陕西洛川黄土剖面上部土层水分入渗规律与含水条件研究

采用双环入渗法研究了洛川L1—S4各层土壤水分入渗特点,并利用各层孔隙度、磁化率、CaCO3含量资料研究了各层土壤含水空间发育特征及其成因。结果表明:洛川城西剖面黄土层稳定入渗率大于红褐色古土壤层,水分入渗达到稳定状态所需的时间比红褐色古土壤层长。黄土层孔隙度高,含水空间较大,利于形成含水层;红褐色古土壤层孔隙度低,含水空间较小,利于形成隔水层。土层含水空间的大小是由气候条件控制的成壤作用强弱造成的。黄土层含水性较好是冷干气候决定的成壤作用较弱造成的,红褐色古土壤层隔水性较好是温湿气候决定的成壤作用较强造成的。对剖面渗水实验数据用3个入渗公式进行拟合,发现通常采用的3个经验公式均适用于描述L1—S4土壤入渗规律。

A study of water infiltration and water-bearing condition of the L_1-S_4 layers in Luochuan,Shaanxi

Through water infiltration experiment of the L_1-S_4 layers in Luochuan using the double-ring method and through determination of porosity,magnetization and CaCO_3 content,this paper examines the water infiltration difference,the development of the water-containing space and their causes between the loess and the red ancient soil.The results indicate that the stable infiltration rates of the loess layers are bigger than that of the paleosol layers,and the time when the water infiltration reaches a stable condition of loess layers are longer than that of the paleosol layers.The porosity of loess is bigger,showing that the moisture-contained space is greater and the loess layers tend to form moisture-contained layers.The porosity of paleosol is smaller,showing that the moisture-contained space is less and the paleosol layers tend to form moistureseparated layers.The bulk of moisture-contained space is caused by the intension of the pedogenic process controlled by the climate conditions.The bigger moisture-contained space of the loess is caused by the slighter pedogenic process controlled by the cold and dry climate conditions,and the less moisture-contained space of the paleosol is caused by the stronger pedogenic process controlled by the warm and humid climate conditions.Three experience formula can be used to describe water-seeping rule of the loess and paleosol developed since 400 ka BP by fitting of experience data.The results show that climate change of the Pleistocene plays an important part in the enrichment condition and has an important effect on the soil water and groundwater.