Investigation of groundwater level changes in Markazi province (period 1981 to 2018)

Groundwater depletion in recent decades has always been considered due to the supply of water needs as well as its improper abstraction. Groundwater levels are continuously changing over time and in a spatial range. The main purpose of this study is to investigate the changes in groundwater levels in Markazi province from 1981 to 2018 at ten-year intervals. The innovation of this research is the study of spatiotemporal changes by creating continuous groundwater levels in different years. In order to implement the research, first, the desired data were collected and after controlling the accuracy of the data, continuous levels were created for the starting year of each decade. Grubbs analysis was used to remove the outlier data and Universal Kriging (UK) interpolation method was used to create surface data for each year. To determine the amount of change, each level was subtracted from the previous level. This process was performed consecutively for ten-year periods. The results of the comparison in the first, second, third, and last ten years show an average decrease of 1.8, 4.9, 5.7, and 3.1 meters in groundwater level, respectively. Therefore, the greatest decrease in water level occurred at the beginning of the new century and then the groundwater level has been decreasing sharply. An average of 15.5 meters decrease in 37 years shows that the necessary measures should be taken regarding the crisis of groundwater depletion, which has a direct impact on agricultural water supply and subsidence in the province