基于地理探测器的中国陆地生态系统土壤有机碳空间异质性影响因子分析

中国陆地生态系统土壤有机碳库对全球生态系统碳平衡具有显著影响.为揭示土壤碳库空间分布的潜在主控因子并为今后建立碳库空间分布模型提供依据,利用地理探测器对中国陆地生态系统表层土壤(0—20 cm)有机碳密度的影响因子(气温、降水量、DEM、NDVI、陆地生态系统类型、人口密度)进行空间分异性探测和定量归因.结果表明:自然...     

基于GIS的湖泊区域地表水环境影响评价方法

对地理信息系统（Geographic Information System,GIS）技术在地表水环境影响评价中的应用进行了系统分析,指出了应用GIS的技术优势。通过实例研究,提出了基于GIS的区域地表水环境影响评价的方法步骤。在环境监测数据的基础上,利用计算机软件ArcView对BOD5和COD两个评价参数的监测值在水域中的空间分布进行分析,绘制区域等值线,结合地表水评价标准,进行水质评价,确定不同等级水质的空间分布区域。最后对应用GIS应注意的问题进行了分析。     

陕西省PM2.5时空分布及影响因素区域差异研究

为了解陕西省PM_2.5分布特征及影响因素区域差异,基于陕西省2019年PM_2.5浓度数据,采用空间数据统计方法、空间自相关分析法和地理探测器法对PM_2.5时空分异特征及驱动因素进行探究,以期为陕西省PM_2.5研究与治理提供可靠的科学依据。结果表明：陕西省PM_2.5污染呈“冬高夏低”、“中部高、南北低”的特点。陕西省PM_2.5浓度空间分布表现为极显著的空间正相关性,陕南部分县域为低低聚集区,关中地区渭南、西安、咸阳部分县域为高高聚集区。对陕西省PM_2.5浓度影响最大的是社会经济因子(0.328—0.548),陕北地区为GDP(0.932),关中地区为人口密度(0.936),陕南地区为相对湿度(0.710)。交互探测结果表明：陕西省主导交互因子为人口密度∩GDP,各种复杂的自然因素和人为活动因素耦合会大大加强对PM_2.5浓度的解释力。     

基于“3S”的红树林资源调查方法研究

论文研究了“3S”技术与地面调查相结合进行红树林资源调查的技术方法。以SPOT和Landsat7ETM+为信息源,经预处理后在GIS支持下进行目视判读和编制工作手图,实地采用GPS实测和目测勾绘修正小班界线,进入林内调查林况因子。结果表明,群落类型调查精度为100%;小班面积平均误差、小班周界平均位移、小班中心位置平均相对位移分别为11.8%、18.3m、13.1%,远小于常规方法(1∶10000地形图目测勾绘)的76.6%、108.7m和274.9%;效率比GPS实测高2.04倍,有效地解决了传统方法调查中存在的红树林空间位置和分布境界线定位准确性差、面积精度低,一般航天遥感调查分类精度低和GPS方法效率低等问题。     

CHANGING NEAR‐STREAM LAND USE AND RWER CHANNEL MORPHOLOGY IN THE VENEZUELAN ANDES1

ABSTRACT: The shape of a river channel is linked to surrounding land use through interacting hydrologic and geologic processes. This study analyzes the relationship between the change in near‐stream land use and the shape of the adjacent river channel over time. Three watersheds in the foothills of the Venezuelan Andes that have experienced differing degrees of development were studied to determine river channel width, sinuosity, and position relative to surrounding land use. Change in land use over time was obtained from multiple‐date aerial photographs (1946 and 1980) referenced to 1996 Landsat Thematic Mapper (TM) satellite imagery, and verified by field inspection. Measurements of land‐use type and amount and river channel morphology from the two dates were made using geographic information system (GIS) methods. The three watersheds differed in the extent of deforestation, the location of remaining forested land, and how much land‐use change had already occurred by 1946. Change in river channel morphology was greatest at the most deforested sites. Valley shape and channel constraint also had a discernible effect on change in channel morphology. This study introduces a method for analyzing change in coupled terrestrial‐aquatic systems based on multiple‐date, remotely sensed data and GIS analysis of spatial properties. The results document human impacts on river channels through a comparison of multiple watersheds over a 35‐year time interval.     

