【作者】 赵辉；

【导师】 解明曙； 郭索彦；

【作者基本信息】 北京林业大学 ， 山地灾害防治， 2008， 博士

【副题名】以湖南武水流域为例

【摘要】 土壤侵蚀是自然界中普遍存在的山地灾害现象之一,已成为当今资源和环境问题研究重点。本论文以长江以南花岗岩地区典型流域---湖南武水流域为研究对象,从坡面小区、小流域和中流域三种空间尺度,研究红壤侵蚀与径流输沙规律;基于流域30年土地利用变化,研究其与径流和输沙的耦合关系;基于ArcGIS建立基本属性数据库,构建研究流域分布式水文模型---PRMS_Storm模型,并在中流域尺度对径流与输沙进行模拟与预报。以期在建立土壤侵蚀—土地利用—径流输沙三者有机联系的基础上,为定量监测和科学评价区域水土流失与生态环境状况,研究揭示典型流域侵蚀与径流输沙规律,指导区域水土保持生态建设提供理论依据与技术支持。通过调查取样,运用统计分析和分形理论,研究表明,不同土地利用类型间土壤理化性质、土壤结构及其分形特征分异规律明显。分形维数能客观反映土壤结构特征及其稳定性,林地土壤结构改善,稳定性好,人为扰动不利于土壤良好结构形成。同时,弹性分析与边际分析表明,土壤结构分形维与土壤基本理化性质指标相关程度不一。采用土壤理化性质综合指标法,选用16项指标进行主成分分析,可得到无机及胶粒因子、团聚类因子、水稳性团聚体因子和有机及微团聚类因子等4个主成分因子。等级聚类分析表明,不同土地利用类型间土壤抗蚀性分异规律显著,仅就土壤抗蚀性能而言,典型林分林地抗蚀性最强,依次为疏林地、旱地、荒地,最差为坡耕地,说明坡耕地、荒地、旱地、疏林地是研究区主要的流失地类,尤其是坡耕地。研究流域土壤侵蚀以水蚀为主,局部伴有崩岗重力侵蚀发生,30年(1978~2007年)来,土壤侵蚀面积减少,侵蚀强度也有所降低。本文以自然坡面小区为基本侵蚀单元,基于19场有效降雨实测资料,研究表明不同土地利用类型间地表径流与侵蚀产沙分异规律明显,裸露荒地、坡耕地、旱地和疏林地的实测地表径流分别是典型林分林地的1354.9%、1099.9%、712.3%和285.4%,土壤侵蚀模数排序为裸露荒地7744.2 t/km2>坡耕地3826 t/km2>旱地942.2 t/km2>疏林地336.5 t/km2>典型林分林地10.2 t/km2,裸露荒地、坡耕地、旱地、疏林地为研究区主要的流失地类,植被能有效地调蓄地表径流和保土减蚀。运用SPSS进行统计分析,建立了各土地利用类型坡面小区尺度次降雨条件下的径流与侵蚀产沙多元回归模型。以小流域、中流域两种空间尺度流域为研究对象,分别研究了降雨、径流及输沙规律;运用分形理论,研究表明,相同尺度间(小流域尺度)、以及两种空间尺度流域日降雨、日径流均具有明显的分形特征,即存在自相似性。这可为实现相同尺度间或不同尺度间资料、参数的引用,以及解决尺度转换问题提供一种思路与实现途径,同时也可为相同尺度间或不同尺度间资料、参数等的获取提供一种可行的研究手段。运用SPSS进行统计分析,分别建立了小流域、中流域两种空间尺度流域次降雨条件下的径流与输沙的多元回归模型。运用分形理论,研究了坡面小区尺度不同土地利用类型侵蚀泥沙和武水流域悬移质、推移质泥沙的组成及其分形特征。研究表明,在坡面小区尺度,不同土地利用类型侵蚀泥沙组成差异显著,悬移质(入池泥沙)中值粒径排序为裸露荒地<坡耕地<旱地<疏林地<典型林分林地;<0.005 mm中粉(砂)粒以下含量排序为裸露荒地>坡耕地>旱地>典型林分林地>疏林地;最大粒径排序为坡耕地>旱地>裸露荒地>疏林地>典型林分林地。由于人为耕作扰动,坡耕地、旱地土壤抗蚀性能减弱,大量泥沙被地表径流侵蚀、搬运,其坡面地表组成物质呈粗骨化趋势。对于推移质(留槽泥沙),裸露荒地坡面小区推悬比为9.42,粗颗粒含量较高,坡耕地、旱地坡面小区推悬比分别为3.61、2.9。而在中流域尺度---武水流域,悬移质泥沙颗粒组成为粘粒11%、粉(砂)粒51%、细砂粒32%和粗砂粒6%,以粉(砂)粒和细砂粒为主。1981年以后,悬移质泥沙颗粒中粘粒和粉(砂)粒含量相对减少,颗粒组成呈变粗趋势;推移质泥沙以砂、石砾为主,平均中值粒径为0.874mm。分析表明,两种空间尺度流域悬移质、推移质泥沙颗粒组成均具有显著的分形特征。运用ArcGIS和景观分析软件FRAGSTATS,研究了武水流域30年来(1978~2007年)土地利用景观格局动态变化规律及其驱动力因素;基于流域不同时期土地利用变化及其对应的径流与输沙实测资料,探讨了流域径流、输沙与土地利用变化的耦合关系,并建立了相应的多元回归耦合模型。基于ArcGIS建立基本属性数据库,构建武水流域分布式水文模型--- PRMS _Storm,通过模型拟合、验证和参数优选,典型降雨条件下,流域径流模拟平均预报精度为0.719,洪峰预报合格率为75%;流域输沙模拟平均预报精度为0.664,输沙总量预报(<20%)合格率为62.5%,输沙量峰值预报合格率为75%。按雨型分,长历时降雨预报精度普遍高于短历时降雨,大暴雨、暴雨预报精度高于大雨、中雨。基于2007年两次典型降雨过程,进行径流模拟和输沙量预报,其结果均可达到精度要求。更多还原

