Search

• Classical aquitard drainage model COMPAC utilized for a heterogeneous aquitard. • Geostatistical model used to deal with aquitard heterogeneity. • To interpret the heterogeneity from multi-extensometer data. • Comparison between geostatistical and geological models in fitting observation data. • Both synthetic and field application cases implemented. The classical aquitard drainage model COMPAC was used to simulate the deformation of a one-dimensional vertically heterogeneous aquitard (i.e. Heter-COMPAC). By coupling Heter-COMPAC with the quasi-linear geostatistical inversion approach, the vertical heterogeneities of hydraulic conductivity (K v), elastic specific storage (S ske ) and inelastic specific storage (S skp ) fields could be characterized with the availability of long-term multi-extensometer data. The methodology was first tested through a group of ten synthetic cases with randomly generated K v , S ske and S skp fields. Results of the synthetic cases revealed that a geostatistical model could characterize the variability of aquitard hydraulic parameter fields, and yields improved fits of simulated versus observed zone deformation than a geological model that treats each zone to be homogeneous. Subsequently, the methodology was applied to a research site situated in Changzhou city, Jiangsu Province, China, where long-term deformation behaviors of the strata within the aquifer-aquitard system have been monitored. Vertical heterogeneities of K v , S ske and S skp fields of the investigated aquitard at the site were characterized using the quasi-linear geostatistical approach. The correlation length of the three fields that yielded the best-quality fit was assessed to be approximately 50 m, and the fitting quality was slightly improved in comparison with that produced from calibrating a geological or zonation model. Through Monte Carlo analysis of aquitard deformation utilizing the inversed parameters and corresponding uncertainties, the investigated aquitard is estimated to have compacted −914.8 ± (42.6) mm before the rise in groundwater levels in adjoining aquifers. [ABSTRACT FROM AUTHOR]