Abstract:
The West Taijinar Lake area in the Qaidam Basin is within a typical arid inland salt-lake environment characterized by complex hydrogeological conditions and strong aquifer heterogeneity. The permeability characteristics play an important role in controlling regional groundwater flow, solute transport, and resource assessment. However, the applicability of existing theoretical and empirical models describing the depth-dependent variation of hydraulic conductivity of aquifer has not yet been systematically examined and evaluated using measured borehole data from the West Taijinar Lake area. In this study, a two-parameter model for depth-dependent attenuation of hydraulic conductivity of aquifer was proposed. Measured hydrogeological data from four boreholes in the West Taijinar Lake area were used to calibrate and validate the proposed model. The depth-dependent variation characteristics of hydraulic conductivity of aquifer in the study area were analyzed, and the performance of the proposed model was further compared with several representative depth-attenuation models reported in previous studies. The nonlinear generalized reduced gradient (GRG) algorithm was employed for parameter optimization, and model performance was evaluated using the coefficient of determination (R
2) and root mean square error (RMSE). The results indicate that the hydraulic conductivity of the aquifer in the study area presents an overall pronounced decreasing trend with increasing depth, while the measured data show considerable scatter. The proposed two-parameter model for the depth-dependent attenuation of hydraulic conductivity, as well as the single-exponential model and two-parameter logarithmic regression model proposed by previous researchers, all show good applicability in the study area. Among these models, the proposed model exhibits overall higher fitting accuracy and greater parameter stability than the traditional single-exponential model and the logarithmic regression model, and is capable of effectively capturing the characteristic pattern of rapid attenuation of hydraulic conductivity in shallow depths and the transition to more gradual variation at greater depths within salt-lake sedimentary environments. This study can provide theoretical basis for the rational characterization and prediction of deep hydrogeological parameters in inland salt-lake areas, and provide scientific support for groundwater flow simulation and deep brine resource evaluation.