不同下垫面土壤凝结水特征及其影响因素

Characteristics of Soil Condensation Water and Its Influencing Factors on Different Underlying Surfaces in the Lower Reaches of the Tarim River

凝结水是干旱区生态系统重要的水分来源。2010年6—7月采用底部连通和不连通的微渗计对塔里木河下游地区胡杨林、柽柳丛和裸地3种典型下垫面土壤凝结水的变化特征、形成时间及其影响因素进行了研究。结果表明:①观测期间研究区裸地土壤凝结水总量最多,其次为柽柳丛的,而胡杨林的最小,其凝结水总量分别为2.60、2.49、1.26 mm,方差分析显示,不同下垫面类型土壤的日均凝结水量之间存在极显著差异(P<0.01);②凝结过程一般从22:00持续到次日8:00,晴天日出后一定时间范围内凝结现象仍继续发生,3种下垫面土壤凝结水量的变化趋势均呈双峰曲线,2:00～4:00左右达到第1个峰值,第2个峰值出现在8:00左右;③连通微渗计产生的凝结水量显著高于不连通微渗计的(t<0.01)。凝结水量主要受气温、大气相对湿度、地温、风速以及下垫面等因素的影响。

Condensation water is an important source of water for ecosystem in arid region.Connected and unconnected micro-lysimeters were used to study the variation characteristics of soil condensation amounts,condensation processes and its influencing factors on three underlying surfaces（Populus euphratica forest,Tamarix bosk and bare land） in the lower reaches of the Tarim River.The results showed that the total soil condensation amount on bare land was more than that on Tamarix bosk and Populus euphratica forest,and the value was 2.60,2.49 and 1.26 mm,respectively.ANOVA analysis results indicated that the average daily soil condensation amounts on different underlying surfaces were significantly different（P0.01）.Condensation water began at 22：00 and ended at 8：00 the next morning,and a continuous condensation water was also observed after sunrise.Diurnal dynamics trend of soil condensation amounts on three underlying surfaces showed a clear double-peak curve,with the first peak value at 2：00-4：00 and the second at 8：00.Condensation amounts in connected micro-lysimeters were significantly more than that in unconnected micro-lysimeters（t0.01）.And condensation water was mainly affected by air temperature,air relative humidity,soil temperature,wind speed and underlying surface.The results may assist in the calculation of rational ecological water demand and ecological restoration in the lower reaches of the Tarim River.