Modelling sediment (dis)connectivity across a river network to understand locational-transmission-filter sensitivity for identifying hotspots of potential geomorphic adjustment     

Sana Khan  Kirstie Fryirs  Simone Bizzi 《地球表面变化过程与地形》2021,46(14):2856-2869

Rivers act as ‘jerky conveyor belts’ that transmit fluxes of flow and sediment downstream. This transmission of fluxes can be highly variable within a drainage basin resulting in either abrupt or gradational sediment (dis)connectivity patterns and processes. This study assesses sediment (dis)connectivity across a basin as a means to understand the locational, transmission and filter sensitivity properties of a fluvial system. Drawing upon the case study of Richmond River Catchment, New South Wales, Australia we use the concepts of effective catchment area and buffers, along with graph theory and an empirical sediment transport model CASCADE (Catchment Sediment Connectivity and Delivery), to assess (1) the degree to which modelled sediment cascades along the river network are connected or disconnected (2) how the position, pattern and configuration of (dis)connection facilitates or restricts geomorphic adjustment in different parts of a catchment, and (3) use the findings as a basis to explain the locational-transmission-filter sensitivity of the catchment. We use this analysis to segregate supply limited and transport limited reaches and identify various controls on sediment dynamics: in-stream sediment storage units, junctions between different geomorphic river types, tributary confluences and sediment storage units within partly confined floodplain units. Such analysis lays the foundation for network scale identification of potential hotspots of geomorphic adjustment.  相似文献   

浅谈GPS技术在"竿影日照图"测量中的应用     

詹瑞超  王丽君 《测绘与空间地理信息》2004,27(5):75-76

按照规划原理的要求,利用GPS定位技术测定本地区“竿影日照图”,用以规范和指导城市规划中建筑物、构筑物等的日照间距问题,同时对GPS观测中的体会加以总结。  相似文献   

等高线空间关系研究   总被引：4，自引：0，他引：4  

乔朝飞  赵仁亮  陈军 《测绘与空间地理信息》2004,27(5):77-80

地形图上等高线相互之间的空间关系是人们分析地形的重要依据,也是利用GIS模拟地形图认知能力的一个重要出发点在利用计算机模拟人们判读地形图的过程中面临的一个关键问题是：如何在计算机环境下有效地描述、表达及计算等高线空间关系,本文从空间认知的需求出发,在等高线空间关系分类的基础上,利用图论中的树结构(等高线树)形式化表达等高线空间关系,在Voronoi邻近的基础上建立了计算机可执行的等高线空间关系计算方法。  相似文献   

基于超像素图卷积网络的高光谱图像分类     

张佳宝  谢福鼎  金翠 《测绘通报》2023,(1):84-87

高光谱图像分类是遥感领域中一个具有挑战性的问题。基于深度学习框架的高光谱图像分类方法,由于其良好的分类性能受到了越来越多的关注。然而,这些方法普遍存在的问题为：模型的训练不仅需要大量的时间,而且还需要大量的标签样本。针对此问题,本文提出了一种基于超像素图卷积网络的高光谱图像分类方法。该方法以超像素作为图的节点,极大地减小了图的规模,从而提高了分类效率;提出的超像素合并技术能有效地融合光谱-空间信息,增强了空间信息在分类中的作用;为了验证该方法的有效性,在Indian Pines、Pavia University两个实际数据集上进行试验,并与一些先进的基于深度学习框架的高光谱图像分类方法进行比较。结果表明,本文方法在分类精度和分类效率上均优于其他方法。  相似文献   

基于GIS的房产信息管理系统设计   总被引：1，自引：0，他引：1  

李璇  刘汉湖  王炜 《测绘与空间地理信息》2014,(7):50-52,56

随着社会经济的快速发展,城市化进程也在不断加快,城市面积持续扩大,各种房屋建筑面积快速增加,这给房产管理部门的各项工作带来了新的挑战。作为一种新的综合性新技术,地理信息系统(GIS)可以把房产管理的各种信息与反映地理位置的图形有机地结合在一起,并可以根据用户的需求对信息进行检索分析,从而使房产管理实现以图管房,以房管档,图、文、档一体化的管理模式。本文结合房产管理行业特点,探讨了GIS在房产管理方面的应用。  相似文献   

基于航飞LIDAR数据制作数字线划图方法探索     

王媛媛  段建刚 《东北测绘》2014,(1):196-197

一些大型的工程项目在前期使用航飞LIDAR系统采集地面数据,获取了大量的三维点云数据和DOM影像数据,要制作该项目全区域的线划图,使用传统的制图方法,不仅效率低,而是几乎不可能完成该项工作。因为海量数据已经让传统的AutoCAD平台制图软件不堪重负,基于此原因,必须研究探索新的方法,就是使用GIS方法来生产线划图。  相似文献   

