基于空间信息的烤烟种植适宜性 评价与轮作规划

基于遥感计算的气温和土壤水分及DEM计算的太阳辐射等地表参数代替站点观测数据,采用100m×100m栅格和适宜性评价指数对泸西县的烤烟种植适宜性进行评价,分析其空间分布规律。在此基础上,进行了烤烟的烟田轮作规划与核查监督。研究表明,泸西县的烤烟种植最适宜区的耕地利用率偏低,仅为28.1%,尚有2165ha的最适宜耕地有待开发利用。烤烟轮作率虽然逐年增长,最高也仅为63.7%,离95%的目标轮作率仍存在较大差距。适宜性评价时,利用遥感和DEM计算的地表参数代替观测站点的插值数据,能获得可靠的数据支持,弥补因观测站点缺失而导致的数据失真。基于空间信息的轮作规划与核查监督,可有效改善烤烟轮作率,提高烤烟的质量和产量。     

巢湖西湖岸新石器-商周遗址空间分布规律及其成因

将地理信息系统空间分析方法引入巢湖西湖岸新石器-商周遗址考古工作,通过点密度分析、空间距离分析、三维分析、缓冲区分析等方法研究遗址空间分布规律及其影响因素。研究表明自新石器至商周时期研究区内遗址时空分布呈现:随时间推移由湖岸边逐渐向西北部扩展,后迁移至南部,再均匀扩散的遗址迁移轨迹;先民多选择靠近水源、地势平坦、土壤肥沃的自然岗地、河谷阶地、山麓面居住,导致古遗址空间上大致呈线状、团聚状、分散状等分布特征,具有明显的河谷谷地指向性、阶地岗地指向性、土壤指向性等规律。提出遗址分布在早期可能主要受到气候水文、地貌、植被土壤等自然因素影响,后期生产力发展水平、经济生活方式等人文因素影响加重。本研究为GIS支持下区域考古研究提供了合适的研究实例,同时GIS方法得到一些推论假设仍需要田野考古调查与发掘等进一步佐证。     

基于GIS的新疆气温数据栅格化方法研究

以新疆99个气象台站1971-2010年年平均气温为数据源,采用多元回归结合空间插值的方法对新疆区域气温数据进行栅格化研究。建立了年平均气温与台站经纬度和海拔高度的多元回归模型,对于残差数据的插值采用了反距离权重法(IDW) 、普通克立格法 (Kriging)和样条函数法(Spline)3种目前应用广泛的空间插值方法,针对于这3种方法进行了基于MAE和RMSIE的交叉验证和对比分析,结果表明在新疆的年平均气温的GIS插值方案中,IDW方法精度总体要高于其他两种插值方法。     

遥感图像纹理信息提取方法综述

纹理是遥感图像的重要特征，它提示了图像中辐射亮度值空间变化的重要信息。要利用图像空间信息提高分类精度，合理而有效地度量纹理至关重要。目前遥感图像纹理信息提取方法主要有：统计描述法、小波变换法、分维分形法和地统计学4类。分别就各种方法的优缺点、适用领域和应用情况进行了阐述，最后展望了遥感图像纹理信息提取方法的发展方向和研究热点。     

Is the seismic moment–frequency relation universal?

We evaluate the seismic moment–frequency relation for the Harvard catalogue in the period 1977–1994. This catalogue is composed of about 12 000 earthquakes. After selection of events in terms of depth and energy, we retain about 8000 data points. We estimate two parameters of the seismic moment distribution: the power exponent β and the cut-off value M _m . The method used is a least-squares linear fit on a log–log scale performed over a range selected on the basis of the standard deviation from the histogram. The analysis is carried out for different subdivisions of the Earth in square grids of different sizes. Neither parameter exhibits a dependence on cell size, suggesting the universality of their values and the interpretation of the existence of a cut-off as a finite size effect linked to a finite catalogue length. The variations of the parameters are investigated as a function of time (duration of the catalogue) and versus the number of events used for building up the distribution. Again, β and M _m do not depend on time, but M _m depends on the number of events, reaching a stable value for N ≈ 1000. The only significant change in the parameters is observed for different values of M _0upper in the catalogue, revealing the existence of universality classes.     

