黄土高原降水对土壤含水量和导热率的影响

Response of Soil Water Content and Soil Thermal Conductivity on Precipitation in Loess Plateau

基于局地降水是引起黄土高原塬区土壤含水量变化的主要原因,利用黄土高原白庙塬区20052010年观测的土壤含水量和降水资料以及2012年夏季观测的土壤温度和含水量资料,分析了土壤含水量、导热率与降水的相关关系,重点分析了10.0,20.0和40.0 cm土壤含水量的蓄积以及20.0 cm土壤含水量与前期总有效降水的响应。结果表明:(1)不同深度土壤含水量的月变化比较一致,其中降水对5.0 cm土壤含水量的正强迫作用最为显著;(2)10.0 cm和40.0 cm土壤含水量年变化存在两个峰值,分别在3 5月和8 10月;(3)土壤含水量和前期总有效降水的拟合效果在夏季最好,二者在20.0 cm土壤层的相关系数达到0.84,高于其他观测层;(4)在试验前期,土壤含水量迅速增加使得土壤导热率明显升高。持续观测发现虽然土壤导热率会随着降水出现波动,但整体的相关性并不高,没有明显规律。

Regional precipitation is the main cause of the soil water content variation in the climate system. The response of soil water content on the precipitation was analyzed using the datasets of soil water content and precipitation during 2005 2010,and soil water content datasets collected in August of 2010 in the Baimiao mesa of the Pingliang Loess Plateau. The accumulated soil water content at 10. 0,20. 0 and 40. 0 cm soil layers,and the response of soil water content at 20. 0 cm soil layers to the local precipitation are especially considered. The results show that:( 1) The variation trends of soil water content at different depths are similar in the study area,the positive responses of soil water content to the local precipitation are the most at 5. 0 cm soil layers.( 2) There are two peaks( from March to May,July to November) for the annual variation of soil water content at 10. 0 cm and40. 0 cm soil layers.( 3) In the analyses of the relationship between soil water content and local precipitation,it is found that the soil water content at four soil depths is associated with the local antecedent effective precipitation. The correlation coefficient between soil water content at 20. 0 cm soil layers and the antecedent effective precipitation reaches 0. 84. This implies the response of soil water content at 20. 0 cm soil layers to the effective precipitation is most significant.( 4) During the experiment,the soil water content can lead to an obviously increase of the soil thermal conductivity. However,in a long term of observation,the soil thermal conductivity shows irrelevant change with the precipitation.