云南省干旱时空分布规律

Study on Spatial and Temporal Distribution of Drought in Yunnan Province

干旱是云南省主要自然灾害,开展干旱时空分布规律研究很有必要。基于196个水文气象台站降水量资料,以降水量距平百分率(Pa)为指标划分干旱等级,统计各级别干旱发生频次,并利用ArcGIS生成不同级别干旱频次栅格图。结果表明,云南省轻度、中度、严重、特大干旱的平均频次分别为15.8%、5.8%、1.7%、2.3%;春、秋两季轻度干旱发生频次较高,高频次区域面积分别占全省的77.4%、51.1%;冬季发生中度及以上干旱的频次明显偏高,其中中度、严重、特大干旱的平均频次分别为11.2%、4.8%、7.9%,且中高频次的严重干旱、特大干旱基本发生在冬季。可见云南省干旱时空分布差异明显,春、秋两季易发生轻度干旱,冬季各级别干旱均易发生,夏季不易发生干旱;轻度干旱高频次区分布于全省各地;中度和严重干旱高频次区域主要位于滇中、滇西南、滇东南和滇中偏西北地区,特大干旱高频次区域分别位于滇中北部和滇西南地区。

The drought is the main natural disasters in Yunnan Province. So, it is necessary to study on the spatial and temporal distribution of drought. Statistical data of drought frequency at each level, grid chart of drought frequency at each level with application of ArcGIS, were generated on the basis of monthly rainfall data from 196 hydrologic meteor- ological stations and using percentage of rainfall anomaly as drought grade. The results show that the average frequency of drought at each level in Yunnan Province is light drought 15.8%, moderate drought 5.8% , severe droughts 1.7% and serious drought 2.3%; light drought frequency is high in spring and autumn, the proportion of the area of high-frequency region is 77.4% and 51.1% ; the frequency which is 11.20% ,4.8% and 7.9% is high obviously for moderate or above drought level in winter, as well as the higher-frequency severe and serious drought generally happened in winter. The study show that the drought distribution exists space-time difference in Yunnan Province. Light drought often occurs in spring and autumn, drought in different levels may occur throughout winter, drought frequency is low in summer; high-frequency region of light drought is distributed all over the province; high-frequency region of moderate and severe drought is mainly distributed central, southwest and southeast in Yunnan Province; high-frequency region of serious drought is mainly distributed in the northern part of central and southwest in Yunnan Province.