
describes the process of collecting water samples as follows:
2. Materials and methods
2.1. Studying area and Laboratory methods
Naturally, the quality of collector-drainage water is often very poor. This is because such water is
primarily used in agriculture to improve the soil conditions of crop fields through the ‘salt-washing
method’ by farmers or local populations. At times, when there is a shortage of surface water for
irrigation, this water is typically used as an alternative. However, before using it, it is crucial to assess the
water quality. Based on this assessment, measures to improve the water quality are then implemented.
This study covers two years, 2021 and 2023. Since the results of groundwater samples collected in 2022
were almost the same as those in 2021, the data for this year 2022 were excluded. In order to clearly
distinguish significant differences between the annual groundwater sample data in the statistical analysis,
the data for this year 2022 were not included in this study. To make the annual data of the two facilities
the same, the data for collector-drainage water in 2022 were also not included.
Field studies were conducted to study the water composition of the two sites. In addition, data from the
district sanitation and land reclamation departments were also used to collect sufficient data.
Collector-drainage water samples were taken monthly from a pond located in the area and analyzed in
the Reclamation Expedition Laboratory and the Sanitary Hygiene Laboratory. Water samples were taken
horizontally from the pond using special devices with grippers. 1-liter glass bottles were used to collect
water samples. Groundwater samples were collected from a total of 12 observation wells located in the
area. Water samples were taken vertically from the wells. 1-liter sterilized plastic bottles were used to
collect samples. The map shown in Figure 1 below shows the geographical location of the Amudarya
district and the two study sites from which water samples were taken.
The research was used laboratory analysis data on a total of 9 quality indicators of the collector-drainage
water (EC, НСО₃⁻, Cl⁻, SO₄²⁻, Ca²⁺, Mg²⁺, Na⁺, SAR, SAR (EC)).
Water quality was analyzed for a total of 9 physico-chemical indicators of groundwater (TH, Cl⁻, SO₄²⁻,
TDS, F⁻, Fe²⁺, NO₃⁻, Cu²⁺, pH). These indicators in the composition of the two types of water are important
in determining the overall quality of the water.
3. Since the process of analyzing water samples in the laboratory involves a large number of methods,
we have limited ourselves to citing data or standards that provide techniques and methods for
processing water in the laboratory for each indicator, in order not to lose sight of the main parts of the
article. That is, it was limited to providing quotes. Below are the methods for analyzing water samples
in the laboratory for each quality indicator:
2. Materials and methods
2.1. Studying area and Laboratory methods
Naturally, the quality of collector-drainage water is often very poor. This is because such water is
primarily used in agriculture to improve the soil conditions of crop fields through the ‘salt-washing
method’ by farmers or local populations. At times, when there is a shortage of surface water for
irrigation, this water is typically used as an alternative. However, before using it, it is crucial to assess the
water quality. Based on this assessment, measures to improve the water quality are then implemented.
This study covers two years, 2021 and 2023. Since the results of groundwater samples collected in 2022
were almost the same as those in 2021, the data for this year 2022 were excluded. In order to clearly
distinguish significant differences between the annual groundwater sample data in the statistical analysis,
the data for this year 2022 were not included in this study. To make the annual data of the two facilities
the same, the data for collector-drainage water in 2022 were also not included.
Field studies were conducted to study the water composition of the two sites. In addition, data from the
district sanitation and land reclamation departments were also used to collect sufficient data.
Collector-drainage water samples were taken monthly from a pond located in the area and analyzed in
the Reclamation Expedition Laboratory and the Sanitary Hygiene Laboratory. Water samples were taken
horizontally from the pond using special devices with grippers. 1-liter glass bottles were used to collect
water samples. Groundwater samples were collected from a total of 12 observation wells located in the
area. Water samples were taken vertically from the wells. 1-liter sterilized plastic bottles were used to
collect samples. The map shown in Figure 1 below shows the geographical location of the Amudarya
district and the two study sites from which water samples were taken.
The research was used laboratory analysis data on a total of 9 quality indicators of the collector-drainage
water (EC, НСО₃⁻, Cl⁻, SO₄²⁻, Ca²⁺, Mg²⁺, Na⁺, SAR, SAR (EC)).
