数字河流数据的自动综合

本文主要介绍了数据库中水系要素综合中河流的自动综合方法，尤其是对非结构化河网中河流的自动选取作了较为详细的论述，并通过数据库中一幅完整图幅的河流数据对文中介绍的自动综合方法进行了验证。     

GIS Methodology for Characterizing Historical Conditions of the Willamette River Flood Plain, Oregon

Recent environmental developments have stimulated an interest in conservation and restoration of the historical Willamette River flood plain, both to protect against flooding and to provide wildlife habitat. In order to best utilize scarce resources, we characterized historical and modern river channel and flood‐plain conditions to evaluate changes and help prioritize restoration sites. Using cartographic and photographic data sources, we developed a Geographic Information System (GIS) to map active channels, side channels, islands and tributaries for four separate dates, as well as riparian and flood‐plain vegetation characteristics for pre‐European settlement and modern time periods. Coverages based on flood records and other boundaries were used to partition the flood plain into spatial subsets for analysis. The GIS allowed comparisons between historical and present conditions for a variety of environmental factors. Much of the pre‐settlement channel complexity has been removed. Total channel length in 1995 was 26% less than in 1850, with almost 58% of the river's side channels disconnected from the system. In addition, we found a 72% loss of flood‐plain forest from 1850 to 1995, since it was converted to agricultural and urban land uses. Selected river and flood‐plain variables were made available for a spatial model to prioritize potential locations for flood‐plain restoration.     

Migration behaviour of river ganga between Allahabad and Buxar using remotely sensed data

Channel migration includes any change of river channel geometry within the context of the cross-section, pattern or network in a drainage basin. To study the dynamic behaviour of a river, measurements taken with conventional ground-based instruments are time-consuming and expensive. Remote sensing techniques are capable of providing a measure of surface variability including dynamic behaviour of channels, reasonably quickly due to availability of the repetitive remotely-sensed data. These data are well suited for the assessment and monitoring of dynamic changes on the surface of the earth. In the present study Landsat MSS and TM data of winter season in the form of false colour composites (FCC) of years 1982 and 1987 were used for the delineation of river Ganga course lying between Allahabad and Buxar. The interpretation of satellite data was carried out using visual interpretation technique for the assessment of channel migration. The shift in river banks delineated from satellite data were measured with respect to river banks identified from topographical base map. The maximum shift observed in mid channel is 4. 55 km while maximum left and right banks shifts are 4.6 and 4.8 km, respectively.     

基于不同数据源的数字河网提取方法与空间分析

为了研究不同数据源提取数字河网的方法,本文从地形图、DEM和遥感影像三种不同来源的数据源,选取天水市麦积区颖川河为研究对象,通过采用对地形图的数字矢量化、Hc-DEM水文分析和遥感影像解译等不同方法分别提取数字化河网,并对提取结果进行空间分析。     

基于分形理论的水系要素制图综合研究

在研究水系要素具有分形现象的基础上，提出了水系要素的分维数的确定方法，并利用水系的分数维规律进行地图制图综合，取到了较好的结果。     

地图上等高线信息度量的层次方法研究

地图信息定量度量是地图学研究一个基础问题,亦是评价地图设计、地图综合、制图质量的一个重要依据。本文以等高线地图为例,提出了一种基于空间认知的等高线信息的层次度量方法。首先,分析了现有基于Shannon 信息论的地图信息度量方法。然后解析了地图等高线信息的产生原理,并将等高线信息划分为三个层次,分别为单条等高线信息度量层次（即元素层次）、基本地貌单元邻接等高线信息度量层次（即邻域层次）、全局地图等高线信息度量层次（即整体层次）。在此基础上,依据空间信息多样性和差异性特征,分别建立了各层次信息定量度量方法。最后,通过实验初步验证了本文所提的等高线信息定量度量方法的合理性和正确性。     

Channel pattern transformation of the Burhi‐Gandak river,Bihar, India: A study based on multidata sets

The Burhi‐Gandak river is one of the major tributaries of the Ganga River in the middle Ganga basin. The river is i known to have an oscillatory character and has changed its course in Recent times. In the present study, a variety of remote sensing data combined with surface and subsurface data have been used to delineate the fluvial palaeofeatures of this river. The palaeofeatures of the Burhi‐Gandak indicate that the river has shifted from N to S over a distance of 30 km. Further, its is observed that Burhi‐Gandak river had a larger channel width and higher discharge on earlier times and was very active. On detailed examination, a past link between the now northerly flowing Baghmati and Burhi‐Gandak rivers is detected. Based on the above features, three distinct stages of migration of the river have been identified and a summary of fluvial palaeohistory is presented.     

