大气环境变化的泥炭地质档案   总被引：2，自引：0，他引：2       下载免费PDF全文

鲍锟山  赵红梅  于晓菲  吕宪国  王国平 《地质论评》2011,57(2):234-242

雨养泥炭沼泽是一种重要的泥炭沼泽类型,具有全球广泛分布的特点,其养分补给主要源于大气降水(包括雨、雪和空气尘埃).它是一个记录大气环境变化的积极的信息储备系统,记录有大气输入的海盐气溶胶、沙尘颗粒、酸沉降、重金属和有机污染物等信息.采用地质定年技术将泥炭深度剖面转化到年代坐标上,并结合泥炭生物地球化学指标检测分析,提取...  相似文献   

高分辨湖泊沉积和孢粉记录对气候、水文变化的响应   总被引：4，自引：2，他引：2  

于革 《沉积学报》2011,29(1):118-124

通过对长江中游网湖钻孔高精度分层样品(1.5年/样品)的沉积学和孢粉学研究,试图揭示过去百年网湖在由开放到封闭体系变化中,沉积孢粉与气候、水文动力变化的过程及其相互关系.相关分析和低频滤波分析,反映出沉积物和孢粉的变化对流域降水和长江流量的敏感响应.在过去130年中的多雨洪水年份,湖泊受长江倒灌影响,沉积物以黏土细颗粒...  相似文献   

Spatio-temporal changes in land cover and aquatic macrophytes of the Danube floodplain lake     

Helena O?ahe?ová  Ján O?ahe?  Robert Pazúr  Richard Hrivnák  Milan Valachovi? 《Limnologica》2011,41(4):316-324

The aquatic vegetation of ?í?ov Lake in the Danube floodplain, which is listed in the Ramsar Convention, was investigated to address three main questions: (1) how have landscape composition and the structures of the lake and its buffer zone changed from the mid-20th century; (2) how have species richness and the abundance of the aquatic macrophyte assemblage in this lake ecosystem changed over the last 34 years; and (3) which landscape metrics can best explain these temporal changes for floating-leaved macrophytes? Two methodological approaches, remote sensing and botanical field surveys, were applied. Historical (1949, 1970, 1990) and contemporary (2006) aerial photographs were analysed to determine land cover. Landscape configuration and structure were analysed using eight landscape metrics selected in advance to measure spatio-temporal changes and the fragmentation of the lake ecosystem and its corresponding buffer zone. The species diversity, abundance and distribution of true aquatic macrophytes were surveyed eleven times in five survey stretches between 1973 and 2007.At the landscape level, a decrease in the area covered by floating-leaved macrophytes, as well as an increase in open water surface and fragmentation of the land cover classes in the lake ecosystem, were recorded from 1949 to 2006. Overall, 30 true aquatic macrophytes were found from 1973 to 2007. Species richness did not change considerably, but the abundance of aquatic species fluctuated over the years. Three groups of true aquatic vegetation, based on common structural characteristics, were found in 1973–1983, 1989–2002, and 2004–2007 over the last 34 years. The landscape metrics NP, PD, LPI, and SHDI, which all express patterns of landscape fragmentation mostly indicate temporal changes in floating-leaved macrophytes.  相似文献   

Long-term morphological river response to hydrological changes     

Stefano Tealdi  Carlo CamporealeLuca Ridolfi 《Advances in water resources》2011,34(12):1643-1655

Hydrologic changes have a great impact on the long-term river morphology. The most common anthropic cause is the construction of dams, which often reduces both the discharge regime and sediment transport, producing a narrowing and degradation of the river bed. In this study we propose a simple, lumped morphodynamic model that describes fluvial cross-section dynamics consequent to changes in discharge and sediment transport induced by external factors. The model provides the temporal dynamics of the river width and bed quote. These dynamics result not to be trivial and can exhibit non monotonic behavior, with aggradations and degradations, and narrowing and widening. The model has been tested on real rivers using data obtained from field studies. The agreement between the outcomes and the data measured in the field works is always satisfactory.  相似文献   

A Dutch multi-date land use database: Identification of real and methodological changes     

Gerard W. Hazeu  Arnold K. Bregt  Allard J.W. de Wit  Jan G.P.W. Clevers 《International Journal of Applied Earth Observation and Geoinformation》2011

Land cover and land use are important information sources for environmental issues. One of the most important changes at the Earth's surface concerns land cover and land use. Knowledge about the location and type of these changes is essential for environmental modeling and management. Remote sensing data in combination with additional spatial data are recognized as an important source of information to detect these land cover and land use changes.  相似文献   

