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

应用介电常数法测量土壤的体积含水率来估算土壤的干容重。体积含水率与质量湿度或湿体积密度耦合可产生干体积密度。用时域反射仪(TDR)探头和幅度域反射仪(ADR)探头进行试验，结果良好。估算的干容重与扰动土壤干容重的实测值吻合较好。对于原状土样，精度不如有扰动土样，但精度足以满足实际需要。相对而言，用体积含水率和湿容重估算的干体积密度要好于用体积含水率和质量湿度相结合的方法。这是由于数据计算的算术过程造成的。最显著的估计误差来源是含水率传感器的传感杆上的含水率分布不均匀。实验室实验表明，尤其对于ADR探头，水分的不均匀分布使体积含水率测量的可靠性下降。估算的饱和导水率分布与实测值具有相似的空间结构。采用拉力渗透仪作为土壤水力性质的现场测量装置，对其性能进行了考察。张力渗滤仪有几个改进，这提高了测量的简易性和时间。与饱和导水率和圆筒吸水率等常用方法相比，张力仪的计算结果更好地解释了旱地土壤的淋溶现象。

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.