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。     

基于Delaunay三角网的河流中线提取方法

鉴于水系自动综合中河系数据模型建立的复杂性,利用ArcObject提供的组件在双线河和狭长湖泊间构建约束的Delaunay三角网,继而提取其骨架线,从而得到双线河和狭长湖泊的中轴线,之后进行拓扑关系的保持,有效地简化了水系数据模型的建立,为后续的空间分析打下基础。     

利用国产GF-1卫星数据实现山区细小河流河宽的自动提取

以国产GF-1卫星影像为数据源,选取皇甫川流域内山区细小河流密集的上游1421 km²作为研究区域,针对因山区河流河道狭窄、形态复杂等导致的河流边界提取难度大、精度差、河宽无法自动提取的难题,首先利用改进的变异系数法筛选水体指数,再采用改进的决策树法结合DEM河网精确获取河流边界,最后通过自动化河宽提取算法实现对山区细小河流及其河宽的自动提取。结果表明,本文方法对山区河流判别的总体精度为89.5%,有效地排除了山体阴影等地物的干扰。对河宽为0~10 m的极细河流,本文方法提取河宽的误差为18.54%;10~30 m的细小河流,提取误差为12.07%。     

基于线状特征增强的TM遥感影像细小河流提取方法

混合像元效应是导致难以从TM影像中提取细小河流的主要原因。提出一种综合多种数字图像处理技术的细小河流自动识别方法。首先,利用阈值分割区分水体指数影像中的细小河流与面状水体;第二,对水体指数进行线状信息增强,突出线状河流信息,并抑制其他地物信息;第三,利用双阈值线段追踪方法,提取影像中的细小河流;第四,通过三种方法分别去除阴影、道路和其他类型噪声。结果表明,本文方法能有效地提取细小河流,同时排除多种噪声的干扰,结果的检测率高于82%、虚警率低于7%、检测质量高于79%、完整度高于90%。     

Application of DEM,Remote Sensing and Geomorphic Studies in Identifying a Recent [or perhaps Neogene?] Upwarp in the Dibru River Basin,Assam, India

The Dibru river basin of Assam is investigated to examine the influence of active structure by applying an integrated study on geomorphology, morphotectonics, subsurface structure, Digital Elevation Model (DEM) using topographic map, IRS 1D LISS III, IRS P6 LISS III, SRTM, seismic and subsurface data. Seismic data reveals existence of an upwarp and an important fault in the basement around the central and eastern parts of the Dibru basin, respectively. The influence of these structures is well observed on all the younger formations inferring their active nature possibly till the Recent Period. Existence of fluvial anomalies, viz. annular drainage pattern, lineaments, abrupt changes in the direction of river course, beheaded stream and valley incision infer role of structural control on the fluvial features of this basin. Most commonly used indices for morphotectonic analysis, viz. basin elongation ratio (Re), transverse topographic symmetry (T), asymmetric factor (AF), valley floor width to valley height ratio (Vf) have been used to identify the evidences of active structures in the area. The values of Re indicated tectonically active, T indicated an asymmetric nature, AF indicated tilting and Vf indicated active incision in the Dibru basin. The DEM, profiles across the valley and superimposed longitudinal profiles of incised channel bed and valley shoulder of the Dibru clearly reveal valley incision by the river. Three large paleochannels located in different parts of the basin had their headwaters towards east at the common source, i.e. the Diyun river. These paleochannels had been resulted when their headwaters avulsed to create new rivers due to affect of the subsurface structures during Recent (or perhaps Neogene?) Period.     

基于约束D-TIN的等高线簇与河网协同综合方法

传统制图综合中针对水系、地貌等不同地理要素的分治策略,往往导致综合后要素目标之间在空间与语义上的冲突.考虑地形与河流之间的空间依赖性,提出一种等高线簇与河网协同的制图综合方法,即利用两种要素目标顶点在约束D-TIN描述下的空间邻近关系,并通过提取和组织谷地等高线弯曲段数据,构建两要素有效协同关系.在此基础上将等高线按所...     

