【作者】 郑誉寰；

【导师】 马祥庆；

【作者基本信息】 福建农林大学 ， 水土保持与荒漠化防治， 2009， 硕士

【摘要】 水土资源是人类赖以生存的物质基础,近几十年来,人口增长、社会经济发展和资源的高强度开发,直接导致土地退化和区域生态环境恶化,水土流失问题日渐成为我国头号环境问题。宁化县地处“三江源头”,是福建省水土流失最严重的地区之一,也是我国南方紫色土丘陵区水力侵蚀的典型代表,境内水土流失已有上百年历史,严重制约了社会、经济的可持续发展,加剧了区域贫困和生态环境恶化。由于长期研究的侧重点不同,我国南方紫色土丘陵区水土流失理论、生态恢复与重建实践等工作相对滞后,而已有的研究大多集中于室内、坡面等小尺度范围内,研究空间窄,时间跨度短;此外,以往的土壤侵蚀研究由于技术手段的限制,多集中于定性和定量方面,动态研究应用不多。因此,深入研究紫色土丘陵区大尺度范围内水土流失多年变化规律,建立土壤侵蚀数据库,定量地评价强化治理的效果,可以有效地指导当地水土保持实践,为更好地在政府宏观调控下开展水土流失综合防治工作奠定基础。随着遥感、地理信息系统技术和空间分析模型的深入发展,利用遥感和地理信息系统技术研究典型区域水土流失及其动态变化,成为最迅速可靠的理想手段之一。自2000年宁化县开展大规模的水土流失综合治理实践以来,在社会、经济及其它因素影响下,区域土壤侵蚀面积、景观要素等发生了很大变化。本文以水土保持学、生态学的相关理论为基础,以宁化西部典型紫色土流失区为研究区域,基于地形图、ALOS遥感数据等,综合利用“3S”技术和ArcView、ArcGIS、Erdasimagine等软件,采集包括地形(主要利用DEM提取高程、坡度、坡向等地形因子)、土地利用类型、植被、土壤侵蚀和水土保持措施五个方面数据,建立了大比例尺、高精度的区域土壤侵蚀地理空间数据集,在野外实地判读验证和专家咨询的基础上综合生成土壤侵蚀现状图;分析了宁化西部2000-2007年土壤侵蚀的强度、数量结构在时间和空间上的演变及其变化原因,定量评价治理效果;同时,结合宁化县紫色土综合治理实践经验,提出防治对策。研究的主要结论如下:1. 2007年水土流失现状。2007年福建省宁化县西部区域水土流失总面积为13123.82 hm2,占土地总面积的27.04%,土壤侵蚀以微度和轻度为主,随着侵蚀强度的增加,土壤侵蚀面积呈下降趋势。由生成的2007年宁化西部土壤侵蚀现状图可知,该区水土流失集中分布在以石壁乡为中心的中部低山丘陵区,向周围山区呈辐射下降趋势。石壁、淮土乡两个乡镇仅占区域土地总面积的45.2%,其水土流失面积约占了流失总面积的近4/5(为79.73%)。2. 2000-2007年治理期间土壤侵蚀数量、强度动态变化规律。根据土壤侵蚀分级统计结果可知,从总体变化趋势上看,自2000年以来,宁化西部区域水土流失面积呈下降趋势,2007年与2000年相比,共减少水土流失面积1509.86 hm2,下降了3.11%,年变化率为1.47%。从各侵蚀强度类型变化趋势来看,微度侵蚀和中度侵蚀明显增加,其它各侵蚀类型均呈减少趋势,其中以中度和轻度侵蚀面积变化幅度最大;中度和极强度侵蚀年变化率最大。说明7年间宁化西部紫色土地区土壤侵蚀经过治理已初显成效。3.各侵蚀类型的转移动向和新增来源构成变化。7年中约有15462.98hm2面积发生不同程度的变化,占区域总面积的31.85%。其中微度侵蚀主要转化成轻度侵蚀;轻度、中度和极强度侵蚀均主要转化为微度侵蚀,主要聚集在中部采取封禁保护和强化治理措施的地区。微度、中度侵蚀分布主要由轻度、强度侵蚀转化而来;轻度、强度侵蚀主要由微度转化而来,极强度侵蚀绝大部分由轻度、微度侵蚀转化而来,主要聚集在全垦式山地开发、火烧山、项目开发建设等人为活动干扰严重的区域,呈零星散状分布。4.利用土壤侵蚀地域分布重心模型对各侵蚀类型空间位置转换分析得出,7年间宁化西部地区土壤侵蚀分布总重心向西北偏移,整体上偏移了1945.813m;从侵蚀类型上看,微度、轻度侵蚀重心分别向东南、西北方向偏移,中度和极强度侵蚀重心均向西南方向偏移,而强度侵蚀向东南方向偏移,其中以极强度侵蚀偏移距离最大,整体上偏移了8066.912m。5.运用SEIC和SEII指标对区域内不同地形因子土壤侵蚀结构动态变化特征进行分析,说明了海拔、坡度、坡向等地形因子的不同带来的土壤侵蚀严重程度及土壤侵蚀等级类型结构差异较大;绝大部分高程带、坡度等级和坡向类别上的SEII和SEIC均是2007年低于2000年,表明人为干预作用己经超过了自然因素的影响,宁化西部地区7年间,通过采取封禁、营造防护林草、坡耕地改造等综合措施,地表植被覆盖明显增加,水土流失有所减轻。更多还原

