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雅鲁藏布江流域植被覆盖度的时空变化遥感分析
Alternative TitleAnalysis on spatial-temporal changes of vegetation fraction in the Basin of Yarlung Zangbo River based on remote sensing
郭兵
Thesis Advisor陶和平
2013
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name硕士
Degree Discipline地图学与地理信息系统
Keyword遥感 植被覆盖度 动态监测 Ndvi 像元二分模型 空间分异格局
Abstract为了更好地分析雅鲁藏布江流域植被覆盖度近13年来的变化状况及植被的生长与各因子的相关性,本研究在传统的像元二分模型的基础上对NDVIsoil值的提取方法进行了改进,经过野外240个站点的实测数据的验证:改进后的模型相比原模型每个站点的盖度精度提高了2.14%.基于改进后的像元二分模型提取了雅鲁藏布流域1998、2004、2010三期植被覆盖度,并针对三期植被覆盖度的变化面积、变化强度以及不同的地形因子如坡度、坡向、海拔高度、地形起伏度对植被盖度变化强的影响做了较深入的分析,发现: (1) 总体上近13年来雅鲁藏布江流域的植被覆盖度呈现一个上升趋势;局部地区,年楚河流域植被盖度改善状况最好,尼洋河流域植被盖度变化情况最差。 (2) 低海拔带为植被盖度改善最好的地区,其次为中海拔高度带,而亚高海拔地区则是植被盖度变化状况最差的区域。 (3) 随着坡度的增加植被盖度减少区(轻微减少区、减少区、剧烈减少区)所占面积比例逐渐增加,即植被变化(退化)程度增加。 (4) 北坡、西坡、西北坡、东北坡上植被盖度改善状况比南坡、东坡、东南坡、西南坡要好,原因在于西坡、北坡、西北坡、东北坡的水热条件比较稳定因此其植被盖度变化受外界影响相对较小,而南坡、东坡则处于阳面 受气温、光照影响较大,而由于平地面积较小各指标意义不大。 (5) 随着地形起伏度的增大植被盖度减少区(剧烈减少区、减少区、轻微减少区)所占面积比例逐步增加,在大起伏山地达到最大值,而植被盖度增加区(剧烈增加区、增加区、轻微增加区)所占面积比例则随着地形起伏度的增大而减小,说明地形起伏度的大小与植被盖度变化强度有很大的相关性。 MODIS 250mNDVI数据与SPOT 植被指数数据(1000m)构建了NDVI数据序列并结合755气象站点数据、TRMM卫星数据以及MODIS红、近红外波段数据从时间、空间两个方面对植被的NDVI与降水、气温、土壤湿度数据进行了分析:时间序列方面主要是从年内、年际等方面进行了相关性分析并对植被NDVI与三个因子的旬、月间滞后性进行了研究;空间方面则主要是基于重心模型、空间差异模型、相关系数模型等方法对气候因子与植被的生长进行了定量分析。研究结果表明: 降水、气温在雅鲁藏布江流域不同的地区对植被的生长产生不同程度正相关性,而PDI指数与植被NDVI则表现为一定程度的负相关性。
Other AbstractBased on the traditional Dimidiate Pixel Model ,the extraction methods of NDVIsoil value was improved。Validated by measured data of 145 sites, the vegetation fraction accuracy of each site is developed by 2.14% compared with that of the original model. The vegetation fractions of 1998, 2004, 2010 were calculated with the improved Dimidiate Pixel Model in the Basin of Yarlung Zangbo River, then this paper has analyzed changes in area of different leves of vegetation fraction, change intensity and the effects which the terrain factors such as slope, aspect, elevation, topographic relief have on the vegetation fraction change intensity deeply. The results show that: (1) During the past 13 years, the vegetation fraction of Yarlung Zangbo River watershed has showed a rising trend on the whole. Meanwhile in the local region ,the change situation of vegetation fraction in Nianchu River Valley is better while that of Niyang River Valley is the worst. (2) The vegetation fraction of low altitude zone was the best improved, followed by the mid-elevation zone, while the high altitude zone has the poorest changes. (3) With the increase of slope degree, the area proportion that the vegetation fraction reduction zone (reduction zone, slight reduction area, dramatic reduction area) has takes increased gradually. (4) The situation of vegetation fraction has been improved better in the aspects of north , West, northwest, northeast than that of south, east, southeast, southwest, because the conditions of water and heat in the aspects of west 、northwest 、northeast are more stable so that the changes of vegetation fraction has been influenced less by the outside factors, while the vegetation of the south, east is positively affected by temperature 、light largely. (5) With the increasing of topographic relief, the area proportion of vegetation fraction reduction (reduction region、dramatic reduction region、 slight reduction region) has increased gradually, which reached the maximum in high mountainous region,however,the region of vegetation fraction increased region ( increased area、 dramatically increased area 、slightly increased area) occupied smaller with the decrease of topographic relief. Above all ,we the results showed that the change intensity of vegetation fraction and the topographic relief have great relevance. Using the dataset of the NDVI which was composed of the MODIS NDVI (250m)、the SPOT VGT(1000m) and datas of the 755 sites、TRMM satellite and MODIS red, near infrared band images , the search has studied the correlation of the vegetation NDVI and precipitation, temperature, soil moisture from two dimensions: Time -series is mainly conducted from the inter annual、inner-years on the correlation of vegetation NDVI and three factors ,besides time-lagging effect is also studied; the dimension of space is mainly from gravity model, spatial differentiation model, coefficient model ,and then the correlation among the vegetation and main factors is studied quantitatively. The results show that the influences that precipitation, temperature, soil moisture factor have on on the growth of vegetation varied in different part of the Yarlung Zangbo River Basin:the precipitation, temperature has positive effects on the growth of different vegetation types,however soil moisture factor and the vegetation index has negative correlation.
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/6982
Collection数字山地与遥感应用中心
Recommended Citation
GB/T 7714
郭兵. 雅鲁藏布江流域植被覆盖度的时空变化遥感分析[D]. 北京. 中国科学院研究生院,2013.
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