煤矿复垦区土壤水动力学特性对下渗过程的影响

煤矿复垦区土壤水对植物生长、溶质运移以及土壤环境的变化起着至关重要的作用。定量揭示煤矿复垦区土壤水下渗过程是亟待诠释的关键科学问题。本研究通过测定典型矿区不同深度土壤非饱和导水率、容重、总孔隙度和粒径等水动力学参数,结合染色示踪试验,刻画矿区非饱和带土壤水运移过程。染色示踪结果显示30、60 L和90 L这3种实验下渗水量条件下,水流沿X方向侧向扩散的最大距离分别为10、30 cm和35 cm,沿Y方向侧向扩散的最大距离分别为10、25 cm和30 cm。互相关函数显示随着下渗水量增大,水流扩散作用也在加强,但过多水量并没有明显增加下渗深度和扩散距离。吸力大于300 hpa时,0.01—0.05 mm土壤粒径含量和非饱和导水率呈负相关关系;吸力和非饱和导水率采用指数函数拟合效果较好(r~20.9),对拟合参数a、b和土壤容重(x)进行回归分析:a=0.0015x~2-0.00499x+0.0004,b=0.0583x~2+0.1234x-0.072。同一吸力下土壤容重大的土样非饱和导水率较小;吸力值为300 hpa是非饱和导水率的转折点;非饱和导水率和土壤容重呈现负相关关系,和总孔隙度呈现正相关关系,且二者的相关性随吸力的增加而降低。

The influence of hydrodynamic characteristics on the infiltration process of soil water in a coal mine reclamation area

Soil water plays an important role in plant growth, solute transport, and soil environment changes. It is a key scientific problem to reveal the infiltration process of soil water in the unsaturated zone. This study used a typical mining area as the study area to investigate the unsaturated hydraulic conductivity, soil bulk density, porosity, and particle size in the different depths of soil layer by conducting a dye tracer experiment. This study aimed to elucidate the infiltration process of soil water and distribution characteristics in the unsaturated zone. The results showed that, at the experimental infiltration water of 30, 60, and 90 L, the greatest diffusion distance are 10, 30, and 35 cm, respectively, along the X direction and 10, 25, and 30 cm, respectively, along the Y direction. Soil water infiltration showed obvious heterogeneity and spatial variability. With more amount of water, it infiltration deeper and diffusion wider, and this was noted in a declining trend. When suction was greater than 300 hpa, the content of soil particle size between 0.01 and 0.05 mm was negatively correlated with unsaturated hydraulic conductivity. Unsaturated hydraulic conductivity decreased nonlinearly with increase in suction, suction and unsaturated hydraulic conductivity fitting with the exponential function (r² > 0.9), and regression analysis was performed for the parameters a, b, and soil bulk density (x) as follows:a=0.0015x² - 0.00499x + 0.0004, b=0.0583x² + 0.1234x - 0.0726. Under the same suction, bulk density of soil was greater, whereas unsaturated hydraulic conductivity was smaller. when the suction value is 300 hpa, the unsaturated hydraulic conductivity reaches a peak value. Unsaturated hydraulic conductivity was negatively correlated with bulk density, whereas positively correlated with total porosity, and the correlation rate decreased with increasing suction.