无人机技术在海岛测绘中的应用     

李雪瑞  魏征  田松  李明杰 《测绘通报》2020,(1):150-153

为提高海岛测绘的技术手段，将无人机引入海岛地形调查中，以Swallow-P小型固定翼无人机开展惠州市大亚湾虎洲海岛大比例尺测图为例，系统归纳了无人机外业数据采集与内业数据处理的具体流程，并制作了DEM和DOM成果；经过实测地面点精度分析得出虎洲无人机大比例尺测图成果平面位置中误差和高程中误差符合1∶1000测图精度要求。  相似文献   

内蒙古狼山地区早二叠世花岗闪长岩的年代学、地球化学特征及其构造背景     

田健  滕学建  刘洋  滕飞  郭硕  何鹏  王文龙 《中国地质》2020,47(3):767-781

内蒙古狼山山脉西侧分布有大面积的晚古生代岩浆岩,其时代集中在早石炭世—晚二叠世,不同时代岩浆岩岩石组合对于认识狼山地区晚古生代构造背景具有重要的意义。文章通过岩石学、岩相学、地球化学及Hf同位素等方法,对狼山地区查干乃呼都格一带花岗闪长岩体进行了研究。该岩体岩性为花岗闪长岩,LA-ICP-MS锆石U-Pb年龄显示,其206Pb/238U加权平均年龄为(299±1)～(293±2) Ma。岩石暗色矿物为角闪石及黑云母,富含闪长质包体,P_2O_5含量与SiO_2含量之间显示良好的负相关性,富钠(Na_2O含量为3.45%～4.96%),高钠钾比值(Na_2O/K_2O比值为1.33～2.52),岩石地球化学特征显示花岗岩成因类型为Ⅰ型花岗岩。岩石具有负的ε_(Hf)(t)值(-6.3～-2.0)及T_(DM2)为1437～1704 Ma(平均值为1606 Ma),显示了古—中元古代古老地壳熔融的特点,ε_(Hf)(t)-t及角闪石成因图解显示源区有幔源岩浆参与。花岗岩富集大离子亲石元素Rb、K、Pb,不同程度的亏损高场强元素Nb、Ta、P、Ti,轻稀土富集,重稀土亏损,弱的负Eu异常,显示了岩浆弧的地球化学特征。结合晚石炭世—早二叠世狼山地区侵入岩岩石组合为闪长岩+石英闪长岩+花岗闪长岩(英云闪长岩),早—中二叠世大石寨组火山岩岩石组合为玄武岩+玄武安山岩+安山岩+英安岩,总体反映了陆缘弧的岩石组合;狼山地区早二叠世处于大陆边缘弧的构造背景,与华北地块北缘中东部可以对比。  相似文献   

海南岛海岸带土地利用强度与生态承载力分析     

李通  闫敏  陈博伟  张丽  宋茜茜 《测绘通报》2020,(9):54-59

随着海南省进一步开放发展，海岸带区域的土地利用强度逐渐加强，生态保护需求日益增强。利用4期（1990、2000、2009、2015年）海岸带土地利用分类数据，研究海岸带土地开发利用强度，并分析了其生态承载力。结果表明：①耕地和林地是海南岛海岸带地区的主要土地类型。②25年间，海南岛海岸带土地利用强度整体较高且逐年上升，2000—2009年土地利用强度增速最高，达2.03%；海口市和澄迈县土地利用强度4期均值最大，分别为300.5和286.1。③25年来海南岛海岸带生态状况呈下降趋势，57%的海岸带市县实际生态承载压力增长了1倍以上。  相似文献   

Swelter in the city: Urban greenery and its effects on temperature in Guwahati,India     

Monjit Borthakur  Anup Saikia  Kiran Sharma 《Singapore journal of tropical geography》2020,41(3):341-366

Changing urban landscape with multistoried high rises, roads and pavements is continuously reducing urban green space. These structures result in high surface temperature variation within cities. To explore the relationship between surface temperature and normalized difference vegetation index (NDVI), this study estimates two models—geographically weighted regression (GWR) and a fixed effect panel data model in relation to the Guwahati Metropolitan Area (GMA), a secondary city in north east India. The results indicate the superiority of GWR regression in presence of spatial dependence. Panel data analysis shows that the densely populated urban areas in the GMA with less than 10 per cent greenery are 1°C warmer than the sub-urban areas with 50 per cent greenery.  相似文献   

