Assessment of wetland fragmentation in the Tarim River basin, western China

The wetlands in the middle and lower reaches of the Tarim River are a rich area of biodiversity and natural resources in the inland arid region of China. However, this wetland area has decreased in size during the past several decades. Water quality and biodiversity has declined due to expanded agricultural activities since 1960s. Using remote sensing (RS), geographic information system (GIS) and global positioning system (GPS) techniques, we investigated the dynamics, spatial patterns and fragmentation of the wetlands in the middle and lower reaches of the Tarim River from 1980 to 2000. We found that the total area of the wetlands was reduced by 45.8% and the density of the patches increased four times from 1980 to 1990. From 1990 to 2000, though the total area of the wetlands slightly increased the number of the patches increased three times and the density of the patches doubled. Based on the analyses of transition matrixes, diversity and fragmentation indexes, and spatial distribution alternation of the wetlands, we found the landscape diversity and fragmentation indices increased while wetland dominance index decreased dramatically. Among the wetland types, the areas of the river-channel, reservoir and pond wetlands increased while the areas of the lake and marsh wetlands decreased continuously.     

中国冰川地貌空间分布格局研究

分布,对各山脉及地区冰川地貌类型的空间分布特征进行了分析.该研究对促进我国冰川地貌的研究具有一定意义.     

Three‐dimensional Evolutionary Models of the Qiongxi Structures,Southwestern Sichuan Basin,China: Evidence from Seismic Interpretation and Geomorphology

Fold terminations are key features in the study of compressional fault-related folds. Such terminations could be due to loss of displacement on the thrust fault or/and forming a lateral or oblique ramp. Thus, high-quality seismic data would help unambiguously define which mechanism should be responsible for the termination of a given fault-related fold. The Qiongxi and Qiongxinan structures in the Sichuan Basin, China are examples of natural fault-propagation folds that possess a northern termination and a structural saddle between them. The folds/fault geometry and along-strike displacement variations are constrained by the industry 3-D seismic volume. We interpret that the plunge of the fold near the northern termination and the structural saddle are due to the loss of displacement along strike. The fault geometry associated with the northern termination changes from a flat-ramp at the crest of the Qiongxinan structure, where displacement is the greatest, to simply a ramp near the northern tip of the Qiongxi structure, without forming a lateral or oblique ramp. In this study, we also use the drainage pattern, embryonic structure preserved in the crest of the Qiongxinan structure and the assumption that displacement along a fault is proportional to the duration of thrusting to propose a model for the lateral propagation of the Qiongxinan and Qiongxi structures. Specifically, we suggest that the structure first initiated as an isolated fault ramp within brittle units. With increased shortening, the fault grows to link with lower detachments in weaker shale units to create a hybridized fault-propagation fold. Our model suggests a possible explanation for the lateral propagation history of the Qiongxinan and Qiongxi structures, and also provides an alternative approach to confirming the activity of the previous Pingluoba structure in the southwestern Sichuan Basin in the late Cenozoic.     

青藏高原上空甲烷的时空分布特征及其夏季高值形成机制分析

利用搭载在美国Aqua卫星上的大气红外探测仪(AIRS)观测资料反演的全球甲烷(CH_4)产品和NCEP再分析资料,分析了2003~2014年青藏高原上空CH_4的时空变化特征,探讨了夏季CH_4高值变化与季风的关系。研究结果表明:就青藏高原整体而言,CH_4浓度随高度增加递减;对流层中高层CH_4含量季节变化较为明显,其平均浓度在7~9月处于高值,6月、10月次之,其余月份处于低值。2003~2014年CH_4含量呈逐年上升趋势,年增长率约为4.66ppb(10-9)。高原上空CH_4空间分布分析显示,高原北部CH_4浓度高于南部地区。夏季风期间,随着高原上的强对流输送和上空南亚高压的阻塞,对流层中高层CH_4浓度明显增加并不断积累,在8月底至9月初出现最大值。在分析季风指数的基础上发现,夏季季风影响下的强对流输送是高原对流层中高层CH_4高值形成的主要原因之一,对流层中高层CH_4浓度最大值出现时间较季风指数的峰值滞后约半至一个月,随着夏季风的撤退,CH_4浓度高值迅速降低。     