An analytical method of stage–fall–discharge rating     

Reuy‐Bean Wu  Jinn‐Chuang Yang 《水文研究》2008,22(16):2959-2973

This paper presents an analytical method for establishing a stage–fall–discharge rating using hydraulic performance graphs (HPG). The rating curves derived from the HPG are used as the basis to establish the functional relation of stage, fall and discharge through regression analysis following the USGS procedure. In doing so, the conventional trial‐and‐error process can be avoided and the associated uncertainties involved may be reduced. For illustration, the proposed analytical method is applied to establish stage–fall–discharge relations for the Keelung River in northern Taiwan to examine its accuracy and applicability in an actual river. Based on the data extracted from the HPG for the Keelung River, one can establish a stage–fall–discharge relation that is more accurate than the one obtained by the conventionally used relation. Furthermore, the discharges obtained from the proposed rating method are verified through backwater analysis for measured high water level events. The results indicate that the analytical stage–fall–discharge rating method is capable of circumventing the shortcomings of those based on single‐station data and, consequently, enhancing the reliability of flood estimation and forecasting. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Hydrochemical regime and its mechanism in Yamzhog Yumco Basin,South Tibet   总被引：1，自引：1，他引：0  

Meng Zhe  Xueqin Zhang  Buwei Wang  Rui Sun  Du Zheng 《地理学报(英文版)》2017,27(9):1111-1122

The hydrochemistry of alpine lakes reflects water characteristic and its response to climatic change. Over 300 water samples had been collected from 52 sites of 5 lakes and 7 inflowing rivers in the Yamzhog Yumco Basin, South Tibet, during 2009–2014, basing which the hydrochemical regime and its mechanism were analyzed along with the adoption of hydrological investigations in 1979 and 1984 as well. Results revealed that the waters were hard with weak alkalinity for the Yamzhog Yumco Basin. Most of them were fresh, and the rest were slightly saline. The hydrochemical types of 5 lakes (i.e., Lake Yamzhog Yum Co, Puma Yum Co, Bajiu Co, Kongmu Co, and Chen Co) were SO₄ ^2––HCO₃ ^––Mg²⁺–Na⁺, HCO₃ ^––SO₄ ^2––Mg²⁺–Ca²⁺, SO₄ ^2––Mg²⁺–Na⁺, SO₄ ^2––HCO₃ ^––Ca²⁺, and SO₄ ^2––Na⁺–Mg²⁺–Ca²⁺, respectively. As for rivers, HCO₃ ^– and SO₄ ^2– were the major anions, and Ca²⁺ was the dominant cation. Lake Yamzhog Yum Co, the largest lake in the basin, exhibited remarkable spatial variations in hydrochemistry at its surface but irregular changes with depth. The weathering of evaporates and carbonates, together with evaporation and crystallization, were the major mechanisms controlling the hydrochemistry of waters in the Yamzhog Yumco Basin. Global warming also had significant impacts on hydrochemical variations.  相似文献   

A graph-based algorithm to define urban topology from unstructured geospatial data     

J.-P. de Almeida  J.G. Morley  I.J. Dowman 《International journal of geographical information science》2013,27(8):1514-1529

Interpretation and analysis of urban topology are particularly challenging tasks given the complex spatial pattern of the urban elements, and hence their automation is especially needed. In terms of the urban scene meaning, the starting point in this study is unstructured geospatial data, i.e. no prior knowledge of the geospatial entities is assumed. Translating these data into more meaningful homogeneous regions can be achieved by detecting geographic features within the initial random collection of geospatial objects, and then by grouping them according to their spatial arrangement. The techniques applied to achieve this are those of graph theory applied to urban topology analysis within GIS environment. This article focuses primarily on the implementation and algorithmic design of a methodology to define and make urban topology explicit. Conceptually, such procedure analyses and interprets geospatial object arrangements in terms of the extension of the standard notion of the topological relation of adjacency to that of containment: the so-called ‘containment-first search’. LiDAR data were used as an example scenario for development and test purposes.  相似文献   

A Franco-American Geographical Encounter     

《The Professional geographer》2013,65(3):367-368

ATLAS?GRAPHICS (Version 3.0).

AutoCAD (Release 9.0 with ADE+1, ADE+2 and ADE+3).

AutoSketch (Speed Enhanced Version 1.02).

NUMERICAL RECIPES FORTRAN. Numerical Recipes Software

SCIPLOT.  相似文献