【Abstract】 As a typical and ubiquitous mountain disaster in the nature, soil erosion was regarded as a keystone in the research fieldes of resource and environment now. Based on the Wushui watershed of Hunan province which was taken as a typical example in granite region in the south of Yangtse rive, the law of red soil erosion and runoff & sediment transport were researched on natural sloping plot scale and small watershed scale and middling watershed scale. The coupling relationship among landuse change and runoff and sediment transport were studied based on the landuse change of 30 years from 1978 to 2007. Basic property database were constructed by using ArcGIS, and the storm event distributed hydrological model (PRMS_Storm) with physical mechanism were also built up based on MMS ( Modular Modeling System) . And the model was used to simulate runoff and forecast sediment on Wushui watershed. The purpose of this paper was to provide theory and technique to build monitoring and quantitative evaluation system on the fieldes of soil erosion and sediment and environment, and to guide the ecological construction of soil and water conservation.Based on typical investigation and sampling, five typical landuse types were selected for search, and the differentiation law of physical and chemic property of soil and soil structure and their fractal dimensions were analyzed by the methods of statistical method, elasticity analysis, marginal yield analysis and the fractal theory. The results showed that the differentiation were distinct and influenced by land-use effectively. The fractal dimensions could be used to indicate the characters of soil structure and their stability. The soil structure and stability of woodland were improved, and man-made had made against of them. The results also showed the correlation between the fractal dimensions and indexes of physical and chemic property of soil were different.Sixteen indexes were chosen to analyze the anti-erodibility of different landuse types by the means of index synthesis, PCA and Hierarchical Cluster analysis. And the indexes could be divided into 4 categories, i.e. inorganic colloid, aggregate, water-stable aggregate, organic and micro-aggregate. As a result, the soil anti-erodibility of typical forestland was the best one, the second one was sparse woodland, the third one was dry land, the fouth was wilderness land and the worst was sloping farmland. The results showed these 4 landuse types except the forestland were the major landuse types of soil erosion and water loss under similar condition in watershed researched. Water erosion was the main erosion type in Wushui watershed researched, and gravity erosion such as collapse of mound erosion was also occurred in granite region partly. But the area of erosion was decreasing and erosion intensity was receded since 1978. The natural sloping plots of different land-use were taken as unit of soil erosion and based on observation of 19 single effective rainfall, the differentiation law of surface runoff and erosion under different land-use types were researched. The results indicated that the surface runoff of wilderness land and slope farmland and dry land and sparse-wood land were respectively 13.55,10.99,7.12 and 2.85 times as those of typical forest land. and for the soil erosion modulus, it were in ordere of bareness and wilderness land (7744.2t/km2) > sloping farmland (3826 t/km2) > dry land (942.2 t/km2) > sparse woodland (336.5 t/km2) > typical forestland (10.2 t/km2). The results showed that surface runoff could be store up and soil erosion could be decreased with the cover of vegetation effectually. It could be concluded that the bareness wilderness land and sloping farmland and dry land and sparse woodland were the major landuse types of water loss and soil erosion. Lastly, the multi-factor regression models of surface runoff and soil erosion sediment were built up under single rainfall on natural sloping plot scale by using software of SPSS.The laws of rainfall and runoff and sediment transport were studied on two different spatial scales such as