Analysis of evaporation of high-salinity phreatic water at a burial depth of 0 m in an arid area

摘要

High-salinity phreatic water refers to which with total dissolved solids（TDS）>30 g/L. Previous studies have shown that high salinity phreatic water evaporation is different at different depths. High salinity phreatic water evaporation under 0 m depth is the basis of the high salinity phreatic water evaporation studies. In this study, evaporation of high-salinity phreatic water at a burial depth of 0 m in arid area was investigated. New insights were gained on evaporation mechanisms via experiments conducted on high-salinity phreatic water with TDS of 100 g/L at 0 m at the study site at Changji Groundwater Balance Experiment Site, Xinjiang Uygur Autonomous Region in China, where the lithology of the vadose（unsaturated zone） was silty clay. Comparison was made on the data of high-salinity phreatic water evaporation, water surface evaporation(EΦ20) and meteorological data obtained in two complete hydrological years from April 1, 2012 to March 31, 2014. The experiments demonstrated that when the lithology of the vadose zone is silty clay, the burial depth is 0 m and the TDS is 100 g/L, intra-annual variation of phreatic water evaporation is the opposite to the variation of atmospheric evaporation EΦ20 and air temperature. The salt crust formed by the evaporation of high-salinity phreatic water has a strong inhibitory effect on phreatic water evaporation. Large volumes of precipitation can reduce such an inhibitory effect. During freezing periods, surface snow cover can promote the evaporation of high-salinity phreatic water at 0 m; the thicker the snow cover, the more apparent this effect is.