中文摘要：

在重庆四面山的4块农地上，通过前期洒水使样地具有不同的土壤前期含水量，应用优先流染色法和室内图像提取技术分析样地垂直剖面和水平剖面的土壤染色情况，并在染色过程中用TDR记录样地每层土壤含水量的变化，分析不同前期含水量下优先流的入渗深度及入渗速率，研究土壤前期含水量对优先流的影响。结果表明：（1）土壤前期含水量低的样地，湿润锋的渗透速率随土层深度的增加而增加，湿润锋平均入渗速率为1520mm／h；土壤前期含水量高的样地，湿润锋的渗透速率随土层深度的增加而减小，湿润锋平均入渗速率为515mm／h；（2）土壤前期含水量较低的样地垂直剖面的染色示踪物平均最大入渗深度为56．00cm，大于前期含水量较高的样地的33．76cm，说明土壤前期含水量低的样地优先流渗透深度更大；（3）土壤前期含水量较高的样地，优先流主要发生在土壤A层和B层的20-30cm土层深度处，而前期含水量低的样地优先流在A层、B层和C层均有发生。而且土壤前期含水量较低的样地，垂直剖面每层的平均染色面积均大于前期含水量高的样地，说明土壤前期含水量较低的样地优先流现象更明显。

英文摘要：

Four plots of agricultural land were selected in Simian mountain ot L;hongqmg city as tleld site to analyze the depth of dye infiltration and the rate of infiltration under different antecedent soil moisture and then research the effect of antecedent soil moisture on preferential flow. The early pre-watering was applied to make the plots with different soil moisture. The dying situation of the vertical and the horizontal cross- sectional profile were analyzed by brilliant blue dying method and image processing techniques and the chan- ges of moisture in each soil profile. The results showed that. （1）In the plot with lower antecedent soil mois- ture, the wetting front velocity decreased with depth, the average estimated wetting front velocity was 1 520 mm/h. Whilst in the plots with higher antecedent soil moisture, the wetting front velocity increased with depth, the average estimated wetting front velocity was 515 mm/h. （2）The maximum depth of dye infiltra- tion in the plots with lower antecedent soil moisture was 56.00 cm, and the maximum depth of dye infiltra- tion in the plots with higher antecedent soil moisture was 33.76 cm, indicating that the maximum depth of dye infiltration with lower antecedent soil moisture was deeper than that with higher antecedent soil mois- ture. （3）In the plot with lower antecedent soil moisture, preferential flow occurs mainly in A soil layer and at a depth of 20--30 cm in B soil layer, whilst in the plots with higher antecedent soil moisture, preferential flow occurs in A, B and C soil layer. And the average percentage of stained area of each layer of vertical sec- tion and horizontal cross-section in the plots with lower antecedent soil moisture was II larger than those with higher antecedent soil moisture, indicating that the phenomenon of preferential flow in the plots with lower antecedent soil moisture was more obviously.