small watershed and middling watershed. By using the fractal theory, the rainfall and runoff daily among same scale watershed and different spatial scale watershed were proved to have similar fraction characters, and the rainfall and runoff daily on watershed scale were also proved to have multi-fraction characters. The results showed that the fractal theory would be used as an available method to quote information and parameter under same scales and different scales, and it also could be used to scaling. Lastly, the multi-factor regression models of runoff and sediment on two spatial scales watershed were built up under single rainfall by using software of SPSS.The size distribution of suspended and bed load sediment and their fraction characters were analyzed on the sloping plot scale and middling watershed scale by using the fractal theory. On the sloping plot scale, the results showed that the differentiation of sediment by erosion under different land-use were distinct, the average d50 of suspended sediment were in order of bareness and wilderness land < sloping farmland < dry land < sparse woodland < typical forestland, and the content of exiguous grain (<0.005mm) were in order of bareness and wilderness land > sloping farmland > dry land > typical forestland > sparse woodland. The maximum of grain size were in order of sloping farmland > dry land > bareness and wilderness land > sparse woodland > typical forestland. The reason could be concluded that the soil anti-erodibility of sloping farmland and dry land were decreased and the component of surface soil grain would be increased gradually because of soil erosion. To the bed load sediment, the content of gruff grain of bareness and wilderness land was dominated, and the proportion of content of bed load sediment and suspended sediment of bareness and wilderness land was 9.42, sloping farmland was 3.61 and dry land was 2.9 correspondingly.On the middling watershed scale such as Wushui watershed, the proportion of size distribution of suspended sediment yearly of clay and silt soil and fine sand and coarse sand were 11%、51%、32% and 6%, the content of silt and small sand were dominated. Since 1981, the content of clay and silt of suspended sediment were decreased and the component of bigger grain was increased gradually. To the bed load sediment, the content of sand and gravel were dominated, the average d50 was 0.847mm. And the results showed that the size distribution of sediment on two different spatial scales was proved to have fraction characters.Then, the dynamic change of landuse and landscape pattern in Wushui watershed from 1978 to 2007 were researched by using ArcGIS and software of FRAGSTATS, and its driving factors including natural resource factors and eco-society factors were analyzed. The coupling relationship among landuse change and runoff and sediment transport of different years were studied, and the multi-factor regression coupling models were also constructed.Lastly, the basic property database of watershed was established by using ArcGIS, the storm event distributed hydrological model ( PRMS_Storm) of Wushui watershed with physical mechanism were built up based on MMS (Modular Modeling System). Then by validation and selection of parameters, the model was used to simulate runoff and forecast sediment on Wushui watershed under typical single rainfall. The average model-fit efficiency of runoff simulation was 0.719, and their percent of pass on forecast runoff peak was 75%. On the sediment transport simulate, the average model-fit efficiency was 0.664, the percent of pass on forecast quantity of sediment was 62.5%, and the percent of pass on forecast sediment peak was 75%. For different rainfall types, the model-fit efficiency of long-time single rainfall was higher than short-time single rainfall usually, and the model-fit efficiency of big rainstorm and rainstorm were higher than downfall and middle rain usually. And the model were simulated and forecasted runoff and sediment under two typical single rainfall in 2007, the results were attained the request of precision.更多还原