海洋表层沉积物中金属镉的来源解析     

谭赛章  杨涛  可愚  刘材材  张昊飞 《海洋通报》2019,38(6):683-689

利用2015年8月份对长江口及其邻近海域表层沉积物的监测数据,基于主成分分析/绝对主成分分数(PCA/APCS)受体模型定量解析了重金属元素镉(Cd)的可能来源,并结合地统计学插值了Cd的源贡献量的空间分布状况,结果表明沉积物中镉污染主要存在3个可能来源,源头及贡献率分别为工业污染(18.8%)、陆地径流输入(66.0%)、生物活动等自然因素(13.6%),并且各个源头贡献量具有不同的空间分布状况,其中工业污染的高值区主要集中在靠近陆地区域,陆地径流输入的分布呈现由近岸向外海逐减降低的特征,生物活动等自然因素的高值区主要集中在远离陆地的外海区域。  相似文献   

Determination of subcatchment and watershed boundaries in a complex and highly urbanized landscape          下载免费PDF全文

Aimé Kayembe  Carl P. J. Mitchell 《水文研究》2018,32(18):2845-2855

Urban development significantly alters the landscape by introducing widespread impervious surfaces, which quickly convey surface run‐off to streams via stormwater sewer networks, resulting in “flashy” hydrological responses. Here, we present the inadequacies of using raster‐based digital elevation models and flow‐direction algorithms to delineate large and highly urbanized watersheds and propose an alternative approach that accounts for the influence of anthropogenically modified land cover. We use a semi‐automated approach that incorporates conventional drainage networks into overland flow paths and define the maximal run‐off contributing area. In this approach, stormwater pipes are clustered according to their slope attributes, which define flow direction. Land areas drained by each cluster and contributing (or exporting) flow to a topographically delineated catchment were determined. These land masses were subsequently added or removed from the catchment, modifying both the shape and the size. Our results in a highly urbanized Toronto, Canada, area watershed indicate a moderate net increase in the directly connected watershed area by 3% relative to a topographically forced method; however, differences across three smaller scale subcatchments are greater. Compared to topographic delineation, the directly connected watershed areas of both the upper and middle subcatchments decrease by 5% and 8%, respectively, whereas the lower subcatchment area increases by 15%. This is directly related to subsurface storm sewer pipes that cross topographic boundaries. When directly connected subcatchment area is plotted against total streamflow and flashiness indices using this method, the coefficients of variation are greater (0.93 to 0.97) compared to the use of digital elevation model‐derived subcatchment areas (0.78 to 0.85). The accurate identification of watershed and subcatchment boundaries should incorporate ancillary data such as stormwater sewer networks and retention basin drainage areas to reduce water budget errors in urban systems.  相似文献   

岛屿海岸线自动化提取及其时空变迁研究——以大连市獐子岛为例   总被引：1，自引：1，他引：0  

丁小松  单秀娟  陈云龙  金显仕  杨涛 《海洋科学》2018,42(2):46-55

海岸带是受人类活动和全球海平面上升影响的敏感地带,海岸线的提取和监测是海岸带生态系统研究和社会管理的重要内容。本文在遥感和地理信息系统的支持下,以修正的归一化水体指数(Modified Normalized Difference Water Index,MNDWI)为基础,结合遥感影像处理和直方图均衡化等技术,实现了大连市獐子岛1985—2016年海岸线的自动化提取。结果表明:(1)通过与三位专家目视解译的成果比对,本文提取海岸线的精度能满足后续研究的要求(相对误差分别为0.045%,0.032%和0.023%);(2)近30年来,獐子岛海岸线总体呈现蚀退趋势,岸线长度与岛屿面积分别呈现变短和变小的趋势,獐子岛(主岛)和大耗岛的岸线蚀退速率最大,褡裢岛次之,小耗岛最小;在人类活动较为密集的区域,海岸线呈现出较为强烈的增长趋势,海水养殖和圈海建坝是岸线增长的主要驱动力;(3)獐子岛海岸线具有显著的分形性质,分形维数随时间呈现增大的趋势,獐子岛(主岛)的分形维数最大,褡裢岛的分形维数最小。  相似文献   

基于高斯两步移动搜寻法的村镇避难场所可达性研究     

但文羽  肖映辉  胡周灵  詹庆明 《地球信息科学学报》2018,20(10):1412-1421

避难场所可达性是指避难场所与受灾居民之间的通达性,即灾害发生时,避难人员通过避难疏散通道到达避难场所的难易程度,是评价避难场所布局合理性的重要指标。本研究结合高斯两步移动搜寻法和网络分析法,从供需双向出发对村镇地区避难场所进行可达性分析。2种方法的结合,既充分考虑了需求点与设施点的相互作用,又充分考虑了设施点的吸引力随距离的衰减关系,并基于实际道路,以步行疏散时间作为搜索半径,降低了传统研究中因忽略供需间相互作用及实际距离而引起的可达性结果的误差。最后,以神农架松柏镇区为例,验证该方法的实际应用价值。结果表明,该方法能够有效测定村镇地区避难场所的空间可达性,同时,基于GIS软件可以直观地揭示研究区域内避难场所可达性空间分布差异。该方法可为制定科学的村镇防灾减灾规划提供方法支持。  相似文献   

