DEM空间分辨率对流域水文特征信息提取及径流模拟影响研究

DEM是构建分布式水文模型的重要输入。以岷江上游为研究区,基于8种不同空间分辨率DEM构建SWAT模型,研究分析DEM空间分辨率对流域水文特征提取及径流模拟影响。研究表明,DEM空间分辨率越低,洪峰模拟精度越低,模拟流量与实测流量间的误差越大,曲线吻合度越低;DEM空间分辨率由25m降低到200m时,径流模拟误差变化不明显,而DEM空间分辨率由200m降低到3 200m时模拟误差显著增大;另外,DEM空间分辨率与径流总量的模拟精度间未表现出显著相关性。     

广东省1960～2007年降雨侵蚀力变化趋势分析

降雨侵蚀力反映由降雨引起的土壤侵蚀的潜在能力.本文利用广东省25个站点48年(1960～2007)的日雨量资料计算了各站的降雨侵蚀力,并用Mann-Kendall(M-K)非参数检验和克里格空间插值法分析了降雨侵蚀力的时空变化规律.结果表明:广东省降雨侵蚀力的空间分布呈沿海向内陆逐渐递减的趋势.全省大部分地区的年降雨侵蚀力呈现不明显上升趋势,且存在较明显的年代际和年际变化.降雨侵蚀力的年内分布特征和降雨量分布类似,呈"双峰型",主要集中在4～9月的雨季.对于季节序列,冬季、春季和夏季大部分地区的降雨侵蚀力有不同程度的上升,秋季全省几乎所有地区呈下降趋势.汛期的降雨侵蚀力变化特征与年降雨侵蚀力相似.     

Controls on mineral deposit occurrence inferred from analysis of their spatial pattern and spatial association with geological features

In this paper, point pattern analysis, fractal analysis and Fry analysis were employed to study the spatial pattern of known occurrences of mineral deposits of the type sought, whereas distance distribution method was applied to study the spatial associations between various geological features and known occurrences of mineral deposits of the type sought. In the Aroroy district (Philippines), the results of the applications of these spatial analytical techniques support a conceptual model of district-scale mechanism of geologic controls on low-sulphidation epithermal Au mineralization, which involves a more-or-less regular mesh of interlinked zones of extension faults/fractures at and/or around intersections of NNW- and NW-trending strike-slip faults/fractures. Integration of spatial evidential data layers representing these structural controls and surficial geochemical anomalies, via knowledge-guided application of data-driven evidential belief functions, results in delineation of prospective areas occupying about 25% of the district, in which there is about 70% likelihood of undiscovered occurrences of low-sulphidation epithermal Au deposits.     

卫星遥感反演土壤水分研究综述

土壤水分是影响地表过程的核心变量之一。精准地测量土壤水分及其时空分布,长期以来是定量遥感研究领域的难点问题。简要回顾基于光学、被动微波、主动微波和多传感器联合反演等卫星遥感反演土壤水分的主要反演算法、存在的难点和前沿性研究问题,介绍了应用土壤水分反演算法所形成的3种主要全球土壤水分数据集,包括欧洲气象业务卫星（ERS/MetOp）数据集、高级微波扫描辐射计（AMSR-E）数据集、土壤湿度与海洋盐分卫星（SMOS）数据集,并结合目前存在的问题探讨卫星遥感反演土壤水分研究的发展趋势。     

Designing an optimal multivariate geostatistical groundwater quality monitoring network using factorial kriging and genetic algorithms

The optimal selection of monitoring wells is a major task in designing an information-effective groundwater quality monitoring network which can provide sufficient and not redundant information of monitoring variables for delineating spatial distribution or variations of monitoring variables. This study develops a design approach for an optimal multivariate geostatistical groundwater quality network by proposing a network system to identify groundwater quality spatial variations by using factorial kriging with genetic algorithm. The proposed approach is applied in designing a groundwater quality monitoring network for nine variables (EC, TDS, Cl⁻, Na, Ca, Mg, SO ₄ ²⁻ , Mn and Fe) in the Pingtung Plain in Taiwan. The spatial structure results show that the variograms and cross-variograms of the nine variables can be modeled in two spatial structures: a Gaussian model with ranges 28.5 km and a spherical model with 40 km for short and long spatial scale variations, respectively. Moreover, the nine variables can be grouped into two major components for both short and long scales. The proposed optimal monitoring design model successfully obtains different optimal network systems for delineating spatial variations of the nine groundwater quality variables by using 20, 25 and 30 monitoring wells in both short scale (28.5 km) and long scale (40 km). Finally, the study confirms that the proposed model can design an optimal groundwater monitoring network that not only considers multiple groundwater quality variables but also monitors variations of monitoring variables at various spatial scales in the study area.     

