近50年来广东不同强度降水的变化特征及其对农业的影响

Characteristics of different intensity precipitation and its impact on agriculture in Guangdong Province in recent 50 years

广东降水时空分布不均,暴雨大暴雨集中,导致降水利用率不高,造成降水与农业需水的时间供需错位,且近年来广东旱涝灾害有加剧趋势。根据广东省气象局提供的降水观测资料,结合广东降水概率累积曲线,利用百分位法将广东省降水分为6个强度等级,对广东不同地区各个强度的降水日数和降水强度的相对变化趋势及降水日数和强度对降水总趋势的贡献进行分析。研究结果表明:(1)近50年来,广东弱降水和较弱降水的降水日数减少,而强降水和极强降水的降水日数有增加趋势,且I区变化幅度要比II区大,降水日数在秋季的减少趋势最明显,可能导致秋旱的程度加剧。(2)对于广东整个地区而言,各强度等级降水强度变化幅度较小。(3)广东降水量增加主要由降水日数的增加引起,尤其是I区夏季降水日数增加,降水强度对该区降水量总趋势的贡献变化不大,降水日数增加对降水量要略大于降水强度变化对降水量总趋势的贡献。I区夏季强降水降水日数增加可能加大广东农业洪涝灾害的发生;秋季降水日数的减少则会使得秋冬甚至秋、冬、春三季连旱的程度加剧。

Spatial and temporal distribution of precipitation in Guangdong is uneven and the precipitation is concentrated on heavy rain,which led to the precipitation is not efficient and resulting in precipitation and agricultural water supply dislocation of time.the floods have droughts and floods become more severe in Guangdong in recent years.Based on the Guangdong meteological Bureau of precipitation observations,combined with cumulative probability of precipitation,and usied percentile method,precipitation intensity was divided into six levels.This article analyze the relative trend of rain days and rain intensity and the contribution of rain days and intensity to the general trend of precipitation,and draw the following conclusions,first,in the past 50 years,weak and weaker precipitation days reduced,heave precipitation and heaveier and heavest rainfall days increased.The change in the I district is bigger than II district in Guangdong Province.Second,Change of the rainfall intensity was not obvious.Third,for the Guangdong as a whole,the increase of precipitation is mainly caused by the number of rain days,especially the increasing number in summer.Contribution of intensity change to the increasing precipitation was not big.The contribution of rain days to the precipitation general trend is more than rain intensity.I district,the number of summer heavy rain days increasing may lead to occurrence of landslide and debris flow in the mountain areas and waterlogging on Pearl River Delta.The reduced number of rain days in autumn will make the autumn,winter and spring drought.