A New Sampling Method of Vertical Infiltration Water in Unsaturated Soil without Disturbing Soil Moisture Condition
A New Sampling Method of Vertical Infiltration Water in Unsaturated Soil without Disturbing Soil Moisture Condition
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不扰动土壤水分条件的非饱和土垂直入渗水采样新方法
DOI：
10.3178/jjshwr.13.462
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
K. Kosugi
中科院分区：
文献类型：
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作者：
K. Kosugi
降雨和灌溉水在非饱和土壤中的垂直入渗过程对于预测自然灾害和环境污染具有重要意义，但目前还没有定量的认识。这可能是由于现有的非饱和土壤水取样技术，这是不一定合适的土壤水分流动的机制，无张力蒸渗仪不能保持土壤水分条件下的采样剖面在自然土壤剖面相同，和张力蒸渗仪不能测量入渗速率。此外，据报道，用张力蒸渗仪取样的水的质量取决于所施加的真空压力。本研究提出一种新的非饱和土壤水分取样方法，以减少取样剖面上土壤水分状况的干扰。新开发的设备包括一个连接到真空系统的多孔板和两个张力计。以3秒的间隔测量水平安装的多孔板上方和天然土壤剖面中相同深度处的土壤基质压头。真空系统是自动控制的，使得两个基质压头的读数彼此匹配。通过室内试验和现场试验对该装置进行了测试。结果表明，在土壤水分状况基本保持不变的情况下，采样剖面的土壤水分状况与自然剖面的土壤水分状况基本一致，采样率与自然入渗率基本一致。
Vertical infiltration process of rainand irrigation-water in unsaturated soil is not quantitatively understood, in spite of its importance for predicting natural disasters and environmental pollutions. This can be attributable to the existing sampling techniques of unsaturated soil water, which are not necessarily appropriate considering the mechanism of soil water flow; the tension-free-lysimeter cannot keep the soil moisture condition at the water-sampling profile identical to that at the natural soil profile, and the tension-lysimeter cannot measure infiltration rate. Moreover, the quality of sampled water by the tensionlysimeter reportedly depends on the applied vacuum pressure. This study proposes a new sampling method of unsaturated soil water which minimizes the disturbance of soil moisture condition at the sampling profile. The newly-developed equipment consists of a porous plate connected to a vacuum system and two tensiometers. Soil matric pressure heads just above the horizontally-installed porous plate and at the same depth in the natural soil profile, are measured at 3-second intervals. The vacuum system is automatically controlled so that the readings of the two matric pressure heads match each other. The equipment was tested by both of laboratory and field experiments. The results showed that the soil moisture condition at the water-sampling profile was kept almost identical to that at the natural soil profile, and the water sampling rate was about the same as the natural infiltration rate.