基于探地雷达的滨河带藤本和次生乔木林土壤优先流特征

滨河带是河流生态系统和森林生态系统的过渡带，该区域林分的土壤优先流特征对流域的地表水文过程会产生重要影响。探究土壤异质性与优先流的关系，为当地地下水安全和河流上下游水生态安全提供参考。本研究以永定河滨河带的藤本和次生乔木林两种植被为研究对象，结合传统亮蓝(Brilliant Blue FCF)染色示踪法，利用探地雷达(Ground Penetrating Radar, GPR)技术进行测线扫描。提取探地雷达图像的单道波形图，对反射波各参数与染色面积比进行拟合，并结合优先流染色特征进行分析。染色形态特征表明，藤本样地土壤染色形态呈现断离式零散分布，优先流发育带为土壤表层以下5—30 cm的土层深度，而次生乔木林土壤呈现大面积斑块状分布，优先流发育较为迟缓，其发育带为土壤表层以下10—25 cm的土层深度，且平均染色面积比藤本小1.68%。探地雷达测线表明，土层深度为0—15 cm时，最大振幅和总振幅面积均随土层的深度增加而下降，土层深度为15—35 cm时，两参数开始波动变化，且藤本样地的最大振幅和总振幅面积大于次生乔木林样地。经拟合发现，染色面积比与最大振幅呈y=25.104lnx+2...

Characteristics of preferential flow of liana and secondary arbor forests along riverside based on Ground Penetrating Radar

The riparian zone is a transition zone between river ecosystem and forest ecosystem. The characteristics of preferential flow in forest belt along riverside have an important influence on the surface hydrological process of the watershed. Therefore, study of the relationship between soil heterogeneity and preferential flow is of great significance to local groundwater security and water ecological security of upstream and downstream rivers. In this paper, using the technique of Ground Penetrating Radar (GPR) combined with the traditional staining tracing method, the liana and secondary arbor forest sample plots along Yongding Riverside (the junction of Beijing and Hebei) were detected. The single channel oscillogram of the GPR image was extracted, and then the parameters of reflected wave and dye area ratio were fitted. Finally, the key step was to analyze the preferential flow staining features. The staining morphological characteristics showed that the preferential flow segment of liana sample plot was 5-30 cm below the soil surface, while the secondary arbor forest sample plot was 10-25 cm below the soil surface. The average dye area of the secondary arbor was 1.68% smaller than that of liana. The GPR lines results showed that the maximum amplitude and the total amplitude area decreased with the increase of soil depth at 0-15 cm. At 15-35 cm below the soil surface, the two parameters began to fluctuate. The maximum amplitude and total amplitude area of liana plot both were larger than that of secondary arbor plot. It was found that the dye area ratio was logarithmic with the maximum amplitude and the total amplitude area. The logarithm relationship between the dye area ratio and the maximum amplitude was y=25.104lnx+25.137 (R²=0.8697), and the logarithm relationship between the dye area ratio and the total amplitude area was y=23.874lnx-26.862 (R²=0.6173). The soil compactness of secondary arbor forest was better than that of liana. Therefore, there was less electromagnetic signal lost in the secondary arbor forest during the physical process. The electromagnetic signal of liana plot fluctuated greatly and lost more signals. It could be seen that the difference of soil structure between different layers of liana vegetation was more distinct than that of the secondary arbor, which led to preferential flow more frequently under liana coverage. In order to protect the safety of groundwater, it is necessary to cut down lianas appropriately and moderately in areas with poor drainage such as riverside bed zone and low-lying depression in front of hills. It could inhibit the over-development of preferential flow in soil under lianas coverage.