利用小基线集技术(SBAS)监测泉州地区地表形变

差分干涉测量(DInSAR)技术可用于监测厘米级甚至毫米级的地表形变。文中选用2007—2011年期间19景日本ALOS1/PALSAR数据,采用短基线集技术(SBAS)获取了该地区的形变时间序列和平均沉降速率。研究结果表明:泉州东南部地区整体上呈抬升态势,上升速率为5mm/a左右,主要是受到亚欧板块和西太平洋板块互相挤压作用的结果;泉州东南部有多处出现地表沉降,沉降的结果与泉州市统计的地区地下水开采数据相当吻合,因此沉降主要与地下水过度开采相关。     

地理国情监测技术路线研究

针对目前地理国情监测过程中遇到的信息采集涉及行业广、种类多、工作繁琐等问题,该文提出了一种新的技术路线,并详细探讨了不同部门、不同行业信息的获取方式。对于基础地理信息采集时地理国情及地表覆盖分类中存在的特殊道路、特殊河流、特殊房屋信息难以采集的情况,给出具体采集办法,提高了采集效率和采集精度;规范地理国情监测框架要求的其他部门、行业信息采集标准,并针对数据量大、类型复杂、调用部门多等问题,提出以云数据库存储数据,解决了后期数据库需多次扩展问题。通过分析与研究表明:此技术路线具有良好的可行性,采用此技术路线可有效采集地理信息并进行数据整合。     

模平方阈值去噪法在沉降监测中的应用

针对现有去噪方法中存在的噪声信号提取、粗差定位等问题,该文基于小波阈值去噪的原理,提出一种基于软阈值改进的模平方阈值去噪法。通过仿真数据实验对比分析了软阈值去噪法、加权平均阈值去噪法及模平方阈值去噪法的去噪实际效果,并应用于汽车试验场沉降数据预处理。实验结果表明,基于模平方的阈值去噪法能够较好地保留观测信号原始信息,并且可以有效地去除噪声,其去噪效果优于软阈值和加权平均阈值去噪法,能在汽车试验场沉降数据处理中得到较好的应用。     

Measuring land-use and land-cover change using the U.S. department of agriculture’s cropland data layer: Cautions and recommendations

Monitoring agricultural land is important for understanding and managing food production, environmental conservation efforts, and climate change. The United States Department of Agriculture's Cropland Data Layer (CDL), an annual satellite imagery-derived land cover map, has been increasingly used for this application since complete coverage of the conterminous United States became available in 2008. However, the CDL is designed and produced with the intent of mapping annual land cover rather than tracking changes over time, and as a result certain precautions are needed in multi-year change analyses to minimize error and misapplication. We highlight scenarios that require special considerations, suggest solutions to key challenges, and propose a set of recommended good practices and general guidelines for CDL-based land change estimation. We also characterize a problematic issue of crop area underestimation bias within the CDL that needs to be accounted for and corrected when calculating changes to crop and cropland areas. When used appropriately and in conjunction with related information, the CDL is a valuable and effective tool for detecting diverse trends in agriculture. By explicitly discussing the methods and techniques for post-classification measurement of land-cover and land-use change using the CDL, we aim to further stimulate the discourse and continued development of suitable methodologies. Recommendations generated here are intended specifically for the CDL but may be broadly applicable to additional remotely-sensed land cover datasets including the National Land Cover Database (NLCD), Moderate Resolution Imaging Spectroradiometer (MODIS)-based land cover products, and other regional, national, and global land cover classification maps.     

