【作者】 傅涛；

【导师】 谢德体； 魏朝富； 涂仕华；

【作者基本信息】 西南农业大学 ， 土壤学， 2002， 博士

【摘要】 坡面侵蚀过程包括降雨溅击和径流冲刷引起的土壤分离、泥沙输移和沉积3大过程，研究和分析这些过程发生、发展的水力、土壤、地形条件以及各过程间相互转化、相互影响的机理，是建立土壤侵蚀物理模型的前提条件。根据我国实际情况，开展坡耕地土壤侵蚀分离、输移和沉积过程及其关系的研究，对于建立具有我国特色的土壤侵蚀模型，进而指导水土保持生产实践具有十分重要的理论和实践意义。目前对坡面土壤侵蚀的研究大多集中在三个方面，一是对坡面土壤侵蚀的方法研究，包括实验研究方法和土壤侵蚀评估方法两个部分，二是对坡面土壤侵蚀机理的研究，三是对减轻坡面土壤侵蚀的各种措施研究及评价。国内对坡面的研究方法以定性和统计分析为主，在坡面水土流失机理及过程，养分流失所造成的面源污染的预测及评价，坡面流失定量预测模型以及控制措施与坡面的相互作用等方面仍需作进一步研究。目前在长江流域仅有坡面流失土壤颗粒特征和坡面农林复合系统养分流失时间过程的研究报道，而对三峡库区坡面土壤泥沙及养分流失的机理及过程参数的获得尚无报道，还没有一个较系统的泥沙径流及养分流失的预测预报模型，更谈不上构成坡面治理措施的效益评价模型。 近40多年来，由于诸多不合理的土地利用方式，使长江流域内水土保持面积和强度越来越大。举世瞩目的三峡工程把防治库区周围及长江上游水土保持工作提到了一个崭新的高度，三峡大坝建成后，以库周分水岭为界，库区面积将达到 5．42万 ho，而山地面积占这一区域的74％。随着移民搬迁，使陡坡地的耕垦率已高达43．7％，而三峡地区坡耕地是水土流失的主要物质来源己是无可争议的事实。因此当前的主要问题是如何臧轻坡耕地土壤侵蚀，减少进入三峡库区的泥沙量，延长三峡工程的运转时间，保障长江中下游河道的安全。另外，按土壤平均厚度78。m计算，长江上游100X旷r 2地区土壤孔隙度之和达1973X”m’，但土壤水库的总库容量乙总空隙容量）正随着土壤侵蚀的加剧而损失严重。同时，土壤是农业生产的根本，治理水土流失的关键是要保住土壤，而土壤养分绝大部分是随着泥沙流失的，严重的水土流失造成土层浅簿、养分贫瘠，土地质量退化，产量下降，对三峡库区移民工作和农业可持续发展造成严重威胁，制约三峡库区经济发展。因此进行三峡库区坡耕地土壤侵蚀机理研究，探索减轻坡耕地土壤流失的方法措施，具有全局性的重大意义。 本研究共分三个部分，第一部分是通过室内模拟实验，进行坡面土壤、养分、径流的流失机理研究，为坡面侵蚀水土流失预测预报模型的建立提供必要的参数。第二部分是坡面径流小区观测，以便对室内模拟试验获得的模型进行验证。通过对影响侵蚀各因素指标的确定，建立起坡面水土流失预测模型。第三部分是运用试验获得的水土流失预测模型结合GIS技术进行流域尺度的水上流失预测预报。通过对水土流失模型在不同空间尺度下的转换，将坡面土壤侵蚀的微观机理研究与宏观流域的水土流失量预测有机联系起来，位坡面土壤侵蚀微观机理研究成果能运用到宏观的流域水土流失量的预测，而宏观水土流失量的预测模型有微观试验结果的支持，形成坡面水土流失研究在“点一坡面一流域”不同空间尺度下的有机结合及其相应空间尺度模型转换的研究新思路。研究结果如下：l坡面产流机理 通过紫色土和黄壤两种土壤进行坡面降雨入渗室内模拟降雨试验发现，两种土壤的入 I渗过程i＊似及入渗量1（O均可采用霍顿（Horton）公式来表达： 术产生径流时：j（t）＝R（t），帅）叫叫仰（t＜t。） 开始产流时：im＝I（t）八，帅）＝0刷t）一以t）（t＞h）通过引入产流历时知的概念，对紫色土和黄壤在人工栓拟降雨条件下的产流历时进行了观 【二 测，发现坡面产流晚于壤中流的发生，即勺Z。说明紫色土和黄壤产流类型均属饱和产流 （蓄满产流）。要想获得坡面人渗参数，由公式分析可知，只需求得产流历时即可，在实验 室条件下，产流历时勺可直接观测获得．研究中还发现，坡面产流历时勺与降雨强度R） 和土坡前期含水量0均呈显著负相关，即雨强和土壤前翊含水量越大，开始产流时间越早， 并得出了产流历时与降雨强度和土坡前朋含水量的线性回归方程． 土体内排水是土壤入掺水分再分田的重要组成部分。研究发现壕中流的产生与降雨强 度无直接关系，而与土壤前期含水量和地面坡度有关．土场前期含水量越大，壤中流出现的 时间越早，而坡度越大，壤中流流速越大． 坡面产流过程可用动力波方程推导，通过公式推导可得出坡面任意一点的径流强度的 理论解，从公式中可推出坡面产流分为三个阶段：即入渗阶段?更多还原