Water quality was analyzed for a total of 9 physico-chemical indicators of groundwater (TH, Cl⁻, SO₄²⁻,
TDS, F⁻, Fe²⁺, NO₃⁻, Cu²⁺, pH). These indicators in the composition of the two types of water are important
in determining the overall quality of the water.
Below is a brief description of the main reagents and instruments used to determine parameters in the
composition of collector-drainage water in a laboratory setting, for a 1-liter volume.
1. EC: Determined using a Conductometer [31, 32].
2. HCO₃⁻: Determined by titration with sodium bicarbonate (NaHCO₃) or sodium sulfate (Na₂SO₄) [33].
3. Cl⁻: Determined by titration with silver nitrate (AgNO₃) [34].
4. SO₄²⁻: Two drops of methyl orange (C₁₇H₁₉N₃O₂) and 2 N hydrochloric acid (HCl) are added, the
mixture is boiled, then 10% barium chloride (BaCl₂) is added, and the solution is kept for one day.
Afterward, it is boiled with distilled water (H₂O), washed five times, filtered through filter paper, and
then placed in a crucible and ignited in a muffle furnace [35].
5. Ca²⁺ and Mg²⁺: Determined by titration with Trilon B (Na₃C₆H₅O₇).
6. Na⁺: Several methods are available for determining sodium ions. Among them, flame photometry, ion
selective electrodes (ISE), and caprotozel-colorimetric methods are commonly used. In flame photometry,
sodium ions are atomized in the flame, and their spectral lines are measured to determine concentration.
In the ISE method, a specific electrode measures the potential difference of sodium ions. In the
caprotozel-colorimetric method, sodium ions react with colored reagents, causing a color change that is
used to determine their concentration [36].
3. Minor changes have been made to the SAR calculation:
2.2. Calculation of SAR
The sodium adsorption ratio (SAR) is a key parameter for evaluating the potential impact of irrigation
water on soil structure. High SAR levels lead to increased sodium accumulation in the soil, which
adversely affects soil infiltration and percolation, thereby causing soil compaction and reduced aeration,
both of which are detrimental to plant health. In addition, electrical conductivity (ECw) and total
dissolved solids (TDS) are critical for assessing salt-related risks in water. While a high ECw can help
mitigate the adverse effects of sodium, it simultaneously deteriorates overall water quality *1-3, 37+.
When converting ion concentrations from mg/L to milliequivalents per liter (mEq/L), the process involves
using the atomic masses and valence of each ion, as listed in Dmitry Mendeleev’s periodic table. The
calculation method entails dividing the ion’s concentration (in mg/L) by its atomic mass and valence,
which allows for standardized comparison with laboratory results.
This procedure can be outlined as follows:
1. Determine the atomic mass and valence of each ion based on Mendeleev’s periodic table.
2. Divide the ion concentration (mg/L) by its corresponding atomic mass to obtain the value in
equivalents.
3. Adjust for valence by dividing by the ion's valence to convert the result to mEq/L. This method ensures
accurate comparison with laboratory-derived values and aligns the results with international standards
for water quality analysis *37+.
e.g. НСО3⁻ (mEq/L) = (1/61.02) × 311.1 = 5.10
4. The article responded to the comments about TH and TDS indicators as follows:
2.3.2. Groundwater quality indicators
In the assessment of groundwater quality, not only the chemical composition but also the
hydrogeological conditions play a crucial role. In particular, there is a strong correlation between water
table elevation, soil moisture, and the degree of salinization. In saline soils, when the water table is close
to the surface, salts tend to rise through capillary action, leading to soil degradation and a deterioration in
groundwater quality.
In the study, groundwater samples were taken from wells located at depths ranging from 10 to 25 meters
below the surface. A comparison between the water samples taken at 10 meters and those from 25 meters
revealed significant differences. It became evident that as the depth of groundwater increases, the water
quality tends to improve. However, this is accompanied by a parallel increase in water mineralization *39,
40+.
Total hardness (TH):
The total hardness (TH) of drinking water significantly influences both its quality and practical use in
daily life. TH is primarily determined by the concentrations of calcium (Ca²⁺) and magnesium (Mg²⁺) ions.
