径流对缓坡饱和土壤溶质影响的实验研究

Experimental Study on the Effect of Runoff on Solutes in Saturated Soil on Gentle Slopes

降雨条件下,土壤溶质随径流的产生发生迁移。利用室内实验,研究缓坡饱和土壤溶质流失的时间规律、溶质浓度在垂直入渗和坡面径流两个方向上的变化规律。结果表明:在径流过程中,溶质流失速度变小,流失量减少并趋于稳定,幂函数比指数更适合描述这类变化;垂直方向上,土壤溶质向下层渗透扩散受深度的影响,随深度的增加溶质浓度先增后减并趋于稳定,此规律适合用对数描述;在坡面表层,土壤溶质随径流的迁移规律清晰,土壤溶质浓度远处高于近处,多阶多项式模型更适合描述浓度变化;随土层深度增加,溶质浓度变化有明显分界线,在分界线及以下溶质浓度变化规律性较差,总体呈降低趋势。

In the process of interaction between runoff and soil,soil solute will migrate with runoff.The indoor experiments are conducted to investigate the loss pattern of solute and the change law of solute concentration in two directions on saturated soil,including vertical infiltration and slope runoff.The results as follows:During runoff,the solute rate decreases,and the amount of solute loss also decreases,eventually reaching a stable state over time.As a result,a power function is more suitable for describing such changes than index;In the vertical direction,the penetration and diffusion of soil solute in the lower layer are affected by the depth.As the depth increases,the solute concentration first increases and then decreases,and tends to stabilize.Therefore,a logarithmic description is suitable for capturing this pattern.On the surface of the slope,the migration rule of soil solute with runoff is clear that the concentration of soil solute is higher at a distance compared to nearby areas.So a multi-order polynomial model is more suitable for describing concentration change.There is a clear boundary for the change of solute concentration,and the change regularity of solute concentration is poor below the boundary,but overall,it shows a decreasing trend.