珠峰及周边地区强震影响垂直形变特征研究

2015年尼泊尔地震对珠穆朗玛峰高程的影响,近年一直受到全世界关注。2020年珠穆朗玛峰高程测量在珠穆朗玛峰及周边地区布设了高精度的全球导航卫星系统(global navigation satellite system, GNSS)形变监测网,收集了1999—2020年跨喜马拉雅山脉的32个连续运行参考站(continuously operating reference stations, CORS)的GNSS连续观测数据。利用GNSS数据监测了珠穆朗玛峰周边地区地壳三维形变特征,定量获取了2015年尼泊尔强震对珠穆朗玛峰周边CORS同震位移,以及地震对区域地壳三维形变长期趋势的影响,特别是对该地区垂直形变的影响。研究结果表明,该区域地壳垂直形变由南至北跨喜马拉雅山脉呈明显的阶梯型分布特征;震后印度板块与欧亚板块存在加速汇聚趋势,导致震后地壳隆升速率同步增大。     

喜马拉雅主逆冲断层闭锁程度与滑动亏损特征研究

基于融合的GPS速度场结果,使用DEFNODE负位错反演程序估算了喜马拉雅主逆冲断层（the main Himalayan thrust,MHT）的闭锁程度和滑动亏损空间分布,并结合剖面结果分析了断层远、近场的运动特征。结果表明,MHT的闭锁深度基本达到18~24 km,断层面闭锁宽度达到102~136 km,两次历史大地震破裂区域之间的未破裂段落和未发生大地震的段落闭锁深度更深,闭锁断层面更宽,2015年尼泊尔Mw7.8大地震就发生在两次大地震破裂区域之间的段落;MHT总滑动亏损速率和垂直断层挤压滑动亏损速率自东向西逐渐减小,平行断层右旋滑动亏损速率则基本上自东向西逐渐增加;MHT 3条剖面拟合结果也反映出其存在很强的闭锁。根据估算的此次Mw7.8地震的复发周期230年和最近500多年发生的大地震分布,认为MHT整条段落尤其是尼泊尔西部与印度接壤处和可能还没有破裂的不丹地区依然有发生8级大地震的危险。     

尼泊尔Mw 7.9级地震同震垂直位移与断层运动模型

2015年4月25日尼泊尔地区发生了Mw 7.9级地震,发震断层位于印度板块与欧亚板块碰撞边界带,此次地震是一次典型的板块逆冲型事件。利用中国境内加密的GPS同震观测资料,融合ALOS-2卫星L波段的InSAR（interferometric synthetic aperture radar）同震形变数据,基于最小二乘方法获得了此次地震的同震垂直位移场。同震垂直位移结果表明,此次地震造成尼泊尔加德满都地区抬升约0.95 m,珠穆朗玛峰地区受地震的影响有所下降,其主峰的沉降量为2~3 cm,中国境内的希夏邦马主峰沉降约为20 cm。地区利用改进的二维弹性半空间位错模型反演了发震断层运动参数,本文模型显示此次地震的断层面破裂宽度约为60 km,平均滑动量达到4 m,相当于Mw 7.89级。     

Plate Motion of India and Interseismic Strain in the Nepal Himalaya from GPS and DORIS Measurements

We analyse geodetically estimated deformation across the Nepal Himalaya in order to determine the geodetic rate of shortening between Southern Tibet and India, previously proposed to range from 12 to 21 mm yr^?1. The dataset includes spirit-levelling data along a road going from the Indian to the Tibetan border across Central Nepal, data from the DORIS station on Everest, which has been analysed since 1993, GPS campaign measurements from surveys carried on between 1995 and 2001, as well as data from continuous GPS stations along a transect at the logitude of Kathmandu operated continuously since 1997. The GPS data were processed in International Terrestrial Reference Frame 2000 (ITRF2000), together with the data from 20 International GNSS Service (IGS) stations and then combined using quasi- observation combination analysis (QOCA). Finally, spatially complementary velocities at stations in Southern Tibet, initially determined in ITRF97, were expressed in ITRF2000. After analysing previous studies by different authors, we determined the pole of rotation of the Indian tectonic plate to be located in ITRF2000 at 51.409±1.560° N and ?10.915±5.556°E, with an angular velocity of 0.483±0.015°. Myr^?1. Internal deformation of India is found to be small, corresponding to less than about 2 mm yr^?1 of baseline change between Southern India and the Himalayan piedmont. Based on an elastic dislocation model of interseismic strain and taking into account the uncertainty on India plate motion, the mean convergence rate across Central and Eastern Nepal is estimated to 19±2.5 mm yr^?1, (at the 67% confidence level). The main himalayan thrust (MHT) fault was found to be locked from the surface to a depth of about 20 km over a width of about 115 km. In these regions, the model parameters are well constrained, thanks to the long and continuous time-series from the permanent GPS as well as DORIS data. Further west, a convergence rate of 13.4±5 mm yr^?1, as well as a fault zone, locked over 150 km, are proposed. The slight discrepancy between the geologically estimated deformation rate of 21±1.5 mm yr^?1 and the 19±2.5 mm yr^?1 geodetic rate in Central and Eastern Nepal, as well as the lower geodetic rate in Western Nepal compared to Eastern Nepal, places bounds on possible temporal variations of the pattern and rate of strain in the period between large earthquakes in this region.     

