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

采用介电常数法测定土壤的体积含水量，评价土壤的干容重。体积含水量与质量湿度或湿容重的耦合可以产生干容重。用时域反射探针（TDR）和幅域反射探针（ADR）进行了试验，取得了良好的效果。估算的干容重与实测的干容重吻合较好。对于未受扰动的土，其精度较扰动土差，但在实际应用中精度足够好。相对而言，用体积含水量和湿容重估算的干容重比用体积含水量和质量湿度组合估算的干容重要好。这是由于数据计算的算术过程。估算误差最显著的来源是含水量随传感器传感杆分布的异质性。室内实验表明，特别是对于ADR探针，含水量分布不均匀破坏了体积含水量测量的可靠性。用干容重对饱和导水率进行了标度。估算的饱和水力导率分布与实测值具有相似的空间结构。这是用半方差图来评估的。对张力渗透仪作为土壤水力特性原位测量装置的性能进行了试验研究。张力渗透计作了若干改进，提高了测量的方便性和时间。张力渗透计的计算结果较饱和导水率和缸内进水率等常用方法能较好地解释旱地浸出现象。

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.