基于图幅的地形图数据自适应更新实现

随着城市建设的快速发展,城市基础地形图数据的更新与管理越来越受到城市规划部门和测绘部门的重视,地形图数据的自动化更新成为了一种迫切的需求。针对这一需求,在分析地形图数据特点的基础上,提出采用基于图幅更新的方式来保证地形图数据的现势性,详细地阐述了基于图幅更新的整个流程和历史数据回溯的过程,并开发了基于图幅更新的地形图数据自适应更新系统,同时以珠海市1：2000地形图矢量数据为实例,验证了该方法的可行性。试验结果表明该方法能够很好地保证地形图数据的现势性。     

关于矿床学创新问题的探讨

为保证矿产资源的持续供应和国家资源安全,需要加强矿床研究以指导矿产勘查的重大突破。在简要回顾矿床学百年发展历史的基础上,初步概括了矿床学开拓创新的基本条件,包括:①矿业发展是推动矿床学发展的原动力;②地学的整体发展为矿床研究提供了基础;③新技术装备提高了发现和创新的能力;④科学的思维方法;⑤个人创造和几代人的共同努力。针对国家需求、学科发展前缘和中国矿床特色相结合的原则,提出了重大地质事件与大规模成矿,深部过程、浅表环境与成矿作用等需要深入研究的10个矿床学科学问题。最后提出了改进矿床学研究的6点意见和建议,强调矿床研究要主动服务于矿产勘查,要深入野外一线并将继承与开创很好地结合。     

主要发达经济体从碳达峰到碳中和的路径及启示

随着气候变化影响加剧,全球气候治理进程加速,实现碳达峰已经成为全球气候行动的核心,各国也相继制定碳中和目标并开展行动。中国在第75届联合国大会一般性辩论上提出了碳达峰碳中和目标,部分已实现碳达峰的发达经济体也提出了各自的碳中和承诺。文中从“整体-阶段”及“焦点-公平”视角分析了欧盟和美国等主要发达经济体碳达峰的历程和特点,以及其碳中和目标和规划。研究发现,发达经济体在碳达峰过程中普遍经历了较长的爬坡期（58~136年）和平台期（4~20年),在碳达峰时,发达经济体的能源结构以油气为主,油气占一次能源消费比重为57%~77%,其人均排放量、历史累计排放以及人均GDP也都处于较高水平,在碳达峰前后总体处于经济与碳排放脱钩状态。各发达经济体的碳中和路径均以能源转型为重点,采用了多元化的政策工具,并且注重低碳和负碳技术的革新。根据发达经济体的政策展望,在实现碳中和时,均难以将绝对排放量降为零,都需要通过碳移除手段进行抵消。通过对比分析,发现中国的碳达峰和碳中和目标是具有雄心的气候承诺,相较其他发达经济体需要付出更大努力。建议运用全面综合的政策工具支撑碳中和目标的有效落实,加快中国的气候立法,在兼顾公正转型的同时推动能源结构调整,注重可再生能源和能效方面的新技术开发应用。     

Biomonitoring of Element Deposition Using Mosses in the 2000 French Survey: Identifying Sources and Spatial Trends

In the year 2000, the elemental composition of mosses collected from 528 French sites has been studied as part of the 2000 European Moss Survey. Five moss species were collected: Scleropodium purum (56%), Pleurozium schreberi (18%), Hypnum cupressiforme (18%), Thuidium tamariscinum (4.5%.) and Hylocomium splendens (3.5%). Mosses were kept whole for analysis, including green and brownish parts. Summary statistics on element concentrations (Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Na, Ni, P, Pb, Rb, Sr, V and Zn), and comparisons made with data from the other 27 participating European countries are shown here. The sources of these elements are identified using calculations of enrichment factors (EF) and principal component analysis (PCA). Finally, the spatial distribution in France of 10 elements is also shown, using maps underscoring areas showing highest concentration levels for each metal.     

A comprehensive assessment framework for attributing trends in streamflow and groundwater storage to climatic and anthropogenic changes: A case study in the typical semi-arid catchments of southern India

The clearest signs of hydrologic change can be observed from the trends in streamflow and groundwater levels in a catchment. During 1980–2007, significant declines in streamflow (−3.03 mm/year) and groundwater levels (−0.22 m/year) were observed in Himayat Sagar (HS) catchment, India. We examined the degree to which hydrologic changes observed in the HS catchment can be attributed to various internal and external drivers of change (climatic and anthropogenic changes). This study used an investigative approach to attribute hydrologic changes. First, it involves to develop a model and test its ability to predict hydrologic trends in a catchment that has undergone significant changes. Second, it examines the relative importance of different causes of change on the hydrologic response. The analysis was carried out using Modified Soil and Water Assessment Tool (SWAT), a semi-distributed rainfall-runoff model coupled with a lumped groundwater model for each sub- catchment. The model results indicated that the decline in potential evapotranspiration (PET) appears to be partially offset by a significant response to changes in rainfall. Measures that enhance recharge, such as watershed hydrological structures, have had limited success in terms of reducing impacts on the catchment-scale water balance. Groundwater storage has declined at a rate of 5 mm/y due to impact of land use changes and this was replaced by a net addition of 2 mm/y by hydrological structures. The impact of land use change on streamflow is an order of magnitude larger than the impact of hydrological structures and about is 2.5 times higher in terms of groundwater impact. Model results indicate that both exogenous and endogenous changes can have large impacts on catchment hydrology and should be considered together. The proposed comprehensive framework and approach demonstrated here is valuable in attributing trends in streamflow and groundwater levels to catchment climatic and anthropogenic changes.     