基于GIS技术的河流水质评价系统的设计与实现

本文以惠州市河流水质评价为研究对象,介绍了基于GIS技术的河流水质评价系统的总体设计和功能实现。并以污染指数评价模型为例,详细阐述了河流水质评价系统所实现的河流评价功能,以实现对河流的合理保护与科学管理。     

2015年尼泊尔地震同震滑动及震后余滑的三角位错模型反演

2015年尼泊尔Mw 7.9级地震发生在印度板块向欧亚板块低角度俯冲的喜马拉雅断裂带上。对该地震的滑动模型进行精化,对于理解喜马拉雅断裂带的孕震模式具有重要意义。采用三角形位错元构建主喜马拉雅断裂“双断坡”几何模型,联合全球定位系统（Global Positioning System,GPS）和合成孔径雷达干涉测量（interferometric synthetic aperture radar,InSAR）资料反演2015年尼泊尔地震同震滑移及震后余滑。结果表明,尼泊尔地震最大同震滑移达到7.8 m,深度为15 km,位于中地壳断坡和浅层断坪的接触部位。不考虑中地壳断坡结构会使反演的最大滑移量偏低。震后余滑主要分布在同震破裂区北侧,释放的地震矩为1.02×1020 N·m,相当于一次Mw 7.3级地震,约占主震释放地震矩的12%。同震库伦应力变化和震间断层闭锁分布均表明,尼泊尔地震破裂区南部宽约60 km的区域仍具有较高的地震危险性。     

基于遥感影像和矢量数据的水系变化检测

介绍了基于遥感影像和矢量数据的水系变化检测方法。根据矢量的拓扑结构,将水系分为主干河流、湖泊和支流水系网。对主干河流采用"模式分类、区域生长、形态学处理、边缘提取、缓冲区检测"的流程,对湖泊采用"区域生长、形态学处理、多边形面积相减"的处理,对支流水系网采用"金字塔分解和多尺度模板匹配、Ziplock Snakes模型优化、缓冲区检测"的策略。实验结果验证了上述方案的可行性。     

基于"一张图"的河长制技术体系研究

2016年12月,中共中央办公厅、国务院办公厅印发了《关于全面推行河长制的意见》,要求全国各地区各部门全面落实河长制.贯彻落实"河长制"相关文件精神,结合"河长制"管理工作的实际需要,使得河长制能够顺利推行和执行,需要利用信息化的手段作为支撑.本文系统分析了河长制信息化建设的需求,提出了基于"一张图"的河长制技术体系,涵盖了数据、服务、应用、规范等多层次的技术范畴,有利于实现河长系统数据的科学高效管理,可为河长管理信息资源的交换共享与分析挖掘提供必要条件.     

GZCORS在广州轨道交通水下地形测量中的应用

水下地形图是轨道交通工程规划、设计、施工的重要基础资料,本文以广州轨道交通三号线流溪河水下地形测量为例,阐述了广州市连续运行参考站城市3维定位系统(GZCORS)在水下地形测量中的作业模式、方法及精度。该种作业模式在河道、沿海港口等水下地形测量中有着广阔的应用前景。     

Drainage Analysis in a Part of the Brahmaputra Valley in Sivasagar District, Assam, India, to Detect the Role of Neotectonic Activity

An analysis of the drainage network of a part of Sivasagar district, Assam, India, is undertaken to reveal the role of neotectonic activity of the area. A number of fluvial geomorphic anomalies have been identified in the area. A prominent annular drainage anomaly is displayed by the major rivers—the Dikhu, Jhanzi, Namdang, Dorika and Disang, whose courses are carved in response to the ongoing tectonic deformation in the area. This study reveals that the development of topography and drainage system of the study area have been influenced by active subsurface geological structures. Formation of paleochannels, compressed meanders, reticulate streams, swamps, sagging of grounds, stream alignments, lineaments, knick points and abandonment of rivers as well as development of smaller drainage anomalies also substantiate the active nature of the subsurface structures.     

