MEASURING WATER EXCHANGE BETWEEN SOIL AND ATMOSPHERE WITH TDR‐MICROLYSIMETRY
MEASURING WATER EXCHANGE BETWEEN SOIL AND ATMOSPHERE WITH TDR‐MICROLYSIMETRY
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使用 TDR 微溶测定法测量土壤和大气之间的水交换
DOI：
10.1097/00010694-199407000-00003
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
Gbert J.A. Spaans
中科院分区：
文献类型：
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作者：
J. Baker;Gbert J.A. Spaans
土壤蒸发是一个重要的水文和能量传递过程，但历来难以测量。称重微渗仪是一种常用的和公认的技术，它是准确和廉价的，但是，它是耗时和劳动密集型的，具有有限的时间分辨率。我们修改的方法，通过拟合时域反射（TDR）探头在每个微蒸渗仪从底部延伸到顶部。当它们被安装时，探针刺穿衬在微蒸渗仪底部的塑料膜。这样形成的洞允许自由排水时，降雨量足以诱导它，但他们防止不饱和流的任何方向。自动TDR系统的使用允许在多个蒸渗仪中连续、无人值守地测量蒸发损失和降雨增加。TDR数据与通过称重在离散时间间隔测量的含水量变化以及通过波文比方法和雨量计测量的每日蒸发损失和降雨量增加的独立测量结果进行了比较。短期（例如，每小时）费率估计显示出相当大的分散性，但应该有可能进一步改进。TDR微蒸仪的更换频率低于标准微蒸仪，尽管下了很多雨，但没有造成严重后果。该方法应该是有用的，在许多研究中，土壤/大气水交换的信息是必需的。
Soil evaporation is an important hydrologic and energy transfer process, yet it has historically been difficult to measure. Weighing microlysimetry is a commonly employed and accepted technique that is accurate and inexpensive, but, it is time consuming and labor intensive, with lim-ited temporal resolution. We modified the method by fitting a time domain reflectometry (TDR) probe in each microlysimeter extending from the bottom to the top. When they are installed, the probes pierce a plastic film lining the bottom of the microlysimeter. The holes thus created allow free drainage when rainfall is sufficient to induce it, but they prevent unsaturated flow either direction. The use of an automated TDR system allowed continuous, unattended measurement of both evaporative losses and rainfall additions in multiple lysimeters. The TDR data compared favorably with water content changes measured at discrete intervals by weighing, and also with independent measurements of daily evaporation losses' and rain-fall additions measured by the Bowen ratio method and a rain gauge. Short-term (e.g., hourly) rate estimation exhibited considerable scatter, but further improvement should be possible. The TDR-microlysimeters were replaced less frequently than typically the case with standard microlysimeters, without serious consequences despite numerous rains. The method should be useful in many studies where information on soil/atmosphere water exchange is required.