【Abstract】 Ninghua City, locating in the area of "the source of three rivers", suffers the most serious soil erosion in Fujian Province. It is one of typical representatives of purple soil erosion region in South China, and its history of soil erosion has been more than a century. Study and investigation on the status quo of purple soil erosion and degradation, on changes in the law for many years, the establishment of a database concerning related data on soil erosion, proposals on prevention and control measures, all of those mentioned above can effectively guide local treatment on soil erosion and lay good foundation for better integrated soil erosion control under the government’s macro-control foundation.With in-depth developments on remote sensing, geographic information systems technology and spatial analysis model, remote sensing and geographic information systems have become one of the most rapid and reliable means to study soil erosion and its changes in the typical regional. Ninghua City has launched a large-scale and comprehensive treatment on soil erosion since 2000. With the social, economic and other factors, great changes for both soil erosion and landscape have taken place in the western part of the city. In this paper, on the basis of the relevant theories on soil and water conservation, ecology, setting the most serious purple soil erosion area, the western part in Ninghua City, as research region, with help of topographic maps, ALOS and other remote sensing data, "3S" technologies and ArcView, ArcGIS, Erdasimagine and so on, data in the five fields including topography (mainly using DEM to extract data of elevation, slope, aspect and other terrain factors), land-use types, vegetation, soil erosion and soil conservation measures have been acquired, and then large-scale, high-precision regional geo-spatial data sets on soil erosion have been established as well as the the status quo of soil erosion that based on the verification and expert advice in the open field. In addition, reasons for soil erosion evolution and changes of both intensity and quantity structure in time and space have been analyzed in west Ninghua during the period from 2000 to 20007. Finally, treatment and control strategies have been proposed according to integrated treatment and related experience in Ninghua county. Main conclusions are come up as follows:1. Soil erosion situation in 2007. In 2007, the total soil erosion area in the western region of Ninghua county, Fujian Province, is 13123.82 hm2, 27.04% of the total land area. And the extent of soil erosion is slight and mild-oriented. With the increase of erosion intensity, soil erosion area becomes downward. From soil erosion status chart of Ninghua county generated in 2007, the soil erosion region mainly locates in central hilly areas around Shibi. The land area of Shibi and Huaitu only accounts for 45.2% of total regional land area, however the soil erosion area is about 4 / 5 (that is 79.73%) of the total erosion area.2. Dynamic changes law of soil erosion quantity and intensity during 2000-2007. Based on statistical results of soil erosion classification, from overall changes trend, the soil erosion area in western NingHua is declining since 2000. By comparing the erosion area in 2007 with that in 2000, soil erosion area reduced 1509.86 hm2 in total with the rate of 3.11% and annual change rate of 1.47%. From changes trend of erosion intensity, slight and moderate degree erosion increased obviously, other types of erosion declined, with the biggest area change at moderate and slight erosion, and the most obvious annual changes rate at moderate and extreme strong erosion. Aforesaid results have proved early fruits in soil erosion treatment on purple soil erosion in west Ninghua in past seven years.3. From transfers of various erosion types and new erosion sources, there are about 15462.98hm2 area that suffered changes of different degrees erosion in past 7 years, accounting for 31.85% of the total regional area. Among erosion changes, slight erosion manly turned into mild erosion; slight, moderate and extreme strong erosions all turned into moderate erosion, extreme strong erosion turned into moderate erosion mainly locating in the central region areas where banned and strengthened protection measurements have been taken. Slight and moderate erosions mainly conversed from mild and strong erosions; mild and strong erosions mainly from slight erosions; extreme strong erosions mainly from mild and slight erosions locating sporadically and mainly in regions inferred seriously by human activities such as fully-cultivated land developing, mountains burining, project development and construction.4. Using the soil erosion distribution model to analyse spatial locations of the different erosion types, it is concluded that the center of soil erosion distribution in the west Ninghua has moved to the northwest, with an overall movement of 1945.813m in past 7 years. From erosion types, the shift direction for slight and mild erosion centers were southeast and northwest respectively, for both moderate and extreme strong erosion centers are southwest, for extreme strong erosion southeast. Among them, most intensive erosion is extreme strong erosion with an overall deviation distance of about 8066.912m.5.Through the analysis for different terrains on regional soil erosion dynamic changes based on SEIC and SEII indicators, it indicates that different terrain factors such as elevation, slope angle and slope direction brought about great discrepancies in severity and structure types of soil erosion. Through the comparison of related data between 2000 and 2007, it is found that indicators in 2007 on most the vast majority of elevation, slope grading, slope direction types for both SEIC and SEII are less than those in 2000, which means the role of human intervention overrun the impact of natural factors. In the west Ninghua in past 7 years, through comprehensive measures such as closure, fertilization, forest and grassland protection, economic orchard, sloping land transformation, shallow gully treatment, the surface vegetation cover has significantly increased. As a result soil erosion alleviates continuously.更多还原