【作者】 徐金英；

【导师】 陈晓燕；

【作者基本信息】 西南大学 ， 水土保持与荒漠化防治， 2009， 硕士

【副题名】以三峡库区万州戴家沟小流域为例

【摘要】 我国紫色土分布较为广泛,面积为2200万hm²,主要分布在16个省区市,其中四川、重庆和云南3省市分布最广,占紫色土总面积的74.56%。紫色土质地较好,具有丰富的毛管孔隙和良好的透水性,且土壤肥力较高,已被广泛的开发利用,是我国宝贵的农业土壤资源。但紫色土成土母岩结构疏松,易风化,抗蚀性低;加上地形、降雨及人为因素,导致该地区水土流失严重。我国紫色土的侵蚀面积及强度仅次于北方的黄土。因此,我国众多学者对紫色土侵蚀规律、侵蚀机理及其影响因素等方面展开了研究,取得了较大的进展。本文运用¹³⁷Cs示踪技术,对戴家沟小流域各地貌部位和土地利用类型的土壤侵蚀与沉积状况进行了定量分析和评价。戴家沟小流域位于重庆市三峡库区万州长岭镇境内,属于五桥河流域的次级支流。对戴家沟小流域开展土壤侵蚀研究,分析流域侵蚀来源,探讨流域不同地貌部位、不同土地利用类型的土壤侵蚀强度差异,可为三峡库区小流域的水土流失治理提供依据。主要研究结论如下:1.戴家沟流域年均侵蚀模数为897.37t/km²·a,属微度侵蚀区,裸岩地的侵蚀模数达9240t/km²·a,农耕地的侵蚀模数达1056.43t/km²·a,控制裸岩面积、合理农作是有效控制流域侵蚀的关键。流域侵蚀特征跟土地利用类型密切相关。除裸岩地外戴家沟小流域以农耕地侵蚀最为严重,流域内不同地貌部位的侵蚀特征差异显著,以坡中＞坡顶＞坡脚。2.综合分析戴家沟小流域的土壤理化性质,表明山地土地利用方式和地貌部位综合影响着土壤的物理化学性质。土壤养分的分布格局主要依赖于土地利用与地貌部位之间的差异,人类活动的影响是加剧这种差异的主要原因。不同土地利用类型中的各物理性质显示裸岩地砂化最为严重,而人为扰动最少的马尾松林物理性状明显较好,从不同地貌部位的物理性质来看,坡中是流域最为严重的部位,而坡脚土壤的粘重化较为明显,结构性也较强。各土地利用类型土壤养分以各林地含量最高,农耕地次之,裸岩地最低。不同地貌部位的土壤化学性质研究表明,坡脚是土壤各化学养分的汇集处,其养分含量均高于坡顶和坡中,坡中的养分流失最为明显。3.统计分析表明:土壤侵蚀模数与¹³⁷Cs面积活度值相关系为-0.43,除全氮和速效磷外,土壤侵蚀模数与土壤各理化性质都达到低度或中度相关。更多还原

【Abstract】 Distribution of purple soil in our country is broad which is up to 22 million hm²,and mainly distributed in 16 provinces and autonomous regions,especially Sichuan,Chongqing and Yunnan Province,which reach to 74.56%.Purple soil is rich in capillary porosity and good permeability, high soil fertility and it is our country’s precious agricultural soils resources which has been developed in wide range.But the structure of purple soil parent material is loose and easy to efflorescent,anti-erodibility;and also serious soil erosion in the region because of the topography, rainfall and human factors,.In our country,purple soil erosion area and the intensity is only inerior to the loess in the North.Therefore,many scholars in China studied on the purple soil erosion, erosion mechanism and influence factors such as the field and has made great progress.In this paper,I use the ¹³⁷Cs tracer technique to analyse and evaluate parts of the physiognomy and land use types of soil erosion and deposition conditions of small drainage daijiagou.Daijiagou small watershed is located in the Three Gorges reservoir area in Changling town Wanzhou district Chongqing city,and belong to the Wuqiao river watershed tributaries.Base on research of soil erosion in daijigou small watershed,analysis of soil erosion sources,discussion of different parts of the physiognomy and land use types of soil erosion intensity differences it can provide the basis of the Three Gorges reservoir area for small watershed management.The main conclusions of the study as follows:1.Annual average erosion modulus of Daijiagou watershed is 897.37t/km²·a,and which belongs to a Micro-erosion degrees areas.The erosion modulus of Uncovered Rock is 9240 t/km2·a and farmland erosion modulus reach to 1056.43t/km2·a,reasonable farming and control Uncovered Rock area is the key problem of Effective control watershed erosion.Erosion characteristics of watershed are closely related with land-use types.Erosion of agricultural land is most serious except the uncovered Rock,There is a significant difference between the erosion characteristics of different parts of the slope in the watershed,as follows:mid-slope>top of slope> base of slope.2.It shows that mountain land use and landscape position of the combined effects the physical and chemical properties of soil base on analysis of small watershed in the soil physical and chemical properties.The distribution pattern of soil nutrients mainly depends on differences land use and Geomorphological sites,and the main reason for intensity the difference is the impact of human activities.Physical properties of different land use types figures out that the Uncovered Rock desertificates most serious,and the physical properties of masson pine forest is better because of less human disturbances, From different parts of the physical properties of topography,the mid-slope is the most serious parts,and the soil on the base is Clayey and strong structural.Forest land has highest soil nutrient of all kinds of land-use types,followed by farmland,Uncovered Rock for next.The chemical nutrients assemble at the foot of the slope according to the study of the soil chemical properties of different parts of the topography,The nutrient content of the foot of the slope is higher than the top of slope and the mid-slope,and the mid-slope is the worst.3.Statistical analysis showed that:the value of the relevant department of soil erosion modulus and 137Cs area activity is-0.43.The modulus of soil erosion and soil physical and chemical properties low or moderate correlate except of total nitrogen and available phosphorus.更多还原