【Abstract】 The hillslope erosion processes include soil separation, sediment transport and sediment precipitate, which these three process result from the rainfall splash erosion and runoff erosion. To study and analyze the happening and developing conditions of hydraulic, soil and terrain, and the mechanisms of transitions and influences of these processes each other is the prerequisite to set up physical model of soil erosion. Study on the processes and relationships of soil erosion separation and sediment transport and precipitate of slope cultivated land according to Chinese practical status have a very important theory and production significance to built Chinese specific soil erosion model and further instruct the water and soil conservation practice. Studies on Ilillslope erosion concentrate mainly on three aspects now, first, the study method of hillslope soil erosion including experiment research method and evaluation method of soil erosion; secondly, the researches of hillslope erosion mechanism; thirdly, the researches and evaluations of measure to reduce the hillslope erosion. The inland hillslope research methods are dominated by qualitative analysis and statistic analysis, therefore, much more studies need to be made to the hillslope water and soil mechanisms and processes, the prediction and evaluation of plane source pollutionresulting from nutrient loss, the quantitative prediction model of hillslope water and soil loss and the interaction between the control measures and hillslops. There are only researches about the slope loss’s soil particle characteristics and the temporal process of hillslope agro-forestry compound system nutrient loss in the Yangtze river watershed, and deficient to the mechanism and process parameters of hillslope sediment and nutrient loss of three gorges area, and there is not a preferable systematic prediction model of sediment runoff and nutrient loss also, let alone forming benefits evaluation model of hillslope harnessing measures.The area and intensity of soil and water conservation in the Yangtze River watershed have been increased for past nearly 40 years by many irrational land use patterns. The eminent three gorges engineering’s make soil and water conservation in the regions nearby three gorges area and the uppers of Yangtze River are more important significantly. After the completion of three gorges dam, the area of three gorges regions will add up to 54200km2 divide by divide, and the mountain area will make up of 74% of total area of this region. With the people’s transporting of three gorges area the reclamation ratio of steep slope sloping plantation has increased to 43.7%, however, it is a unquestionable fact that the three gorges region’s slope cultivated land is the major material resource of water and soil loss. Therefore, nowadays major problem is how to reduce the slope cultivated land’s soil erosion and sediment concentration transporting to three gorges reservoir in order to prolong the three gorges engineering’s use time and protect the safety of the middle and lower reaches channel of Yangtze river. In addition, if the soil average thickness is calculated as 78cm, then the total soil interspaced in the uppers of Yangtze River about 1,000,000km2 areas adds up to 197,300,000,000m3, but this total soil reservoir carrying capacity (total interspaced carry capacity) is decreasing with aggravating of soil erosion. Soil is the base of agriculture production, the key measure to prevent water and soil loss is to conserve soil, but most soil nutrient is lost with the sediment loss, and serious water and soil loss make the soil thickness degrease, the soil nutrient be deficient and lean, the land quality degrade and the yield of plant decrease, all this results is going to threaten the people’s transplanting and the agriculture sustainable development, and restrict the economy development of three gorges regions. Therefore, there is a whole significance to study the soil erosion mechanism and to explore methods and measures to reduce the soil loss of hillslo更多还原