近30a陕西省气象干旱灾害时空分布特征

干旱灾害是陕西省主要的自然灾害之一,素有"十年九旱"之称,给人民生活和社会生产造成了不同程度的影响。因此,对干旱灾害进行科学分析及风险评估,为各级政府制定防灾减灾的措施具有重要意义。利用陕西省96个气象台站1981—2010年的降水量等气象资料,采用降水量距平百分率干旱指标,对陕西省干旱灾害的发生特征进行了详细分析。(1)陕西省的干旱灾害分布极不均匀,其总体特征是北多南少。(2)陕西省干旱灾害出现既有全省性的大范围干旱,也有区域性的局部干旱,陕北、关中发生区域性干旱频率高于陕南。(3)陕西省的干旱灾害发生季节在陕北、关中、陕南有显著差别,陕北干旱灾害季节性差异最大,关中次之,陕南最小。(4)持续性干旱灾害有的出现在同一季节,有的要跨2个季节。陕西省的干旱灾害总体上是春旱、秋旱、秋冬连旱或冬春连旱较多,陕南连续性干旱较少。

Spatial and Temporal Distribution of Meteorological Drought Disasters in Shaanxi Province over Past 30 Years

Drought disaster is one of the main natural disasters in Shaanxi Province,which is often called "9 droughts out of 10 years".It impacts the people′s lives and social production to different extents.Therefore,it is of great significance to scientifically analyze and assess drought disaster for all levels of government to develop prevention and mitigation measures.The precipitation and other meteorological data from the 96 weather stations of Shaanxi Province in the period of 1981—2010 were used for analyzing drought disaster features by the means of the percentage of precipitation anomaly drought index in detail.The following conclusions are drawn.(1) Drought disasters in Shaanxi Province distributed extremely unevenly,and basically,more in Northern Shaanxi Province and less in Southern Shaanxi Province.(2) There were both widespread drought disasters over all the province and regional drought disasters in Shaanxi Province and the frequencies of regional drought disasters in Northern Shaanxi Province and Guanzhong area were higher than that in Southern Shaanxi Province.(3) The seasonal variations of drought disasters have the significant differences in Northern Shaanxi Province,Southern Shaanxi Province and Guanzhong area.The seasonal variation of drought disasters was the greatest in the North Shaanxi Province,followed by in Guanzhong area and Southern Shaanxi Province in turn.(4) Some of persistent drought disasters occurred in the same season and some persisted for two seasons.On the whole,the occurrence of drought disasters was more in spring,autumn or in the periods from spring to autumn and from autumn to winter.The persistent drought disasters were less in Southern Shaanxi Province.