摘要:元谋干热河谷冲沟沟头土壤的渗透性是制约坡面径流,遏制沟头前进的重要因素,也间接影响着沟头土体崩塌方式.通过对元谋干热河谷区,3种典型土壤(燥红土,变性土和古红土)沟头表层土壤结构指标的测定和对入渗速率的野外定点观测,分析表层土壤结构特性及其分维特征对入渗过程的影响.结果表明:燥红土和变性土土壤结构要优于古红土;土壤颗粒和微团聚体分维数随着粉粘粒(<0.02mm)含量的增加而增大,随着砂砾(0.02~2mm)含量的增加而减小;孔隙分维数与颗粒分维和微团聚体分维呈负相关.3种土壤的入渗速率较低,用通用经验公式能够较好的模拟这3种土壤的入渗过程(R2>0.99).表层土壤的非毛管孔隙和颗粒分维(D粒)对燥红土和古红土的初渗速率影响最大,毛管孔隙度,D粒和孔隙分维(D孔)对变性土的初渗速率影响最大,除了D粒的偏相关系数为负相关外,其余的影响因素都呈正相关;燥红土和变性土的毛管孔隙,D孔对稳渗速率影响最大,D孔和微团分维(D微)对古红土稳渗速率影响最大

The soil infiltration capacity in gully head was an important restricted factor of slope runoff and extending of gully head, and also influenced indirectly the collapse type of soil body in gully head. The paper analyzed the impacts of surface soil structure characteristics and fractal dimension of tree typical soils(dry red soil, vertisol and red paleosol) on infiltration process through the measurement of surface soil structure indictors and field fixed-point observation of infiltration rate in Yuanmou dry-hot valley. The result showed that the soil structures of dry red soil and vertisol were better than red paleosol. The higher content of silt and clay particles(<0.02 mm) had higher fractal dimensions of soil particles and micro-aggregate, the fractal dimensions of soil particles and micro-aggregate decreased gradually with the increase of sand content(0.02~2 mm). There was the negative correlation between soil pore fractal dimension and fractal dimensions of soil particles and micro-aggregate. The infiltration rates of three soils were low. Using the general formula could well simulate the infiltration processes of three soils(R2>0.99).The non-capillary pore and fractal dimension of soil particles had greater influence on the initial infiltration rate of dry red soil and red paleosol. The capillary pore, fractal dimension of soil particles and pore had greater effect on the initial infiltration rate of vertisol. The partial correlation coefficients of remaining influence factors were positively correlation except fractal dimension of soil particle was negative correlation. The capillary pore and fractal dimension of soil pore had greater impact on steady infiltration rates of dry red soil and vertisol. The fractal dimension of soil pore and micro-aggregate had greater influence on steady infiltration rate of red paleosol