重庆市干旱时空分布特征与规律研究

发布时间：2018-08-21 12:30

【摘要】：干旱作为世界上最常见、影响范围最广的自然灾害之一,在全球变暖的大背景下,其发生频率和强度都呈增加趋势,造成的直接经济损失和间接经济损失也日益加重,对社会安定和经济发展产生了深远的影响。近年来,随着国民经济快速发展、人口增长以及城市建设进程加快,旱涝影响的范围和领域已经从农业、农村发展到城市和生态。在这样的背景下,做好干旱灾害风险评估和管理,构建不同地区不同作物的防灾减灾体系,减轻干旱灾害对农作物的不利影响,对降低农业生产损失,提高农民生活水平具有重要的意义。重庆市由于其独特的地理位置和气候环境,各种灾害频发,加上农业基础设施较差,农业资金投入较少,农业抵御自然灾害的能力较低,全市农作物受灾严重,成灾率一直高居不下。因此,研究重庆市干旱时空分布特征与规律为研究重庆市干旱的发生发展、监测预报;应对安全生产以及趋利避害提供科学依据和参考。本文基于重庆市地方标准《气象灾害标准》,利用重庆市34个国家基本气象站1961-2010年日降水量数据,采用数理统计方法统计1961-2010年重庆市34个区县干旱类型及其等级,运用Hurst指数法、滑动t突变检验法、Morlet小波分析法进行时间序列的分析以及运用Arc GIS空间插值法,对季节性干旱从干旱频率、持续天数、干旱站次比以及干旱综合强度等几个方面进行分析,最后分析年干旱强度综合指数的时空分布特征和规律。研究的主要结论如下:(1)区县季节性干旱在时间上有不同的变化趋势,有明显的年代际变化。近50a(1961-2010年)重庆市春旱、伏旱和冬旱持续天数呈小幅度下降趋势;夏旱、秋旱持续天数呈微弱上升趋势。1961-2010年间,重庆市季节性干旱持续天数和干旱站次比均有明显的年代际变化,20世纪60年代的春旱发生范围最大,20世纪90年代的春旱发生范围最小;20世纪90年代的夏旱发生范围最大,20世纪70年代的夏旱发生范围最小;20世纪70年代的伏旱发生范围最大,20世纪80年代的伏旱发生范围最小;20世纪80年代的秋旱发生范围最大,21世纪初的秋旱发生范围最小;20世纪60年代的冬旱发生范围最大,21世纪初的冬旱发生范围最小。(2)区县季节性干旱频率的空间分布差异较大。重庆市西部的潼南区、大足区、荣昌区、中部的丰都县、忠县和东北部的云阳县、巫溪县等地是春旱发生的主要区域,春旱频率较大;渝东南部和渝中部的长寿区、万盛等地春旱频率小。渝西部的潼南区、大足区、荣昌区和渝东北部的奉节县、巫溪县、巫山县等地夏旱频率较大;渝东南部和广大的渝中部地区夏旱频率小。重庆市西部以及中部长江流域河谷地区,尤其是长江、嘉陵江和綦江等河谷地区是伏旱发生的主要区域,伏旱频率高;渝东北部的城口县和渝西南部的万盛等地是伏旱较轻。重庆市东北部的巫溪县、巫山县、奉节县、东南部的秀山县、酉阳县和西部的潼南区等地是秋旱发生主要区域,秋旱频率较高。重庆市东北部的云阳县、奉节县、巫溪县等地是冬旱发生的主要区域,冬旱频率较大。(3)区县季节性干旱历年总强度的空间分布差异较大。春旱历年总强度的高值区主要在渝西部的潼南区、大足区、荣昌区、渝东北部的云阳县等地;低值区主要在渝东南部的秀山县、酉阳县、渝东北部的城口县和渝西南部的万盛等地。历年夏旱总强度高值区在渝西部的潼南区、铜梁区、大足区、荣昌区、永川区和渝东北部的城口县、巫溪县等地;低值区在渝东南部的秀山县、酉阳县、黔江区、彭水县和渝中部的万盛、南川区、长寿区、丰都县、忠县等地。历年伏旱总强度高值区在渝西部的江津区和中部的长寿区、涪陵区等地;低值区在渝中部的万盛和渝东北部的城口县等地。历年秋旱总强度高值区在渝东北部的云阳县、奉节县、巫山县、巫溪县等地;低值区在渝西部的铜梁区、渝中部的巴南区、万盛、南川区、长寿区、涪陵区、垫江县、忠县等地。历年冬旱总强度高值区在渝东北部的云阳县、巫山县、巫溪县等地;低值区在广大的渝中部和渝西部地区。(4)区县年干旱强度在时间上呈下降趋势,多年平均干旱强度在空间上呈中间高、南北低的分布特征。时间特征:近50a(1961-2010年)重庆市区县年干旱强度呈小幅度下降趋势。空间分布特征:重庆市西部的潼南区、璧山区、中部的涪陵区、武隆区和渝东北部的巫溪县、巫山县等地年干旱强度大;渝中部的南川区、万盛、渝东南部的酉阳县、秀山县和渝东北部的城口县等地年干旱强度轻。(5)重庆市年干旱强度时间上呈下降趋势,具有明显的阶段性,存在多重时间尺度的振荡周期。近50年(1961-2010年)重庆市年干旱强度呈小幅度下降趋势,变化倾向率为-7.89/10 a。重庆市年干旱在20世纪70年代强度最大,20世纪90年代后期干旱强度最小。重庆市年干旱强度突有1个变年份,为1979年前后的年干旱强度由增强变为减弱。重庆市年干旱强度存在准2a、5a和18a三个振荡周期,重庆市1961-2010年年干旱强度经历了弱→强→弱→强→弱→强几个阶段。
[Abstract]:Drought is one of the most common and widespread natural disasters in the world. Under the background of global warming, the frequency and intensity of drought are increasing. The direct and indirect economic losses caused by drought are becoming more and more serious, which have a profound impact on social stability and economic development. With the development, population growth and urban construction accelerating, the scope and fields of drought and flood have developed from agriculture, rural areas to cities and ecology. In this context, drought risk assessment and management should be well done, disaster prevention and mitigation systems should be established for different crops in different areas, and the adverse effects of drought on crops should be mitigated to reduce the impact of drought on agriculture. The loss of agricultural production and the improvement of peasants'living standards are of great significance.Because of its unique geographical location and climate environment, various disasters occur frequently, coupled with poor agricultural infrastructure, less investment in agricultural funds, low ability of agriculture to withstand natural disasters, the disaster rate of crops in Chongqing has been high. The spatial and temporal distribution characteristics of drought in Chongqing are studied in order to study the occurrence and development of drought in Chongqing, monitor and forecast, and provide scientific basis and reference for safe production and avoiding disasters. Statistical method was used to analyze the types and grades of drought in 34 districts and counties of Chongqing from 1961 to 2010. Hurst index method, sliding T mutation test method, Morlet wavelet analysis method were used to analyze time series and Arc GIS spatial interpolation method was used to analyze seasonal drought from drought frequency, duration days, ratio of drought stations and comprehensive drought intensity. The main conclusions are as follows: (1) Seasonal drought in different districts and counties has different trends in time and has obvious Inter-decadal changes. In recent 50 years (1961-2010), the spring drought, the drought in summer and the drought in winter in Chongqing showed a small decline trend. The duration of summer drought and autumn drought showed a slight