1960-2015年西南水稻干旱的空间分布和时间演变特征

Spatial Distribution and Temporal Variation Characteristics of Rice Drought in Southwest China in 19602015

分析西南地区水稻的干旱演变特征和空间分布规律对稳定西南地区粮食生产有重要意义。穂始分化期和开花期是水稻的需水关键期,该时期对水分最敏感,发生干旱对产量的影响最大。为分析水稻生育关键期及其他生育阶段的干旱特征,把水稻生育期划分为出苗穂始分化、穂始分化开花和开花成熟3个阶段,并采用相对湿润度指数,分析了西南地区水稻各生育阶段干旱的空间分布规律和年代际演变特征。分析结果表明:西南地区水稻出苗穂始分化阶段,干旱主要分布在云南大部、川南边缘和川北边缘地区,干旱高发区在云南中北部及蒙自等地,相对湿润度指数为-0.76~-0.25,频率为3年2遇以上。该阶段从20002009年到20102015年,干旱强度呈增强、干旱频率呈增加趋势,20102015年干旱强度达到近56年的最强。水稻需水关键期和开花成熟阶段的干旱主要发生在重庆、贵州大部、四川东北部及金沙江和元江河谷地区。其中,水稻需水关键期干旱强度、频率较开花成熟阶段的弱,高发区为重庆中南部及贵州东北部,频率为10年3遇至2年1遇。总体来看,20102015年干旱强度呈显著增强、干旱频率呈显著增加趋势,达到近56年来的最强强度和最高频率。在气候变化影响下,该生育阶段面临的干旱风险显著升高。水稻开花成熟阶段的干旱强度、频率介于前2个生育阶段的之间,20002009年到20102015年,重庆大部、四川东北部地区的干旱强度略有增强、频率略有增高,而贵州地区的干旱强度减弱、频率降低。

Analyzing the drought evolution characteristics and spatial distribution of rice in Southwest China is of great significance for stabilizing grain production in Southwest China.The initial differentiation period and the flowering period of rice growth are in a critical demand for water.This period is the most sensitive to water,so occurrence of drought has significant impact the rice yield negatively.In order to explore the drought characteristics of the critical period of rice growth and other growth stages,the growing stage of rice is divided into three stages,i.e.,emergence-initial differentiation,initial differentiation-flowering,and flowering-maturity.Besides,the spatial distribution and interdecadal evolution characteristics of drought in different growth stages of rice in Southwest China are analyzed by using relative humidity index.The analysis results show that,in the emergence-initial differentiation stage,drought is mainly concentrated in most of Yunnan,the southern and northern edges of Sichuan,and the intensity and frequency of drought are higher than in the other two stages.The drought-prone areas are in the central and northern parts of Yunnan and Mengzi,with the occurrence frequency being more than twice in 3 years and the relative humidity index ranging from-0.76 to-0.25.In this stage,drought intensity and frequency from 20002009 to 20102015 showed an increasing trend,and especially in 20102015,drought intensity reached the peak level in recent 56 years.During the critical period of rice water demand and the flowering-maturity stage,drought mainly occurs in Chongqing,most parts of Guizhou,northeastern Sichuan and the Jinshajiang River and Yuanjiang River valleys.Among them,the drought intensity and frequency during the critical period of rice water demand is weaker than those during the flowering-maturity phase,and the high-incidence areas of drought are in south-central Chongqing and northeastern Guizhou,with a frequency ranging from 3 in 10 years to 1 in 2 years.On the whole,from 2010 to 2015,the drought intensity and frequency increased significantly,both reaching the highest levels in the past 56 years.Under the influence of climate change,drought risk at this stage of rice growth is significantly increased.The intensity and frequency of drought in the flowering-maturity stage of rice are between those of the first two growth stages.From 20002009 to 20102015,the drought intensity and frequency of rice in most of Chongqing and northeastern Sichuan increased slightly,but showed a decreasing trend in Guizhou.