## 3 Materials and Methods
### Hydrus Model Parametrization  
The Hydrus-2D model was applied to simulate the distribution of soil water content in the soil lysimeter used for the laboratory experiment. As described above, the lysimeter was placed on the balance, to measure daily soil evaporation. The experiment was carried out from 28 September to 2 November 2016; during the first period (28 September-9 October) the lateral area of the soil cylinder was coiled by the plastic container and only the upper side was opened. Then, the plastic container was removed and a fan heater was placed 0.1 m away from the soil cylinder to accelerate the drying process. In order to account for the different boundary conditions, two simulations were run, by considering a simulation domain of 0.2 m width and 0.18 m depth. The first was carried out by assuming atmospheric conditions at the soil surface and the absence of flux along the other boundary surfaces. In the second simulation it was assumed that the evaporative surface corresponded to the upper soil surface and the lateral area of the soil cylinder.  
The daily evaporation rate was calculated as the difference between the two consecutive records of weight divided by the evaporative area.  
Figure 1: Image of the platform **(a)** and its schematic view showing the transported devices **(b)**. Target of acquisition **(c)** and section (A-A\({}^{\prime}\)) of buried lysimeters **(d)**.  
\begin{table}
\begin{tabular}{c c c} \hline
**Start Time** & **End Time** & **\(\Delta t\) (h)** \\ \hline
12/7/13 05:00 & 12/7/13 12:59 & 7:59 \\
18/7/13 13:32 & 18/7/13 16:37 & 3:05 \\
30/7/13 13:21 & 30/7/13 20:00 & 6:39 \\ \hline \end{tabular}
\end{table}
Table 2: Start and end time (solar time) of the proximity sensing acquisitions.  
The initial soil water content was assumed constant and equal to 0.46 m\({}^{3}\) m\({}^{-3}\) (corresponding to saturation), whereas in the second simulation, the distribution of SWC obtained at the end of the previous simulation was taken into consideration. Table 1 indicates the van Genuchen-Mualem model parameters assumed for the soil hydraulic functions.  
In the field experiment, both the examined conditions (dry and wet) were schematized according to a 0.30 m depth simulation domain, by assuming one-dimensional infiltration and redistribution processes along a vertical plan. A constant flux of 0.53 m h\({}^{-1}\), was obtained by dividing the emitter flow discharge by the surface of the container, was considered at the upper boundary surface during wetting events, whereas the absence of flux was considered during the redistribution process following each watering. Atmospheric conditions were therefore assumed at the soil surface, as well as the absence of flux along the lateral sides and the bottom of the simulation domain.  
Simulations were run from 11 to 31 July 2013 and the initial soil water content within the soil profile was assumed to be linearly variable between 0.33 m\({}^{3}\) m\({}^{-3}\) and 0.37 m\({}^{3}\) m\({}^{-3}\) (wet) and between 0.03 m\({}^{3}\) m\({}^{-3}\) and 0.04 m\({}^{3}\) m\({}^{-3}\) (dry), based on the values measured at the beginning of the experiment. Even in this case, the van Genuchen-Mualem model was assumed to represent the soil hydraulic functions.