upward trend. From 1961 to 2010, the duration of seasonal drought and the ratio of drought stations in Chongqing had obvious interdecadal changes. The spring drought occurred in the 1960s was the largest, the spring drought occurred in the 1990s was the smallest; the summer drought occurred in the 1990s was the largest, and the drought occurred in the 1970s was the largest. Summer drought occurred in the smallest range; the 1970s drought occurred in the largest range, the 1980s drought occurred in the smallest range; the 1980s drought in the autumn of the 20th century the largest range, the early 21st century the smallest range; the 1960s drought in the winter of the 20th century the largest range, the early 21st century the smallest range of winter drought. (2) District and county seasonal drought. The spatial distribution of drought frequency varies greatly. Tongnan District, Dazu District, Rongchang District, Fengdu County, Zhongxian County and Yunyang County in the north-east and Wuxi County in the middle of Chongqing are the main areas where spring drought occurs, and the frequency of spring drought is relatively high. The frequency of summer drought is relatively high in Rongchang and Fengjie, Wuxi and Wushan counties in northeastern Chongqing. The frequency of summer drought is small in southeastern Chongqing and central Chongqing. Wuxi County, Wushan County, Fengjie County, Xiushan County, Youyang County and Tongnan District in the southeast of Chongqing are the main areas of autumn drought, and the frequency of autumn drought is higher. Yunyang County, Fengjie County and Wuxi County in the northeast of Chongqing are the main areas of winter drought. (3) The spatial distribution of the total seasonal drought intensity varies greatly in different districts and counties. The high value areas of the total spring drought intensity are mainly in Tongnan District, Dazu District, Rongchang District, Yunyang County in northeastern Chongqing and other places; the low value areas are mainly in Xiushan County, Youyang County, Chengkou County in northeastern Chongqing and southwestern Chongqing. The high-value areas of summer drought over the years are Tongnan District, Tongliang District, Dazu District, Rongchang District, Yongchuan District and Chengkou County and Wuxi County in the northeast of Chongqing; the low-value areas are Xiushan County, Youyang County, Qianjiang District, Pengshui County and Wansheng, Nanchuan District, Changshou District, Fengdu County and Zhongxian County in the southeast of Chongqing. The high value areas of total drought intensity in autumn are Yunyang County, Fengjie County, Wushan County and Wuxi County in the northeast of Chongqing; the low value areas are Tongliang District in the west of Chongqing, Banan District in the middle of Chongqing, and Wansheng County in the northeast of Chongqing. Sheng, Nanchuan, Changshou, Fuling, Dijiang, Zhongxian and other places. The high-value winter drought areas in Yunyang, Wushan and Wuxi counties in northeastern Chongqing; the low-value areas in the vast central and Western Chongqing. (4) The annual drought intensity of the county showed a downward trend in time, the average annual drought intensity in space was high in the middle, north and south. The annual drought intensity of Chongqing in the past 50 years (1961-2010) showed a small decline trend. Spatial distribution characteristics: Tongnan District in the west of Chongqing, Bishan District in the middle, Fuling District in the middle, Wulong District in the northeast of Chongqing, Wuxi County and Wushan County in the middle of Chongqing, Wansheng District in the middle of Chongqing and southeast of Chongqing. The annual drought intensity of Youyang County, Xiushan County and Chengkou County in the northeast of Chongqing is light. (5) The annual drought intensity of Chongqing has a downward trend in time with obvious phases and multiple time-scale oscillation cycles. The annual drought intensity in Chongqing changed from enhanced to weakened before and after 1979. There were three oscillation periods of quasi-2a, 5A and 18a in the annual drought intensity of Chongqing, and the drought intensity in 1961-2010 experienced weakening to strong. Several stages: weak, strong, weak, strong.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P426.616

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