Sensitivity of hydrogeomechanical parameters in highly compressible aquitards via inverse modeling of one-dimensional subsidence

• Deformation rates show greater sensitivity to hydraulic conductivity than compression index. • Compression index determines deformation magnitude. • Hydraulic conductivity influences drawdown propagation and subsidence rates. • Sensitivity is influenced by groundwater flow patterns within the hydrogeologic system. Land subsidence induced by groundwater extraction is a significant issue worldwide. Some of the highest subsidence rates occur in aquifer systems overlain by thick and heterogeneous aquitards composed of highly compressible sediments. Identifying the key parameters controlling vertical deformation can guide model setup and improve model efficiency and reliability. This study employs inverse modeling to evaluate the composite sensitivity of land subsidence to hydrogeological and geomechanical parameters in a stratified, heterogeneous, and highly compressible aquitard undergoing intensive groundwater extraction from an underlying aquifer. The research site, located in the Mexico Basin, features an aquitard approximately 100 m thick, monitored over 10 years using piezometric stations and multi-extensometers. Two conceptual models of vertical deformation distribution were analyzed: Case 1, with deformation occurring both within the aquitard and in compressible interbeds within the underlying aquifer, and Case 2, with deformation confined solely to the aquitard. Calibration was performed by coupling a one-dimensional nonlinear subsidence algorithm with stress-dependent parameters and the PEST parameter-estimation tool. Results indicate that total settlement and vertical deformation are more sensitive to hydraulic conductivity ( K ) than to compression index ( C c ) or void ratio ( e ), with sensitivity increasing with depth, consistent with drawdown propagating upward from the aquifer. While C c governs the potential magnitude of deformation, K controls the rate of change in hydraulic head, h , and thus the temporal evolution of deformation and land-subsidence rates. Case 1 best reproduced observed deformation and yielded field-consistent calibrated parameters.