四套土壤湿度再分析数据在中国西北东部—华北—江淮地区的适用性研究

基于1992~2010年全国778个农业气象站土壤湿度观测资料、ERA-Interim、JRA55、NCEP-DOE R2和20CR土壤湿度再分析资料,通过平均差值、相关系数、差值标准差、标准差比四个参数,利用Brunke排名方法和EOF(Empirical Orthogonal Function)分析,对四套土壤湿度再分析资料在中国西北东部—华北—江淮区域的适用性进行了分析。主要结论如下:不同季节的平均偏差空间分布上,JRA55资料同观测数据的平均偏差在±0.08m~3 m~(-3)之间,春、夏季西北东部JRA55土壤湿度偏小,ERA-Interim、NCEP-DOE R2、20CR资料较观测数据偏湿,华北南部、江淮地区平均偏差小于西北东部、华北北部。在年际变化上,各个季节ERA-Interim资料同观测资料最为接近,能稳定地再现西北东部、华北、江淮地区土壤湿度干湿变化趋势,反映出重要的旱涝年。整体而言,四套再分析资料中ERA-Interim资料同观测资料接近,JRA55、NCEP-DOE R2资料次之,20CR资料最差。     

中国民航客运(国内)空间格局与竞争态势分析

利用统计分析和可视化方法,综合考虑行政、经济、人口和旅游吸引指标,采取抽样方法选择了60个具有代表性的国内大中城市,以近期发布的中国民航班期数据为基础,研究了构成中国民航运输网络的9家民航公司的通航城市和航线网络特征,并分析了各公司相互问的竞争关系。结果表明,三大航空集团和海航的航线呈多中心网状分布,而其他5家航空公司航线呈明显的单中心/双中心放射状分布;在运营中,三大航空集团和海航具有明显的垄断优势。而它们之间也存在明显的竞争关系。其他航空公司在构成中国民航运输网络骨架的大中城市航线运营中处于明显的竞争劣势。研究成果对航空公司航线、航班调整、代码共享和民航政策制订具有参考作用。     

国土资源信息交换体系建设模式分析与应用

国土资源信息蕴涵了多种数据类型和海量的数据,而且在日常管理和经营中还不断产生新的数据,为了更好地获取和利用国土资源信息,迫切需要解决国土资源管理部门定期更新或交换数据的任务,其中,空间数据是数据交换的重点和难点。本文介绍了在国土资源行业之间空间信息交换的总体思想,即在实现国家一级数据中心的基础上,由市地、省到国家级数据中心的数据逐级汇总和增量备份的方式,并进一步分析了国土资源信息交换体系的实现模式以及可采用的技术等方面内容,最后介绍了国土资源信息交换体系建设的实践。     

波动有限元方程显式逐步积分格式稳定性分析

对常用的波动有限元方程的两种显式格式的稳定性进行了分析,利用单元的最大频率乃是系统的特征频率的上界的概念结合模态分析方法,给出了便于实际应用的稳定性必要条件。同时,利用Von Neumann方法给出了这两种格式稳定性的充分条件,并通过算例对这两种稳定性条件进行验证。     

Spatial Variation of Sea Level Trend Along the Bangladesh Coast

The Bangladesh coast is threatened by rising sea level due to various factors. The results based on the analysis of past 22 years of tidal data of the Bangladesh coast reveal that the annual mean tidal level in the eastern Bangladesh coast is rising at an alarmingly high rate of 7.8 mm/year, which is almost twice the observed rate in the western region. This type of sea level trend seems to be the result of changing local conditions like increased precipitation and land subsidence during the recent decades. It seems that the higher rate of land subsidence in the eastern Bangladesh coast is the main causative factor for the steeper sea level trends there. The differential sea level trends show that the subsidence component in the sea level rise may be as high as 4 mm/year in the eastern Bangladesh coast. However, this needs to be verified with actual geological observations.     

基于MODIS NDVI的西辽河流域主要粮食作物时空分布格局

研究以西辽河流域为案例区,以MODIS遥感数据为基础,选取2000、2005和2010年时间点,利用NDVI时间序列信息,结合西辽河流域不同作物物候历,运用决策树提取模型,获取西辽河流域春玉米、春小麦和大豆等主要作物的空间分布信息,定量揭示了10年间西辽河流域主要粮食作物的时空分布特征。研究表明：（1）2010年西辽河流域主要粮食作物播种面积为11 965.08 km2,其中春玉米播种面积约占流域主要粮食作物的92.28%,集中在西辽河流域下游地区;春小麦播种面积占比3.14%,以西辽河流域中游面积最大;大豆播种面积占比4.58%,以西辽河上游流域面积最大。（2）2000-2005年西辽河流域主要粮食作物播种面积大幅增加,涨幅达29.77%,集中在西辽河流域下游地区。其中,春玉米播种面积增长38.99%,春小麦播种面积减少39.04%,大豆播种面积增长21.27%。（3）2005-2010年西辽河流域主要粮食作物播种面积增长缓慢,涨幅为5.18%,集中在西辽河流域下游地区。春玉米播种面积呈现增加趋势,春小麦呈现减少趋势,大豆呈减少趋势。