Development of a Large-Scale Environmental Chamber for Investigating Soil Water Evaporation

A large-scale environmental chamber was developed to study soil water evaporation mechanisms. A large soil specimen (300mm high, 800mm wide, and 1000mm long) was used, allowing sensors to be installed with minimal effect on the soil's hydraulic properties. Sensors for measuring soil suction, temperature, and volumetric water content were either buried inside the soil specimen or installed on the chamber's wall at various locations. Other sensors for monitoring air temperature, relative humidity, air flow rate, and soil surface temperature were installed at different locations above the soil surface. Various atmospheric conditions were controlled by an air supply system, and a steady water table at the bottom of the soil was set through a big water tank. Fontainebleau sand was studied, and it was compacted in the chamber in layers. After saturation, an 11.5-day evaporation test was performed. The results obtained are presented in terms of evolutions of suction, volumetric water content, air relative humidity, and soil/air temperature. The data on air relative humidity and air temperature were used further for determining the actual evaporation rate; the data on soil volumetric water content and soil suction were used for determining the soil water retention curve. The quality of the results obtained speaks to the performance of the environmental chamber developed. In addition, these results can be further analyzed for theoretical and numerical developments involving soil water evaporation.