湖北省主体功能区划方法探讨

讨论湖北省主体功能区划方法,认为湖北省主体功能区应分为6类。区划时选择县级行政区为基本分析单元,并遵循“复杂性系统工程—简单化假设处理—合理化分析识别”的总体思路;采用矩阵分类、矩阵分类与标准定位相结合两种路径,基于不同路径的主体功能适宜性评价指标体系既有共性也有差异;区划方法采用综合集成法,包括修正的熵值法和主成分分析法、系统聚类法、矩阵判断、叠加分析和缓冲分析等;区划成果在一定程度上打破了县级行政区界限,但保持乡镇行政区的相对完整性。     

基于空间索引的规则格网DTM内插算法研究

从离散点内插规则格网数字地形模型(DTM)方法的关键是如何提高待插点周围数据的搜索效率。该文针对离散点的空间分布特性,给出了基于网格分块和KD-Tree两种空间索引技术的规则格网内插方法。实验表明,这两种索引方法能显著提高搜索速度,算法内插效率较高。最后,在算法效率分析的基础上,对两种索引方法所适应的条件进行了讨论。     

Human-driven topographic effects on the distribution of forest in a flat,lowland agricul-tural region简

Complex topography buffers forests against deforestation in mountainous regions. However, it is unknown if terrain also shapes forest distribution in lowlands where human impacts are likely to be less constrained by terrain. In such regions, if important at all, to- pographic effects will depend on cultural-historical factors and thus be human-driven （an- thropogenic） rather than natural, except in regions where the general climate or extreme soils limit the occurrence of forests. We used spatial regression modeling to assess the extent to which topographic factors explain forest distribution （presence-absence at a 48x48 m resolu- tion） in a lowland agricultural region （Denmark, 43,075 km2） at regional and landscape scales （whole study area and 10x10 km grid cells, respectively）, how landscape-scale for- est-topography relationships vary geographically, and which potential drivers （topographic heterogeneity, forest cover, clay content, coastal/inland location） determine this geographic heterogeneity. Given a moist temperate climate and non-extreme soils all landscapes in Denmark would naturally be largely forest covered, and any topographic relationships will be totally or primarily human-driven. At regional scale, topographic predictors explained only 5% of the distribution of forest. In contrast, the explanatory power of topography varied from 0%-61% at landscape scale, with clear geographic patterning. Explanatory power of topog- raphy at landscape scale was moderately dependent on the potential drivers, with topog- raphic control being strongest in areas with high topographic heterogeneity and little forest cover. However, these conditioning effects were themselves geographically variable. Our findings show that topography by shaping human land-use can affect forest distribution even in flat, lowland regions, but especially via localized, geographically variable effects.     

无定河流域全新世中期人类聚落选址的空间分析及地貌环境意义

以无定河流域的数字高程模型为主要研究对象,利用地理信息系统软件进行空间分析,与陕西北部无定河流域龙山时期遗址的分布位置叠置和聚类分析,讨论聚落选址与地貌类型、距河流水平距离、河网等级等6个地形地貌因子之间的关系。结果发现,全新世中期无定河流域人类在聚落选址时,对水文条件、地貌和地面坡度条件有较强的倾向性,而对地面朝向无明显倾向性。选址时选择地形地貌影响因子的优先顺序为:地貌类型、遗址距河流距离、遗址处地面坡度、遗址处河流等级、遗址处地面朝向。     

Ice flow physical processes derived from the ERS-1 high-resolution map of the Antarctica and Greenland ice sheets

The ERS-1 satellite, launched in 1991, has provided altimetric observations of the Greenland Ice Sheet and 80 per cent of the Antarctica Ice Sheet north of 82°S. It was placed in a geodetic (168-day repeat) orbit between April 1994 and March 1995, yielding a 1.5  km across-track spacing at latitude 70° with a higher along-track sampling of 350  m. We have analysed the waveform altimetric data from this period to compute maps with a 1/30° grid size. Data processing consists of correcting for environmental factors and editing and retracking the waveforms. A further step consists of reducing the radial orbit error through crossover analysis and correcting the slope error to second order. The high-resolution topography of both ice sheets reveals numerous details. A kilometre-scale surface roughness running at 45° from the flow direction is the dominant topographic characteristic of both continents. Antarctica also exhibits many scars due to local flow anomalies. Several physical processes can be identified: abrupt transitions from deformation to sliding and vice versa, and impressive strike-slip phenomena, inducing en echelon folds.     

