【作者】 李亚娟；

【导师】 沈冰； 宋孝玉；

【作者基本信息】 西安理工大学 ， 水文学及水资源， 2007， 硕士

【摘要】 土壤水分运动参数是土壤中水分运动和污染物迁移预测的基础,土壤水分运动参数的确定可以为生态环境建设和农业可持续发展研究提供依据,土壤水分运动参数的空间变异是确定流域土壤水分运动参数的一个难点。本研究以南小河沟流域为例,在大量试验和分析的基础上,对流域尺度上非饱和土壤水分运动参数的空间分布做了初步研究,取得了以下成果:1.南小河沟流域稳渗率为0.239～4.425mm/min,平均为1.745mm/min。对多点实测资料利用考斯加可夫公式、霍顿公式和通用经验公式的拟合分析表明,在入渗的瞬变阶段(0～10min),考斯加可夫公式的拟合效果较好;在入渗渐变阶段(10～70min),考斯加可夫公式和通用经验公式的拟合点与实测点均配合较好;而在稳渗阶段,则以通用经验公式和Horton公式拟合较好。总体上看来,在塬面和阴坡上宜用考斯加可夫公式进行拟合。2.在试验基础上,建立了南小河沟流域土壤水分运动参数(土壤水分特征曲线、土壤水分扩散率、非饱和土壤导水率)的单一参数模型。各模型具有较高的拟合精度;模型中只有一个参数,而且随土壤质地或地貌变化而变化,可以作为描述土壤水分运动参数空间变异的变异系数,适合流域尺度上土壤水分运动参数空间变异性的研究。3.南小河沟流域土壤分形维数为2.392~2.593,随着土壤粘性的增加,分形维数有增大的趋势,南小河沟流域的土壤粘粒含量对分形维数有显著影响,呈指数关系;本文建立的分形维数与土壤粘粒含量的关系式可以估算南小河沟流域土壤颗粒组成的质量分形维数。对不同地貌下的土壤剖面上土壤颗粒质量分形维数的变化分析表明,土壤粘粒百分含量和土壤质量分形维数表现出一致的变化规律,质量分形维数与地貌和土地利用类型有关。4.推求了非饱和土壤水分扩散率的分形模型,并根据实测资料进行了分形维数的拟合,研究表明,土壤含水量较小时具有明显的分形特征。此模型是由土壤水分特征曲线和导水率分形模型推导而来的,只能从试验中验证其准确度,尚不能从理论上加以证明。5.用Brooks-Coreys模型估算了南小河沟流域的土壤水分特征曲线,具有较高的精度,该模型可以用在大区域上水分特征曲线的估算。6.建立了土壤水分运动参数的空间分布图和土壤物理参数的空间分布图,并对空间分布特征进行了分析。更多还原

【Abstract】 The selection and determination of soil hydraulic parameters is the basis of predicting water movement and solute transfer in soils. Soil hydraulic parameters provide evidence for the selection and determination of soil hydraulic parameters in the study of ecological environment construction and sustainable agriculture development.The problem of spatial variability of unsaturated soil is complicated, here we make the first step study on the spatial variability of unsaturated soil hydraulic properties based on the experiment and analyse exampled for Nanxiaohegou basion. The main results are showed as fllowing:1. Stable infiltration rate were between 0.239 and 4.225 mm/min in the Nanxiaohegou basin, with the mean of 1.745mm/min. Kostiakov expression had higher accuracy in transient stage, both Kostiakov and common experience could be used to estimate infiltration, common experience and Horton expression had higher accuracy in stable stage. As a whole, Kostiakov expression was fitter to estimate infiltration rate on the plateau and shady slope.2. The one parameter models of the unsaturated soil hydraulic properties are established according to the experiments. These models had higher accuracy and could be used as the variation coefficient to describe the spatial variability of soil hydraulic properties of the large scales for unlimited by soil. The single parameter varies with soil texture and topographical feature.3. The mass fractal dimension were between 2.392 and 2.593, it varied with clay grain content, the mass fractal dimension of soil particles was significant correlated with the mass percentage of soil clay content ; and propose a correlation to predict the mass fractal dimension ,the result was satisfactory. In the soil profile of different land, both the mass percentage of soil clay content and the mass fractal dimension of soil particles showed the same tendency of increasing with the soil depth, and the mass fractal dimension relates to the land uses and topographic feature.4. Fractal model of unsaturated soil water diffusivity was proposed and applied to fit fractal dimension according to measured fractal dimension, the result proved that fractal characteristic was obvious when soil water content was low. The fractal model was deduced by fractal model of soil water characteristic curve and soil unsaturated conductivity, and it could not proved in theory, only proved by measured data.5. Soil water characteristic curve was estimated by Brooks - Coreys model in Nanxiaohegou basin, the model has high accuracy and it could be applied to the large basin.6. Based on one parameter model and fractal model, the spatial distribution maps of the parameters were established for soil hydraulic properties and the physics parameters of soil.更多还原