A simplified linear feature matching method using decision tree analysis,weighted linear directional mean,and topological relationships

Linear feature matching is one of the crucial components for data conflation that sees its usefulness in updating existing data through the integration of newer data and in evaluating data accuracy. This article presents a simplified linear feature matching method to conflate historical and current road data. To measure the similarity, the shorter line median Hausdorff distance (SMHD), the absolute value of cosine similarity (aCS) of the weighted linear directional mean values, and topological relationships are adopted. The decision tree analysis is employed to derive thresholds for the SMHD and the aCS. To demonstrate the usefulness of the simple linear feature matching method, four models with incremental configurations are designed and tested: (1) Model 1: one-to-one matching based on the SMHD; (2) Model 2: matching with only the SMHD threshold; (3) Model 3: matching with the SMHD and the aCS thresholds; and (4) Model 4: matching with the SMHD, the aCS, and topological relationships. These experiments suggest that Model 2, which considers only distance, does not provide stable results, while Models 3 and 4, which consider direction and topological relationships, produce stable results with levels of accuracy around 90% and 95%, respectively. The results suggest that the proposed method is simple yet robust for linear feature matching.     

长江三角洲近900年来气候变化对洪水事件的影响

Wide collection on the historic records of the climatic changes and flood events is performed in the Yangtze Delta. Man-Kendall (MK) method is applied to explore the changing trends of the time series of the flood discharge and the maximum high summer temperature. The research results indicate that the flood magnitudes increased during the transition from the medieval warm interval into the early Little Ice Age. Fluctuating climate changes of the Little Ice Age characterized by arid climate events followed by the humid and cold climate conditions give rise to the frequent flood hazards. Low-lying terrain made the study region prone to the flood hazards, storm tide and typhoon. MK analysis reveals that the jumping point of the time series of the flood discharge changes occurred in the mid-1960s, that of the maximum summer temperature changes in the mid-1990s, and the exact jump point in 1993. The flood discharge changes are on negative trend before the 1990s,they are on positive tendency after the 1990s; the maximum high summer temperature changes are on negative trend before the 1990s and on positive tendency after the 1990s. These results indicate that the trend of flood discharge matches that of the maximum high summer temperature in the Yangtze Delta. The occurrence probability of the maximum high summer temperature will be increasing under the climatic warming scenario and which will in turn increase the occurrence probability of the flood events. More active solar action epochs and the higher sea surface temperature index (SST index) of the south Pacific Ocean area lying between 4°N-4°S and 150°W-90°W correspond to increased annual precipitation, flood discharge and occurrence frequency of floods in the Yangtze Delta. This is partly because the intensified solar activities and the higher SST index give rise to accelerated hydrological circulation from ocean surface to the continent, resulting in increased precipitation on the continent.     

Migration Drift

For perhaps the first time since the founding of the United States the net direction of interstate migration was to the east rather than the west for the period 1992–1993 through 1994–1995. This and other findings, such as a general slowdown in the southward tendency of U.S. population movement over the period 1980–1981 to 1994–1995, are highlighted using the concept of migration drift. I propose the migration drift measure to summarize the net directionality and distance moved by migrants in any country's population system. Like the concept of a center of population or a population centroid, migration drift is an intuitive one. Unlike the population centroid, however, migration drift summarizes the pure effects of population movement without confounding those influences with spatial variations in birth, death, and net foreign immigration rates.     

THE STORM OF NOVEMBER 1826 IN THE CANARY ISLANDS: POSSIBLY A TROPICAL CYCLONE?

This work analyses a storm that occurred in the Canary Islands early in November 1826. Through a study based on historical climate data, some of the adverse effects of the storm are described and some of the possible causes are discussed. The main goal of this work is to establish an approximate reconstruction of this historical event which will allow us to compare it to a recent meteorological event that had a great impact on the archipelago: “Tropical Storm Delta”, in November 2005. Studying and reviewing the origin of the 1826 storm verifies the hypothesis that extremely violent perturbations have not only occurred in the Canaries on other occasions, but that these past events were also more intense and had more serious consequences than Delta. Therefore, the idea that other tropical perturbations have occurred in the region of the Canary Islands before Delta is presented.