Elevated levels of these ions reduce soap lathering efficiency and lead to the formation of scale deposits in
pipes and heating systems, thereby decreasing the efficiency of heat exchange processes. Conversely,
excessively soft water (very low hardness) can induce corrosion in metal pipelines, increasing the risk of
heavy metals such as lead and copper leaching into the drinking water *41+.
Total dissolved solids (TDS):
The concentration of total dissolved solids (TDS) in drinking water directly affects its taste, quality, and
safety. TDS primarily consists of beneficial ions such as calcium, magnesium, sodium, and potassium.
However, when present in concentrations exceeding recommended limits (typically above 1000 mg/L),
elevated TDS levels may indicate contamination from anthropogenic sources such as agricultural runoff
and the excessive use of fertilizers. High TDS not only deteriorates the organoleptic properties of water
(taste and odor) but also contributes to the formation of scale deposits in heating systems and may
increase the presence of harmful heavy metals, such as nitrates or lead, posing potential health risks *42+.
Sulfate ions (SO₄²⁻):
High concentrations of sulfate in drinking water are considered hazardous to human health. When
sulfate levels exceed 500 mg/L, they can cause health issues such as diarrhea, nausea, and inflammation
of the intestines. Therefore, regularly monitoring the sulfate content in drinking water is crucial for
ensuring water quality and public health *43+.
Nitrate anions (NO₃⁻):
High nitrate concentrations in drinking water pose significant health risks, especially in agricultural
regions. Elevated nitrate levels can lead to methemoglobinemia (blue baby syndrome), cancer, and other
adverse health effects. Therefore, continuous monitoring of nitrate levels in drinking water is crucial to
ensure public health safety *44+.
Copper cations (Cu²⁺):
High concentrations of copper in drinking water can lead to health issues such as gastrointestinal
problems, liver, and kidney damage. However, low concentrations of copper are beneficial for the body,
supporting the activity of metalloenzymes and proteins *45+.
Iron cations (Fe²⁺):
Elevated concentrations of iron in water do not pose an immediate direct health risk; however, they may
increase water hardness, which can cause issues in daily use. Increased iron levels can interact with other
minerals in the water, potentially disrupting the mineral balance in the human body. Additionally,
excessive iron intake may lead to gastrointestinal issues, including problems in the stomach and
intestines *46+.
We hope that the revisions and explanations provided meet your expectations. Once again, thank you for
your constructive feedback, which has significantly contributed to improving the quality of our
manuscript.
Sincerely,
Nilufar Rajabova
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe topic of this paper is of great interest for the management of groundwater resources. The results are presented clearly and are convincing. However, before it can be published, the following issue should be addressed:
- the management of groundwater from the qualitative point of view is essential. The procedure proposed by the Authors is correct. However, the role of the water table elevation is not mentioned at all in the manuscript. I do not want to forse the Authors to report water table elevation data, that could be correlated with quality data, but such a feature should be mentioned at least. In this perspective, the value of soil moisture close to the water table is relevant, particularly when unconfined aquifers. In fact, in a recent paper [a], it has been shown that soil moisture data can be correlated with water table elevation. In particular, data from Copernicus archive, that are open access, allow to evaluate this feature in any part of the world. I do hope this suggestion may be of interest for the Authors to point out the relevance of the water table elevation data in the groundwater management.
[a] Bongioannini Cerlini, P., Silvestri, L., Meniconi, S., and Brunone, B. (2021). Simulation of the water table elevation in shallow unconfined aquifers by means of the ERA5 soil moisture dataset. The Umbria region case study. Earth Interactions, 25(1), 15-32 (doi: 10.1175/EI-D-20-0011.1).
Author Response
Cover Letter
Nilufar Rajabova
PhD Student, National University of Uzbekistan named after Mirzo Ulugbek
Tashkent, Uzbekistan
Email: ni.rajabova@nuu.uz
Phones: +998 93 203 75 32, +998 50 120 75 32
Dear Reviewer,
We are pleased to submit our manuscript titled ‘An Assessment of Collector-Drainage Water and
Groundwater – An Application of CCME WQI Model’ (ID: water - 3520276) for your consideration.
We appreciate the valuable feedback provided by the reviewers of the Water journal to improve the
quality of our manuscript and to correct its shortcomings. We have carefully reviewed all comments and
revised the manuscript accordingly. Below, we respond to each comment point by point.
