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Development of a tool to monitor distribution of soil hydrological properties in situ.

开发现场监测土壤水文特性分布的工具。

基本信息

批准号：
13556036
负责人：
NISHIMURA Taku
金额：
$ 7.62万
依托单位：
National University Corporation Tokyo University of Agriculture and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2004
项目状态：
已结题

项目摘要

Apply dielectric constant method to measure volumetric water content of soils to assess dry bulk density of the soil. Volumetric water content couple with either mass wetness or wet bulk density can produce dry bulk density. Trials with time domain reflectometry(TDR) probe and Amplitude domain reflectometry(ADR) probe gave good results. Estimated dry bulk density agreed well with the measured dry bulk density of disturbed soils. For non disturbed soils, accuracy was worse than that of the disturbed soil however accuracy was good enough for practical purpose. Relatively, dry bulk density estimated by using volumetric water content and wet bulk density was better than that by using the combination of volumetric water content and mass wetness. This was due to arithmetic process of data calculation. Most significant source of estimation error was heterogeneity of water content distribution along with sensing rod of water content sensors. Laboratory experiment showed that especially for ADR probe, uneven distribution of water content collapsed reliability of measurement of volumetric water content.Scaling of saturated hydraulic conductivity by using dry bulk density was conducted. Estimated saturated hydraulic conductivity distribution had similar spatial structure with measured ones. This was evaluated by using semrvariogram.Performance of tension infiltrometer as in-situ measurement device of soil hydraulic property was examined. There were several improvements in tension infiltrometer and this improved easiness and time for measurement. Result of tension infiltrometer well explained leaching phenomena in upland field than common methods such as saturated hydraulic conductivity and cylinder intake rate.

采用介电常数法测量土壤的体积含水量，以估算土壤的干容重。体积含水量与质量湿度或湿容重耦合可以产生干容重。使用时域反射仪（TDR）探头和振幅域反射仪（ADR）探头进行试验，结果良好。扰动土的干容重估算值与实测值吻合较好。对于非扰动土壤，精度比扰动土壤差，但精度足够好，用于实际目的。相对而言，用体积含水率和湿容重估算干容重的效果要优于用体积含水率和质量湿度联合估算。这是由于数据计算的算术过程。估计误差的最重要来源是水分含量分布的不均匀性沿着与水分传感器的传感棒。室内试验表明，特别是对于ADR探头，含水量的不均匀分布破坏了体积含水量测量的可靠性。估算的饱和导水率分布与实测值具有相似的空间结构。并对张力入渗仪作为土壤水力性质原位测量装置的性能进行了检验。张力入渗仪有几个改进，这提高了测量的容易性和时间。与饱和导水率和圆筒进水率等常规方法相比，张力入渗仪的结果更能解释高地土壤的淋溶现象。