Physical Habitat Assessment of the Ganjal and Morand River Using GIS Techniques

Physical habitat is the living space of in-stream biota which is an important factor that can affect both the quality and quantity of available habitat and the structure and composition of resident biological communities. It is a spatially and temporally dynamic entity determined by the interaction of the structural features of the channel and hydrological regime. Ganjal River is a left bank tributary of River Narmada and Morand river is the major tributary of it. At these rivers Physical Habitat Assessment was carried out using USEPA Rapid Bioassessment Protocols to know habitat suitability conditions in rivers for aquatic life thrive in. In the study habitat assessment parameters were scored according to the existing conditions for each section of the rivers and were categorised under four conditions i.e. optimal, suboptimal, marginal and poor. On the basis of result obtained from the study Habitat Suitability Map (HSM) was generated using GIS as an interface and it suggests that the habitat quality of both rivers is suitable for aquatic life.     

2020珠峰测量与高程确定

为实现中国和尼泊尔共同宣布珠峰高程,我国于2019—2020年开展了珠峰高程测量工作,并于2020年5月27日完成峰顶测量.首次在珠峰北侧区域实施航空重力测量、开展峰顶地面重力测量,首次联合航空和地面重力等数据确定了基于国际高程参考系统(international height reference system,IHR...     

河网多尺度Morphing的变换方法研究

本文基于Morphing连续变形技术的一种技术探讨河网的多尺度变换方法,主要涉及对应河流间的Morphing变换和无对应河流的河流删除这两类问题。本文首先对两个不同比例尺的对应河网进行河流匹配,确定河流的对应情况,然后以较大比例尺河网向较小比例尺河网变化的方式进行河网的多尺度变换。对于在两个不同比例尺河网中对应存在的河流,采用顾及交汇点信息及河流结构信息的形状内插方法进行Morphing变换;对于仅在较大比例尺河网中存在而在较小比例尺河网中不存在的河流,则以河流的干支总长作为其重要性标准,进而依据给定的变换程度参数删除重要性较小的河流。最后,通过实验分析与对比,验证了本文方法能够有效改善河流间的Morphing变换效果,提高河流选取的准确性。     

山水林田湖草生态保护修复项目遥感监测及辅助绩效评价

山水林田湖草生态保护修复是保障国家生态安全的重要举措,科学合理的生态保护修复项目监测和绩效评价方法,有助于保障生态保护修复工程的顺利实施和生态保护修复成果的可持续发展。本研究采用文献综述和案例分析相结合的方法,论述了遥感技术在山水林田湖草生态保护修复项目监测和绩效评价中的具体应用。从关注区域生态系统格局和质量两方面出发,选择遥感数据获取的土地覆盖类型、植被长势、水质参数作为评价指标,整体实现了山水林田湖草各生态要素的监测;从维护和提升区域生态系统服务出发,选择水源涵养、水土保持、生态系统承载力等指标,论述了遥感数据在辅助山水林田湖草生态保护修复项目绩效评价中的作用。最后指出积极探索新的遥感数据挖掘方法,并结合遥感技术与传统的调查方法,有望形成更客观、更快速且具备可执行性的山水林田湖草生态保护修复项目监测及绩效评价体系。     

Applications of Point-to-Point Distances with Regional and Global Datasets

We developed an ATL software component that calculates point-to-point distance with geographic latitude, longitude, and elevation. GEODIST3D was also developed with the ATL component to handle the PolylineZ shapefile format. GEODIST3D was applied to the Amazon and Nile rivers, as well as to the Seoul road network. Distance calculation results showed about a 4% increases in the Amazon and Nile rivers compared with ellipsoidal geodesic distances. Roughly a 0.2% increase was also found in the total length of the major roads in Seoul, South Korea. Survey professionals and GIS analysts will benefit from using the ATL component and GEODIST3D by calculating distance more accurately with digital geospatial features.     

