Mobile-immobile model in solute transport through porous and fracture media

Investigation of analytical models of solute transport is a key point especially in parameter identification in both micro-scale and field-scale. The advection-dispersion equation (ADE) is used to describe the movement of the solute transport in porous media traditionally. However, more and more researches indicate the ADE model have problems in heterogeneous media, in fractured media even in "homogeneous" media. In this paper, an alternative method mobile-immobile (MIM) model is employed both in porous and fracture media. To compare the ADE with MIM model, four groups of tracer experiments in porous and fracture media were carried out, respectively. Then the breakthrough curves (BTC) of the tracer tests were fitted by the two models. By the comparison we can found that: the MIM model does better than ADE both in porous and fracture media, especially in capturing the peak value. The MIM model, which is physically sound, can explain the BTC better in the rough fracture than in the parallel smooth fracture.