![]() When such hydraulic connection is absent, the vaporization plane develops downward and salt precipitates as subflorescence. ![]() ![]() The simulated results indicated that as long as the hydraulic connection between the near surface soil layer and the water source in the interior soil layer exists, vaporization occurs near the surface, and salt precipitates exclusively as efflorescence. The model was applied to simulate four evaporation experiments in soil columns with and without a fixed shallow water table, and was found to replicate well the experimental observations. A numerical model is developed to simulate the transport of water, solute, and heat in the soil, and resulting evaporation and salt precipitation with the hypothesized feedback mechanism incorporated. We hypothesized that efflorescence exerts a mulching resistance to evaporation, while subflorescence reduces the pore space for water vapor to move through the soil. However, it is not clear how much the precipitated salt in turn affects the water transport in the soil and hence the evaporation rate. Evaporation from bare saline soils in coastal wetlands causes salt precipitation in the form of efflorescence and subflorescence.
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