Are carbonate barrier islands mobile? Insights from a mid to late-Holocene system,Al Ruwais,northern Qatar     

John Rivers  Max Engel  Robert Dalrymple  Ruqaiya Yousif  Christian J. Strohmenger  Ismail Al-Shaikh 《Sedimentology》2020,67(1):534-558

Barrier islands are important landforms in many coastal systems around the globe. Studies of modern barrier island systems are mostly limited to those of siliciclastic realms, where the islands are recognized as mobile features that form on transgressive coastlines and migrate landward as sea-level rises. Barrier islands of the ‘Great Pearl Bank’ along the United Arab Emirates coast are the best-known carbonate examples. These Holocene islands, however, are interpreted to be anchored by older deposits and immobile. The mid-Holocene to late-Holocene depositional system at Al Ruwais, northern Qatar, provides an example of a mobile carbonate barrier island system, perhaps more similar to siliciclastic equivalents. Sedimentological and petrographic analyses, as well as ¹⁴C-dating of shells and biogenic remains from vibracored sediments and surface deposits, show that after 7000 years ago a barrier system with a narrow back-barrier lagoon formed along what is now an exposed coastal zone, while, contemporaneously, a laterally-extensive coral reef was forming immediately offshore. After 1400 years ago the barrier system was forced to step ca 3 km seaward in response to a sea-level fall of less than 2 m, where it re-established itself directly on the mid-Holocene reef. Since that time, the barrier has retreated landward as much as 1000 m to its current position, exposing previously-deposited back-barrier lagoonal sediment at the open-coast shoreline. In modern neritic warm-water carbonate settings mobile barrier island systems are rare. Their construction and migration may be inhibited by reef formation, early cementation, and the relative inefficiency of sourcing beach sediments from open carbonate shelves. Carbonate barrier island systems likely formed more commonly during geological periods when ramps and unrimmed shelves predominated and in calcite seas, when meteoric cementation was minimized as a result of initial calcitic allochem mineralogy. As with their siliciclastic analogues, however, recognition of the influence of these transient landforms in the rock record is challenging.  相似文献   

基于空间分析技术的海岛地震灾害风险分析研究          下载免费PDF全文

郑秋红  贾婧  高惠瑛  杨树桐  李蓓 《世界地震工程》2019,35(3):168-176

我国约有1.1万个海岛，多处于地震活跃带，地震灾害特征明显，目前地震领域研究主要针对城市展开，海岛地震灾害风险的研究较少。此背景下，该研究收集了海岛地震相关的地质和地震数据，形成海岛地震灾害空间数据库；从地震危险性、承灾体易损性和防震减灾能力3个方面构建海岛地震灾害风险评价指标体系；利用ArcGIS空间分析技术，采用熵权法与AHP法相结合建立海岛地震灾害风险综合评价模型，以长岛县、洞头区和东山县为例进行分析，并将海岛地震灾害风险等级划分为4个等级。结果显示:东山县为地震灾害高风险区，洞头区和长岛县为地震灾害较低风险区。该研究对海岛工程抗震规划与设计有重要意义。  相似文献   

Nishinoshima volcano in the Ogasawara Arc: New continent from the ocean?     

Yoshihiko Tamura  Osamu Ishizuka  Tomoki Sato  Alexander R. L. Nichols 《Island Arc》2019,28(1)

Nishinoshima, a submarine volcano in the Ogasawara Arc, approximately 1 000 km south of Tokyo, Japan, suddenly erupted in November 2013, after 40 years of dormancy. Olivine‐bearing phenocryst‐poor andesites found in older submarine lavas from the flanks of the volcano have been used to develop a model for the genesis of andesitic lavas from Nishinoshima. In this model, primary andesite magmas originate directly from the mantle as a result of shallow and hydrous melting of plagioclase peridotites. Thus, it only operates beneath Nishinoshima and submarine volcanoes in the Ogasawara Arc and other oceanic arcs, where the crust is thin. The primary magma compositions have changed from basalt, produced at considerable depth, to andesite, produced beneath the existing thinner crust at this location in the arc. This reflects the thermal and mechanical evolution of the mantle wedge and the overlying lithosphere. It is suggested that continental crust‐like andesitic magma builds up beneath submarine volcanoes on thin arc lithosphere today, and has built up beneath such volcanoes in the past. Andesites produced by this shallow and hydrous melting of the mantle could accumulate through collisions of plates to generate continental crust.  相似文献   

