【作者】 毕小刚；

【导师】 周心澄；

【作者基本信息】 北京林业大学 ， 生态环境工程， 2007， 博士

【摘要】 土壤流失是国际社会广泛关注的环境问题，严重的土壤流失加剧了生态环境的恶化，造成了水资源短缺、洪涝灾害、水环境恶化等突出问题，严重地制约了经济社会的可持续发展和人类生存环境的改善。洁净的淡水和可耕作的土壤已成为21世纪人类最为重要的战略资源，水是生命之源，土是生存之本，保护水土资源是世界各国人民的共同责任。北京地处华北平原北端，全市总面积16410km~2，其中山区面积10072km~2，占全市总面积的62％。山区是首都主要的水源涵养及供给源地，是天然生态屏障，也是居民休闲旅游度假胜地。但北京山区坡陡土薄，坡度大于25°的面积占山区总面积的40％左右，近50％的地区土层厚度小于30cm；据2000年土壤侵蚀遥感调查，全市土壤侵蚀面积4089km~2，水土流失导致山区土地生产力降低，生态环境恶化，同时，水土流失及携带的污染物污染了水资源，加重了北京水资源的短缺程度。因此，水土保持工作是北京山区经济可持续发展的基本保障。北京市从实际出发，提出了以水源保护为中心，根据水土流失的发生发展规律，构筑“生态修复、生态治理、生态保护”三道防线，治理水土流失，建设生态清洁型小流域的水土保持思路。为此，我们需要一门技术和工具来定量评价北京市土壤流失和泥沙输移规律，调查土壤流失的现状、规模和发展趋势，确定最佳治理管理方案，减少直至避免土地退化，为水土保持生态环境建设提供科学依据，为政府决策提供依据。土壤侵蚀预报模型及土壤流失调查是有效“诊断”土壤流失现状和进行土壤流失评价的工具。参考国外较为完善且广泛使用的土壤侵蚀预报模型结合北京地区的观测资料来建立适合北京山区的土壤流失方程显得尤为重要。根据调研认为，物理模型由于参数多且获取难度大的特点，还处于研究阶段；而经验模型通过应用区域大量的观测统计数据就可建立，实用性强，因此，选用最成熟、世界上应用最广的经验模型美国通用土壤流失方程式为北京地区土壤流失方程的基本模型框架。北京的坡地水土流失观测始于1987年，2000年对坡地径流场又进行了系统的补充完善，在全市7个山区区(县)均布设了坡地径流场。本文利用北京市水务局在7个山区区(县)的11个坡地径流场127个径流小区近1000个坡面径流小区的年降雨、径流和泥沙资料、60多场次人工降雨试验资料和北京地区10个水文站1980-2004年25年2894次降雨过程资料以及24个水文站1980-2004年日雨量等资料，在总结国内外学者研究成果的基础上，研发计算土壤流失方程式中各个水土流失因子在北京地区的计算方法或参数值，确定了北京山区坡面土壤流失方程降雨侵蚀力因子R、土壤可蚀性因子K、坡度和坡长因子SL、植被覆盖与管理因子C以及水土保持工程措施因子P的计算公式或计算值。研究中发现，在石质山区，土壤表层常有大量的砾石(土壤中直径大于等于2mm的矿物颗粒)存在，通过小区实际观测资料及人工降雨模拟试验，发现土壤侵蚀量随砾石覆盖度增大而减少。因此在北京土壤流失方程中，增加砾石覆盖因子(R_F)作为一个单独因子在方程中加以考虑，通过人工降雨模拟试验，得出土壤侵蚀量和砾石覆盖二者关系，最终得到适合于北京山区的土壤流失方程A=RKLSCPR_F。利用实际坡地径流场观测资料验证，该模型确定性系数为0.974，模型计算结果与实测值非常接近，证明土壤流失方程及其参数的取值合理。以该方程为技术工具应用抽样调查法和网格法，在北京已开展大范围土壤侵蚀现状调查，并取得阶段性成果；2004年-2006年的《北京市水土流失监测公报》中，利用该方程及全市123个雨量点年降雨资料，得到全市年降雨侵蚀力等值线图，通过年降雨侵蚀力的分布，用全市山区7个坡地径流场的水土流失观测数据推算全市坡地土壤流失量，大大提高了公报的准确性与科学性。北京将继续进行坡地径流场的观测，用长序列的观测资料对模型参数不断进行率定与模型修正，使模型更加完善。同时，将加强模型应用的研究，特别是模型在水土流失预测和水土保持规划应用方面的研究，为北京山区水土资源管理、水土流失防治及生态建设服务。更多还原