山区县域聚落演化的空间分异特征及其影响因素——以豫西山地嵩县为例

综合运用GIS空间分析、地形起伏度和地形位指数等方法,分析了1975-2015年嵩县聚落演化的空间分异特征,进而运用因子分析、地理探测器和多元回归分析方法研究了影响因素及其变化。得出：① 40年间嵩县聚落数量减少了将近四分之一,而聚落总规模增加1.28倍,其数量减少量以1975-1995年阶段居多,规模扩张程度以1995-2015年阶段更为显著。② 受山区地形限制聚落在空间上多沿道路和河流呈条带状分布,沿县城和乡镇中心呈团状分布,且随时间变化具有很强的路径依赖性;聚落空间分布呈现明显的低地、小地形起伏、平缓坡度和小地形位指向性,且随时间趋于向丘陵、平起伏和微起伏、坡度<6°、地形位指数<0.4地区布局;此外,聚落区位的南坡指向性和聚落规模空间分布的南坡、东南坡和西南坡指向性趋于加强。③ 聚落区位主要受地形、生产条件以及道路、乡镇中心、县城中心和工矿企业的辐射影响,但随时间变化,地形影响在减弱,而道路和乡镇中心的辐射影响在增强。④ 聚落规模空间分布受自然、社会和经济等方面因子的解释作用均较为显著并随时间有所变化,其中,地形的影响相对较大,社会经济因子中乡镇和县城中心的影响次之;但随城镇化进程的不断加快,县城中心的影响逐渐增强,而乡镇中心和地形的影响逐渐减弱。基于以上研究为山区聚落未来选址及规划布局提出几点建议。     

A palaeolimnological meta-database for assessing the ecological status of lakes

We describe a palaeolimnological meta-database (“LakeCores”) that includes information for lakes in Europe that have been cored for studies of recent environmental change. Only cores with intact mud-water interfaces and good chronologies for the last ~100–200 years are currently included. The information provided in the database includes the general characteristics of the lakes cored, the methods used for dating and analysis and the bibliographic source of the information selected. At present the database contains information on 1847 studies from 975 sites. Here we use the database to identify cores for which diatom-based pH and total phosphorus (TP) reconstructions have been derived and, from an inspection of the relevant papers, we compile summary data for the timing and extent of acidification and eutrophication of lakes across Europe. We show that there were few cases of acidification and eutrophication in Europe prior to about 1850, and therefore that conditions prior to 1850 can be used for reference with respect to current attempts to restore surface waters to “good ecological status”. We also show the extent to which pH and TP levels have changed across the continent both for all lakes, and, in the case of TP, for lakes of different types covering a range of alkalinities, altitudes, water depths and surface areas.     

Traction image method for irregular free surface boundaries in finite difference seismic wave simulation

In this study, we propose a new numerical method, named as Traction Image method, to accurately and efficiently implement the traction-free boundary conditions in finite difference simulation in the presence of surface topography. In this algorithm, the computational domain is discretized by boundary-conforming grids, in which the irregular surface is transformed into a 'flat' surface in computational space. Thus, the artefact of staircase approximation to arbitrarily irregular surface can be avoided. Such boundary-conforming gridding is equivalent to a curvilinear coordinate system, in which the first-order partial differential velocity-stress equations are numerically updated by an optimized high-order non-staggered finite difference scheme, that is, DRP/opt MacCormack scheme. To satisfy the free surface boundary conditions, we extend the Stress Image method for planar surface to Traction Image method for arbitrarily irregular surface by antisymmetrically setting the values of normal traction on the grid points above the free surface. This Traction Image method can be efficiently implemented. To validate this new method, we perform numerical tests to several complex models by comparing our results with those computed by other independent accurate methods. Although some of the testing examples have extremely sloped topography, all tested results show an excellent agreement between our results and those from the reference solutions, confirming the validity of our method for modelling seismic waves in the heterogeneous media with arbitrary shape topography. Numerical tests also demonstrate the efficiency of this method. We find about 10 grid points per shortest wavelength is enough to maintain the global accuracy of the simulation. Although the current study is for 2-D P-SV problem, it can be easily extended to 3-D problem.     

