近55年以来漳卫河流域干旱演变特征分析

以漳卫河流域11个气象基准站1957-2011年降水日值资料为基础，基于标准化降水指数选取干旱发生频次、干旱影响范围、干旱强度与历时、干旱重心等指标，分析了流域降水突变前后气象干旱演变特征。结果表明：流域降水在1976年发生突变，降水突变前后，年尺度干旱发生频次和影响范围显著增加，分别由20%、23.2%增加到40%、34.1%；在季尺度上，春旱发生频次和影响范围均有较大程度减少，夏旱和秋旱的发生频次和影响范围有所增大，冬旱的发生频次和影响范围分别有小幅度的增大和减少；年尺度和季尺度干旱的平均干旱历时和强度增加显著，而月尺度干旱的干旱历时和强度略有下降；流域干旱重心在降水突变前后未发生明显的变化。

Analysis of Drought Evolution Characteristics in the Zhangwei River Basin in Recent 55 years

Based on the daily precipitation data at 11 meteorological stations in the Zhangwei River Basin during the period from 1957 to 2011, several SPI-based indices, including drought frequency, drought-affected area, drought severity and duration, and drought barycentric coordinates, have been selected to analyze the meteorological drought evolution before and after the precipitation mutation. The results showed that (1) precipitation mutation occurred in 1976, and the frequency and affected area of drought in the year scale have increased significantly from 20% and 23.2 % to 40% and 34.1% before and after precipitation mutation, respectively; (2) in the season scale, drought frequency and affected area decreased to some extent in the spring but increased greatly in both summer and autumn, and the drought frequency increased while affected area decreased in the winter; (3) the average drought duration and severity increased significantly in both the year and season scales, but decreased in the month scale; and (4) the drought barycentric coordinates showed insignificant change before and after the precipitation mutation.