碘-淀粉显色试验研究植被发育斜坡非饱和带土体水流路径

Flow Paths of Water in Unsaturated Soil Slope with Well Vegetation Using Iodine-starch Staining Experiments

植被发育斜坡非饱和带土体中共同存在基质孔隙和大孔隙。为研究强降雨条件下植被发育斜坡非饱和带土体中水流路径分布模式及水流运动过程。在云南螳螂川流域的马卡山开展碘-淀粉显色示踪试验,基于顺坡方向的垂直染色剖面,采用经典K均值聚类算法和一般统计法研究水流路径分布特征。结果表明:1.水流路径分布是非均匀的,顺坡方向的异质性比垂直方向显著,湿润前锋面不是平面,降雨入渗不是活塞式,Darcy定律和Richards方程等均匀多孔介质水流理论不能完整地描述强降雨条件下植被发育斜坡非饱和带土体的水流运动过程;2.随着非饱和带土体深度增加,水流从基质流渐变到优先流与基质流的过渡流,深部土体以优先流为主;3.应该从三维流场方面对植被发育斜坡非饱和带土体中的水流运动过程进行精细描述。

Matrix porosity and macropore are coexisted in unsaturated slope soil with well vegetation. The objectives of this study were to study flow path distribution patterns and water flow process in unsaturated soil in well vegetated slopes under intensive rainfall. Iodine-starch staining experiments were carried out in the Maka Mountain the Yunnan Province,China. Based on vertical stained profiles,classical K- means clustering algorithm and common statistical method were used to study flow path distributions. The results show that： 1） the flow path distribution of water was heterogeneous and the heterogeneity of flow paths of distribution of water in vergence direction was more significant than those in vertical direction. Rainfall infiltration in unsaturated soil of well vegetated slopes is shortcircuiting type infiltration. Homogeneous porous medium water flow theory,such as Darcy Law and Richards＇ Equation,isn＇t capable of completely describing the water flow process in unsaturated soils of well vegetated slopes under intensive rainfall. 2） The changes from matrix flow to transition flow between matrix flow and preferential flow with the depths of unsaturated soils become larger,and the main flow in deep soils is preferential flow. 3） Water flow process in unsaturated soils of well vegetated slopes should be studied on basis of three-dimension flow.