Modelling evaporation dynamics versus phreatic level in lithium-rich salars: a tool for water resource management

A simplified model was proposed to calculate the relationship between evaporation and phreatic level, determining the capacity of a system to compensate for brine abstraction in salars. This model was developed from the joint application of mass transfer balance and moisture retention curves. It was tested using climatic values from Salar de Pocitos and a representative brine composition, with results presented for the common soil types found in salars. The model was extended to different soil types using a dimensionless set of variables that represent changes in hydraulic conductivity, porosity, and capillary suction head. This dimensionless model creates constitutive relationships that reduce system complexity. Well-sorted and permeable soils offer a higher buffering capacity for sustainable brine abstraction. Finally, the case study of Salar de Pocitos is presented, showing how the model can help identify facies that sustain capillary evaporation at greater depths, thereby influencing the brine concentration.