Tridimensional reconstruction of the Co-Seismic Ionospheric Disturbance around the time of 2015 Nepal earthquake

The Co-Seismic Ionospheric Disturbance of the 2015 Nepal earthquake is analyzed in this paper. GNSS data are used to obtain the Satellite-Station TEC sequences. After removing the de-trended TEC variation, a clear ionospheric disturbance was observed 10 min after the earthquake, while the geomagnetic conditions, solar activity, and weather condition remained calm according to the Kp, Dst, F10.7 indices and meteorological records during the period of interest. Computerized ionosphere tomography (CIT) is then used to present the tridimensional ionosphere variation with a 10-min time resolution. The CIT results indicate that (1) the disturbance of the ionospheric electron density above the epicenter during the 2015 Nepal earthquake is confined at a relatively low altitude (approximately 150–300 km); (2) the ionospheric disturbances on the west side and east sides of the epicenter are precisely opposite. A newly established electric field penetration model of the lithosphere–atmosphere–ionosphere coupling is used to investigate the potential physical mechanism.     

数学形态学与拓扑约束支持的单条河流骨架线提取

为解决当前遥感手段提取河流骨架线自动化程度不高、精度有限、易发生断裂等问题,提出一种基于数学形态学与拓扑约束理论的完整单条河流骨架线自动化提取方法。该法综合利用归一化水体指数(NDWI)和数学形态学方法提取遥感影像中的河流及河流初始骨架线;从河流初始骨架线二值图中获取断点,并自动计算膨胀系数,利用局部膨胀细化法进行连接;结合拓扑约束,利用初始骨架线对连接线进行去伪操作。结果表明,该方法能有效解决细小、易发生断裂的单条河流的完整骨架线自动提取的难题。     

基于3维GIS的镇江市内河水上搜救应急指挥管理系统设计与实现

针对镇江市内河水上突发事件的特点,在3维GIS平台的基础上,整合CCTV视频监控系统、GPS定位系统、海事通等先进的手段,在突发事件发生时,该系统能及时预警,准确定位突发事件的位置,进行总体指挥调控,形成实施应急预案的交互式实战指南,为应急管理提供便捷的工具,为指挥决策提供辅助支持手段。     

Integration of WorldView-2 and airborne LiDAR data for tree species level carbon stock mapping in Kayar Khola watershed,Nepal

Integration of WorldView-2 satellite image with small footprint airborne LiDAR data for estimation of tree carbon at species level has been investigated in tropical forests of Nepal. This research aims to quantify and map carbon stock for dominant tree species in Chitwan district of central Nepal. Object based image analysis and supervised nearest neighbor classification methods were deployed for tree canopy retrieval and species level classification respectively. Initially, six dominant tree species (Shorea robusta, Schima wallichii, Lagerstroemia parviflora, Terminalia tomentosa, Mallotus philippinensis and Semecarpus anacardium) were able to be identified and mapped through image classification. The result showed a 76% accuracy of segmentation and 1970.99 as best average separability. Tree canopy height model (CHM) was extracted based on LiDAR’s first and last return from an entire study area. On average, a significant correlation coefficient (r) between canopy projection area (CPA) and carbon; height and carbon; and CPA and height were obtained as 0.73, 0.76 and 0.63, respectively for correctly detected trees. Carbon stock model validation results showed regression models being able to explain up to 94%, 78%, 76%, 84% and 78% of variations in carbon estimation for the following tree species: S. robusta, L. parviflora, T. tomentosa, S. wallichii and others (combination of rest tree species).     

Pinpointing the sources and measuring the lengths of the principal rivers of the world

Abstract

Cultures throughout the world are associating with the rivers. People depend upon the rivers and their tributaries for food, water, transport, and many other aspects of their daily lives. Unfortunately, human beings have not calculated the accurate lengths for the great rivers even today. The lengths of the rivers are very different in popular textbooks, magazines, atlases and encyclopedias, etc. To accurately determine the lengths of the principal rivers of the world, the combination of satellite image analysis and field investigations to the source regions is proposed in this paper. The lengths of the Nile, Amazon, Yangtze, Mississippi, Yellow, Ob, Yenisey, Amur, Congo and Mekong, with lengths over or close to 5000 km, were calculated using the proposed method. The results may represent the most reliable and accurate lengths of the principal rivers of the world that are currently achievable.