基于标准化降水指数的淮河流域近50年干旱时空分布特征

Spatial-Temporal Patterns of Droughts Based on Standard Precipitation Index (SPI) during Past Fifty Years in Huai River Basin

根据淮河流域30个国家基本气象站近50年的月降水量资料,采用标准化降水指数(SPI)作为干旱指标,从干旱频率、干旱站次比、干旱强度三个角度并结合气象要素倾向率对淮河流域的干旱时空分布特征进行分析。结果表明:年度与夏季干旱站次比和强度均呈轻微减少趋势,春季、秋季和冬季干旱站次比呈增加趋势,干旱强度呈轻微增加趋势;年度和各季节发生的主要是全局性和局域性干旱,干旱强度都以轻度干旱为主;流域西部的河南境内的年度、季节性的各类干旱频率相对较高。夏季的干旱(轻旱及以上)、中旱、重旱的相对较高频率的分布范围最广,各季节各类型干旱发生频率地区分布规律不太明显。

The spatial and temporal distribution characteristics of the frequency, coverage and intensity of drought combined with the meteorological element tendency rate in Huai River basin were analyzed based on the standardized precipitation index (SPI) as a drought index with the past 50-year datasets of monthly precipitation of 30 national principal meteorological stations. The drought coverage is defined as the ratio of stations with drought occurring to overall stations. Results showed that both the trends of the annual and summer drought coverage and intensity decreased slightly, while the trend of drought coverage in spring, fall and winter was increased and the drought intensity trend increased slightly. The main drought types of the annual and all the seasonal scales were whole and local basin, while the drought intensity exhibited a mild level. The west of Huai River basin in Henan province was a region where the various drought frequencies of the annual and all seasonal are relatively high. The high frequency of moderate, heavy, severe drought and the drought worse than slight in summer covered the vastest. The rule of regional distribution of various droughts in four seasons was not obvious.