Experiments on Evaporation of High-TDS Phreatic Water in an Arid Area

Abstract

The experimental research on evaporation of high-TDS phreatic water in arid areas is rarely involved at home and abroad. In order to analyze high-TDS phreatic water evaporation laws in arid areas, phreatic evaporation experiments in different TDS (3, 30, 100 and 250g/L) were carried out, with focus on the analysis of phreatic cumulative evaporation dynamics, daytime evaporation dynamics and diurnal variation laws in different treatments. The results showed that phreatic cumulative evaporation had significant linear positive correlations to duration, also the same relationship between TDS of phreatic water and cumulative salinity in soil profile; significant delay existed in phreatic evaporation as compared to EФ20 water-surface evaporation variation; both water-surface and phreatic evaporation dynamics showed intense night variations, and the average night phreatic evaporation capacities in the treatments with different TDS accounted for a larger share of the daily evaporation capacity, which reached about 60% for all treatments except the treatment with the TDS of 3 g/L. The influence of high-TDS phreatic water evaporation process on soil texture showed a non-linear and non-single direction. Driving factors of night phreatic evaporation consisted of the delay driving of daytime atmospheric evaporation capacity and the negative pressure driving caused by night moisture condensation.