淮河流域冬小麦干旱时空分布特征

Spatial and temporal distribution characteristics of drought of winter wheat in Huai River Basin

基于1961-2016年140个气象站点的日尺度降水数据和月尺度地表温度(LST)、归一化植被指数(NDVI),利用标准化降水指数(SPI)和温度植被干旱指数(TVDI)分别表征淮河流域气象干旱和农业干旱,分析淮河流域冬小麦气象干旱和农业干旱时空变化特征。结果显示:(1)气象干旱时空变化特征:冬前生长期和灌浆成熟期降水量呈上升趋势,越冬期和返青抽穗期呈下降趋势;轻度干旱以上占比表现为:冬前生长期>返青抽穗期>灌浆成熟期>越冬期。(2)农业干旱时空变化特征:时间上,轻度干旱以上占比在越冬期和返青抽穗期呈上升趋势;空间上,冬前生长期轻度干旱以上占比明显高于返青抽穗期和灌浆成熟期,因此有利于冬小麦的生长发育。(3)农业干旱与气象干旱异同性:时滞性,冬前生长期、越冬期和返青抽穗期,TVDI表征的农业干旱较SPI表征的气象干旱时滞小于1个月;灌浆成熟期,TVDI表征的农业干旱较SPI表征的气象干旱时滞1至2个月;空间上,在冬前生长期二者轻度干旱占比差异主要位于东部沿海地区,在返青抽穗期和灌浆成熟期二者轻度干旱占比差异主要位于高海拔地区。而且,从TVDI表征的农业干旱与SPI表征的气象干旱的轻度干旱占比空间分布来看,农业干旱比气象干旱强度大。

Based on the daily precipitation data,the monthly surface temperature(LST)and normalized difference vegetation index(NDVI)of 140 meteorological stations from 1961 to 2016,the standardized precipitation index(SPI)and the temperature vegetation drought index(TVDI)were used to characterize the meteorological drought and agricultural drought in Huai River Basin to analyze the temporal and spatial variation characteristics of meteorological drought and agricultural drought of winter wheat.The results showed that,firstly,on the aspect of temporal and spatial variation characteristics of meteorological drought,the precipitation increased in the growth period and filling maturity period before winter,decreased in overwintering period and turning green-heading stage.The proportion of drought above mild showed the following order:pre-winter growth period>returning green-heading stage>filling maturity stage>overwintering stage.Secondly,on the aspect of temporal and spatial variation characteristics of agricultural drought,drought above mild showed an upward trend in overwintering period and returning green-heading stage on the time scale,the proportion of drought above light in the growth period pre-winter was significantly higher than that in returning green-heading stage and filling maturity stage on the space scale,so it was beneficial to the growth and development of winter wheat.Thirdly,on the aspect of the similarities and differences between agricultural drought and meteorological drought,the agricultural drought represented by TVDI was one month less than the meteorological drought represented by SPI during the pre-winter growth period,overwintering period and returning green-heading period in the comparison of time lag.At the stage of filling maturity,the agricultural drought represented by TVDI lagged about one to two months compared with the meteorological drought represented by SPI.On the spatial scale,the proportion difference of mild drought represented by TVDI and SPI mainly located in the eastern coastal area during the pre-winter growth period,and the proportion difference of the mild drought represented by TVDI and SPI in the periods of returning green-heading and filling maturity mainly located in the high altitude area.Moreover,from the aspect of the spatial distribution of agricultural drought characterized by TVDI and meteorological drought characterized by SPI,the intensity of agricultural drought was higher than that of meteorological drought.