Transport pathway identification in fractured aquifers: A stochastic event synchrony-based framework

Several approaches are commonly applied to modeling fractured aquifers, including stochastic continuum (SC) and discrete fracture network (DFN) models. While DFN models provide a more realistic representation of the system, their development necessitates an accurate characterization of the fracture network. Extensive, and often prohibitive, resources are typically required to map a reliable fracture network, which is essential to develop an effective DFN model. The present study develops and demonstrates a simple framework for mapping transport pathways in fractured systems utilizing the coherence between solute transport and the lagged interdependence between two time series evaluated through the stochastic event synchrony (SES) technique. The SES-based framework was applied to solute breakthrough curves obtained i) analytically at different locations along a single, synthetic fracture both with and without matrix diffusion; and, ii) numerically at multiple locations within a synthetic, impervious fracture network. In all cases, the framework was capable of accurately mapping the transport pathways represented by direct pathes between the locations considered. The framework was also capable of identifying the hydrogeologic characteristics within each connection (i.e., flow velocity or its relationship to the dispersion coefficient). This framework is expected to significantly reduce the extensive resources required to identify the transport pathways within complex fractured aquifers. Additionally, the SES-based transport pathways identified may be used to enhance the reliability of other fracture network mapping, or generation, approaches by representing an additional constraint. This study is the first in the field of hydrogeology to adopt synchronization analysis and is expected to open the gate for using SES to address related problems