基于分区间泛化Kriging近似模型的船舶局部结构形状优化     

张干锋  王德禹 《海洋工程》2018,36(6):46-57

为提高Kriging近似模型在船舶结构性能多维度响应预测方面的适用性,对常规Kriging近似模型进行分区间泛化改进:一是对设计样本点的各个维度(分量)进行划区,并在每一个分区间内采用最优拉丁超立方(OLhd)取样;二是引入比例系数w1组合高斯与指数型相关函数提高模型对数据的泛化能力,从而在每个划分的区间内建立泛化的Kriging近似模型。通过SCH测试函数,验证了构造的分区间泛化Kriging模型有效性。结合参数化建模和改进Kriging近似模型对某过渡肘板和舱口角隅边界进行形状优化,优化第一阶段由改进的近似模型通过多岛遗传算法得到全局初步的最优解,第二阶段在初步解的基础上缩小优化变量范围,由少量的FEM计算即可在小范围内搜寻到精确的最优设计变量。结果表明:分区间泛化Kriging近似模型在预测多维度响应时较常规Kriging模型预测精度更高;分阶段的形状优化流程在保证极小误差和缩小计算成本的情况下能够得到理想的应力分布和重量优化结果,有助于船舶结构的轻量化研究。  相似文献   

The Impact of Urbanization on Groundwater Quantity,Quality,Hydrothermal Changes and Its Countermeasures     

Wanbin Huang  Chunhua Yan  Xiaonan Zhang  Guoyu Qiu 《地球科学进展》2020,35(5):497-512

Groundwater, as a drinking water source for nearly one third of the world’s urban population, plays a strategic role in the development of urbanization. The object of this study is urban areas with the largest demand for water resources, the heaviest load of groundwater pollution and the most intense development of underground projects. This study sorted out the eco-hydrological problems such as the variation of the groundwater hydrological process, the groundwater pollution, and the urban heat island of groundwater in urban areas under the background of urbanization. Furthermore, the mechanism of changes in the quantity, quality and heat of groundwater was also systematically analyzed, and the intrinsic interaction among these three factors was revealed. The study showed that changes in land use and land cover caused by the urbanization are the main reasons for the variation of groundwater hydrological process. The pollution load of urbanization construction and domestic production waste has aggravated the deterioration of groundwater quality. The increase in vertical heat flux caused by urbanization gives rise to the warming of groundwater. By summarizing the eco-hydrological problems and causes of groundwater in urbanized areas, several suggestions were proposed: \mathrm{①} Establishing the evaluation method and system of urban groundwater resources; \mathrm{②} Speeding up the technological breakthroughs of groundwater pollution control; \mathrm{③} Improving the regional control strategies for groundwater pollution; \mathrm{④} Optimizing the allocation of groundwater resources. This study will provide the theoretical basis and technical support for ensuring urban water safety, building ecological civilized cities and further promoting the sustainable development of economy and society.  相似文献   

典型喀斯特城市的热岛时空变化及其成因分析     

陈炫炽  陈蓉  廖瑶  吴愈锋  王跃跃 《测绘通报》2019,(11):93-97

利用1989、2003、2018年的Landsat影像对安顺市西秀区的地表温度进行反演，分析研究区在30年发展中的热岛时空变化及其成因。使用基于影像的反演算法，结合分类回归树算法进行地表温度的反演，用气象站数据对反演结果进行精度验证，并建立缓冲区对研究区进行相关性分析等定量分析。结果表明：研究区受喀斯特地貌的影响，除主城区外，郊区也存在大量高温区；近30年研究区热效应与不透水面、绿地的面积有极显著相关；1989-2003年研究区城市热岛面积随城市扩张逐渐增大，但2018年主城区城市热岛现象几乎完全消失，排除气象因素和城市形态因子影响的可能后，发现这与安顺市城市绿化的大力进行有密切关系。  相似文献