1. We have changed the title of the article, in consultation with our team, from ‘An Assessment of
Collector-Drainage Water and Groundwater – An Application of CCME WQI Model’ to ‘An Assessment
of Collector-Drainage Water and Groundwater In the Amudarya Region of Karakalpakstan – An
Application of the CCME WQI Model’.
We decided to change the title to align the title with the content of the full article.
2. We have decided, in consultation with our team, to add one author to our article, namely the fifth
author. The reason is that we did not have enough time to fix the article in a timely manner. For this
reason, we have decided to add an author to the article.
1. Based on the ideas and considerations presented in the third review, we have provided a brief
general understanding of the importance of water table height (i.e., the depth of the groundwater table
and the quality of water formed in its part closer to the ground surface (water table elevation)) in a
paragraph in the methodological section of the article.
2.3.2. Groundwater quality indicators
In the assessment of groundwater quality, not only the chemical composition but also the
hydrogeological conditions play a crucial role. In particular, there is a strong correlation between water
table elevation, soil moisture, and the degree of salinization. In saline soils, when the water table is close
to the surface, salts tend to rise through capillary action, leading to soil degradation and a deterioration in
groundwater quality.
In the study, groundwater samples were taken from wells located at depths ranging from 10 to 25 meters
below the surface. A comparison between the water samples taken at 10 meters and those from 25 meters
revealed significant differences. It became evident that as the depth of groundwater increases, the water
quality tends to improve. However, this is accompanied by a parallel increase in water mineralization [39,
40].
Total hardness (TH):
The total hardness (TH) of drinking water significantly influences both its quality and practical use in
daily life. TH is primarily determined by the concentrations of calcium (Ca²⁺) and magnesium (Mg²⁺) ions.
Elevated levels of these ions reduce soap lathering efficiency and lead to the formation of scale deposits in
pipes and heating systems, thereby decreasing the efficiency of heat exchange processes. Conversely,
excessively soft water (very low hardness) can induce corrosion in metal pipelines, increasing the risk of
heavy metals such as lead and copper leaching into the drinking water [41].
Total dissolved solids (TDS):
The concentration of total dissolved solids (TDS) in drinking water directly affects its taste, quality, and
safety. TDS primarily consists of beneficial ions such as calcium, magnesium, sodium, and potassium.
However, when present in concentrations exceeding recommended limits (typically above 1000 mg/L),
elevated TDS levels may indicate contamination from anthropogenic sources such as agricultural runoff
and the excessive use of fertilizers. High TDS not only deteriorates the organoleptic properties of water
(taste and odor) but also contributes to the formation of scale deposits in heating systems and may
increase the presence of harmful heavy metals, such as nitrates or lead, posing potential health risks [42].
Sulfate ions (SO₄²⁻):
High concentrations of sulfate in drinking water are considered hazardous to human health. When
sulfate levels exceed 500 mg/L, they can cause health issues such as diarrhea, nausea, and inflammation
of the intestines. Therefore, regularly monitoring the sulfate content in drinking water is crucial for
ensuring water quality and public health [43].
Nitrate anions (NO₃⁻):
High nitrate concentrations in drinking water pose significant health risks, especially in agricultural
regions. Elevated nitrate levels can lead to methemoglobinemia (blue baby syndrome), cancer, and other
adverse health effects. Therefore, continuous monitoring of nitrate levels in drinking water is crucial to
ensure public health safety [44].
Copper cations (Cu²⁺):
High concentrations of copper in drinking water can lead to health issues such as gastrointestinal
problems, liver, and kidney damage. However, low concentrations of copper are beneficial for the body,
supporting the activity of metalloenzymes and proteins [45].
Iron cations (Fe²⁺):
Elevated concentrations of iron in water do not pose an immediate direct health risk; however, they may
increase water hardness, which can cause issues in daily use. Increased iron levels can interact with other
minerals in the water, potentially disrupting the mineral balance in the human body. Additionally,
excessive iron intake may lead to gastrointestinal issues, including problems in the stomach and
intestines [46].
Thank you for your review and constructive feedback on improving the quality of our manuscript.
Best regards,
Nilufar Rajabova
Author Response File: Author Response.pdf
