University of Tehran Press Journal of Ecohydrology 2423-6098 9 3 2022 09 23 Spatial and temporal changes of groundwater quality in Damghan plain using geostatistics Spatial and temporal changes of groundwater quality in Damghan plain using geostatistics 461 474 90275 10.22059/ije.2022.335442.1587 FA Behnaz Mostofipour M. Sc graduated, Department of sciences and watershed management, Sari Agricultural Sciences and Natural Resources University, Sari, Iran Fatemeh Shokrian Assistant professor, Department of sciences and watershed management, Sari Agricultural Sciences and Natural Resources University, Sari, Iran Mansoureh Kargar Ph.D Natural Resources and Watershed Management Administration of Alborz province, Karaj Leila Gholami Associate professor, Department of Sciences and Watershed Management, Sari Agricultural Sciences and Natural Resources University, Sari, Iran Journal Article 2021 12 22 Damghan plain located in Semnan province and due to lack of water resources need to study the status of water resources for better management. Water resources used in this area supplied from springs and wells. the present study aimed to prepare a spatial distribution map of groundwater quality parameters and compare them in different parts of the aquifer surface using geostatistical methods. Measurement parameters in wells, springs and qanat are (TDS, pH, EC, HCO₃^-, Cl, Ca⁺⁺, Na⁺, %Na, SO₄^2-). The results of descriptive statistics in deep well showed that the highest percentage of changes related to Mg and SO₄² variables and the lowest percentage of changes were related to pH. The highest percentage of changes in the semi-deep well is related to HCO₃ variable and in the spring it is related to Cl. Also, the highest percentage of changes in Qanat is related to chlorine and calcium, while the lowest percentage of changes is related to TDS. The highest percentage of changes in semi-deep well was allocated to bicarbonate anion and the lowest percentage of changes was related to pH. Among the underground water sources, the spring showed better results in terms of regression coefficients and variogram models. The results of the time changes indicated that the measured qualitative parameters had the most changes in autumn and late spring. The general result of this research indicates that the kriging method with spherical semi-variograms is a suitable method for spatial evaluation of groundwater quality variables in Damghan plain. Damghan plain located in Semnan province and due to lack of water resources need to study the status of water resources for better management. Water resources used in this area supplied from springs and wells. the present study aimed to prepare a spatial distribution map of groundwater quality parameters and compare them in different parts of the aquifer surface using geostatistical methods. Measurement parameters in wells, springs and qanat are (TDS, pH, EC, HCO₃^-, Cl, Ca⁺⁺, Na⁺, %Na, SO₄^2-). The results of descriptive statistics in deep well showed that the highest percentage of changes related to Mg and SO₄² variables and the lowest percentage of changes were related to pH. The highest percentage of changes in the semi-deep well is related to HCO₃ variable and in the spring it is related to Cl. Also, the highest percentage of changes in Qanat is related to chlorine and calcium, while the lowest percentage of changes is related to TDS. The highest percentage of changes in semi-deep well was allocated to bicarbonate anion and the lowest percentage of changes was related to pH. Among the underground water sources, the spring showed better results in terms of regression coefficients and variogram models. The results of the time changes indicated that the measured qualitative parameters had the most changes in autumn and late spring. The general result of this research indicates that the kriging method with spherical semi-variograms is a suitable method for spatial evaluation of groundwater quality variables in Damghan plain. https://ije.ut.ac.ir/article_90275_c672301a453d77d4c07648bc6f117e18.pdf