Joint Consistent Mapping of High-Dimensional Geochemical Surveys

Geochemical surveys often contain several tens of components, obtained from different horizons and with different analytical techniques. These are used either to obtain elemental concentration maps or to explore links between the variables. The first task involves interpolation, the second task principal component analysis (PCA) or a related technique. Interpolation of all geochemical variables (in wt% or ppm) should guarantee consistent results: At any location, all variables must be positive and sum up to 100 %. This is not ensured by any conventional geostatistical technique. Moreover, the maps should ideally preserve any link present in the data. PCA also presents some problems, derived from the spatial dependence between the observations, and the compositional nature of the data. Log-ratio geostatistical techniques offer a consistent solution to all these problems. Variation-variograms are introduced to capture the spatial dependence structure: These are direct variograms of all possible log ratios of two components. They can be modeled with a function analogous to the linear model of coregionalization (LMC), where for each spatial structure there is an associated variation matrix describing the links between the components. Eigenvalue decompositions of these matrices provide a PCA of that particular spatial scale. The whole data set can then be interpolated by cokriging. Factorial cokriging can also be used to map a certain spatial structure, eventually projected onto those principal components (PCs) of that structure with relevant contribution to the spatial variability. If only one PC is used for a certain structure, the maps obtained represent the spatial variability of a geochemical link between the variables. These procedures and their advantages are illustrated with the horizon C Kola data set, with 25 components and 605 samples covering most of the Kola peninsula (Finland, Norway, Russia).     

1961-2010年中国400mm和800mm等雨量线时空变化

以中国1961-2010年逐日降水数据为基础,利用等值线加权平均位置的方式对400 mm和800 mm等雨量线的空间位置进行定量化处理。采用Kendall 秩次相关检验法、Morlet小波分析法、滑动t-检验法和Yamamoto法时间序列分析方法,对全国50年来 400 mm和800 mm等雨量线的空间位移特征进行了系统揭示:1961-2010年期间,400 mm和800 mm等雨量线加权平均位置坐标分别为（106°07'12"E,39°25'13"N）和（110°16'31"E,34°12'04"N）。趋势性结果表明,全国400 mm和800 mm等雨量线有向西和向南发生移动的趋势,其中400 mm等雨量线向西移动明显,800 mm等雨量线向南移动明显;周期性结果表明,全国400 mm等雨量线在经向和纬向上发生迁移的主周期分别为9年和 12年,800 mm等雨量线在经向和纬向变化均存在7年的主周期;突变性结果表明,400 mm等雨量线空间位置的突变年为1995-1996年（纬度）,800 mm等雨量线空间位置的突变年为1975年、2002年（经度）和1980年、1982年和1987年（纬度）。     

基于多源卫星观测的中国土壤湿度时空特征分析

为了揭示中国表层土壤湿度的时空分布特征及主要影响因子,通过SMAP、SMOS、AMSR2、FY3B和FY3C 5个卫星平台的遥感信息,采用集合平均法合成了2015-2016年中国25 km、逐日表层土壤湿度信息,通过比较5套产品之间的差异来分析卫星产品的不确定性,分析了中国土壤湿度的空间和季节分布特征以及同降雨量和蒸散发量的关联。结果表明:中国表层土壤湿度呈较明显带状分布,与干湿气候带的分布基本一致,总体由西北向东南和东北增加;土壤湿度在大部分地区呈现明显季节变化,主要表现为夏高冬低,不同地区的季节变化特征有所不同;中国60%以上地区,土壤湿度受同步和前期降雨量的强控制影响;中国87.5%的地区土壤湿度和蒸散发呈显著正相关和强依存关系。     

Spatial variability of soil nutrients in disturbed riverine mangrove forests at different stages of regeneration in the San Juan River estuary,Venezuela

