甘肃酒泉盆地营尔凹陷层序地层特征与岩性勘探目标

甘肃酒泉盆地营尔凹陷发育中生代陆相断陷沉积,沉积构造研究表明下白垩统具备形成岩性油气藏的石油地质条件,但前人对该区岩性油气藏勘探领域的研究较少,目前尚未开展针对岩性油气藏的勘探。借助东部陆相断陷盆地的成功经验,利用钻井、地震等资料,开展了层序地层研究;将区内下白垩统划分为4个三级层序,自下而上依次为赤金堡组下段层序（Ⅰ）、赤金堡组上段层序（Ⅱ）、下沟组下段层序（Ⅲ）和下沟组上段层序（Ⅳ）;重点对区内主要勘探目的层段赤金堡组上段（层序Ⅱ）和下沟组下段（层序Ⅲ）进行了体系域划分。各层序及体系域具有不同的岩性、电性及地震反射波组特征响应,在体系域格架内利用三维属性反演、地震相分析、切片等手段开展了沉积相和岩性圈闭识别研究,发现3个岩性圈闭,综合评价认为1号岩性体是本区岩性勘探的有利目标。     

基于GIS与确定性系数分析方法的汶川地震滑坡易发性评价

汶川Ms 80级大地震诱发了数以万计的滑坡灾害。在大约48678 km2的滑坡影响区域内,作者采用震后遥感影像解译并结合野外调查的方法,共解译出48007处滑坡。应用GIS技术,建立了汶川地震诱发滑坡灾害及相关地形、地质空间数据库。采用地震滑坡确定性系数分析方法,分析了地震滑坡关于地震烈度、岩性、坡度、断层、高程、坡向、河流与公路等8个因素的易发程度。基于GIS栅格分析方法,分别对16种不同影响因子组合类型进行地震滑坡易发性评价。最后,应用AUC（Area Under Curve,评价曲线下面积）方法得到最佳因子组合及其对应的评价结果,使用自然分类法则方法将研究区按滑坡易发程度分为极高易发区、高易发区、中易发区、低易发区与极低易发区5类,极高易发区与高易发区面积之和约1169046km2,占研究区总面积的2402%,其中发育滑坡面积为52484 km2,占滑坡总面积的7373%。结果表明了极高与高易发区与实际滑坡之间有着良好的一致性,方法的评价结果成功率（AUC值）达到82107%。     

Estimated Sand and Gravel Resources of the South Merrimack, Hillsborough County, New Hampshire, 7.5-Minute Quadrangle

A computer methodology is presented that allows natural aggregate producers, local governmental, and nongovernmental planners to define specific locations that may have sand and gravel deposits meeting user-specified minimum size, thickness, and geographic and geologic criteria, in areas where the surficial geology has been mapped. As an example, the surficial geologic map of the South Merrimack quadrangle was digitized and several digital geographic information system databases were downloaded from the internet and used to estimate the sand and gravel resources in the quadrangle. More than 41 percent of the South Merrimack quadrangle has been mapped as having sand and (or) gravel deposited by glacial meltwaters. These glaciofluvial areas are estimated to contain a total of 10 million m³ of material mapped as gravel, 60 million m³ of material mapped as mixed sand and gravel, and another 50 million m³ of material mapped as sand with minor silt. The mean thickness of these areas is about 1.95 meters. Twenty tracts were selected, each having individual areas of more than about 14 acres (5.67 hectares) of stratified glacial-meltwater sand and gravel deposits, at least 10-feet (3.0 m) of material above the watertable, and not sterilized by the proximity of buildings, roads, streams and other bodies of water, or railroads. The 20 tracts are estimated to contain between about 4 and 10 million short tons (st) of gravel and 20 and 30 million st of sand. The five most gravel-rich tracts contain about 71 to 82 percent of the gravel resources in all 20 tracts and about 54–56 percent of the sand. Using this methodology, and the above criteria, a group of four tracts, divided by narrow areas sterilized by a small stream and secondary roads, may have the highest potential in the quadrangle for sand and gravel resources.

Spatial modeling of environmental vulnerability of marine finfish aquaculture using GIS-based neuro-fuzzy techniques

Combining GIS with neuro-fuzzy modeling has the advantage that expert scientific knowledge in coastal aquaculture activities can be incorporated into a geospatial model to classify areas particularly vulnerable to pollutants. Data on the physical environment and its suitability for aquaculture in an Irish fjard, which is host to a number of different aquaculture activities, were derived from a three-dimensional hydrodynamic and GIS models. Subsequent incorporation into environmental vulnerability models, based on neuro-fuzzy techniques, highlighted localities particularly vulnerable to aquaculture development.The models produced an overall classification accuracy of 85.71%, with a Kappa coefficient of agreement of 81%, and were sensitive to different input parameters. A statistical comparison between vulnerability scores and nitrogen concentrations in sediment associated with salmon cages showed good correlation.Neuro-fuzzy techniques within GIS modeling classify vulnerability of coastal regions appropriately and have a role in policy decisions for aquaculture site selection.     