基于GIS的石家庄市雾霾分析     

苏亚聪  史娟  徐爽 《北京测绘》2020,(2):233-237

为了得出雾霾气象成因机制、影响因素和时空分布特征,以石家庄市区与郊县为研究区域,将2013年9月至2016年12月石家庄市各市区、郊县的PM2.5历史监测数据中的有效数据进行了数据分析处理得到雾霾浓度数据,还有温度、降水、风速、地形和人口密度等数据,运用GIS分析的方法,模拟绘制石家庄雾霾的时空分布图、雾霾与各影响因子的专题对比图,得到雾霾形成机制的因子、雾霾的时空分布规律、雾霾季节变化特征、雾霾与地形间的关系等;运用数据分析软件OriginPro8.SR3分析雾霾浓度与风速数据、降雨数据、温度数据间的相关性。  相似文献   

“地理素养与测绘技能”双驱动的GIS专业大学生创新能力培养模式的探索     

蔡忠亮  翁敏  苏世亮  亢孟军  费腾  田晶  任福 《测绘通报》2020,(8):148-152

在信息技术快速发展和万众创新、大众创业的时代背景下，创新与创新人才已成为国家发展的重要推动力，创新教育和创新人才培养成为高校的重要任务。本文以武汉大学地理信息科学（GIS）专业为例，结合专业特点和优势，探索了"地理素养、测绘技能"驱动下的GIS专业大学生创新能力的培养模式和"厚基础、重知识、强技能"的贯通式培养途径。围绕创新人才培养和成长的内在因素和外部条件，从人才培养方案与课程体系、创新型教师团队与新型教学方法、教学科研创新平台与创新条件、创新人才发展评价与激励机制等4个方面开展了创新型发展探索。结合实践表明，本模式取得了显著的创新成果，产生了良好的示范辐射作用。  相似文献   

基于噪声谱比法的内蒙古西部地区台站场地响应研究     

张珂  王鑫  王树波  张红才  宋晓燕 《大地测量与地球动力学》2020,40(6):646-651

利用内蒙古西部12个台站的地脉动噪声数据，采用噪声谱比法研究台站的场地响应情况。分析表明，台站场地响应按曲线形态可分为3类，且可能受地形地貌、局部构造和台基状况等条件影响。对比分析噪声谱比法与Moya方法的场地响应结果发现，场地响应曲线形态基本一致，只有极少数台站存在明显差异。结果表明，内蒙古西部区域大部分台站的台基状况总体较好，场地响应曲线较为平坦，无明显频率放大点。  相似文献   

A machine learning approach for predicting computational intensity and domain decomposition in parallel geoprocessing     

Peng Yue  Fan Gao  Boyi Shangguan  Zheren Yan 《International journal of geographical information science》2020,34(11):2243-2274

ABSTRACT

High performance computing is required for fast geoprocessing of geospatial big data. Using spatial domains to represent computational intensity (CIT) and domain decomposition for parallelism are prominent strategies when designing parallel geoprocessing applications. Traditional domain decomposition is limited in evaluating the computational intensity, which often results in load imbalance and poor parallel performance. From the data science perspective, machine learning from Artificial Intelligence (AI) shows promise for better CIT evaluation. This paper proposes a machine learning approach for predicting computational intensity, followed by an optimized domain decomposition, which divides the spatial domain into balanced subdivisions based on the predicted CIT to achieve better parallel performance. The approach provides a reference framework on how various machine learning methods including feature selection and model training can be used in predicting computational intensity and optimizing parallel geoprocessing against different cases. Some comparative experiments between the approach and traditional methods were performed using the two cases, DEM generation from point clouds and spatial intersection on vector data. The results not only demonstrate the advantage of the approach, but also provide hints on how traditional GIS computation can be improved by the AI machine learning.  相似文献   

2002 Leonid storm fluxes and related orbital elements     

《Icarus》2004,171(1):219-228

  相似文献   

格网DEM地形模拟的形态保真度研究   总被引：3，自引：0，他引：3  

王春  刘学军  汤国安  陶旸 《武汉大学学报(信息科学版)》2009,34(2)

分析了现有格网DEM地形模拟的失真现象,研究DEM地形模拟失真的根源.提出了DEM地形形态保真度的概念,探讨了建设高保真DEM必须解决的问题.  相似文献