Behaviour of salt distribution in dry soils

The behaviour of soil salinity in dry conditions is investigated by means of analytical tools. We present a closed solution for advective transport, and apply it to two typical real-world scenarios: i) a finite depth-distributed (i.e. Heaviside-type), and ii) an instantaneous top-surface broadcasted (i.e. Dirac-type) saline pulse. Our analytical solution is then incorporated into a stochastic stream tube model to compute the mean salinity profile in a heterogeneous field. An unusual phenomenon of plume contraction is observed when the soil is getting drier and drier (typically at long times during a water redistribution period). It is emphasized that our results are in agreement with previous analytical studies (see e.g. Severino et al., 2005; Severino and Indelman, 2004, Severino and Santini, 2004), and match quite well synthetic as well as real data provided that sandy soils are dealt with.