A simple velocity random-walk model for macrodispersion in mildly to highly heterogeneous subsurface formations

•Development of temporal velocity-based random walk model.•Applicable for mildly to highly heterogeneous formations.•Model has a clearly motivated and light-weight formulation. Recently, we have analytically derived a temporal velocity random-walk model for macrodispersion or transport uncertainty quantification based on velocity statistics from classical first-order perturbation expansions. The applicability of these expansions is limited to mildly heterogeneous formations with log-conductivity variances σY2