University of Tabriz Hydrogeology 2588-3011 10 1 2025 08 23 Studying the trend of some qualitative variables of the Shahrekord Plain aquifer over a 20-year period Studying the trend of some qualitative variables of the Shahrekord Plain aquifer over a 20-year period 77 91 21640 10.22034/hydro.2025.21640 FA Navid Rad Boroujeni M.Sc. Graduate, Department of Water Engineering, Shahrekord University, Shahrekord, Iran. Sayyed-Hassan Tabatabaei Professor, Department of Water Engineering, Shahrekord University, Shahrekord, Iran. Mahdi Radfar Assistante Professor, Department of Water Engineering, Shahrekord University, Shahrekord, Iran. Rasoul Mirabbasi Associate Professor, Department of Water Engineering, Shahrekord University, Shahrekord, Iran. Journal Article 2025 04 17 Groundwater is a valuable resource for supplying water for various uses in most regions, especially arid and semi-arid regions of Iran, so continuous monitoring of groundwater quality is essential. In this study, temporal changes in groundwater quality in the Shahrekord Plain over the past 20 years were investigated. For this purpose, groundwater quality parameters measured in 11 wells in the Shahrekord Plain during the statistical period 2001-2021 were used. The trend of changes was examined using the nonparametric modified Mann-Kendall test and by removing the complete autocorrelation structure. The results showed that groundwater quality in the western and central regions of the Shahrekord Plain has been slightly decreasing in recent years and most variables did not have a significant trend. In the eastern and southern regions of the plain, the Na and SAR variables have had a significant decreasing trend. Also, in the northern and southern regions of the plain, the TH variable has had a significant decreasing trend. However, the trend of this variable in the Abdullah well in the center of the plain has been increasing at a significant level of 5%, which is related to the feeding of the plain with urban wastewater in this location. The results of this study indicate the importance of long-term monitoring of groundwater quality in the central region of the Shahrekord plain Groundwater is a valuable resource for supplying water for various uses in most regions, especially arid and semi-arid regions of Iran, so continuous monitoring of groundwater quality is essential. In this study, temporal changes in groundwater quality in the Shahrekord Plain over the past 20 years were investigated. For this purpose, groundwater quality parameters measured in 11 wells in the Shahrekord Plain during the statistical period 2001-2021 were used. The trend of changes was examined using the nonparametric modified Mann-Kendall test and by removing the complete autocorrelation structure. The results showed that groundwater quality in the western and central regions of the Shahrekord Plain has been slightly decreasing in recent years and most variables did not have a significant trend. In the eastern and southern regions of the plain, the Na and SAR variables have had a significant decreasing trend. Also, in the northern and southern regions of the plain, the TH variable has had a significant decreasing trend. However, the trend of this variable in the Abdullah well in the center of the plain has been increasing at a significant level of 5%, which is related to the feeding of the plain with urban wastewater in this location. The results of this study indicate the importance of long-term monitoring of groundwater quality in the central region of the Shahrekord plain https://hydro.tabrizu.ac.ir/article_21640_16d109c2ccfd4ac197e39a9551696be4.pdf