Can a 25-year trend in Soudano-Sahelian vegetation dynamics be interpreted in terms of land use change? A remote sensing approach   总被引：3，自引：0，他引：3  

Agnès Bégué  Elodie VintrouDenis Ruelland  Maxime Claden 《Global Environmental Change》2011,21(2):413-420

This study is based on the premise that, in the Sahel/Sudanian belt of Africa, the main determinants of interannual variation in vegetation dynamics are rainfall and land cover type. We analyzed the spatio-temporal sensitivity of the NOAA-AVHRR 8 km-resolution vegetation index (NDVI) to (i) annual rainfall variability (0.5° × 0.5° resolution) acquired over a 25-year period (1982-2006); and (ii) land use changes in the different eco-climatic regions of the Bani catchment in Mali (130 000 km²). During the period 1982-2006, there was no clear trend in rainfall over the catchment, whereas there was a strong positive trend in the NDVI, both when the NDVI values were corrected using annual rainfall variability and when they were not. We divided the catchment into three eco-climatic regions based on the relationship between the annual NDVI and rainfall. In each region, we analyzed the observed greening in relation to changes in land use after correcting for the effect of annual rainfall on the NDVI. Results show that there is a mixed level of agreement between the land cover changes at the grid cell scale and the spatial pattern of the NDVI trend. Increased cropping does not explain the increase in the annual NDVI, except in the Sahelian part of the catchment. We hypothesize that the natural vegetation dynamics related to the non-linear rainfall patterns during the 25-year study period were responsible for these results.  相似文献   

对流单体在杭州湾入海时的强度变化分析   总被引：2，自引：0，他引：2  

陈淑琴  黄辉  周丽琴  陈佩佩 《气象》2011,37(7):889-896

为了研究对流单体在杭州湾入海时的强度变化情况,更好地预报对流单体的变化趋势,统计了2007年1月到2010年6月舟山雷达观测到的148个对流单体,以组合反射率因子、顶高、垂直液态含水量、径向速度、冰雹指数等条件来判断对流单体是加强还是维持或减弱。发现对流单体在海岸线附近加强或维持的几率比较大,在北岸入海后加强以及在南岸入海后减弱的几率较大,在傍晚到凌晨加强或维持的几率较大。对三个加强的典型个例,分别分析了海岸线附近的温湿特性、地面风的辐合、大气的层结稳定性等情况。对148个单体所处时刻的气温和相对湿度资料用GRADS进行插值,绘出等值线,然后统计整个杭州湾海域的最大气温差和相对湿度差以及水平风切变情况。统计结果：加强的单体,其环境温度、湿度梯度、风切变明显比减弱的大。最后得出结论,判断一个对流单体在杭州湾入海时是加强还是减弱,应从海岸线附近的温湿特性、地面风的辐合情况、大气的层结稳定性三方面的条件综合考虑。  相似文献   

Spatio-temporal characteristics and causes of changes in erosion-accretion in the Yangtze (Changjiang) submerged delta from 1982 to 2010     

SONG Chengcheng  SUN Xiaojing  WANG Jun  LI Mengya  ZHENG Lu 《地理学报(英文版)》2015,25(8)

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Land desertification and restoration in Middle East and North Africa (MENA) region     

Hassan M. El Shaer 《寒旱区科学》2015,7(1):0007-0015

The Middle East and North Africa (MENA) region is characterized by high population growth, degraded and fragile nat-ural ecosystems, and a limited amount of arable lands. It is one of the most water-sc...  相似文献   

基于遥感技术的近30年中亚地区主要湖泊变化   总被引：2，自引：0，他引：2  

成晨  傅文学  胡召玲  李新武 《国土资源遥感》2015,(1):146-152

在全球气候变暖的背景下,研究中亚干旱半干旱地区主要湖泊的变化不仅对内陆水资源管理和可持续发展有着重要意义,也为进一步研究湖泊变化对气候变化和人类活动的响应提供基础。获取1978年MSS、1989年TM、1998年TM及2010年ETM的同季相4期遥感图像数据,通过人工解译提取中亚地区7个湖泊信息,获得近30 a的湖泊面积变化;利用T/P和Envisat雷达高度计提取1992—2012年的湖泊水位信息;基于湖泊面积和水位的时空变化特征分析了湖泊变化的影响因素。结果表明:近30 a来,由于湖泊类型的不同,除萨雷卡梅什湖外的其他6个湖泊均出现不同程度的面积缩减;其中,平原尾闾湖面积变化最显著,高山封闭湖相对平稳,吞吐湖泊的面积变化相对复杂;湖泊的水位变化模式因流域和湖泊类型而异;高山封闭湖泊受气候的影响较大,而吞吐湖泊受人为因素影响显著。  相似文献