Application of 3D hydrodynamic and particle tracking models for better environmental management of finfish culture

Hydrographic conditions, and particularly current speeds, have a strong influence on the management of fish cage culture. These hydrodynamic conditions can be used to predict particle movement within the water column and the results used to optimise environmental conditions for effective site selection, setting of environmental quality standards, waste dispersion, and potential disease transfer. To this end, a 3D hydrodynamic model, MOHID, has been coupled to a particle tracking model to study the effects of mean current speed, quiescent water periods and bulk water circulation in Mulroy Bay, Co. Donegal Ireland, an Irish fjard (shallow fjordic system) important to the aquaculture industry. A Lagangrian method simulated the instantaneous release of “particles” emulating discharge from finfish cages to show the behaviour of waste in terms of water circulation and water exchange. The 3D spatial models were used to identify areas of mixed and stratified water using a version of the Simpson-Hunter criteria, and to use this in conjunction with models of current flow for appropriate site selection for salmon aquaculture.The modelled outcomes for stratification were in good agreement with the direct measurements of water column stratification based on observed density profiles. Calculations of the Simpson-Hunter tidal parameter indicated that most of Mulroy Bay was potentially stratified with a well mixed region over the shallow channels where the water is faster flowing. The fjard was characterised by areas of both very low and high mean current speeds, with some areas having long periods of quiescent water. The residual current and the particle tracking animations created through the models revealed an anticlockwise eddy that may influence waste dispersion and potential for disease transfer, among salmon cages and which ensures that the retention time of waste substances from cages is extended.The hydrodynamic model results were incorporated into the ArcView^TM GIS system for visualisation and interrogation of results and to allow effective holistic environmental management and site selection for fish cage aquaculture.     

The NASA environment remote sensing analysis facility (ERSAF) support for space shuttle earth observations

Abstract

A major concept in urban geography deals with determining the spheres of influence for urban centers. This paper describes an instructional module used in two different geography courses showing students how a model might be developed to measure spheres of influence for multiple urban centers within a given region. A geographic information system (GIS) is employed throughout the development of the model. This module is incorporated into a traditional undergraduate urban geography course and a beginning GIS course. The software packages used are MapViewer and Grapher. The region is the Mississippi Lowlands with five urban centers: New Orlenas, Memphis, Little Rock, Jackson, and Baton Rouge. Keywords: GIS, spheres of influence, MapViewer, urban geography.     

A population based assessment of the geographical accessibility of outdoor recreation opportunities in New Zealand

Active participation in the outdoors not only provides enjoyment and adventure, but it is also important for health and promoting conservation values. The latter is particularly important for young people as they are at an impressionable stage in their lives. Geographical accessibly of recreation opportunities can be a major barrier to utlization of the New Zealand outdoors. While it would be ideal to have a variety of opportunities available to everyone regardless of residence, the distribution of opportunities is constrained by the extent of suitable lands. This research provides a population based assessment of the geographical accessibility of recreational opportunities. Accessibility has many dimensions and includes cultural, financial, and geographical barriers; therefore this research is only addressing one dimension of accessibility. Geographical Information Systems is used for the analysis, which involves a function called least-cost path analysis. This identified the travel time (using a private vehicle) via the quickest route from where people live (represented by census enumeration points) to the entry point of the recreation sites. The outputs of this research are maps and spatial statistics on the travel times to a range of recreation opportunities for different parts of New Zealand. This information is important for recreation planning. In addition, the information also provides research opportunities for modelling recreation use, especially when accessibility information is combined with landscape experience information and recreation usage statistics.     

Pervasive geo-security – a lightweight triple-A approach to securing distributed geo-service infrastructures

Security has recently become a major concern in distributed geo-infrastructures for spatial data provision. Thus, a lightweight approach for securing distributed low-power environments such as geo-sensor networks is needed. The first part of this article presents a survey of current security mechanisms for authentication and authorisation. Based on this survey, a lightweight and scalable token-based security infrastructure was developed, which is tailored for use in distributed geo-web service infrastructures. The developed security framework comprises dedicated components for authentication, rule-based authorisation and optimised storage and administration of access rules. For validation purposes, a prototypical implementation of the approach has been created.     

Prediction of Aquifer Vulnerability to Pesticides Using Fuzzy Rule-Based Models at the Regional Scale

Contamination of ground water has been a major environmental concern in recent years. The potential for ground-water contamination by pesticides depends on porous media, solute, and hydrologic parameters. Although sophisticated deterministic computer models are available for assessing aquifer-contamination potential on a site-by-site basis, most deterministic models are too complex for vulnerability assessment on a regional scale because they require input data that are spatially and temporally variable, and which may not be available at this scale. Therefore, development of an affordable model that is robust under conditions of uncertainty at the watershed scale with minimum input of field data becomes a useful ground-water management tool. The purpose of this study was to examine the usefulness of fuzzy rule-based techniques in predicting aquifer vulnerability to pesticides at the regional scale. The objectives were to (1) develop fuzzy rule-based models using the same input parameters contained in an index-based model (i.e., the modified DRASTIC model), (2) determine the sensitivity of fuzzy rule model predictions, (3) compare the outputs of the fuzzy rule-based models with those of the modified DRASTIC model and with the results of aquifer water-quality analyses, and (4) examine the spatial variability of field parameters around contaminated wells of the Alluvial aquifer in Woodruff County Arkansas. The fuzzy rule-based model for objective (1) was developed using similar parameter weights and ratings as the modified DRASTIC model. For objective (2), fuzzy rule-based models were created using fewer parameters than the modified DRASTIC model. Sensitivity of the fuzzy rule-based models was determined using different combinations of weights of the four input parameters in DRASTIC. It was found that variations in the weights of the input parameters and number of fuzzy sets influenced the location of the aquifer-vulnerability categories as well as the area within each fuzzy category. The fuzzy rule models tended to predict somewhat higher vulnerabilities of the Alluvial aquifer than the modified DRASTIC model. The fuzzy rule base that had the soil-leaching index (S) as the highest weight was chosen as the best fuzzy rule model in predicting potential contamination by pesticides of the aquifer. In general, the fuzzy rule models tended to overestimate the vulnerability of the aquifer in the study area.