基于Palmer旱度模式的四湖流域旱涝急转特征分析

发布时间：2019-07-01 21:17

【摘要】：受全球气候变化、下垫面条件改变以及剧烈人类活动的影响,我国旱涝急转事件呈现广发、频发的态势,严重威胁着我国的水安全和粮食安全,成为我国水旱灾害的一种新趋势。本文选取荆州站1956～2013年逐日气象资料以及1960～1962年和1981～2002年(共计25年)土壤墒情资料,建立能识别旱涝急转的Palmer旱度模式,再采用游程理论从Palmer指标中分离出早涝急转事件的三个特征变量,进而应用Archimedean Copula函数构建两变量联合概率分布以及三变量联合分布,并计算相应的条件概率和组合重现期,以期为地区旱涝交替灾害防治工作提供一定的依据。本文主要得到以下几点结论:(1)基于PMDI序列的Palmer旱度模式进行旱涝急转识别,在原有Palmer干旱指数的基础上进行修正,修正后建立的Palmer旱度模式对旱涝急转现象的描述更为精确,考虑的因素更为全面,PMDI指标具有明确的物理意义,不仅考虑多种气象因素,还兼顾土壤墒情因素,同时考虑前期水分状况的影响,具有时间和空间上的可比性。(2)不同程度旱涝遭遇,轻旱转轻涝发生频率最高,占所有旱转涝事件的一半,其次是中旱转轻涝和轻旱转中涝,分别占18.00%和12.99%,重旱转重涝发生频率最低,仅为0.59%;轻涝转轻旱发生频率最高,占所有涝转旱事件的48.34%,其次是中涝转轻旱和轻涝转中旱,分别占18.58%和12.43%,重旱转重涝发生频率最低,仅为0.68%。(3)旱涝急转事件作为随机水文事件,其特征变量间具有相依关系,用GH Copula函数构造的两变量联合分布以及三变量联合分布拟合精度是满意的。基于GH Copula函数得到三个旱涝急转特征变量的二维条件概率以及多变量组合重现期,可以为地区水利工程规划和风险评估工作提供依据。
[Abstract]:Under the influence of global climate change, the change of underlying surface conditions and violent human activities, the rapid transition events of drought and flood in China show a widespread and frequent trend, which seriously threatens the water security and food security of our country, and has become a new trend of flood and drought disasters in our country. In this paper, based on the daily meteorological data of Jingzhou Station from 1956 to 2013 and the soil moisture data of 1960 ~ 1962 and 1981 / 2002 (a total of 25 years), the Palmer drought degree model which can identify the rapid rotation of drought and flood is established, and then three characteristic variables of early waterlogging and rapid transition events are separated from the Palmer index by using run distance theory, and then the joint probability distribution of two variables and the joint distribution of three variables are constructed by using Archimedean Copula function, and the corresponding conditional probability and combination recurrence period are calculated. In order to provide a certain basis for the prevention and control of alternate disasters of drought and waterlogging in the area. In this paper, the main conclusions are as follows: (1) the Palmer drought model based on PMDI sequence is used to identify the drought and waterlogging, and the Palmer drought model is modified on the basis of the original drought index. The modified Palmer drought model is more accurate and comprehensive in describing the phenomenon of drought and waterlogging, and the PMDI index has a clear physical significance, not only considering a variety of meteorological factors, but also taking into account the soil moisture factors. At the same time, considering the influence of water status in the early stage, it has the comparability of time and space. (2) the frequency of light drought to light waterlogging is the highest, accounting for half of all drought-to-waterlogging events, followed by medium drought to light waterlogging and light drought to waterlogging, accounting for 18.00% and 12.99%, respectively, and the lowest frequency of heavy drought to heavy waterlogging, which is only 0.59%; The frequency of light waterlogging to light drought is the highest, accounting for 48.34% of all waterlogging to drought events, followed by moderate waterlogging to light drought and light waterlogging to moderate drought, accounting for 18.58% and 12.43%, respectively. The frequency of heavy drought to heavy waterlogging is the lowest, which is only 0.68%. (3) as a random hydrological event, the characteristic variables of drought and waterlogging are dependent. The fitting accuracy of the joint distribution of two variables and the joint distribution of three variables constructed by GH Copula function is satisfactory. Based on GH Copula function, the two-dimensional conditional probability and multivariable combination recurrence period of three characteristic variables of drought and waterlogging are obtained, which can provide the basis for regional water conservancy project planning and risk assessment.
【学位授予单位】：武汉大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P426.616;P458.121

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