地质灾害监测预警中的精密空间对地观测技术

21世纪以来,随着世界环境恶化和人类活动剧烈,地质灾害呈现频发态势,精密对地观测技术成为其监测预警的重要手段。本文首先介绍了常见地质灾害特点和监测方法,并对InSAR、LiDAR、高分遥感和GNSS 4种技术在地质灾害监测预警中的技术特点及应用进行了阐述,其次对高精度空间监测技术融合进行了综述和展望,最后对未来地质灾害监测预警技术趋势进行了总结。     

特长钢箱梁桥GPS监测数据的奇异谱分析

实时准确地监测和分析大型建筑物的变形对于大型建筑物的施工与运行是十分重要的。奇异谱分析(SSA)是一种与经验正交函数相关联的一种统计技术。文中采用奇异谱分析(SSA)的方法,结合功率谱峰值与原序列和RC1-2重建序列均方误差最小的方法确定最优潜入维数M,研究了特长钢箱梁桥索塔的变形趋势和震荡周期。小波分析技术也可以很好地描述时间序列的时频分布,但SSA重构后的结果比小波要平滑些,更能反映出时间序列的特征。结合苏通大桥北索塔监测序列表明,北索塔站的N,E,U方向上均存在明显的趋势和显著的变动周期,而且也含有较多的噪声信息。     

小波与奇异谱分析在地铁保护区监测数据处理中的应用

以南京市地铁沉降监测数据为例,将小波分析和奇异谱分析方法应用在地铁保护区监测数据的处理中。实验证明本方法在探测异常值、获取沉降变形趋势、变形周期等方面具有可行性。     

Institutional change in social-ecological systems: The evolution of grassland management in Inner Mongolia

Communities living in the grasslands of present day Inner Mongolia have experienced dramatic social, economic and ecological changes over the past millennium. More recently, these grasslands have undergone widespread degradation, raising concern for securing local herders' livelihoods. To understand these changes in ecological and welfare outcomes over long time scales, we define five broad periods of relative institutional stability over the past millennium, characterize social-ecological system during each period, and then assess major changes between these periods. Looking at changes in institutional contexts helps explain some of our outcomes of interest. We find that while much attention has been given to the change in grassland lease structures in China, the role of market integration and buffers against historically natural constraints on livestock production (e.g., protection from the winter months) have decoupled formerly tight local social-ecological links. This decoupling, along with weak land tenure security due to a complex and volatile policy landscape, suppresses local incentives for grassland conservation.     

自然灾害对公共安全的影响及其监测预警科技发展战略

改革开放以来,我国在自然灾害监测预警的各个环节均取得了可喜的发展,对减轻灾害损失、保障人民生命财产安全和社会稳定繁荣发展发挥了重要作用。但仍需清醒地认识到,在灾害规律演变、社会经济发展的新形势下,各类自然灾害对国家公共安全仍存在很大的威胁;我国目前灾害监测预警能力与国家防灾减灾“三个转变”需求以及国际先进水平相比仍存在较大差距。因此,本文简要论述了气象、海洋、地质、地震、生物五大自然灾害对国家公共安全的影响,并根据我国目前监测预警状况和存在问题,提出未来5～10 a我国自然灾害监测预警科技发展战略要从加强预测预报基础理论研究、提升综合监测能力、构建高效自然灾害预警系统以及发展减灾避灾和救灾技术四个方面着手推进。     

Changes and continuity of wood-pastures in the lowland landscape in Czechia

The term wood-pastures is usually applied to areas with trees or other woody vegetation, scattered through a mainly grazed grassland area, and reflects one of the oldest land use types in Europe, which plays important ecological, agricultural and socio-cultural roles. However, a rapid decline in their area due to changes in land use and a lack of tree regeneration has recently been observed all over Europe, which has led to the necessity of a deeper understanding of their behaviour in relation to different factors via a detailed analysis of the history of the changes in their distribution over space and time. Despite the recent increase in the number of related studies, information on historic patterns of wood-pastures in many European locations, such as Czechia, remains incomplete. The goal of this study is to assess the habitat continuity of current wood-pastures and to analyse the land-use/land-cover changes of historical and current wood-pastures in lowlands and warm landscapes of hills and basins of Czechia. To achieve this, nine sites covering a total area of 98.6 km² were studied in Czechia. The situation on three time horizons (1820–1840s, the early 1950s and today) was analysed. The results have shown that almost all wood-pastures from the 1st half of the 19th century have now been lost and most of the currently existing ones were formed from the 1950s till today. Most wood-pastures, which were lost by the 1950s, were turned into open habitats, such as arable lands, and the ones lost from 1950 were turned into forest. New wood-pastures are mostly formed from open habitats, often in former military areas.