黄土高原六道沟小流域坡面土壤入渗特性的空间变异研究

水蚀风蚀交错带是黄土高原水土流失最为严重的地区,研究其不同地类土壤的入渗特性及其空间变异规律,有助于揭示黄土高原土壤侵蚀过程和生态环境的脆弱性以及流域水文模型精度的提高。本研究选取在水蚀风蚀交错带的强烈侵蚀中心六道沟小流域进行,采用双环定水头入渗法,在六道沟流域内一个长375m的完整天然坡面上网格布点,应用传统统计学方法和地统计学方法对稳定入渗率和前30min累积入渗量等土壤入渗特性重要参数的空间变异结构进行了研究,结果表明:(1)土壤稳定入渗率和前30min累积入渗量的变异系数分别为0.480和0.404,在坡面上的变异程度均呈现中等变异性;(2)两个入渗特性参数的试验半方差函数与理论半方差函数均拟合较好,自相关特征距离分别为126m和226m;块金值均大于0,表明在采样间隔范围内可能存在更小尺度的空间变异,要进一步研究在采样间隔内是否具有更小尺度的空间相关特征,可以增加采样密度来分析。

Spatial Variability of Soil Infiltration Properties on Natural Slope in Liudaogou Catchment on Loess Plateau

Infiltration is an important process for the exchange of rain water, surface water, soil water,and ground water. It has great significance to the hydrological cycle of a watershed. The water-wind erosion crisscross region initiates the most serious soil and water loss on the Loess Plateau, and studies on the soil infiltration properties and its spatial variability in this region will do help to understand the process of the soil erosion and improve the precision of the watershed hydrological model. On a natural slope (375 meters long) in the Liudaogou catchment, which is typical of the water-wind erosion crisscross region, stable infiltration rate and cumulate infiltration capacity within the initial 30 min were measured with double-ring infiltrometer at 57 sampling plots, and the traditional statistical method and geostatistical method were adopted to study the spatial variability of the soil infiltration properties. The results indicate: (1) The coefficients of variation (C_v) of stable infiltration rate and cumulate infiltration capacity within the initial 30min are 0.480 and 0.404, respectively, and the variation extent on the slope of these two parameters shows medium variation. (2) The theoretical variogram and the experimental variogram of these two parameters match very well, and the ranges are 126 m and 226 m respectively, the nugget values are both above 0, which indicates that some spatial variability may probably exist in a smaller scale than the sampling interval and this means that the sampling interval should be shortened.