基于过程降水量的长江中下游地区单季稻洪涝灾害指标构建

摘要

基于长江中下游地区1961-2014年297个气象站的日雨量数据,耦合单季稻生育期和洪涝灾情数据,统计单季稻不同生育阶段、不同等级的洪涝灾害样本过程降水量序列,基于S-W分布拟合检验,采用t-分布区间估计法计算样本序列95％可信区间的下限值,确定指标阈值,构建各省单季稻分生育阶段洪涝灾害的等级指标,并采用预留独立水稻洪涝灾害样本进行指标验证,分析了区域1961-2010年单季稻洪涝灾害的时空分布和风险分布.结果表明:同等洪涝灾情等级时,抽穗-成熟期的洪涝灾害指标阈值最高,拔节-孕穗期次之,移栽-分蘖期最低;同一生育阶段、同等灾情等级时,5省份的洪涝灾害指标阈值从低到高依次是江苏、安徽、湖北、湖南、浙江;各省每年均有单季稻洪涝灾害发生,发生次数呈波动增减,无明显的线性趋势;随着洪涝灾害等级加大,洪涝发生的次数减少;灾害的多发区主要位于鄱阳湖和黄山地区、浙江沿海及恩施和张家界一带;移栽-分蘖期灾害风险指数普遍较高,大部分地区风险指数在0.6以上;拔节-成熟期,风险指数高值区明显缩小,主要位于浙江沿海地区,其余大部分地区处于低值区,风险指数大都低于0.3.%The single cropping rice is mainly distributed in the north of Yangtze River.Affected by climate,topography and landforms,Middle and Lower Yangtze River is one of the areas where floods occur most frequently.Therefore,it is very important to study the spatiotemporal variation law and risk distribution of single cropping rice flood in this area.In this study,daily precipitation data of 297 meteorological stations from 1961 to 2014,rice phenophase and flood disaster data in Middle and Lower Yangtze River were integrated to count process rainfall sequences at different stages of single cropping rice growth and different disaster levels.The lower limit of 95％ confidence interval for sample sequences was calculated by t-distribution interval estimation method.Flood disaster index for each province in different single cropping rice growth stage was validated by the reserved independent samples of rice flood disaster.Afterwards,spatiotemporal and risk distribution of flood disaster for single cropping rice were analyzed in the area from 1961 to 2010.The results showed that tasselling-maturity stage's index threshold was the highest in the same flood grade,followed by the jointing-booting stage's and transplanting-tillering stage's.In the same growth stage and same flood grade,index threshold of 5 provinces from low to high was Jiangsu,Anhui,Hubei,Hunan,Zhejiang.Single cropping rice flood occurred annually in each province,and without obvious tendency.With flood disaster level increasing,times of rice flood decreased.The high incidence areas of flood disaster for single cropping rice were mainly located in Poyang Lake,Zhejiang coast,Enshi and Zhangjiajie.Transplanting-tillering stage was faced with highest flood risk,with risk index ＞0.6.Except the coastal areas of Zhejiang,risk index in most areas decreased significantly with ＜ 0.3 during the period from jointing to maturity.