Abstract:

 Under white noise infiltration, the temporospatial variations of pressure head in an unsaturated-saturated system were studied. Both the homogeneous and heterogeneous systems were considered. Damping effect of the system and effect of the heterogeneity on the fluctuations of the water flow were analyzed. Results show that both the homogeneous and heterogeneous systems damp the fluctuations of the pressure head as the variance, auto-covariance and power spectrum decrease with depth. The fluctuations of pressure head are non-stationary at early time due to the initial conditions and become stationary at late time. Heterogeneity strengthens the fluctuations of the pressure head and weakens the short-term correlation. The fluctuations of pressure head are mainly caused by the heterogeneity of the system.

Key words:  unsaturated-saturated system, heterogeneity, temporospatial variations of water flow, temporal correlation