月表形貌特征研究进展及趋势分析

在月球探测及科学研究过程中,对月表形貌特征的认识和分析是月球探测计划的关键任务之一,有助于理解和揭示月球的形态特征及空间分异规律,对于分析月球岩石构造、估算月表年龄、反演月壤厚度、恢复月球的起源和演化历史等都具有重要意义。从月表形貌特征的塑造及表达、宏观特征的分析与定量刻画、月表撞击坑的识别与分类及空间分异特征等几方面进行了归纳和分析,提出了未来月表形貌的研究方向,包括全月球形貌特征的多级分区划分、撞击坑类型的划分、全月球撞击坑空间分异特征及规律的研究、基于撞击坑空间分布探讨月球演化、基于形貌特征的比较行星学研究等。     

Using Vertical Aerial Photography to Estimate Mass Balance at a Point

The mass balance distribution over a 0.5 km² area of the lower part of South Cascade Glacier is obtained from remotely sensed measurements of its geometry and velocity field over two periods, 1992–93 and 1993–94. Vertical aerial photography from late summer 1992, 1993, and 1994 is analyzed photogrammetrically to get surface topography of South Cascade Glacier on a 100-meter square grid. The known bed topography is subtracted from the surface topography to get the ice thickness, and the surface topographies are subtracted from each other to get the thickness change. Annual displacement vectors, determined at points where natural features could be tracked from one year to the next, are contoured by hand and interpolated to the grid. Assuming that the ice follows Glen's flow law with exponent n = 3, and that 10% of the ice flow is due to sliding at the bed, the surface velocity is scaled by 0.82 to get the average velocity in the vertical ice column. The average velocities are combined with the thicknesses to calculate the flux divergence at each of 46 gridpoints on a 100-m square grid, where it is subtracted from the thickness change to get the mass balance.
Use of the same control points from year to year makes any systematic error in photogrammetric coordinates temporally constant, so such error has no effect on the mass balance estimate. Random error in coordinates is assumed to be uncorrelated from coordinate to coordinate, from point to point, from year to year; the standard error is estimated to be 1 m, resulting in a standard error in coordinate differences of about 1.5 m. A 1 m error in a vertical coordinate has nearly twice the effect on the estimated balance that one in a horizontal coordinate has and more than ten times the effect that one in ice thickness has. Compared with measurements at a stake, the estimated balances are about 1 m too negative.     

基于格网的甘肃省生态经济分区研究

在讨论以往生态经济分区研究方法与理论的基础上,提出了新的研究思路--基于网格的生态经济分区。利用GIS格网技术和相关统计软件,从甘肃省生态与经济两大系统耦合发展的历程分析入手,选取2010年甘肃省的26个生态经济指标,以6 km×6 km的规则格网,将整个甘肃省分为12 243个研究单元。经过分析比较,甘肃省被分为4个生态经济区即西北干旱区(Ⅰ)、陇中冷温带半湿润区(Ⅱ)、甘南高寒带湿润区(Ⅲ)、陇南暖温带湿润区(Ⅳ)和21个生态经济亚区。结合DEM,进一步对研究区进行分区,以期为促进形成甘肃省可持续发展格局提供科学依据。研究表明,格网技术提高了分区的精度和速度,是进行生态经济分区的有效方式之一。     

Use of large Acacia trees by the cavity dwelling Black-tailed Tree Rat in the Southern Kalahari