【Abstract】 Soil erosion is now regarded as a global environment problem, which gets more and more attention from all people in the world. Serious soil causes many the eco-environment problems, such as water shortage, flood disaster, deterioration of water environmental and so on. Clean water and cultivable lands have become the most important strategic resource in 21st century, water and soil is the foundation of the life. It’s the shared responsibility of all the people in the world to protect soil and water resources.Beijing , with a total area of 16,410 km~2, locates in the north part of North China Plain. Us mountain area is 10,072km~2, accounts for 62% of the total area. Mountain area is the main conservation area of the water, the main resort for the capital people.The soil in the mountain area is very thin and the slope is very deep. The degree of the slope more than 25° accounts for 40% of the whole mountain area, and the soil layer less than 30cm accounts for over 50%. According to remote sensing survey of soil erosion in 2000, the soil erosion area of the whole city is 4,089km~2. Soil erosion and water loss lead to the land productivity decreasing, eco-environment exacerbating and water pollution, and further aggravates the water shortage problem in Beijing. So soil and water conservation is the basic guarantee for economic sustainable development in Beijing mountains area.Set out from practice, Beijing put forward an idea of soil and water conservation that takes water resource protection as a center, according to the law of soil erosion to build the Three Conservation Belts: ecological restoration, ecological management and ecological protection, finally to construct ecological-clean small watershed. So we need a technology and a tool to quantitatively evaluate the rules of soil loss and sediment transport for Beijing, to investigate the status, scale and development trend of soil erosion, determine the best land harness and management program, reduce or try to avoid land degradation, provide a scientific basis for soil and water conservation and eco- environment construction, and a decision-making basis for government to make decision.Soil erosion prediction model and soil loss equation are now the quantitatively evaluation tool to investigate soil erosion status. It is very important to set up a soil loss equation suitable for the Beijing mountainous area by referring to soil erosion prediction models out-seas which are relatively perfect and widely-use and combining with thepractice observation data in Beijing. According to the research ,we find out the physical model is still in the research phase because the parameters relatively more and difficult to get, while the empirical model has more practicability as it could be established only depending on a large number of observation and statistics data. So we choose the most mature and widely used experience mode, the USLA general soil loss equation, as the basic model frame for the Beijing mountains soil loss equation.The slop soil loss observation was stared in 1987 in Beijing, and the slope runoff plots were completed and improved in 2000, the entire seven mountain districts (counties) have emplaced the slop runoff stations. According to use the field observation date of the rainfall, runoff and sediment content in 127 runoff plots and almost 1000 slope runoff fields, artificial rainfall test data of more than 60 times, rainfall process data of 2894 times of 10 hydrometric stations and daily rainfall data of 24 hydrometric stations, and all these data are 25 years from 1980-2004, summarizing the research results both of overseas and domestic, this paper research the calculation methods or the parameter value of all the soil loss factors of soil loss equation suitable for the Beijing area,find and make sure the calculation methods or the calculation value of factors the of Beijing mountain soil loss equation, which are rainfall erosion force factor R, soil erosion possibility factor K, slope length and grade factor SL, vegetation cover and manage factor C, soil and water conservation measures factor P.The researcher also find that in the rocky mountains the soil surface often has a lot of gravel (mineral particles with diameter larger than 2mm ), according to field observation data and artificial rainfall tests, we find that the soil erosion decreases with the increase of gravel coverage. So in the Beijing soil loss equation, adds the gravel cover factor (R_F )as an independent factor, according to artificial rainfall tests to educe the relationship between soil erosion and gravel coverage, and at last put forward the soil loss equationA = RKLSCPR_F which suitable for Beijing mountains. By using the observation data of slope runoff stations, the definite coefficient of this mode is 0.974; the calculated result is very near to the observed value, which proves that both the soil loss equation and the paramcter value are reasonable.Taking this soil loss equation as technology tool, applying both sample survey and grid investigation methods to implement large scale soil erosion status investigation in Beijing has received some initial results. In the bulletin of Beijing Soil Loss Monitoring from 2004 to 2006, combining this soil loss equation with rainfall data of 123 rainfall station all over the city to draw up a rainfall erosivity contour map, according to the distribution of rainfall erosivity and by using the observation data of the 7 slope runoff stations all over the city to calculate the slope soil loss of the whole city, which greatly enhance the veracity and science of the bulletin.We will continue to do the observation in the slope runoff stations in Beijing, using the observation data with long years to revise the parameter and improve the mode, and go onto do the further research on the mode application, especially on the aspects of soil loss forecast and soil and water conservation plan, provide service for the land and water resource management, soil loss prevention and ecological construction of Beijing mountains.更多还原