晋西黄土区不同入渗水量下刺槐林地优先流特征

为探究晋西黄土区刺槐林地是否存在土壤优先流及不同入渗水量条件下对优先流发育程度的影响，本文以山西吉县蔡家川小流域刺槐人工林为研究对象，采用野外染色示踪试验和室内图像处理技术相结合的方法，获取垂直剖面染色形态特征图像并进行特征指标的提取，选取基质流深度、平均最大染色深度、染色面积比、优先流比、长度指数和染色面积比变异系数6个特征指标，基于均方差决策法定量分析不同入渗水量条件下的优先流发育情况。结果表明：（1）刺槐人工林土壤水分入渗过程中存在优先流现象，随入渗水量的增加，优先路径逐步向侧向发展，优先流斜侧入渗现象明显；（2）染色面积比随土层深度的增加呈非线性减小趋势，水分呈现非均匀下渗现象；入渗水量为75 mm时的优先流比达到47.11%，优先流发育程度最高；（3）3种入渗水量条件下的平均最大染色深度分别为25.33 cm、32.20 cm、38.87 cm，与入渗水量的大小呈正相关关系，表明入渗水量的增加可以促进水分向深层运动，有利于优先路径的开启；（4）入渗水量与优先流评价指数之间呈正相关关系，优先流评价指数75mm（0.81）＞50mm（0.39）＞25mm（0.36），入渗水量增加促使优先流发育程度更高。研究结果可为黄土区植被恢复及林-水关系的深度解析提供依据。

Characteristic of preferential flow in Robinia pseudoacacia forests in the Loess Plateau in western Shanxi Province under different infiltration conditions

In order to explore the existence of preferential soil flow in the Loess Plateau in western Shanxi Province and the effect of different infiltration water conditions on the degree of preferential flow development.This paper takes the Robinia pseudoacacia forests of Caijiachuan sub-basin as the research object and uses a combination of field dyeing experiment and indoor image processing technology to obtain morphological images of vertical profile dyeing and extract characteristic indicators. Six characteristic indicators, including the matrix flow depth，the average maximum dyeing depth the dyeing area ratio, the preferential flow ratio，the length index and the coefficient of variation of staining morphology,were selected to quantify the development of preferential flow under different infiltration water conditions based on the root mean square difference decision method.The results showed that:(1)The phenomenon of preferential flow exists in the process of soil water movement of Robinia pseudoacacia forests, with the increase of infiltration water, the preferential path begins to develop laterally, and the phenomenon of preferential flow side infiltration is obvious.(2)The dyeing area ratio shows a non-linear decreasing trend with the increase of soil depth,and there is non-uniformity in the process of water infiltration.The preferential flow ratio reached 47.11% at an infiltration rate of 75 mm, the highest level of preferential flow development.(3)The average maximum dyeing depths under the three infiltration water conditions were 25.33 cm, 32.20 cm and 38.87 cm, respectively, which were positively correlated with the magnitude of infiltration water,indicating that an increase of infiltration water can directly promote the movement of soil water to deeper layers and facilitate the opening of preferential path.(4) There is a positive correlation between infiltration water and the preferential flow evaluation index, with the preferential flow evaluation index of 75mm (0.81) > 50mm (0.39) > 25mm (0.36),and the increase in infiltration water leads to a higher degree of preferential flow development. The results of the study can be used as a basis for vegetation restoration and further analysis of the relationship between forest and water in loess areas.