基于标准化降水指数的西藏昌都市旱涝时空特征

旱涝灾害是昌都市主要自然灾害,了解昌都市旱涝时空分布特征,对减轻该区域旱涝灾害损失、合理利用水资源和生态屏障建设有重要意义。利用1981—2015年昌都市7个气象站的逐月降水数据,采用标准化降水指数(SPI),分析昌都市旱涝变化特征。结果表明:昌都市旱涝变化具有明显的阶段性特征,1981—1995年旱涝交替发生,1996—2004年雨涝频繁,2005年以后以干旱为主;春夏两季降水呈弱增加趋势,春夏旱减少,秋季降水呈弱减少趋势,秋旱增加,冬季则无明显的变化;北部、中部和南部在2002年以前,旱涝存在一致性,2002年后存在较大的差异;20世纪80年代中期旱涝变率最大,旱涝转换频繁,21世纪初早期变率最小,3个区域的旱涝变率总体上与全市相似,2011年以后,南部区域变率较高,旱涝交替频繁。

Spatial and Temporal Characteristics of Drought-flood in Chamdo Based on Standard Precipitation Index (SPI)

Drought-flood is one of the major natural hazards in Chamdo. The paper aims to study the spatial and temporal characteristics of drought-flood changes in Chamdo, and offer scientific basis for reducing the loss caused by regional drought- flood disaster, rational utilization of water resources and ecology barrier construction. Based on the monthly precipitation data of 7 meteorological stations in Chamdo during 1981- 2015 and the standard precipitation index (SPI ), the spatial and temporal characteristics of drought-flood in Chamdo were analyzed. The results indicated that: the characteristics of drought-flood showed an obvious stage characteristic, drought-flood manifested alternately during 1981-1995, the flood was more severe from 1996 to 2004, and drought was more frequent from 2005 to 2015; the precipitation in spring and summer showed a weak increasing trend, and the precipitation in autumn had a weak decreasing trend; the occurrence of drought in spring and summer tended to decrease weakly, while in autumn tended to be more severe, there was no obvious change in winter; there was a relative consistence in variation of drought-flood in the northern part, the central part and the southern part during 1981-2001, but there was a big difference since 2002; the most drastic drought-flood variability occurred in the middle 1980s, and in the early 21st century, the variability was the minimum; the variability in three parts was consistent with that of Chamdo in the mass; the change rate was high in the southern part since 2011, and the characteristics of drought-flood showed a frequent alternation.