【作者】 才业锦；

【导师】 史东梅；

【作者基本信息】 西南大学 ， 水土保持与荒漠化防治， 2010， 硕士

【摘要】 重庆市地处川东山地丘陵区,总面积8124万km2,其中山地、丘陵、平坝分别占总面积的60%、30%、10%,地势起伏多变,是典型的山地丘陵地带,属区域生态脆弱区。同时,重庆市也是三峡库区生态环境重点保护地带,在原生脆弱生态环境和不合理人类开发活动共同作用下产生了严重的水土流失、面源污染,对三峡库区水土保持生态环境安全造成了巨大威胁。水土保持措施体系分类、水土保持措施效应分析及水土保持治理的范式评价是进行水土保持措施选择、规划和设计的重要依据,对水土保持生态环境建设有重要指导意义。本文根据重庆市水土流失和水土保持特点,提出根据治理对象划分水土保持措施体系并结合文献数据定量分析了重庆市及相似地区典型水土保持措施的效应,研究了基于USLE模型的水土保持因子C值的年内变化及不同措施的P值,分别采用流域可持续经营和基于USLE模型的土壤侵蚀减少比例进行了小流域治理范式评价。主要研究结果如下：(1)根据水土保持治理对象,将重庆市水土保持措施划分为小流域综合治理措施、区域水土保持治理措施、专项水土保持治理措施以及开发建设项目水土保持治理措施。不同空间尺度的水土保持措施分类的建立可从水土保持生态建设的外部约束条件做出更为直接和积极的响应,在最优化理论支持下,实现小流域、区域、专项治理、开发建设项目的水土保持生态环境建设目标。(2)在重庆市各项水土保持措施中,坡改梯减沙效益为8.4%,农业措施中的垄作和间作保土保水效应较为突出,分别在41.67%-68.00%、17.78%-45.99%,间作处理的金银花达到17.2%；与坡改梯、耕作措施相比,几种植物措施减沙减水效益都超过75%,说明植物措施的减沙减水效益最为明显。生态修复措施水土保持减沙、减水效益分别达到了42%和61%。不同水土保持措施对土壤改良的分析表明,植被能显著改良土壤结构,提高了土壤肥力,增加土壤入渗。通过对模型和数值的推导表明,水土保持措施因子P值与水土保持减沙效益互为相反数,该值可用于基于USLE模型的水土流失预测中。(3)根据小区观测,不同坡耕地降雨侵蚀累积产沙规律为：荒地(HS-1)>顺坡耕地(HS-2)>横坡耕地(HS-3)>横坡植物篱耕地(HS-4)；利用USLE模型可得各种耕作方式顺坡、横坡和横坡植物篱坡耕地的C值分别为0.174、0.168和0.129,而顺坡、横坡和横坡植物篱坡耕地的P值分别为0.78、0.58和0.51；由实测数据获得的横坡和横坡植物篱坡耕地的P值分别为0.69、0.65,因此可见无论是模型值,还是实测值,都能较好的反映紫色丘陵区的水土保持措施P因子变化,即顺坡耕地>横坡耕地>横坡植物篱耕地。(4)坡耕地水土流失强度因植被覆盖度、种植制度、种植模式以及不同作物种类等多种因素影响而差异很大；对于坡耕地而言,了解不同种植模式下的C值、P值大小及在年内变化特点,通过选择适宜的作物种类、种植制度、种植模式,尤其在降雨集中分布时期可增大地表盖度,可有效地控制水土流失,减少土地退化；并为坡耕地水土流失预测提供基本参数。(5)仙鱼小流域2007年可持续发展度0.641,而2009年可持续发展度0.714,说明在实施了注重生态效益、社会效益、经济效益的小流域综合治理工程后已进入可持续发展状态；从指标贡献角度看,2009年资源环境承载能力明显比2007年高出15.55%,经济发展能力比2007年高出10.95%。采用基于USLE模型的土壤侵蚀减少比例评价表明,小流域土壤流失减少比例为28.19%,各项水土保持措施的土壤流失减少比例分别为石坎坡改梯1%,水土保持林15.03%,经济果林11.25%,封禁治理32.91%；土壤流失减少比例随坡度和坡长的增加而增加,坡度在25°以下土壤流失减少比率变化趋势较缓,坡度在25°以上变化趋势较陡,坡长在70m以下土壤流失减少比率变化趋势较缓,坡长在70m以上土壤流失减少比率增长较快。该小流域综合治理模式可为相似地区小流域治理提供参考范式。更多还原

