衡邵盆地的干旱时空分布特征及其与土地类型的关系

Spatial and temporal distribution characteristics of drought and its relationship with land types in Hengshao basin

利用湖南省97个气象站1975—2015年常规气象资料分析了湖南省降水特征和干旱特征,在此基础上结合衡邵盆地地形,对衡邵盆地2005—2015年的干旱进行时空分布特征分析,并重点研究了该时段干旱与土地利用之间的关系。结果表明,湖南省各地年降水量时空分布不均,大部分地区的降水量主要集中在4—6月,占全年总降雨量的42%,年降水量在地域分配上差异也较大,西、南、东三面山地降水多,中部丘陵和北部洞庭湖平原降水相对较少。湖南省绝大部分地区夏秋干旱日数占全年干旱日数的60%~80%,尤以湘中衡邵盆地干旱出现的频率最高,达70%以上,且区域内各县市干旱的时空分布差别较大,衡邵盆地因受地形性下沉气流影响,过程降雨量往往少于其他地方,干旱概率较其他地区高。对于大部分区域而言,耕地、林园地、草地所占比重与综合气象干旱指数(CI)呈负相关,城乡、工矿、居民用地所占比重与CI呈正相关。

Based on the conventional meteorological data of 97 meteorological stations in Hunan province from 1975 to 2015,the precipitation and drought characteristics in Hunan province were analyzed.On this basis,combined with the topography of Hengshao basin,the spatial and temporal distribution characteristics of drought in Hengshao basin from 2005 to 2015 were analyzed,and the relationship between drought and land use in this period was mainly studied.The results showed that the annual precipitation in Hunan province was different.The spatial and temporal distribution was uneven.The precipitation in most areas was mainly concentrated in April to June,accounting for 42% of the total precipitation in the whole year.The annual precipitation varied greatly in regional distribution.The precipitation in the west,south and east mountainous areas was more than that in the middle hills and the northern Dongting lake plain.The drought days in summer and autumn account for 60%~80% of the total number of drought days in Hunan province,especially in Hengshao basin in central Hunan province,where the frequency of drought was the highest,reaching more than 70%,and the spatial and temporal distribution of drought varies greatly among counties and cities in the region.Because of the influence of topographic subsidence airflow,the process rainfall in Hengshao basin was often less than that in other areas,and the probability of drought was higher than that in other areas.For most regions,the percentage of cultivated land,forest garden land and grassland was negatively correlated with composite meteorological drought index(CI),while the percentage of urban and rural,industrial and mining,residential land is positively correlated with CI.