A Dual Heterogeneous Domain Model for Upscaling Anomalous Transport With Multi‐Peaks in Heterogeneous Aquifers

Natural aquifers are often characterized by multiscale heterogeneity and complex flow networks, challenging the reliable simulation prediction of contaminant transport. Classic stochastic transport models usually assume independent, identically distributed probability density functions when upscaling solute dynamics, but this assumption is not valid for media with heterogeneity. To address issue, a dual heterogeneous domain model (DHDM) was proposed to quantify in where breakthrough curves (BTCs) exhibit multiple peaks transient tailing behaviors. efficiently solve resultant DHDM, Lagrangian solver developed combining renewal-reward process (to capture dynamics each domain) state transition particle transfer between two domains). The DHDM its were then applied simulate three different aquifer settings (alluvial, fractured, karst). Analyses showed that alluvial aquifer, early arrivals bi-peaks observed BTC might be caused interconnected preferential paths consisting high conductivity sediments, while front edge or long tails local result small-scale Fracture networks karst conduits also resulted anomalous peaks, mass channels matrix led retention. All these complex, coexisting characteristics can simultaneously accurately captured unifying approach, significantly expanding capability nonlocal models.