【Abstract】 Chongqing is located in eastern Sichuan mountain and hilly areas, with a total area of 82400 km2.60%,30%,10% of total area are mountains, hills, plain respectively. Chongqing is a typical mountain hill area and regional eco-fragile area. Chongqing also is an ecological environment protection area of Three Gorges Reservoir. Unreasonable development activities of human caused serious soil erosion, non-point pollution, and enormous ecological security threat. Systematic classification of soil and water conservation measures, effects analysis of soil and water conservation measures and evaluation of soil and water conservation paradigm are important basis for selecting measures, planning and designing, and also have an important significance in soil conservation ecological environment construction. According to soil erosion and soil conservation characteristics of Chongqing, presented a classification system based on controlling objects for soil and water conservation measures.This paper quantitatively analysis the typical effects of municipality water conservation measures, changes of factor C values and factor P values under different measures based on the Universal Soil Loss Equation(USLE). According to sustainable management of watershed and the soil erosion’s decrease proportion based on USLE model, it given a paradigm for evaluation of small watershed management. The major results are as follows:(1)According to the controlling objects, Chongqing soil and water conservation measures were divided into four categories, small watershed comprehensive management measures, regional soil and water conservation measures, special soil and water conservation measures and soil and water conservation measures for development and construction project. The establishment of classification of Soil and water conservation measures at different spatial scales can make a more direct and positive response from the external constraints, and also achieve the goal of soil conservation ecological environment construction.(2) In the soil and water conservation measures in Chongqing, terrace sediment reduction efficiency is 8.4%, sediment reduction efficiency of ridge culture and intercropping in agricultural practices are 41.67%-68.00% 17.78%-45.99% respectively, and intercropping treatment honeysuckle 17.2%; Compared with terrace, tillage,the sediment and water reduction efficiency of plant measures is higher than 75%.It indicated that plant measures has the most obvious efficiency for sediment and water reduction. The efficiency of water and sediment reduction of ecological restoration measures are 42% and 61% respectively. Analysis of soil improvement by different soil and water conservation measures shows that vegetation can significantly improve soil structure, increase soil fertility, and soil infiltration. The derivation of the model and numerical indicated that factor P value and benefit of sediment reduction of soil and water conservation measures are opposite to each other, and the value can be used for soil erosion prediction based on USLE model.(3)According to the observation of runoff plots, rainfall erosion and sediment yield characteristics of different sloping cumulative show that:wasteland (HS-1)>downslope cultivated farmland (HS-2)> cross slope farmland (HS-3)>cross slope farmland hedgerows (HS-4);using USLE model to calculate C values of tillage downslope, cross slope and cross slope farmland hedgerows are 0.174,0.168 and 0.129, while the downslope, cross slope and cross slope farmland hedgerow P values are 0.78,0.58 and 0.51;P-values of measured data of the cross slope and cross slope farmland hedgerows are 0.69 and 0.65,It shows that both the model values and measured value can reflect laws of P factor changing in purple hilly area of water conservation measures, that is downslope cultivated land> cross slope farmland> cross slope farmland hedgerows.(4) Soil Loss intensity due to vegetation cover, cropping systems, cropping patterns and crop types and other factors vary widely; through investigating the C value, P value changes in the years of different cropping patterns,we can choose suitable crops, cropping systems, cropping patterns, and increase surface coverage during the rain season. It can effectively control soil erosion and reduce land degradation and provide basic parameters for soil erosion prediction model.(5)Xianyu watershed sustainable development degree is 0.641 in 2007.It indicated small watershed management works have entered the state of sustainable development; In terms of contribution of index, resources and environment carrying capacity of 2009 is 15.55% significantly higher than that in 2007, and economic development capacity is 10.95% higher than that in 2007.Based on USLE model the reduction proportion of soil erosion shows that ratio of reduce soil loss in small watershed is 28.19%, ratio of reduce soil loss in all soil conservation measures are as follow:Terrace is 1%,water and soil conservation forest is 15.03%,economic fruits is 11.25%, blockading administration is 32.91%;The proportion of soil loss reduce increases with the slope and slope length,The ratio of reduce soil loss of slope under 25°has a more moderate trend, The ratio of reduce soil loss of slope above 25°has a more steep trend; when the slope length is longer than 70m,the ratio of reduce soil loss has more moderate trend, otherwise it has a steep trend. The small watershed management could make a reference and paradigm for similar small watershed treatment.更多还原