Experimental study on water evaporation from Fontainebleau sand using an environmental chamber

To investigate the mechanism of soil water evaporation, water evaporation experiment was performed on Fontainebleau sand in a large-scale environmental chamber under controlled atmospheric conditions and with a constant water table at the bottom of soil sample. Both the evolutions of atmospheric parameters (air temperature, relative humidity and air flow rate) and the changes of soil parameters (soil temperature, volumetric water content and matric suction) were monitored during the experiment. Emphasis was put on the measurement of matric suction at the soil surface. The actual evaporation rate and cumulative evaporation were also determined using the experimental data. Results show that the evaporation process is limited to the near surface zone; significant changes of soil volumetric water content and temperature in this zone were identified, whereas negligible changes were observed at deeper levels. Both air temperature and evaporation process have significant influence on the changes of soil temperature. The relative humidity at soil surface is related to the evaporation process. The soil matric suction increases during evaporation. The actual evaporation rate shows a clear three stages.