Investigating the effect of agricultural use on nitrate concentration in underground water sources using mathematical modeling based on regression equations (case study: Ray Plain)
Subject Areas : Environmental pollutions (water, soil and air)
Pegah mohammadpour
1
(PH. D. student Department of Environmental Management, Department of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran.)
Reza Arjmandi
2
(Associate Professor, Department of Environmental Management, Department of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran (Corresponding Author).)
Amirhessam Hassani
3
(Professor of Environmental Engineering, Department of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran.)
Jamal Ghodusi
4
(Associate Professor, Faculty Member of Soil and Watershed Management Institute. Tehran, Iran.)
Keywords: nitrate concentration, Agricultural use, Linear regression, Chemical Fertilizers, Pearson correlation coefficient,
Abstract :
Background and Objective: Relationship between agricultural use area and fertilizer consumed with changes in groundwater nitrate concentrations is one of the direct methods of agricultural use on nitrate concentration and groundwater inflammation in each region that can manage managers in proper management. Help ground water resources. The purpose of this study was to investigate the relationship between changes in agricultural and chemical area of consumed on the increase in nitrate concentrations in groundwater sources in Ray plain. Research method: In this study, Landsat 5 and 8 satellite images for the years 2008, 2011, 2014, 2017 and 2020 were used to monitor land use changes. After processing the images, the area of agricultural land was calculated. According to the statistics obtained from the amount of chemical fertilizer consumed and the qualitative laboratory results of nitrate concentration changes, the effects of these factors on each other and the mathematical relationships between the variables were tested with the Pearson correlation and linear regression method. Findings: The results show that during the investigated period, agricultural land has increased and barren land has decreased. The consumption of chemical fertilizers has also increased. The level of nitrate concentration of underground water sources shows that during the period under review, the concentration of nitrate in underground water wells has increased. The analysis of the correlation coefficient also showed that at the error level of 1% (99% confidence level) there is a significant relationship between the concentration of nitrates in underground water with the area of agricultural land and the amount of fertilizer used. This means that as the area of agricultural use and the amount of chemical fertilizers increase, the concentration of nitrates in underground water resources also increases. In the presented regression model, the accepted square value (R2) is equal to 0.993 and it indicates a relatively strong relationship between the dependent variable (water nitrate concentration in underground water sources) and the independent variables (agricultural area and the amount of chemical fertilizer used). Discussion and Conclusion: The results indicate that with the increase in the area of agricultural land, the consumption of chemical fertilizers has increased in the research area, and due to the nitrate leaching process from the soil surface, the nitrate concentration in underground water sources has increased, which is one of the important reasons for the increase in nitrate concentration in the study wells.
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