【作者】 刘前进；

【导师】 吕国安；

【作者基本信息】 华中农业大学 ， 土壤学， 2004， 硕士

【摘要】 土壤侵蚀模型在空间尺度上可以划分为坡面、小流域和区域3个不同层次。在坡面尺度上，主要考虑坡面侵蚀的垂直分带性及其相互影响；小流域尺度上，不但考虑坡面侵蚀的特点，还要考虑坡面来水来沙对沟道侵蚀产沙的影响、重力侵蚀及泥沙输移情况；在区域尺度上则主要考虑小流域各自的侵蚀产沙特点及其相互影响。因侵蚀的空间尺度不同，在建立土壤侵蚀模型时，要考虑由于空间变化所引起的侵蚀因子对侵蚀产沙响应的不同。 本项研究在分析国内外土壤侵蚀产沙模型基础上，依据大量小流域野外试验小区观测与模拟降雨资料，充分考虑到了空间尺度对流域侵蚀产沙的影响，特别是流域在面积上的变化对侵蚀产沙的影响。以羊道沟几十年的研究成果为基础，将ERODE模型进一步简化，采用流域离散的尺度转换方法，以王家沟支沟小流域为基本计算单元，以沟间地和沟坡地为次单元，将整个流域划分为40个沟间地、40个沟坡地及其它们组成的40个小流域和一个输水通道进行分别计算，其中涉及降雨因子、地貌因子、治理因子、植被覆盖因子、耕作措施因子和土壤因子，共6个主要因子，分别计算各个因子的侵蚀产沙响应系数，对羊道沟基础模型进行修正，从而得到一个包含8个参数，4个修正系数和13个公式的具有物理基础的分布式水力侵蚀产沙模型。利用较大尺度王家沟1963-1968年22次天然降雨资料，对模型进行了检验，模型的预测精度在55％以上。 通过对小流域侵蚀产沙模型的研究，结果表明： 从研究意义方面，本模型采用水文学中流域离散的方法可以充分利用小流域的侵蚀产沙规律来预测较大流域侵蚀产沙；利用分形理论对间接表征面积特征的地貌信息维数引入模型计算当中，反映出了流域空间变化对侵蚀产沙的影响。本模型为从已控区域侵蚀产沙推测未控区域侵蚀产沙，在理论、方法和实践上都作了有益的尝试，为较小尺度向较大尺度流域上的侵蚀产沙预测提供一定的借鉴； 在模型结构方面，采用以沟间地和沟坡地为最基本的计算单元，以水沙汇流关系为主线，建立基于小流域的、次降雨的流域侵蚀产沙模型，能更好地反映出黄土丘陵沟壑区的侵蚀产沙规律； 在研究手段方面，充分利用了GIS强大的空间分析和数据处理功能强，从DEM数据中提取子流域不同地貌部位的地形表面信息，如：平均坡度、沟壑密度、切割裂度、流域面积和坡沟比例等，并且对其中的关系进行分析，揭示出了一定的规律。更多还原

【Abstract】 According to the spatial scale, almost all of the soil erosion models can be classified as field-scale models; catchment-scale models and region-scale models. Each type of erosion models has its instinctive characteristics. As to the field scale, the analysis of the erosion process on field vertical zones and the interaction between them is very important. In addition to the analysis of soil erosion on hill slopes, effects of runoff and sediment from hill slope on erosion and sediment yield of the followed gully zone and the erosion caused by gravitation are complex and pivotal in the catchments scale. In this scale, the sediment delivery is of significant importance to the erosion modeling. Establishing region scale erosion model, the relationship and the interaction of the subordinate drainages together with the style of the runoff yield and runoff concentration should be taken into account.On the base of reviewing the existing soil erosion and sediment yield models, according to field observation and artificial rainfall data in research region, we analyzed deeply and describe quantitatively factors, which had affected on soil erosion and sediment yield, such as the factor of the rainfall, physiognomy, coverage, cultivation, management, and soil, especially the factor of the special scale. Based on the soil erosion and sediment yield of the hill slop and gully in the Yangdaogou small basin, used the ERODE model as reference, taken small watershed as the basic analysis unit, the Wangjiagou watershed was divided as 40 plots of slope fields, 40 plots of gully fields and 40 basic units, constructed by the proper hillslop and gully, and one channel that used to delivery runoff and sediment. This model includes eight parameters of models, four modificatory coefficients and thirteen relevant equations. The model, based on certain physics process, was designed to estimate single storm responses in runoff and sediment yield. Using 22 natural rainfall data from 1963 to 1968 in Wangjiagou, a lager scale area compared with the Yangdaogou watershed, we tested the model; the prediction precision is above 55%, so this model had a certain practical value.The study indicated the following results:Firstly, We engaged the mathod of watershed divition that was always used in the field of hydrology to simulate the runoff and sediment yield in the lager area based on the laws in certain smaller watershed. Using the fractal theory and taking the fractal dimention that stand for the characteristic of area, one aspect of the physiognomy, we got some result from this method that reflect the influence of the spatial transfer on runoff andsediment yield. This study has some significance on the research of modeling the runoff and sediment yield concerned with the spatial scale transfer and this study can be taken as a valuable attempt on the theory, method and practice to predict the soil erosion in larger catchments based on the experiments and data in small-scale watershed.Secondly, as to model structure, we adopted the small watershed as the basic basin and the hillslop and gully as the subordinate unit, by analysis the relationship of the runoff and sediment between the upper filed and the down zones, then we have build the soil erosion and sediment yield models based on the watersheds and each single storm, which could reflect soil erosion and sediment yield rules of loess Plateau much better.Thirdly, as to research meaning, we made full use of the powerful capability of spatial analysis and data procession, extracted deeper information automatically from the digital elevation model (DEM), such as the mean slope, gully density, degree of cutting, watershed area and the proportion of gully to slope, then analized the interrelation of them, from withch some laws abstained.更多还原