Recent extensive harvesting of large, often dead Acacia trees in arid savanna of southern Africa is cause for concern about the conservation status of the arid savanna and its animal community. We mapped vegetation and nests of the Black-tailed Tree Rat Thallomys nigricauda to assess the extent to which the rats depend on particular tree species and on the existence of dead, standing trees. The study was conducted in continuous Acacia woodland on the southern and eastern edge of the Kalahari, South Africa. Trees in which there were tree rat nests were compared with trees of similar size and vigour to identify the characteristics of nest sites. Spatial analysis of tree rat distribution was conducted using Ripley's-L function. We found that T. nigricauda was able to utilize all available tree species, as long as trees were large and old enough so that cavities were existing inside the stem. The spatial distribution of nest trees did not show clumping at the investigated scale, and we therefore reject the notion of the rats forming colonies when inhabiting continuous woodlands. The selection of a particular tree as a nest site was furthermore depending on the close proximity of the major food plant, Acacia mellifera. This may limit the choice of suitable nest sites, since A. mellifera was less likely to grow within a vegetation patch containing a large trees than in patches without large trees.     

Seismic quiescence before the M 7, 1988, Spitak earthquake, Armenia

A detailed analysis of the 35  yr of seismicity between 1962 and 1997 using a gridding technique shows that the M 7, Spitak earthquake of 1988 December 7 was preceded by a quiescence anomaly that started at approximately 1984±0.5, and lasted about 5±0.5  yr, up to the main shock. This quiescence anomaly had a radius of about 20±3  km, estimated from circular areas with 75 per cent rate decrease, centred at the point of maximum significance of the anomaly. The quiescence was clearly present in the aftershock volume during the 5  yr before the 1988 main shock, but its statistically strongest expression was located 30  km NW of the epicentre. This anomaly fulfills the association rules between precursory quiescence anomalies and main shocks, even for a tight definition, and is therefore proposed as a case of precursory quiescence. The largest value of the standard deviate Z , found by random selection of samples by gridding, was Z =14 for a time window of T _w=3  yr, using a sample size of N =300 events. This makes this anomaly the strongest observed so far, and it is the first documented in an environment of continental collision. There are no false alarms exceeding in significance the precursor. The Armenian earthquake catalogue used for this study had 4600 earthquakes with M ≥ M _min=2.2 in the area bounded by 39.5° to 42°N/42.5° to 47°E. From the point of view of homogeneous reporting this is the best catalogue we have analysed so far. The limits of the data used and the density of the grid are dictated by the data, and have no influence on the results. The choice of free parameters does not influence the results significantly within the following limits: 100≤ N ≤500, 2≤ T _w≤7, 2.2≤ M _min≤2.8.     

Hypsographic Demography Across Scale

The typical framework for assessing human population distribution is across a flat, two-dimensional landscape. We alter this perspective by examining population distribution with respect to a third dimension, elevation. This alternative framework, termed hypsographic demography, conceptually provides a more complete visualization and understanding of population distribution. We apply hypsographic demography to North Carolina from the scale of the entire state to streams of different sizes. At the state scale, elevation and population are generally inversely correlated. The flat coastal plain contains the majority of the population at low elevations, whereas higher elevations contain smaller populations due to steep topography, which limits development. At the county scale, the historic location and expansion of cities was more closely correlated with observed patterns of hypsographic demography than elevation or topography. At the scale of the stream, the influence of topography on hypsographic demographics gains importance where topography limits the land available to develop. We use this approach to illustrate how changing the perspective for viewing population distribution can be applied to floodplain policy.     

基于地理信息技术油松(Pinus tabuliformis)根长密度估算及空间分布特征分析

 定量研究植物根系的生长发育及时空分布特征是构建根系吸水模型、计算根系吸水量的基础。选择陇中黄土高原定西安家沟流域为研究区,对研究区内的油松(Pinus tabuliformis)吸水根系空间分布特征进行研究。利用剖面法获取不同空间点上的吸水根系,基于地理信息系统技术估算油松吸水根系的根长密度。结果表明：在水平方向上,油松根长密度呈二次曲线分布,吸水根系主要集中在0～400 cm范围内;在垂直方向上,油松吸水根系呈对数分布,吸水根系主要集中在0～100 cm范围内。并构建了油松吸水根系的二维空间分布方程。