黄淮海平原及其附近地区干旱时空动态格局分析——基于标准化降雨指数

Spatial and Temporal Analysis of Drought over the Huang-Huai-Hai Plain and Its Surroundings Based on the Standardized Precipitation Index

本文根据中国气候区划图将黄淮海及其附近地区划分为4个气候子区域,利用该区域气象站点1961年-2008年的降水数据计算出子区内各站点的不同时间尺度的标准化降雨指数(Standardized Precipitation Index,简称SPI);通过各子区站点的SPI差异分析了研究区内发生干旱的时空差异及其动态格局。结果表明:在3个月尺度上,A区、B区发生严重、极端干旱的频率较高,然而整个研究区发生总体干旱的频率没有明显区别;在6个月尺度上,A区、B区发生干旱的频率较高,C区、D区发生极端干旱的频率较低,其中安徽北部和河南东部地区发生严重等级干旱的频率较高;在12个月尺度上,A区、B区发生总体干旱的频率较高,C区、D区发生严重干旱和极端干旱的频率较高;就季节性干旱而言,在3个月尺度上,4个子区域发生各等级干旱的频率也存在较大差别。此外,从12个月尺度SPI值时间序列变化趋势来看,1962年-2008年全区干旱有轻微加重的趋势,且整个研究区及其各子区域干旱变化趋势处于波动中,全区20世纪60年代和90年代有明显加重趋势,70、80年代以及2000年以来有减缓的趋势。

Drought, one of the most severe hazards resulting in significant economic loses in agriculture and industry, is a natural phenomenon caused by the imbalance between import and demand for moisture. In the context of global climate change, the drought intensity, frequency, and its spatial patterns have been changing. An accurate understanding of these changing processes would be greatly useful in identifying regional climate change, regional drought forecasting, managing droughts, and ultimately restraining the risks incurred by droughts in practice. First, the authors conceptually divided the Huang-Huai-Hai plain and its surroundings into four sub-regions （A, B, C, and D）. Second, the Standardized Precipitation Index （SPI） of different timescales in each sub-region was calculated at point scales. Third, after classifying drought severity into four classes, we performed temporal and spatial analysis of drought over this region based on drought frequencies of varying severity. Results indicate that there were marked spatial and temporal variations in drought over this study area. 1） On a 3-month timescale, sub-regions A and B suffered from more ＂severe＂ and ＂extreme＂ droughts, whereas there was no significant difference for all classes of drought between sub-regions; 2） On a 6-month timescale, sub-region A and B suffered from more ＂normal＂ drought, while sub-regions C and D suffered from relatively less ＂extreme＂ drought except the north of Anhui Province and the east of Henan Province; 3） On a 12-month timescale, sub-regions A and B also suffered from more ＂normal＂ drought, while sub-regions C and D suffered from more ＂severe＂ and ＂extreme＂ droughts; 4） As for seasonal drought, on a 3-month timescale, all sub-regions showed spatial variations in drought frequency. In particular, sub-region D suffered from more ＂extreme＂ drought in the growing season of crops （typically in summer and autumn over this region） compared to less ＂total＂ drought. On a 12-month timescale, sub-regions C and D suffered from more droughts which would have impacted reservoirs, lakes, and groundwater level; 5） From the temporal analysis of SPI12, it was found that aggravating or alleviating trends of drought severity for all sub-regions were essentially fluctuant. There was a slightly aggravating trend during the period 1960s-2000s, suggesting a linear trend of -0.784%. However, there was a significant aggravating trend in the 1960s with a linear trend of -3.837%/9a, alleviating for the period 1970s-1980s with a linear trend of 2.771%/10a and 4.380%/10a, aggravating again during the 1990s with a linear trend of -4.727%/10a, and alleviating again from 2000 with a linear trend of 4.589%/9a.