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基于二维离散小波变换的四川省伏旱的多尺度分析
投稿时间:2018-09-16  修订日期:2019-05-21
中文关键词:  伏旱  四川省  二维小波  多尺度
基金项目:四川省教育厅(17ZA0075),成都市科技局(2016-HM01-00392-SF),国家自然科学基金(41401103),四川省科技厅重点(2017SZ0169),国家自然科学基金(41471305),国家自然科学基金(41505012)
作者单位E-mail
卢晓宁 成都信息工程大学 lxn@cuit.edu.cn 
曾德裕 成都信息工程大学 673526122@qq.com 
黄玥 成都信息工程大学 229071709@qq.com 
杨柳青 成都信息工程大学 819621695@qq.com 
孟成真 成都信息工程大学 279965985@qq.com 
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中文摘要:为研究四川这一复杂地形地貌背景区伏旱的多尺度特性,该文在已完成的2000—2015年7—8月四川省月尺度伏旱的遥感监测研究的基础之上,应用二维离散小波变换的方法,不仅分析伏旱多年平均状况及其演变趋势的多尺度特征,更对导致旱情发生发展的驱动因子进行多尺度的分解分析。结果表明:1)旱情多年平均状况在四川省各地貌类型背景区都以垂直方向(南北方向)的小波方差最大,体现出旱情沿区域垂直方向显著的空间分异特征。2)各地貌类型背景区多年平均伏旱状况的主导尺度的数量和范围不同。川东盆地主要存在5个主导尺度,且以中旱的5 040.75 km2的宏观尺度最为突出,严重干旱和特大干旱等级区则以中观尺度(187.34、560.08 km2)为主,集中体现在成都平原一带。高原与盆地过渡区主要存在3个主导尺度,亦以中旱的2?194.5?km2的宏观尺度为主,严重或特大干旱等级则集中在160.51和418 km2的中观尺度的城市和建成区。川西高原则存在2个主导尺度,以9?487.5?km2的宏观尺度无旱的常绿针叶林和混交林交错分布区为主。3)旱情演变趋势则表现为:川东盆地和高原与盆地过度区呈旱情加重趋势区都以中观尺度为主,而呈旱情减缓趋势区则都以宏观尺度为主,只存在尺度数量和具体值上的差异;川西高原则相反,加重趋势区以宏观尺度为主,减缓趋势区以中观尺度为主。4)三大地形地貌类型区在旱情演变趋势的主导因素方面表现出一致性,旱情加重趋势区的主导尺度以植被的衰退变化趋势为主,而旱情减缓趋势区的主导尺度则都以降水的增加趋势主导。
Multiscale analysis of drought in Sichuan based on two- dimensional discrete wavelet transform
Author NameAffiliationE-mail
LU Xiaoning Chengdu University of Information Technology lxn@cuit.edu.cn 
Zeng Deyu Chengdu University of Information Technology 673526122@qq.com 
Huang Yue Chengdu University of Information Technology 229071709@qq.com 
Yang Liuqing Chengdu University of Information Technology 819621695@qq.com 
Meng Chenzhen Chengdu University of Information Technology 279965985@qq.com 
Key words:Drought  Sichuan province  Two-dimensional wavelet  Multiscale
Abstract: In order to study the multi-scale characteristics of drought and drought in the background area of Sichuan, this paper is based on the remote sensing monitoring of the monthly scale drought in Sichuan Province from July to August 2000-2015. In the background area of the geomorphology, the multi-dimensional analysis of the monthly average drought conditions in Sichuan Province and its evolution trend were carried out by using two-dimensional wavelet analysis method to study the average extent of drought conditions and the extent and extent of the trend in different topographic and geomorphological background areas. Further determine the driving factors that play a major role at each scale. This is to understand the multi-scale characteristics of the drought in this complex topographical background area in Sichuan, to determine the main scale range of the impact of different drought levels, and its main driving force. It is of great theoretical significance to propose different spatial regions and different spatial scales for drought prevention and drought countermeasures. Through the research, it is found that: 1) The average annual situation of drought conditions is the largest in the vertical direction, the second in the vertical direction, the second in the horizontal direction, and the smallest in the diagonal direction, reflecting the significant spatial differentiation of the drought along the vertical direction of the region. The dominant factor that leads to this phenomenon is the significant vertical gradient of vegetation. 2) The number and scope of the dominant scales of the annual average drought conditions in the background areas of different types of appearances are different. There are five dominant scales in the Chuandong Basin, and the medium-scale scales are most prominent in the macro-scale of 5040.75 km2. The severe drought and extra-large drought grades are dominated by the mesoscale (187.34, 560.08 km2), which is concentrated in the Chengdu Plain. A band. There are three dominant scales in the transition zone between the plateau and the basin. The macroscopic scale of 2194.5km2 is mainly characterized by moderate drought and has significant vertical differentiation. The mesoscale scales of 160.51 and 418 km2 correspond to severe or extraordinarily large droughts. The grade area is concentrated in the city and the built-up area. There are two dominant scales in the Western Sichuan High Principles. The macroscopic scale of 9487.5km2 is prominently represented in the diagonal direction as the drought-free area where the evergreen coniferous forest and the mixed forest in the central part of Ganzi Tibetan Autonomous Prefecture are interlaced; the mesoscale scale of 637.82 km2 is prominent in the horizontal and vertical directions. Grassland and mixed forest areas distributed along the horizontal and vertical directions in the northwestern part of the Tibetan and Qiang Autonomous Prefecture. 3) The three major topographical and morphological background areas, the number of dominant scales and the prominent scale characteristics of the drought and evolution trend are inconsistent. There are four spatial scales in the drought aggravation trend area in the Chuandong Basin, but the mesoscale scale is dominant, while the slowdown trend area is dominated by the macro scale of 5023.02 km2. There are mainly three drought-increasing trend areas in the plateau and basin transition areas. The dominant scale is also dominated by the mesoscale scale, while the slowdown trend area is more prominent with the three mesoscale scales. Although there are four dominant scales in the drought-increasing trend area of the western Sichuan Plateau, it is dominated by the macro scale. The mitigation trend area is dominated by the mesoscale. 4) Although the dominant scales of the various geomorphological background areas in the evolution trend of drought are different, they have strong positives in the causes of these scale characteristics, that is, they all show the trend of aggravation of drought and the decline of vegetation. The trend of change is dominant, while the area of drought slowdown is dominated by the increasing trend of precipitation.
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