一种启发式有环河系自动分级算法

在地图综合中,河流分级是对水系要素表达的重点也是技术难点,对精确性和计算速度都有较高的要求。目前对河系分级的研究中,已有分级算法的效率较低,且鲜有针对有环河系的分级。基于此,本文建立了河系分级的属性规则、几何规则、环规则,对河系中存在的不同环类型进行了分类处理,且在求取河流最长路径时,运用启发式算法迭代计算,实现了河系的自动分级。实际河系数据试验表明,该算法能在对有环河系的处理中取得良好的效果,提高了河系分级的计算效率和准确度。     

矢量河网数据的渐进式传输

提出了一个无几何数据冗余的河网渐进式传输多尺度数据结构。结合目标层次的河流选取和几何细节层次上的曲线化简建立河网多尺度数据结构。基于该数据结构,在Web环境下实现了河网数据的渐进式传输。     

DESIGN AND REALIZATION OF MAP DIGITIZATION SYSTEM ON MICRO-COMPUTER BASED MAP GRAPHIC WORKSTATION

The main purpose to develop a Map Graphic Workstation on thewidely used micro-computer is that by it the whole processing of map data fromcapturing,managing,editing,updating to graphic outputting can be realized.Map Digitization System（MDS）is the software system to deal with the initial andalso the most important processing.In this paper,the authors introduce a MDSon a micro-computer based Map Grphic Workstation that has been qualitified forthe producation of digital map.Since the system is designed totally independentlyand in the general frame of the Map Graphic Workstation,the capturing and man-aging and other processings for map data are in an integral manner,in which theproducation of digital map can be fulfilled conveniently.At the same time,thesystem is flexible for function extension and widely applicable to the data from dif-ferent sources and with different information characterisitcs(e.g.,the processingof Chinese characters on map).     

Detection and correction of inconsistencies between river networks and contour data by spatial constraint knowledge

In the representation of topographic data, the distribution of hydrographic networks should be constrained by the contour model’s landform features. During the integration of topographic databases, however, spatial conflicts may destroy these constraints, generating inconsistencies. This study presents a method to detect and correct inconsistencies between river networks and contour data by spatial knowledge. First, structured terrain features are extracted from the contour-based geometric representation and matching relationships between rivers and contours are constructed based on spatial knowledge of the distribution of rivers and talwegs. We then propose a distance metric for measuring differences and identifying inconsistencies between the matched river and contour features. Three correction approaches are provided for different inconsistency situations, including river adjustment referenced to the contour, contour adjustment referenced to the river and adjustment of both river and contour to middle positions. We apply the proposed method to the integration and maintenance of national topographic infrastructure in order to demonstrate its effectiveness.     

河流自动选取中的分级优化

水系是具有高度结构化特征的复杂空间数据,在不同水文条件和地形环境下发育的水系形态可以表现为多种模式,如格状河系、羽毛状河系、平行状河系等,使得水系选取具有较大难度。探讨了河流分级(汇流区域特征)、河网结构层次化(河流分布的地理特征)与水系选取之间的关系,提出了基于流域的河流自动选取,从河流的局部重要性出发,考虑河流的分级主要基于两点:一是确定选取单元为流域;二是对流域内河流通过等级关系选取高等级河流,同等级间河流根据长度、密度、河流间距离等综合指标进行选取。     

顾及密度差异的河系简化

河系简化是地图综合中经常需要处理的任务,其难点主要在于依据上下文环境对河流进行结构化选取,以保持河网密度差异等宏观特征。提出一种新的河流等级规则,依据河流的各级支流的数量确定河流的等级,以反映河流的密度差异;设计一种结合河流等级、长度与所在层次的综合指标进行河流选取;探讨在自动构建河系树的基础上计算河流等级、所在层次等指标的方法;最后使用综合指标进行河流结构化选取试验。结果表明,以新等级规则为基础的综合指标切实可行,能够在一定程度上保持河网密度的区域差异。     

Channel Pattern as Signature of Neotectonic Movements — A Case Study from Brahmaputra Valley in Assam

Spatial characteristies of drainage geometry of Brahmaputra river and its tributaries were studied based on visual interpretation of 1RS IB imagery (on 1:250,000 scale) and topographical maps of different periods. Observed features of drainage lines alongwith possible mechanism of their formation in terms of neotectouie adjustment are discussed It is inferred that selected stretches of Brahmaputra river viz. between Dibrugarh and Jorhat and between Guwahati and Goafpara may represent channels with active boundaries that have restrieted/controlled the width of sinuous lines of discharge of the river within the valley. Local tilting of ground, lying to the south-east of Brahmaputra river, between Noa Dihing and Burhi Dihing rivers, may explain some of the observed features of these drainage lines Movement along some lineaments in recent past has occurred. This inference is based on the evidence of adjustment of several drainage lines viz, Dihing. Burhi Dihing. Dikrang. and Mora Bhareh rivers and displacement of rocks of younger age.