University of Tehran Press Iranian Journal of Soil and Water Research 2008-479X 57 1 2026 03 21 Probabilistic Analysis of Land Subsidence Caused by Groundwater Extraction under Unsteady Conditions in Fine-Grained Soils Probabilistic Analysis of Land Subsidence Caused by Groundwater Extraction under Unsteady Conditions in Fine-Grained Soils 21 38 106701 10.22059/ijswr.2026.407325.670062 FA Maryam Nejati Kalashami Dept. of Water Engineering, Faculty of Agricultural Sciences, University of Guilan, Rasht, Guilan Province, Iran 0009-0001-2259-4298 Amir Malekpour Academic staff, Dept. Water Engineering, University of Guilan 0000-0002-9353-4946 Behnam Shafiei Sabet Dept. of Water Engineering, Faculty of Agricultural Sciences, University of Guilan, Rasht, Guilan Province, Iran 0000-0001-6255-025X Journal Article 2025 12 01 Land subsidence, as a consequence of the excessive groundwater extraction, poses a serious threat to infrastructure and environment. In the current research, the land subsidence caused by groundwater withdrawal was investigated and modeled using a probabilistic analysis approach. A computer program was developed in MATLAB based on the modified Budryk–Knothe influence function and several copula functions were employed to model the dependence among input parameters. Given the significance of incorporating uncertainty in subsidence modeling, two approaches were considered and compared including the application of temporal random variables and the random variables related to mechanical soil properties. A case study was conducted in the Foomanat region of Guilan Province, characterized by silty clay soil. The results demonstrated that when the temporal random variables were considered, the variations in the range of calculated subsidence gradually decreased over time, indicating a more stable subsidence model. In contrast, incorporating the uncertainties associated with mechanical soil properties led to an increased scattering in subsidence values with time. Accordingly, the findings suggest that for short-term subsidence assessments, greater emphasis should be placed on soil mechanical properties, whereas temporal uncertainties become more dominant in long-term analyses. Generally, for the silty clay soil of the study area, the Frank copula was identified as the most appropriate function for modeling the joint probability distributions when the temporal random variables and random soil properties are considered. Land subsidence, as a consequence of the excessive groundwater extraction, poses a serious threat to infrastructure and environment. In the current research, the land subsidence caused by groundwater withdrawal was investigated and modeled using a probabilistic analysis approach. A computer program was developed in MATLAB based on the modified Budryk–Knothe influence function and several copula functions were employed to model the dependence among input parameters. Given the significance of incorporating uncertainty in subsidence modeling, two approaches were considered and compared including the application of temporal random variables and the random variables related to mechanical soil properties. A case study was conducted in the Foomanat region of Guilan Province, characterized by silty clay soil. The results demonstrated that when the temporal random variables were considered, the variations in the range of calculated subsidence gradually decreased over time, indicating a more stable subsidence model. In contrast, incorporating the uncertainties associated with mechanical soil properties led to an increased scattering in subsidence values with time. Accordingly, the findings suggest that for short-term subsidence assessments, greater emphasis should be placed on soil mechanical properties, whereas temporal uncertainties become more dominant in long-term analyses. Generally, for the silty clay soil of the study area, the Frank copula was identified as the most appropriate function for modeling the joint probability distributions when the temporal random variables and random soil properties are considered. https://ijswr.ut.ac.ir/article_106701_e17db4182f16eff00bdf15243d58e75a.pdf