基于DEM的河谷横断面形态算法的设计与实现

发布时间：2018-04-22 19:53

本文选题：河流 + 河谷　；参考：《广西师范学院》2017年硕士论文

【摘要】：对河流地貌的研究是国内外水文、地貌学家普遍关注的热点之一。但在以往的研究中,对河流地貌的研究多以河流本身为研究对象,主要集中在对过水断面面积、水系的提取、水流长度的计算等方面,未延伸到河谷形态。尤其是在对河谷横断面的研究过程中,需要沿流域截取较多的断面,数据量较大,且形态特征比纵剖面更复杂。研究者多通过实地测量或基于地形图手动描绘的方式获取数据。传统河谷横断面参数提取方式工作量大,只能局限在较小研究区域内,并且存在较大的主观性,因此对河谷横断面参数提取的方式需要进一步改进。针对当前河流分类[1]、河流管理等方面的研究不断精细化的需求,都不同程度的需要河谷形态参数,故亟需一种能自动化的快速提取河谷形态的算法服务于社会实践。为此,本文设计了一种基于DEM的河谷横断面形态自动提取算法。该算法从河谷谷底与谷坡坡度值的差异性入手,选择高精度DEM数据,运用GIS空间分析算法原理,设计算法,实现了自动提取河谷横断面剖面图、河谷谷底轮廓线及河谷谷底宽度值等功能。基于算法的设计原理与规范以及GIS数据结构的特点,将算法分为6个步骤。按照V形河谷及U形河谷两种基础形态河谷对算法进行测试,并结合真实河谷形态,对算法的适用性进行了验证。本论文的主要研究内容及成果如下:(1)设计了基于DEM的河谷横断面形态算法模型在河谷地貌特征及地理信息系统算法原理的基础上,综合考虑不同时期河谷横断面的形态特征,以及谷底与谷坡的坡度值的差异性,设计了基于DEM数据的算法模型。算法主要包括直线拟合、曲线分段、河网中心点坐标提取、河网垂线提取、坡度提取、探索点位置计算、谷底轮廓线提取、谷底宽度值计算及河谷横断面剖面图绘制9个子算法。通过算法模型的构建,实现了从理论研究到实际应用的转换,进而为河谷形态的研究提供了新的技术手段。(2)通过对V形、U形两类河谷的实例研究,给出了拟合角度阈值、沿河流垂线方向探索距离阈值及河谷坡度阈值的建议取值。实例研究结果发现:(1)该算法模型能够较为准确的描绘谷底轮廓线;(2)通过与真实谷底宽度值做相关性分析可以发现,该算法模型可较为真实的计算谷底宽度值,且U形河谷的准确性高于V形河谷;(3)该算法能够绘制河谷横断面形态剖面图,且与真实河谷横断面形态剖面图一致性非常高。综合分析算法设计过程中遇到的问题及实例研究结果,从数据精度的选择、阈值的选取等方面提出了算法优化及展望。(3)基于ArcGIS Engine,设计实现了河谷横断面形态提取的ArcGIS插件综上所述,基于DEM的河谷横断面形态自动提取算法是提取谷底轮廓线、计算谷底宽度值、绘制河谷横断面的有效途径。该算法具有绘制效果较好、计算准确性较高的优点,在河谷形态研究领域,具有很强的应用价值及发展潜力。
[Abstract]:The study of river geomorphology is one of the hot spots of hydrology and geomorphologists at home and abroad. However, in the previous studies, the study of river landforms mostly focused on the river itself, mainly focused on the cross section area, the extraction of water system, the calculation of water flow length and so on, and did not extend to the river valley shape. Especially in the process of studying the cross-section of the river valley, it is necessary to intercept more sections along the river basin, the amount of data is large, and the morphological characteristics are more complex than that of the longitudinal section. Researchers often obtain data through field measurements or manual mapping based on topographic maps. The traditional way of extracting cross-sectional parameters of river valley is very heavy, which can only be confined to a small area of study, and has more subjectivity. Therefore, the method of extracting cross-sectional parameters of river valley needs further improvement. According to the needs of river classification, river management and so on, the river valley shape parameters are needed in varying degrees, so an automatic and fast algorithm to extract river valley shape is urgently needed to serve the social practice. Therefore, an automatic extraction algorithm of river valley cross-section based on DEM is designed in this paper. The algorithm starts with the difference between valley bottom and slope gradient, selects high-precision DEM data, designs the algorithm by using GIS spatial analysis algorithm, and realizes automatic extraction of valley cross-section profile. Valley bottom contours and valley floor width value and other functions. Based on the design principle and specification of the algorithm and the characteristics of GIS data structure, the algorithm is divided into six steps. The algorithm is tested according to the V shape valley and the U shape valley, and the applicability of the algorithm is verified by combining the real river valley shape. The main research contents and results of this paper are as follows: (1) the algorithm model of river valley cross section based on DEM is designed. On the basis of the geomorphological characteristics of river valley and the principle of GIS algorithm, the morphological characteristics of river valley cross section in different periods are considered synthetically. The algorithm model based on DEM data is designed. The algorithm mainly includes straight line fitting, curve segmentation, coordinate extraction of center point of river network, vertical line extraction of river network, slope extraction, location calculation of exploration point, contour line extraction of valley bottom, The calculation of the valley floor width and the drawing of the river valley cross-section section are 9 subalgorithms. Through the construction of the algorithm model, the conversion from theoretical research to practical application is realized, and a new technical means for the study of valley shape is provided. The suggested values of distance threshold and valley slope threshold are explored along the perpendicular direction of the river. A case study shows that the algorithm model can accurately describe the outline of the bottom of the valley. By analyzing the correlation with the real value of the floor width, it can be found that the algorithm model can calculate the valley floor width more truthfully. Moreover, the accuracy of U-shaped valley is higher than that of V-shaped valley. The problems encountered in the design of the algorithm and the results of the case study are synthetically analyzed, and the selection of the data precision is given. Based on ArcGIS engineer, the ArcGIS plug-in is designed to extract the shape of the valley cross-section. In summary, the automatic algorithm of extracting the shape of the valley cross-section based on DEM is to extract the outline of valley bottom. It is an effective way to calculate the valley floor width and draw the cross section of the valley. The algorithm has the advantages of good rendering effect and high calculation accuracy. It has strong application value and development potential in the field of valley shape research.
【学位授予单位】：广西师范学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P931.1;P208

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