Geostatistical analysis of selected soil properties were performed in two mangrove sites (B7 and B9) dominated by the mangrove speciesRhizophora mangle along the San Juan River, Venezuela, to evaluate the effect of forest disturbance on nutrient spatial distributions. Plots within area B7 were clear-cut in 1972–1973 and in area B9 in 1982–1983. Four plots within each area were systematically selected and represented natural (2) and regenerated (2) forests. Individual plots were 1.5 ha in B7 and 1.25 ha in B9 and sampled at a resolution of 25 m. Soil samples were obtained at the intersection of an aligned grid with 90 points in B7 and 78 points in B9. Measured soil properties included salinity, total nitrogen, total carbon, total phosphorus, osmolality, and pore water cation concentrations (potassium, calcium, magnesium, and sodium). Sites were sampled in May 1996 and 1997, although spatial analysis was performed only for the data obtained in May 1997. Geostatistical analysis showed that most of the variables tested were spatially auto-correlated within each area and that there were no differences between regenerated and natural plots. Structural variance as a proportion of sample variance ranged from 55–99% for most of the properties. The significant spatial dependence observed for most of the variables in natural and regenerated plots, despite management schedules, indicates that clear-cutting did not have an effect on modifying the distribution of nutrient concentrations. These results suggest that after 15 and 25 yr following forest disturbance nutrient distributions were reestablished either there was not a net effect on patterns of element loss or tidal input was stronger than plant modifications of soils.     

陕西省凤县佐家庄金矿床地球化学特征及找矿前景

佐家庄金矿床是通过对1∶10万的水系沉积物测量预测的金矿远景区开展的1∶2.5万土壤地球化学测量发现的。通过分析研究金及其指示元素的异常特征和分带特征等地球化学特征来预测金矿体的空间位置和找矿潜力。佐家庄金矿床属中型的三台山金矿床。     

三沙湾海岸线时空演变

海岸带是海陆之间的过渡区域,是人类活动和经济发展较为活跃的地区。海岸线时空演变研究对海岸带资源开发与保护有重要意义,但国内外对三沙湾海岸线时空演变研究较少。本文基于25 a的卫星遥感资料,解译出4个时相的三沙湾海岸线,定量分析海岸线变化趋势,并研究海岸线演变的主要因素。研究表明,25 a的三沙湾海岸线总体长度呈增长趋势：1988-1996年岸线总长度变化不大;2003年较1996年增加约6 947 m、增长约11.5%;2003-2013年岸线总长度增加较为明显,2013年较2003年增加约24 128 m、增长约39.6%,其增速约为1996-2003的3.4倍。砂质岸线长度基本稳定,基岩和泥质岸线长度有所减少,人工岸线在逐年增加,这主要是滩地围垦、港口建设和海岸人工改造等人为因素造成的。     

Israel's map of inequality in spatial development

The objectives of the paper are to indicate, on a national and regional level, the areas of geographical inequality in Israel, which create economic and social gaps in the development of the country. Geographical inequality in this study has been analyzed through eleven different criteria, relevant to economic and social welfare situations, as: distance from the nearest big city, road accessibility, rate of population density, natural economic potential, spatial security, distance from the central plain and centers of economic activity, climatic index of discomfort, topography, oldness of the settlements in the surroundings, etc. Each element of inequality has been plotted on a map indicating its quantitative values,on the basis of square units, comprising 25 km² each. A weighting of all the squares according to qualitative criteria enabled to prepare a comprehensive and compilative map with isolines showing the different spatial and inequality degrees.The map which has been elaborated from the data shows districts and localities in a range of different spatial degrees of deprivation. The history of settlement in Israel since the end of the 19th century, the planning guidelines since the establishment of the State in 1948, and the main geographic features of the country are the reasons of regional disparities.     

