Abstract
This study presented the analysis of the modified convergent flow tracing method, which is a modified virtual solute transport approach to retrieve tracer masses from a pulse image (virtual) well to an extraction well. In the convergent flow tracer test, approximate analytical solutions were extended for the pulse image well using a single-well tracing method. This method transformed the drift-and-pumpback conditions of the single-well tracing method. The method requires a prior information of the effective porosity. Using sodium chloride as a tracer mass, the tracer data sampled through field-scale tests were used to obtain breakthrough curves. This modified method was different from the pre-existing single method because it considers both the ambient groundwater movement (the two classes of drifts) and the constant volumetric flow rate during the pumping phase. The method was applied to the tracer test at underground research tunnel for verifying the theory inductively derived from the single tracing method. Through field tests, the values of velocity and porosity were compared to the results of the drift-and-pumpback equations of the single-well test, and the several different equations related to breakthrough curves of the two-well tests conducted on a field scale.
Highlights
Accurate estimates of the advective velocity (AV) and effective porosity (EP) are crucial for understanding the parameters that control solute transport in aquifers and movement of radioactive wastes [1,2]
The tracer injection occurred as a pulse tracer mass (p), which flowed into the convergent flow field from12, anx injection located at a distance (r) away from the pumping well, SP-05
Under a homogeneous flow field of porous media, the diffusion may have little impact on the solute transport compared to the advection–dispersion mechanism, because each pathway is relatively similar to the adjacent travel pathway
Summary
Accurate estimates of the advective velocity (AV) and effective porosity (EP) are crucial for understanding the parameters that control solute transport in aquifers and movement of radioactive wastes [1,2]. Advection and dispersion in aquifers govern solute transport. Darcy’s equation (1856) [3], “Q = KIA”, includes a linear velocity term written as “va = KI/ne ,” or EP, “ne = KI/v,” where Q is the flow rate, K is the hydraulic conductivity, I is the hydraulic gradient, and A is the cross-sectional area. In aquifers, where both Darcy’s equation and the velocity equation (with the consideration of the effects of the regional velocity during the tracer tests) are valid. Leap and Kaplan (1988) [4] reported that the single-well drift-and-pumpback tracer test is useful for estimating the groundwater velocity
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