GIS支持的卫星图像土地利用现状分类和制图

应用卫星图像提取专题要素，综合利用多元地理信息，是克服多光谱数据在解像力和分辨率上所存在的局限性的有效途径。ＧＩＳ技术则提供多种处理功能将图像与地理信息复合，提高分类精度。分类图像数据与地形基础要素数据复合，通过彩色扫描绘图机直接绘制高质量的土地利用现状专题地图。     

A multi-scale coastal vulnerability index: A tool for coastal managers?

Coastal hazard management involves the assessment of vulnerability in natural and human environments. Indices incorporating a diversity of indicators have therefore been used extensively to provide spatial analyses of the degree of vulnerability. Such indices are typically applied at global and national scales, and they involve varying degrees of simplification and aggregation of information. The degree of simplification that is desirable depends on the management scale, and higher resolution is required at the local compared to the global scale. To investigate the implications of spatial scale in depicting coastal hazard risk, coastal vulnerability indices were developed at national (Northern Ireland), local authority and site levels. Variables were separated into three sub-indices: a coastal characteristics sub-index concerned with the resilience and susceptibility of the coast to erosion, a coastal forcing sub-index to characterize the forcing variables contributing to wave-induced erosion and a socio-economic sub-index to assess the infrastructure potentially at risk. The three sub-indices were merged to calculate the overall index, which is portrayed in the form of colour-coded vulnerability maps. While a common tripartite index could be employed at national, regional and local scales, the nature of the data used to quantify many of the variables varies according to the scale of management. Some important local variations in vulnerability are masked by simplifications at the national scale. For some variables more detailed information is available as the spatial resolution of the study increases, while others become obsolete as data are of insufficient resolution to differentiate real variability at more detailed scales. The results highlight the importance of spatial scale in developing indices of vulnerability: while a common index architecture can be applied, the selection of variables must take account of the scale at which the hazard is to be assessed. It is likely that limits on index development will also be imposed by data availability at various scales.     

A METHOD FOR OBTAINING SLOPE INFORMATION FOR HYDROLOGIC MODELS1

: A method is described for obtaining surface slope information for analysis with other land resource and water quality data in hydrologic models of nonpoint sources of water pollution. The method described requires a point sampling scheme, topographic maps, and a coordinate digitizer. Sample point elevation, slope direction, and slope magnitude are calculated from locations of the sample point and the nearest upper and lower contour lines. Details of the data collection methodology and associated problems are discussed.     

Spatial patterns of nitrate,chloride, sulfate,and fluoride concentrations in the Woodbine Aquifer of north-central Texas

A geographic information system was used to map and analyze nitrate, chloride, sulfate, and fluoride concentrations in 110 wells tapping the Woodbine Aquifer. The study area, covering ninecounties in north-central Texas, includes large percentages of both urban and agricultural land uses. Land use maps were compared with solute concentration data, and statistics were applied to detect associations between solutes, well depth, andland use. Anthropogenic sources such as fertilizer applications and natural sources such as gypsum, lignite, and clay deposits controlled nitrate, chloride, and sulfate concentrations, each inversely correlated with well depth. However, only one nitrate observation – from a shallow well in the aquifer's outcrop zone – surpassed the maximum contaminant level (MCL) of 44.3 mg L^-1. By comparison, nearly half of the sulfate and several of the chloride observations surpassed the MCL of 250 mg L^-1for each of those ions. Volcanic ash deposits influenced fluorideconcentrations, which directly correlated with well depth. There were no statistically significant associations between solute concentrations and land use. Low recharge rates and confining layers have mitigated anthropogenic impacts on solute levels in the aquifer.     

Evaluating forest management practices using a GIS-based cellular automata modeling approach with multispectral imagery

The objective of this study was to develop an integrated geographic information system (GIS) cellular automata (CA) model for simulating insect-induced tree mortality patterns in order to evaluate the influence of different forest management activities to control insect outbreaks. High-resolution multispectral images were used to determine susceptibility of trees to attack, whereas the GIS-based CA model simulated the effectiveness of clear-cuts and thinning practices for reducing insect-induced tree mortality. The results indicate that thinning susceptible forests should be more effective than clear-cutting for reducing tree loss to insect outbreaks. This study demonstrates the benefits of an integrated approach for understanding and evaluating forest management activities and expresses the need for spatial analysis and modeling for improving forest management practices.