Spreading of solutes in transport by groundwater in aquifers is governed by the spltial variability of the hydraulic conductivity. To account for its irregular variation and for uncertainty of its distribution, stochastic models regard conductivity as random. As a result, flow velocity and concentration of solutes are also random and characterized in terms of their statistical moments (mean, variance). Most studies in the past have derived the mean concentration of plumes, as function of space and time, and it was found that pore-scale dispersion has a minor effect on it. Only recently models to predict local concentration fluctuations, as characterized by the variance, were developed and the major effect of pore-scale dispersion was assessed. The present paper summarizes the recent studies (Dagan & Fiori, 1997; Fiori & Dagan, 1998) based on the Lagrangian approach. An approximate theoretical method was developed and comparison with numerical simulations and with field experiments show a good agreement.
|Number of pages||4|
|State||Published - 1998|