The evaporation from bare soil driven by the presence of shallow groundwater is a significant component of the hydrological balance in semi-arid and arid locations (Assouline et al.
2014; Quinn et al.
2018; Shokri et al.
2010), although it could be relevant also in temperate climate, particularly in the Mediterranean area (Balugani et al.
2017). Direct evaporation from open waters have been studied in detail (Harwell
2012), as well evapotranspiration from reference crops (Jensen and Allen
2016), but less studies have been developed so far on bare soil evaporation induced by shallow groundwater (Allen et al.
2005; Bittelli et al.
2008; Flammini et al.
2018). The evaporation rate is primarily influenced by the microclimatic condition present at a given site, like temperature, wind speed, solar radiation, relative humidity, etc... (Allen et al.
2005; Martens et al.
2017); and by the soil's physical properties, like texture (Lehmann et al.
2018), soil organic matter content and water table depth (Alkhaier et al.
2012; Assouline et al.
2014). Coarse texture soils are characterized by high capacity to deliver water to the evaporation surface, but limited capillary raise due to lack of silt and clay fractions (Quinn et al.
2018). In fact, the liquid flux is driven by the capillary pressure gradients that develops in the vadose zone and remains active until the capillary gradients are larger than the gravitational and viscous forces (Lehmann et al.
2008). Thus, in coarse texture soils the evaporation rate is largely affected by the water table depth. An increase of the evaporation rate is usually followed by a soil temperature decrease because of the energy loss as latent heat flux (Todd et al.
2000). Many studies on the interaction between liquid water movement, water vapor transfer, and heat flux have found that the movement of heat and soil moisture are coupled (Kurylyk et al.
2019). Although thermal gradients affect the redistribution of water in soils, the most important process, which determines the coupling between water and heat, is the transport of latent heat by vapor flux within the soil and at the interface between the soil and the atmosphere. The soil water and energy fluxes from the land surface have been investigated in detail (Hingerl et al.
2016; Jin et al.
2019; Larsen et al.
2016; Trevisan et al.
2020), but very few studies considered the influence of shallow groundwater on soil surface temperature and the entire vadose zone (Alkhaier et al.
2009; Alkhaier et al.
2012; Doble and Crosbie
2017; Kollet and Maxwell
2008). Although valuable findings have been captured from these studies, most of them focused on the relationship between groundwater and soil surface evaporation. This shows that the influence of shallow groundwater on the evaporation process and its related impact on the subsurface energy balance along a soil profile is still an active area of research as pointed out by Trautz et al. (
2018). The latter highlighted the importance of intermediate-scale experimentation (1-10 m) against the use of column scale data to derive generalizations about bare soil evaporation dynamic upscaling. Therefore, this study was conducted using a large tank with representative scales and instrumentations employed in the field to quantify the spatial distribution of evaporation from shallow groundwater in sandy soils. As the authors are aware, this is the first study that elucidates via numerical modelling the spatial distribution of the evaporation rate from shallow groundwater in well controlled laboratory conditions. This study also investigates the influence of surface evaporation on evapoconcentration effect (increased solute concentration due to evaporation) in both the vadose and saturated zones.