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5040.75km2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、560.08km^2)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2194.5km^2的宏观尺度为主,严重或特大干旱等级则集中在160.51和418km^2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9487.5km^2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。
Based on the remote sensing monitoring results of the monthly scale drought in Sichuan Province from July to August 2000-2015(Lu et al.(2017)), the multi-scale characteristics of drought are studied in such a complex topographical area in this paper. The multi-dimensional analysis of the monthly average drought conditions and its evolution trend are carried out based on two-dimensional wavelet analysis in different topographic and geomorphological areas. The wavelet square difference (WSD) is taken as an index, the larger the wavelet square difference is, the richer the structural information is in the study area at that scale, and the greater the intensity of drought effect is. Through the research, it is found that: 1) The WSD of average annual situation of drought conditions is reaching its maximum in the vertical direction (North-South direction), the second in the horizontal direction (West-East direction), and the smallest in the diagonal direction (Northwest-Southeast 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 the vegetations. 2) The number and scope of the dominant scales for the annual average drought conditions in different are different. There are 5 dominant scales in the Eastern Sichuan basin, and the scale of 5 040.75 km^2 is the most topographic areas in the macro scales. The severe drought and extraordinarily drought grades are dominated by the meso scale at 187.34, 560.08 km^2, which is mainly reflected in Chengdu Plain. For the plateau and basin transition zone, there are 3 dominant scales. The macro scale of 2 194.5 km^2 is mainly characterized by moderate drought and has a significant vertical differentiation. The meso scales of 160.51 and 418 km^2 correspond to severe or extraordinarily droughts, which are mainly reflected in the city and built-up area. For the western Sichuan plateau, there are 2 dominant scales. The macro scale of 9 487.5 km^2 is prominently represented in the diagonal direction as the drought-free area where the evergreen coniferous forest and the mixed forest are interlaced in the central part of Ganzi Tibetan Autonomous Prefecture. The meso scale of 637.82 km^2 is prominent in the horizontal and vertical directions in area where grassland and mixed forest distributed along in the northwestern of the Tibetan and Qiang Autonomous Prefecture. 3) The number of dominant scales and the prominent scale characteristics of the drought and evolution trend are inconsistent in 3 major topographical and morphological areas. For the Eastern Sichuan Basin, there are 4 spatial scales in the drought aggravation trend area, and the mesoscale scale is dominant, while the drought mitigation trend area is dominated by the macro scale of 5 023.02 km^2. For the plateau and basin transition areas, there are mainly 3 scales in drought-increasing trend areas. The dominant scale is also the meso scale, while the mitigation trend area is more prominent with 3 meso scales. There are 4 dominant scales in the drought-increasing trend area of the western Sichuan Plateau, which is dominated by the macro scale. While the drought mitigation trend area is dominated by the meso scale. 4) Although the dominant scales in the evolution trend of drought in different geomorphological areas are different, they have strong consistency in the causes of these scale characteristics, that is, the dominant scale areas of drought aggravation trend show a kind of vegetation decline, while the area of drought mitigation is presented as the increasing trend of precipitation.
作者
卢晓宁
曾德裕
黄玥
杨柳青
孟成真
Lu Xiaoning;Zeng Deyu;Huang Yue;Yang Liuqing;Meng Chengzhen(College of Resources and Environment,Chengdu University of Information Technology,Chengdu 610225,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2019年第9期138-146,共9页
Transactions of the Chinese Society of Agricultural Engineering
基金
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)
国家自然科学基金(41471305)
国家自然科学基金(41505012)
四川省科技厅重点(2017SZ0169)
关键词
干旱
遥感
四川省
二维小波
多尺度
drought
remote sensing
Sichuan Province
two-dimensional wavelet
multi-scale
