基于生育时段的湖南省早稻洪涝等级指标及时空变化特征

Level indicators and temporal-spatial distribution features of early rice flood disaster in Hunan Province based on different growth stages

研究早稻洪涝气象指标对实时开展区域早稻洪涝灾害监测预警与评估具有现实意义。本文以湖南省早稻为研究对象,利用湖南省68个气象站点1961—2010年逐日气象资料、早稻灾情史料,以及早稻生育期资料,筛选基于水稻生育时段、洪涝等级、过程降水量的洪涝灾害样本385个,得到早稻移栽-拔节期、孕穗-抽穗期、乳熟-成熟期的轻、中、重度灾害样本集合9组。采用K-S检验法和学生氏t-分布置信区间方法界定早稻不同生育时段、不同等级洪涝灾害的过程降水量指标阈值,构建基于生育时段的湖南早稻洪涝等级指标,进行独立样本验证。依据建立的洪涝等级指标和Arc GIS技术,分析1961—2010年湖南早稻各生育时段洪涝的时空分布特征。结果表明:各生育时段轻度、中度、重度洪涝下限阈值分别为移栽-拔节期,129、154、241 mm;孕穗-抽穗期,135、170、260 mm;乳熟-成熟期,145、190、295 mm。指标验证结果与历史记录有较好的一致性;1961年以来湖南早稻总洪涝次数总体呈现增加趋势,重度洪涝主要发生在岳阳北部和郴州南部地区;移栽-拔节期洪涝主要发生在湘东及湘南地区,孕穗-抽穗期洪涝主要位于湘东与湘中地区,乳熟-成熟期洪涝主要位于湘东北和湘中以北地区;20世纪90年代是湖南近50年早稻洪涝灾害最为严重的年代,全生育期间均有高频次、高强度的洪涝发生;2000年后早稻在移栽-拔节期和孕穗-抽穗期洪涝主发区有所变化,前者增加了湘中部地区,后者增加了湘中东部至南部地区。

Meteorological indicators of early rice flood are recognized to be of realistic importance to the disaster monitoring,pre-warning and assessment of early rice flood. Taking early rice in Hunan Province as research object,385 flood rainfall amount data samples from 9 early rice flood disaster sample sets based on different rice growth stages（ transplanting-jointing,booting-blooming,milk-maturity） and flood levels（ light,moderate,severe） were built in this paper,integrating daily precipitation data（ 1961 to 2010） from 68 meteorology stations,flood disaster historical data and phenophase data in Hunan Province. K-S test and Student＇s t-distribution were employed for the goodness-of-fit test and parameters determination,and thus,rainfall thresholds for flood levels were determined based on the confidential intervals of 9 sample sets,and verified by independent samples. Afterwards,temporal-spatial characters of early rice flood disaster in Hunan Province were analyzed based on the constructed flood level indicators and Arc GIS. The thresholds of early rice flood disaster were 129,154 and 241 mm for light,moderate and severe floods in transplanting-jointing stage,135,170 and 260 mm in booting-blooming stage,and 145,190 and 295 mm in milk-maturity stage,respectively. Rice flood level indicators were detected to be basically consistent with the historical occurrence levels of rice flood disasters,according to the verification results. Total flood disaster frequency of early rice showed an increasing tendency since 1961,and furthermore,severe floods mainly located in northern Yueyang and southern Chenzhou. South and east regions of Hunan were detected with high frequencies of flood in transplanting-jointing. Flood in booting-blooming stage mainly happened in east and central regions of Hunan,while milk-maturity flood occurred mainly in the north region of Hunan. Considering the frequency and intensity of flood,early rice flood disasters were most serious in the 1990 s in Hunan. Central Hunan and east to south region of Hunan were the flood-prone area during transplanting-jointing and milk-maturity stage respectively,in recent 10 years.