Convergent radial transport in three-dimensional heterogeneous aquifers: The impact of the hydraulic conductivity structure

This paper studies the impact of the hydraulic conductivity structure on solute transport in a radially convergent heterogeneous flow field, which is generated by a well pumping a confined aquifer. The solute is injected instantaneously in a fully penetrating well at a known distance from the pumping well and the analysis is performed numerically by considering four conductivity structures sharing the same two-point statistics, but displaying widely different higher-order moments and connectivity features. The overall objective of the present work is to assess the impact of three-dimensional hydraulic conductivity structures on the Breakthrough Curve (BTC) at a pumping well as a function of a few structural parameters: the logconductivity variance the integral scales along the horizontal and vertical directions, the local-scale dispersivity and the distance of the injection well. The numerical simulations are also compared with two analytical solutions from literature based on the First Order Approximation and the Self Consistent Approximation, respectively. The results indicate that the principal features of the BTC are weakly dependent on the hydraulic conductivity structure, similar to the findings of Janković (2017) for transport in uniform flow. Also, the simple First-Order solution provides a good approximation of the BTC in most of the scenarios considered, and thus it can be a useful and effective tool for screening purposes in applications dealing with aquifers’ contamination.