1- Faculty of Agriculture & Natural Resources, Ardakan University, Ardakan, Iran
2- Assistant Professor of Department of Nature Engineering, Faculty of Agriculture & Natural Resources, Ardakan University, P.O.Box 184, Ardakan, Iran.
3- Associate Professor of Department of Nature Engineering, Faculty of Agriculture & Natural Resources, Ardakan University, P.O.Box 184, Ardakan, Iran
2- Assistant Professor of Department of Nature Engineering, Faculty of Agriculture & Natural Resources, Ardakan University, P.O.Box 184, Ardakan, Iran.
3- Associate Professor of Department of Nature Engineering, Faculty of Agriculture & Natural Resources, Ardakan University, P.O.Box 184, Ardakan, Iran
Abstract: (29 Views)
Introduction and Objective
The Najaf-Abad region relies heavily on groundwater sources for agricultural, drinking, and industrial purposes due to insufficient rainfall and recurrent droughts. The Najaf-Abad aquifer is being exploited unsustainably, leading to a decline in both the quantity and quality of groundwater resources, as well as unregulated consumption by users in the basin. One of the primary reasons for the recent decrease in groundwater quantity and quality is the reduction in rainfall. Recent research has shown that climatic parameters such as temperature and precipitation have played a significant role, comparable to non-climatic factors, in the changes observed in the quality and quantity of groundwater in the Najaf-Abad plain. Therefore, investigating the temporal changes in groundwater quantity and quality alongside trends in climatic variables is crucial. The aim of this study is to analyze the temporal changes in groundwater quantity and quality using the Mann-Kendall test and Sen's slope estimator, as well as to examine the relationship between climatic parameters and groundwater quality trends.
Materials and Methods
The study area is the Najaf-Abad basin, covering approximately 1,712 square kilometers. The average annual rainfall and temperature at the Najaf-Abad synoptic station are 149 mm and 15°C, respectively. According to the Ghosen classification, the region has a severe semi-desert climate. In this study, non-parametric Mann-Kendall and Sen's slope tests were used to analyze temporal changes in groundwater quantity and quality, as well as climatic parameters in the Najaf-Abad plain. Data from 15 wells were used to assess trends in groundwater quality parameters (TH, EC, TDS, SAR, and SO₄²⁻), while data from 30 wells were used to evaluate groundwater level changes over the statistical period (2003–2022). The regression method was employed to address statistical deficiencies. Monthly average precipitation and temperature data from the Najaf-Abad synoptic station over a 19-year period (2003–2022) were used to determine trends in climatic elements.
Results
The results indicate that TH, EC, TDS, and SAR parameters have increased in most wells during the study period. The temporal trend of groundwater quality changes over the 21-year period shows a decline in water quality, with the most significant upward trends observed in EC and TDS. Among the 15 wells, the largest number of increasing trends was recorded in Vilashahr, Shrodan, and Siah-Afshar wells. The slope of the trend line for most qualitative parameters in these wells is upward, indicating an increase in the concentration of these parameters and a decline in groundwater quality. Among all the qualitative parameters, sulfate showed the highest number of downward trends. The Asgharabad well experienced a decline in quality for TH, EC, and TDS, with the steepest upward slope observed for EC in this well. The mean slope of the EC trend is positive at 11.364 µS/cm, adding approximately 113.64 µS/cm to water salinity every decade. The steepest downward slope was observed for TH in the East Polyacryl well. The groundwater level in 26 wells showed a decreasing trend, with the most significant decline observed in Well 22 located in the eastern part of the region. In contrast, Well 30 in the northern part of the region showed the most significant upward trend. The slope of the trend line for annual groundwater level changes was negative in 26 wells, with the steepest decline in Well 22. Overall, the number of wells with declining groundwater levels far exceeds those with increasing levels, indicating a general downward trend in groundwater levels in the Najaf-Abad plain. The most significant downward and upward trends in precipitation were observed in April and July, respectively. The slope of the precipitation trend line was downward in April, November, December, January, February, and March, while it was upward in May. The steepest and mildest downward slopes were observed in April and February, respectively. Given the downward trend in monthly rainfall for most months (7 months), it can be concluded that the overall trend of monthly rainfall in the Najaf-Abad plain is decreasing. The annual precipitation trend also shows a decline.
Conclusion
The upward trend in most qualitative parameters in the majority of wells indicates a decline in groundwater quality in the Najaf-Abad plain over the 21-year study period. Additionally, the groundwater level shows a general downward trend, highlighting a critical situation in the region. Urgent measures are necessary to prevent further environmental degradation. Both monthly and annual precipitation trends are decreasing, while monthly and annual temperature trends are increasing significantly. The temporal changes in precipitation and temperature align with the changes in groundwater quantity and quality, suggesting that reduced rainfall and increased temperatures are key factors contributing to the decline in groundwater resources, alongside management practices. Other environmental factors, such as land use changes, geological formations, soil characteristics, and human activities, may also influence groundwater quantity and quality, though this study focused solely on climatic factors. Given the declining groundwater quality, it is recommended that future research also consider the role of human factors, such as agricultural activities and land use, to develop strategies for improving groundwater resource management.
