Land subsidence is a phenomenon that occurs due to the interaction between groundwater flow and soil deformation.This study investigates the contradiction between land subsidence and groundwater depletion in the Karaj plain. By examining the hydrogeology and measuring land subsidence using leveling and DInSAR methods from 2015 to 2023, the results revealed that the subsidence rate in a crescent-shaped area formed from the northwest to Mohammadshahr is significantly higher than other points, with 158 mm/year. This paradox, considering the minimal groundwater depletion in this zone, raises questions about the direct and always-existing relationship between subsidence and groundwater depletionAn investigation of three hypotheses for land subsidence in the central plain was conducted. The hypotheses included the installation of piezometers in a shallow perched aquifer overlying a main aquifer, annual fluctuations in groundwater levels due to wastewater injection into the aquifer, and erosion of loose particles due to high inflow and outflow rates. Based on the evidence collected, it is most likely that the second hypothesis, the role of the main aquifer in land subsidence, is more probable than the other two hypotheses. The results of leveling are consistent with radar interferometry methods, demonstrating a significant correlation. The negative correlation of 66 to 88% indicates that maximum soil consolidation occurs after two years. In general, points 1 and 2 in the central plain (Mehrshahr) continue to experience high subsidence rates, while the subsidence rates of the three other points in the northwest plain have significantly decreased.