【作者】 刘静楠；

【导师】 秦岩宾； 张廷斌；

【作者基本信息】 成都理工大学 ， 地图学与地理信息系统， 2015， 硕士

【摘要】 三江源区河流密布,湖泊、沼泽众多,是长江、黄河、澜沧江的发源地,是我国江河中下游和周边地区生态环境安全和区域可持续发展的屏障。近几十年来,在全球变暖的大背景下,自然因素和不合理的人类活动使生态环境本来就脆弱的三江源区的生态环境更加恶化,草场严重退化,冰川、湿地退缩,生物多样性锐减,一些湿地甚至消失,部分地区的人类已经难以生存迁往他乡。因此,本文基于MODIS数据提取三江源区2001年、2005年、2010年以及2014年的湿地分布、分析其变化动态并总结影响该区变化的因素,以期为三江源的治理和保护提供依据。主要研究成果如下:(1)确定该区的湿地类型:根据青藏高原湿地分类体系,结合三江源区的特点以及数据特点,将研究区湿地分为湖泊湿地和沼泽湿地两类。(2)获得四个时期的三江源湿地分布图:对数据进行拼接、投影变换、裁剪等处理,并对MODIS数据进行时间序列分析,得到噪声较小、地物光谱特征明显的NDVI数据;利用7/4/1假彩色合成的TM影像随机选取采样点,将所有采样点叠加在每一年的NDVI数据上,分析每类地物的光谱曲线特征,统计并分析每类地物的特征值,创建了先控制光谱曲线形状,然后控制拐点阈值,再利用坡度区分的决策树,并对分类后的图像进行处理,得到四个时期的湿地分布图。通过混淆矩阵计算,总体分类精度达到预期标准,满足分类的最低精度要求。说明使用HANTS对MODIS NDVI进行时间序列分析,然后利用决策树分类提取湿地是可行的。(3)获得四个时期的湿地景观格局分析结果:本次研究从斑块面积变化、景观破碎度、景观优势度以及景观多样性和均匀度四个方面进行评价。结果表明,三江源区的湿地面积总体上呈减少的趋势,且破碎度增加,沼泽湿地的退化速度比湖泊更快,各景观类型优势度差距增大,景观的均匀度减小。2005-2010年湿地退化趋势比2001-2005年退化趋势减弱。(4)分析三江源区湿地景观格局变化的驱动因素:结合该区气候数据、青海统计年鉴、各州的经济和社会发展报告以及前人的研究成果,得出三江源区湿地面积变化的因素大致有五个:复杂高寒的地形地貌容易导致大风、多灾、荒漠、贫水等自然灾害,导致湿地的退化;全球变暖的大背景下,三江源的气候变化尤其明显,气温升高、气候变干,尤其在2000年以后,源区气温上升范围为0.6~0.9℃,气候的变化是该区湿地面积变化的最大影响因素;人口的增长、畜牧业的发展导致该区草地退化、水资源紧缺,在一定程度上导致了湿地的退化;旅游业的发展虽然带来了巨大的经济利益,但是同时也对环境、水资源、空气等造成了一定的污染;三江源自然保护区的建立,一系列保护措施的实施,对该区的湿地退化在一定程度上起到了遏制作用。更多还原

【Abstract】 As the birthplace of the Yangtze River, the Yellow River and the Lancang River, there are many rivers, lakes and swamp here. It is the umbrella for downstream of rivers in our Country and the surrounding area in the ecological environment and regional sustainable development. In the recent years, under the background of global warming, the natural factors and the unreasonable human activities lead grassland degradation,glacier and the wetland retreat, biodiversity, make the fragile ecological worse, even or some people have to leave their hometown to live in other place. Therefore, this paper analysis of the dynamic change and the influence factors of the change through analysed the characteristics of wetlands in spatial-temporal distribution in Three-river source region of 2001, 2005, 2010 and 2014. THE main conclusions are as follows:(1) Wetland classification system of Three-river source region can be built. According to the classification system of wetland in Qinghai Tibet Plateau, combined with the characteristics of Three-river source region and data characteristics, the wetland is divided into two types of lake and marsh.(2) The Wetland distribution map of Three-river source region in four years can be obtained. Mosaic, projection, cutting and other processing of all the data, the NDVI data have small noise and significantly spectral characteristics NDVI data after processing by Harmonic Analysis of Time Series(HANTS).Selected sampling points randomly from the 7/4/1 false color composite TM images,and superimposed on the NDVI data of each year. Analysis of the characteristics of spectral curve of each kind of objects and statistics the value of each object. In the processing of the decision tree building, the digital elevation model(DEM) is good for separating the lakes and others. To control the curves shape and the threshold of the turning point of the curve in order could make useful of the curve of marshes. NDVI time series and finally finished the construction of the decision tree. Through the accuracy testing, the over all classification accuracy reached the excepted standard. The results showed that the time series of MOD13Q1 data and decision tree method could meet requirements of lakes and marshes classification in a vast scale, but how to use them to classify the river needs more studies in future.(3) The analysis result of landscape pattern of wetlands in four periods can be obtained. The changes of patch area in land scape of wetland in research area, as well as fragmentation index, dominance index, diversity index and evenness index are evaluated. The analysis result shows that, the total area of wetlands in Three-river source region was decreasing, the fragmentation degree was decreasing, the degradation rate of marsh is faster than lake. At the same time, the gap of the dominance in various landscapes was increasing while its evenness degree was decreasing. The degradation trend of the wetland between 2005 to 2010 is slower than it between 2001 to 2005.(4) Analysis the driving factors of wetland landscape pattern changes in Three-river source region. Combine the analysis result with the situation of wetlands and economic conditions in Three-river source region, this paper summarize the driving factors of the changing landscape pattern of wetland in Three-river source region. Five factors are as below: The complex and alpine topography always cause strong winds, disaster, desert water and other natural disasters lead to the degradation of the wetland. The climate changed obviously in Three-river source region under the background of global warming. The temperature rise range in the region area is 0.6~0.9 ℃ after the year of 2000 E, the climate change is the most influential factors for the change of the wetland area in the region; The growth of population and the development of the animal husbandry caused the degradation of the grassland and the shortage of water resources, to a certain extent leads to the degeneration of the wetland; Though the development of the tourism industry has brought enormous economic benefits, at the same time, the environment, water resources, air pollution has caused;The establishment of Nature Reserve in Sanjiang source and a series of protective measures has curbed wetland degradation in a certain extent.更多还原