Abstract
Abstract Pore-fractured media is a ubiquitous phenomenon throughout the world and is a high degree of heterogeneity. The mechanism of water flow and solute transport in the media is still not fully clear. In this study, experiments were conducted in pore-fracture media with various hydraulic gradients to establish the relationship between the hydraulic gradient and specific discharge by using a side guide and to test the resistivity of tracer (sodium chloride) by using a high-density resistivity monitoring system. Quantifying models were, respectively, set up, and results were compared with the traditional methods. Main results are obtained that (1) the phenomenon from Darcian flow to non-Darcian flow was found in pore-fractured media. Both the Forchheimer and Izbash equations can well describe the flow process in the back part of the curve; (2) the phenomenon from non-Fickian to Fickian then to non-Fickian was found in fractured media; (3) good performance of CTRW-TPL has been obtained for both the larger R2 and smaller RMSE values, their counterparts resulting from the ADE model.
Highlights
With rapid development in industrial and agricultural production, environmental pollution, especially groundwater pollution, becomes increasingly more serious
In order to investigate the solute transport under the hydraulic head difference of 3.8 cm, the breakthrough curves (BTCs) under the hydraulic head difference of 3.8 cm in pore-fractured media were illustrated and fitted by advection-dispersion equation (ADE) and continuous-time random walk (CTRW)-TPL models
The results reveal the following: It was found that with the increase of specific discharge, the linear relationship between the hydraulic gradient and the specific discharge will deviate
Summary
With rapid development in industrial and agricultural production, environmental pollution, especially groundwater pollution, becomes increasingly more serious. Some pollutants enter the fracture media through the spread of solutes in porous media. Controlling contamination migration in such a fracture media is very important for both pollution control and aquifer remediation. Extensive research studies were conducted in the past to investigate flow and solute transport in porous media or fractured media. A noninvasive image processing method was developed to map the spatiotemporal evolution of solute concentration in two-dimensional porous media [1]. Zaheer et al [2] carried out a series of solute transport experiments in one-dimensional clay soil columns, to identify key parameters controlling the transport process. Chen et al [3] focused on the dispersion process in rough single fractures under non-Darcian flow conditions. Huang et al [4] designed an experiment to perform tracer tests in an unsaturated fractured rock with a horizontal fracture with a negligible matrix
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