Turbulent transport of atmospheric aerosols and formation of large-scale structures

Turbulent transport of aerosols and droplets in a random velocity field with a finite correlation time is studied. We derived a mean-field equation and an equation for the second moment for a number density of aerosols. The finite correlation time of random velocity field results in the appearance of the high-order spatial derivatives in these equations. The finite correlation time and compressibility of the velocity field can cause a depletion of turbulent diffusion and a modification of an effective mean drift velocity. The coefficient of turbulent diffusion in the vertical direction can be depleted by 25 % due to the finite correlation time of a turbulent velocity field. The latter result is in compliance with the known anisotropy of the coefficient of turbulent diffusion in the atmosphere. The effective mean drift velocity is caused by a compressibility of particles velocity field and results in formation of large-scale inhomogeneities in spatial distribution of aerosols in the vicinity of the atmospheric temperature inversion. Results obtained by Saffman (1960) for the effect of molecular diffusivity in turbulent diffusion are generalized for the case of compressible and anisotropic random velocity field. A mechanism of formation of small-scale inhomogeneities in particles spatial distribution is also discussed. This mechanism is associated with an excitation of a small-scale instability of the second moment of number density of particles. The obtained results are important in the analysis of various atmospheric phenomena, e.g., atmospheric aerosols, droplets and smog formation.     

SARS in Singapore—challenges of a global health threat to local institutions

SARS (Severe Acute Respiratory Syndrome) has been declared by WHO (World Health Organisation) as a global health threat. Within a period of four to five months in 2003, the disease infected some 8,000 people in more than 25 countries and left 774 dead. The many studies that have been done on the spread of SARS in Asia as well as countries as far flung as Germany and Canada have focused on the global dimension of the infectious disease as well as the speed of its spread upon emergence in southern China and then Hong Kong. Less attention has been paid to its spatial distribution at the national and local scales. This discussion focuses on the spread of SARS at the national and local spatial scales. In the process, the study presents the management of a hazard, in this case, an emerging infectious disease by national health care institutions such as the hospitals that ultimately proved to have been wholly unprepared for coping with at least the health aspects of the outcome of a globalised national agenda for growth and economic progress.     

库尔勒市城市空间扩展特征及其驱动因素研究

以库尔勒市1990年、1995年、2000年、2005年、2010年以及2015年6个时期的Landsat TM/ETM+影像作为基础数据,借助ENVI 4.5、Arc GIS 10.1等专业软件对影像进行监督分类和空间分析。在此基础上,分析库尔勒市近25 a来土地利用时空变化规律、城市空间扩展趋势及演变过程、城市重心转移方向及距离和城市空间扩展形态变化特征等。研究表明:近25 a间库尔勒市建设用地面积大幅度增加,所占比例不断上升,年均增加速率为15.18%。耕地和未利用地对城市建设用地扩展贡献较大。城市向东南方向扩展,城市重心向东南方向转移了总共2 118.46 m。城市空间扩展紧凑度呈下降趋势,分形维数呈上升趋势,表明城市空间扩展趋于结构疏散化、形状复杂化。针对于以上特征及扩展趋势,分析了库尔勒市城市空间扩展的驱动因素并提出一些对策建议,为城市可持续发展提供科学依据。     

Spatial distribution of major and trace elements in shallow reservoir sediments: an example from Lake Waco, Texas

 Sediment geochemistry of a shallow (6-m average) reservoir (Lake Waco) was evaluated for the spatial distribution of major and trace elements. Sixty bottom and core samples along a 21-km transect within the reservoir, 18 overbank sediment samples, and 8 rock types in the drainage area were collected and analyzed for major (Al, Ca, Fe) and trace elements (As, Ba, Cr, Cu, Hg, Mn, Ni, Pb, Sr, V, Zn). Elemental concentrations in the reservoir sediments closely correspond to concentrations in the regional rocks and represent a mixture of overbank sediment composition of the tributaries. Elemental concentrations were statistically regressed against Al concentrations in order to establish regional baseline levels and thereby distinguish natural from anthropogenic sources. Spatial geochemical trends, considered in terms of element-to-Al ratio versus V-to-Al ratio, relate to the natural and anthropogenic sources contributing to the elemental concentrations. The spatial elemental distribution in the reservoir, which receive sediments from two mineralogically contrasting basins, reflect textural and mineralogical transition within the reservoir and suggest a progressive mixing of sediment from the tributaries. The spatial elemental distribution and sediment texture suggest that the sediment-source, which determines the sediment-type, has a greater influence on the major- and trace-element distributions in shallow reservoir sediments than bathymetry. Received: 25 September 1997 · Accepted: 3 February 1998     

Estimating groundwater recharge using GIS-based distributed water balance model in an environmental protection area in the city of Sete Lagoas (MG), Brazil

