基于SPI指数的白洋淀流域干旱演变特征分析

为探究白洋淀流域在气候变化背景下的干旱时空演变特征,基于1979—2018年0.1°分辨率降水格点数据,采用年尺度和季节尺度的标准化降水指数(Standardized Precipitation Index,SPI),结合Mann-Kendall趋势检验法研究了白洋淀流域干旱频次、干旱面积的时空演变特征。结果表明:(1)研究区发生轻旱的频次最高,中旱、重旱、特旱发生的频次依序减少,春季和夏季是干旱频次发生较高的季节,但特旱主要分布在秋季和冬季。(2)研究区年尺度下干旱程度呈不显著减缓趋势,干旱面积略有减少; 春季和夏季干旱程度呈不显著增加趋势,干旱面积略有增加; 秋季和冬季干旱程度呈显著减缓趋势,秋季干旱面积显著减少。(3)轻旱和中旱在整个流域内分布广泛,下游平原区的发生频率高于上游山区,大清河山区的北部和西部以及流域的东南边缘是重旱和特旱的高发地带。综上,白洋淀流域整体呈干旱缓和趋势,但春夏季干旱情况在未来可能会加重。

Spatial and Temporal Characteristics of Drought in Baiyangdian Basin Based on SPI

In order to explore the temporal and spatial evolution characteristics of drought in the Baiyangdian Basin, with a background of climate change, based on the 0.1° resolution precipitation grid data in the study area from 1979 to 2018, the Standardised Precipitation Index(SPI)at annual and seasonal scales and the Mann-Kendall trend test method were used to study the temporal and spatial evolution characteristics of drought frequency and drought area of the Baiyangdian Basin. The results showed that:(1)The frequency of light drought was the highest in the study area, and the frequency of moderate drought, severe drought, and extra drought was decreasing in order. Spring and summer were the seasons with higher drought frequency, extra drought was mainly distributed in autumn and winter.(2)The degree of drought in the study area showed an insignificant reduction trend at the annual scale, with the drought area being decreased slightly; the degree of drought in spring and summer showed an insignificant increasing trend, with the area of drought increase being minimal; additionally, the degree of drought in autumn and winter showed a significant slowing trend with the drought area being decreased significantly in autumn.(3)Light drought and moderate drought are widely distributed throughout the basin, and the occurrence frequency of the lower plain area is higher than that of the upper mountainous area. The northern and western parts of the Daqinghe mountainous area and the southeastern edge of the basin are areas with high incidence of severe drought, and extra drought. To conclude, the Baiyangdian watershed shows a trend of easing drought as a whole, but the drought in spring and summer may increase in the future.