基于SPEI的湖北省近52年干旱时空格局变化

根据湖北省及周边地区40个气象台站1960~2012年实测气象资料,基于多时间尺度的标准化降水蒸散指数(SPEI),选取干旱频率、干旱站次比和干旱强度等评估指标,研究结果表明:湖北省干旱影响范围总体较大,全域性干旱年份达54%;但干旱强度偏轻,平均干旱强度为0.65,近52a来仅有两次重旱年,干旱强度在中旱及以下的年份占85%,且年际差异较大;省内干旱强度和站次比变化趋势基本一致,近52a来,总体均呈不明显上升趋势,趋势率分别为0.041/10a和3.692/10a,20世纪80年代前后呈先下降后上升趋势;湖北省总体干旱发生频率较小,52a平均干旱频率在16.5%~18.2%之间,空间分布特征呈现东高西低的特征;干旱发生频率呈先下降后上升的趋势,20世纪70、80年代最低;2000年以后干旱强度、站次比和频率均达到最高,并且有持续上升趋势。

TEMPORAL AND SPATIAL DISTRIBUTION OF DROUGHT IN HUBEI PROVINCE DURING 1961-2012 BASED ON SPEI

Drought occurs when precipitation is significantly lower than normal and it has been one of the most severe disasters all over the world. It can cause huge agricultural and economic loss when lasting for a long time. Hubei Province is located in the middle reaches of Yangtze River basin, which belongs to the temperate continental monsoon climate zone. It plays an important role in agricultural production of China. Recently, more frequent drought has occurred in Hubei Province and caused heavy losses. The basic characteristics of drought and its spatiotemporal patterns in this region need to be understood comprehensively. Quantitative analysis is useful to implement the suitable measures for drought mitigation. Based on standardized precipitation evapotranspiration index (SPEI) at different time scales, the meteorological data of 40 observation stations were used to analyze the characteristics of drought in this region. The objective of this study is to analyze drought in Hubei Province and describe its patterns from various aspects objectively and quantitatively, and to provide basis for moving forward and taking counter measures. The SPEI has been widely used for drought analysis and monitoring because of its robustness in multiple time scales. The role of evapotranspiration is also been included in the calculation of SPEI, which can represent water balance well from point of input and output. The evaluation indicators include drought frequency, drought stations proportion and drought intensity. The results showed that drought was widespread in Hubei Province, since 54% of years during 1961-2012 were identified as large-scale drought. However, the drought was not severe. The average intensity was 0.65. Severe drought only occurred in 2 years over the recent 52 years, while slight and moderate drought years accounted for 85%. Both of drought intensity and drought stations proportion has increased during the last 52 years (the tendency is 0.041/10 a and 3.692/10 a respectively.) Specifically, they decreased before the 1980s and then increased significantly after the 1980s. And it's obvious that 1980s was a period of transition which had lowest drought intensity and drought frequency. The similar results have been found from the viewpoints of the average drought intensity, the drought frequency and the drought area. This is consistent with previous studies in South China. Spatially, the drought frequency was higher in the east and lower in the west, ranging from 16.5% to 18.2%. From interdecadal views, the drought frequencies in the 1970s and the 1980s were the lowest (high-incidence area of drought was small in the 1970s and the 1980s), and increased after the 1980s. After the 2000s, the drought intensity, drought frequency and drought area all increased obviously and tended to continue increasing. And the spatial difference of drought frequency was also increasing. The results are in line with previous studies and records, which also indicated that SPEI was suitable for drought analysis in Hubei Province.