The characteristics and modeling for the coupled flow of water, solutes, and heat in heterogeneous soils with an evaporative process

在本研究中，我们开发了一种同时测量土壤水分、溶质和热量的传感器，并在干湿两种条件下进行了非均质沙地的热平衡和土壤水动力学的测量。此外，我们还模拟了沙地土壤水分和温度的动态变化。主要研究成果如下：1)研制了能同时测量土壤水分、溶质和热量的TDR探头测量系统。此外，还提出了一种将TDR张力计和TDR湿度计相结合来测量Pf的简单方法。用TDR-张力计测得的蒸散量与常规方法测得的结果吻合较好，而用TDR-湿度计测得的结果不能令人满意。2)测定了沙地干湿条件下的蒸散量，并对土壤水分运动进行了模拟。阐明了湿润条件下土壤蒸发蒸腾特性和下层土壤水分供应的基本规律。3)利用100 cm~3岩心采样器采集的野外数据，分析了坡耕地样点的空间分布特征和时间稳定性。结果表明，表层土壤水分的变异性随含水率的增加而减小，其分布不符合正态分布。各地区的面积尺度平均含水率表明，低洼地区的平均含水率最高，不同地区的表层土壤含水率也不同。

In this study, we developed a sensor which measured simultaneously the moisture, solutes, and heat in soils, and conducted the measurement of heat balance and soil water dynamics in a heterogeneous sand field under the wet and dry conditions. Moreover, we simulated the dynamics of soil moisture and temperature in a sand field. The main results are follows :1) The thermo-TDR probe measurement system which can measure simultaneously the moisture, solutes, and heat in soils was developed. Moreover, a simple method of pF measurement was developed by combining TDR-Tensiometer with TDR-Hygrometer. The values measured by the TDR-Tensiometer were in good agreement with those of the ordinary methods, but the values measured by TDR-Hygrometer were not satisfactory.2) We measured an evapotranspiration in the sand field under wet and dry conditions, and conducted the simulations of soil water movement. It was clarified that the characteristics of evapotranspiration and that a water supply from lower layer of soil hardly occurred under wet condition. It was also shown that the numerical model had a limit of its application.3) The characteristics of spatial distribution and the time stability of sampling locations for sloping grassland filed were discussed using the field data obtained by 100 cm^3 core samplers. As a result, the variability of surface soil moisture decreased with an increase in water contents, and its distribution was led not to show the normal distribution with the decrease of water contents. The area-scale mean water contents at each area indicated that the mean water content at the low area was the highest, and that the surface soil moistures were different according to each area.