四川省干旱损失风险分析

Risk Analysis of Drought Loss in Sichuan Province

利用四川省1961—2019年的气象观测资料及1991—2019年各县旱情资料,采用信息扩散方法分析了10a、50a一遇干旱的持续天数、经济损失率、人口受旱率和农作物受旱率的空间分布,并采用基于广义帕累托分布(GDP)的极值(POT)模型分析了四川7个干旱气候区,在不同置信水平下可能造成的最大经济损失率(PML)。结果表明:(1)10a重现期干旱持续天数,盆东北、盆中以及盆地西部山区相对较少在60~80d,攀西地区西部、盆地南部、龙泉山脉相对较多在100d以上;50a重现期干旱持续天数,盆地嘉陵江、涪江流域、都江堰灌区、甘孜州中部以及川西高原西北部相对较少在90~120d,攀西地区、甘孜州西南部和中部、盆地南部等局部地区在150d以上。(2)10a和50a重现期农作物受旱率,川西高原北部、盆东北和盆中均偏高,分别大于60%和90%;攀西地区和成都平原等地区相对偏低,均小于60%。(3)10a和50a重现期人口受旱率川西高原和盆地东北部、中部和南部分别在60%和80%以上。(4)10a和50a重现期干旱经济损失率,攀西地区、盆地西部(成德绵、雅乐眉)和南部(宜宾、自贡)均偏小,分别在3%和5%以下;盆东北、盆中和川西高原均相对而言偏高,其中盆东北局地、甘孜州西北部分别大于10%和20%。(5)在不同置信水平下,Ⅳ区(盆地东北部)和Ⅴ区(甘孜州北部和阿坝州中西部)的PML相差较大且明显高于其它5区,最大分别为28.5%和38.6%;Ⅶ区(甘孜州南部和攀西地区北部)的PML在不同置信水平下相差最小且均小于其它区域,最小为3.1%;Ⅰ区(成都平原区)的PML在不同置信水平下均处于偏小位置且整体相差不大。

Based on the meteorological data of Sichuan Province from 1961 to 2019 and the drought data of the counties from 1991 to 2019,this paper adopts the information diffusion method to analyze the spatial distribution of drought duration,economic loss rate,crop drought rate and the rate of population exposed to drought for the 10-year and 50-year return periods.The extreme model based on the generalized Pareto distribution is used to analyze the Possible Maximum economic Loss rate(PML)under different confidence levels in seven arid climate zones of Sichuan Province.The results show that:(1)For the 10-year return period,the drought durations are relatively short,about 60 to 80 days in the northeastern,central and western parts of the Sichuan basin,but longer,about 100 days in the Panxi region,southern Sichuan basin and Longquan mountains.For the 50-year return period,the drought durations are relatively short,about90 to 120 days in the Jialing River basin,Fujiang River basin,Dujiangyan irrigation area,central Ganzi prefecture and northwestern Sichuan Plateau,but longer,about 150 days in the Panxi region,southwestern and central Ganzi prefecture and southern Sichuan basin.(2)For 10-year and 50-year return periods,the drought rates of crops are higher than 60%and 90%respectively,in the northern part of the western Sichuan Plateau,the northeastern and central parts of the Sichuan basin.In the Panxi region and Chengdu Plain,the drought rates of crops are less than 60%.(3)For the 10-year and 50-year return periods,the rates of population exposed to drought in the western Sichuan Plateau and the northeastern,central and southern parts of the Sichuan basin are over 60%and 80%,respectively.(4)For the 10-year and 50-year return periods,in the Panxi region,the western and southern Sichuan basin,the economic loss rates are less than 3%and 5%,respectively.In the western Sichuan Plateau and the northeastern and central part of the Sichuan basin,the economic loss rates are higher.Especially for some areas in the northeast Sichuan basin and northwestern Ganzi prefecture,the loss rates are larger than 10%and 20%,respectively.(5)At different confidence levels,the PMLs of ZoneⅣ(the northeastern Sichuan basin)and ZoneⅤ(the northern Ganzi prefecture,the central and western Aba prefecture)are quite different and obviously higher than those of other five zones,with the maximum values of 28.5%and 38.6%,respectively;The PMLs of ZoneⅦ(the southern Ganzi prefecture and the northern Panxi prefecture)have the minimum difference under different confidence levels,and the minimum difference is 3.1%.The PMLs of ZoneⅠ(Chengdu Plain)are small under different confidence levels and the overall difference is not significant.