The Najaf-Abad region relies heavily on groundwater sources for agricultural, drinking, and industrial purposes due to insufficient rainfall and recurrent droughts. The Najaf-Abad aquifer is being exploited unsustainably, leading to a decline in both the quantity and quality of groundwater resources, as well as unregulated consumption by users in the basin. One of the primary reasons for the recent decrease in groundwater quantity and quality is the reduction in rainfall. Recent research has shown that climatic parameters such as temperature and precipitation have played a significant role, comparable to non-climatic factors, in the changes observed in the quality and quantity of groundwater in the Najaf-Abad plain. Therefore, investigating the temporal changes in groundwater quantity and quality alongside trends in climatic variables is crucial. The aim of this study is to analyze the temporal changes in groundwater quantity and quality using the Mann-Kendall test and Sen's slope estimator, as well as to examine the relationship between climatic parameters and groundwater quality trends.
Materials and Methods
The study area is the Najaf-Abad basin, covering approximately 1,712 square kilometers. The average annual rainfall and temperature at the Najaf-Abad synoptic station are 149 mm and 15°C, respectively. According to the Ghosen classification, the region has a severe semi-desert climate. In this study, non-parametric Mann-Kendall and Sen's slope tests were used to analyze temporal changes in groundwater quantity and quality, as well as climatic parameters in the Najaf-Abad plain. Data from 15 wells were used to assess trends in groundwater quality parameters (TH, EC, TDS, SAR, and SO₄²⁻), while data from 30 wells were used to evaluate groundwater level changes over the statistical period (2003–2022). The regression method was employed to address statistical deficiencies. Monthly average precipitation and temperature data from the Najaf-Abad synoptic station over a 19-year period (2003–2022) were used to determine trends in climatic elements.
Results
The results indicate that TH, EC, TDS, and SAR parameters have increased in most wells during the study period. The temporal trend of groundwater quality changes over the 21-year period shows a decline in water quality, with the most significant upward trends observed in EC and TDS. Among the 15 wells, the largest number of increasing trends was recorded in Vilashahr, Shrodan, and Siah-Afshar wells. The slope of the trend line for most qualitative parameters in these wells is upward, indicating an increase in the concentration of these parameters and a decline in groundwater quality. Among all the qualitative parameters, sulfate showed the highest number of downward trends. The Asgharabad well experienced a decline in quality for TH, EC, and TDS, with the steepest upward slope observed for EC in this well. The mean slope of the EC trend is positive at 11.364 µS/cm, adding approximately 113.64 µS/cm to water salinity every decade. The steepest downward slope was observed for TH in the East Polyacryl well. The groundwater level in 26 wells showed a decreasing trend, with the most significant decline observed in Well 22 located in the eastern part of the region. In contrast, Well 30 in the northern part of the region showed the most significant upward trend. The slope of the trend line for annual groundwater level changes was negative in 26 wells, with the steepest decline in Well 22. Overall, the number of wells with declining groundwater levels far exceeds those with increasing levels, indicating a general downward trend in groundwater levels in the Najaf-Abad plain. The most significant downward and upward trends in precipitation were observed in April and July, respectively. The slope of the precipitation trend line was downward in April, November, December, January, February, and March, while it was upward in May. The steepest and mildest downward slopes were observed in April and February, respectively. Given the downward trend in monthly rainfall for most months (7 months), it can be concluded that the overall trend of monthly rainfall in the Najaf-Abad plain is decreasing. The annual precipitation trend also shows a decline.
Conclusion
The upward trend in most qualitative parameters in the majority of wells indicates a decline in groundwater quality in the Najaf-Abad plain over the 21-year study period. Additionally, the groundwater level shows a general downward trend, highlighting a critical situation in the region. Urgent measures are necessary to prevent further environmental degradation. Both monthly and annual precipitation trends are decreasing, while monthly and annual temperature trends are increasing significantly. The temporal changes in precipitation and temperature align with the changes in groundwater quantity and quality, suggesting that reduced rainfall and increased temperatures are key factors contributing to the decline in groundwater resources, alongside management practices. Other environmental factors, such as land use changes, geological formations, soil characteristics, and human activities, may also influence groundwater quantity and quality, though this study focused solely on climatic factors. Given the declining groundwater quality, it is recommended that future research also consider the role of human factors, such as agricultural activities and land use, to develop strategies for improving groundwater resource management.
Type of Study: Research |
Subject:
ساير موضوعات وابسته به مديريت حوزه آبخيز
Received: 2024/08/13 | Accepted: 2025/04/21
Received: 2024/08/13 | Accepted: 2025/04/21
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