Improvement in modern water resource management has become increasingly reliant on better characterizing of the spatial variability of groundwater recharge mechanisms. Due to the flexibility and reliability of GIS-based index models, they have become an alternative for mapping and interpreting recharge systems. For this reason, an index model by integrating water balance parameters (surface runoff, actual evapotranspiration, and percolation) calculated by Thornthwaite and Mather’s method, with maps of soil texture, land cover, and terrain slope, was developed for a sustainable use of the groundwater resources. The Serra de Santa Helena Environmental Protection Area, next to the urbanized area of Sete Lagoas (MG), Brazil, was selected as the study area. Rapid economic growth has led to the subsequent expansion of the nearby urban area. Large variability in soil type, land use, and slope in this region resulted in spatially complex relationships between recharge areas. Due to these conditions, the study area was divided into four zones, according to the amount of recharge: high (>?100 mm/year), moderate (50–100 mm/year), low (25–50 mm/year), and incipient (>?25 mm/year). The technique proved to be a viable method to estimate the spatial variability of recharge, especially in areas with little to no in situ data. The success of the tool indicates it can be used for a variety of groundwater resource management applications.     

Assessment of deforestation,biodiversity loss and the associated factors: case study of Ijesa-Ekiti region of Southwestern Nigeria

Deforestation is driven by a variety of factors, and has resulted in land use changes that threaten biodiversity, water and energy resources. However, lack of reliable data and survey information in Nigeria has made the estimation of the effect of deforestation difficult to establish. Consequently, the extent and rate of deforestation are less well known. The study therefore, examined and analyzed the spatial and temporal patterns of deforestation over the period of 25 years (1978–2003); measured the rates, trends and explained the factors that determined deforestation in Ijesa-Ekiti region of southwestern Nigeria. The major sources of data for the study were satellites images. These were Landsat MSS 1978, with spatial resolution of 80 m, SPOT XS 1986, SPOT XS 1994, with 20 m spatial resolution and NigeriaSat_1 2003, with 32 m spatial resolution. To make them comparable, they were georeferenced to the same coordinates system, filtered, resampled and enhanced for visualization in a GIS environment. Furthermore, Ilesa, Ijebu-Ijesa, Efon-Alaaye, Iloko-Ijesa, Erin-Oke and Erin-Ijesa were identified and selected for ground truthing to validate the tonal values recorded in the images with the features on the ground. The result of ground truthing was combined with visual image interpretation as training sites for supervised classification. Focus Group Discussions were held with people who had lived in the area for over 20 years as a means of eliciting factors of deforestation and the effects on forest biodiversity. The results indicated forest loss of 53,469.23 ha over the period of 25 years at an annual deforestation rate of 7.21, 2.47, and 5.40% per year for 1978–1986, 1986–1994 and 1994–2003, respectively. FGDs with various categories of people in the bigger towns confirmed deforestation in the area and were due to illegal lumbering, intensive agricultural practices and growth of settlements resulted from increase in human population. FGDs also revealed extinction of many forest species in their communities. In conclusion, the study advanced our understanding on techniques of analyzing deforestation using geo-spatial technology. It also generated a synthesis of information on the rates of deforestation and its driving forces, which are a complex mix of anthropogenic factors, the chief of which has been the conversion of forest resources to agricultural land use.     

Assessment of NO<Subscript>3</Subscript><Superscript>−</Superscript> contamination in a karstic aquifer,with the use of geochemical data and spatial analysis

Kopaida plain is a cultivated region of Eastern Greece, with specific characteristic related with the paleogeographic evolution and the changes in land use. The present article examines the contamination that derives from nitrates, in terms of contaminant levels, definition of sources and spatial distribution of contaminant plume. For this purpose, 50 water samples were collected from the karstic aquifer and analyzed for 15 parameters including major ions, trace elements, physicochemical parameters, and stable isotopes. The assessment of the above parameter values along with the notes derived by the statistical process revealed the existence of nitrate contamination which has been spatial defined with the aid of spatial interpolation techniques. The correlation of NO₃ ⁻ concentrations with the stable isotope values, defined the infiltration conditions and showed contaminant transport. Nitrate values revealed the potential environmental threat for local people, as 10% of the samples exceeded the parametric value of 50 ppm and 54% of them are above 25 ppm, indicating no optimal quality conditions. The origin of nitrate contamination seems to derive exclusively from the application of N-fertilizers, since the rest of potential sources were not verified by analytical data and field works.