南盘江流域近30年季节性干旱时空分布特征

SPATIAL AND TEMPORAL VARIABILITY OF SEASONAL DROUGHTS IN THE NANPAN RIVER BASIN OVER THE PAST 30 YEAR

根据南盘江流域22个水文站、雨量站31a(1979～2009年)的逐月降水资料,选用标准化降水指数(SPI)为研究指标,以11～3月为研究时段,统计近30a来5个月时间尺度的干旱站次,分析南盘江流域季节性干旱特征;以11～3月5个月时间尺度的SPI多年平均值为指标,进行空间插值,分析南盘江流域干旱的空间分布特征。结果表明:(1)从年际上看,SPI总体上30a来(1980～2009年)呈下降趋势,气象干旱加剧;从年代际上看,1995年以后气象干旱程度有加剧趋势;(2)南盘江流域各个地区都会发生不同程度的气象干旱,旱情总体上由南向北递增,东北部各站点11～3月的降水占全年的比例相对较小,流域内东北部干旱最严重;(3)南盘江流域冬春连旱较严重,应加强水利工程建设,为防旱、抗旱做好相应的准备措施。

According to the monthly data of precipitation collected from 22 hydrographic stations of the Nanpan River basin in 31 years （1979--2009）,taken standardized precipitation index（SPI）as the indicator and the period from November to the next March as the time period, the seasonal arid characteristics of the Nanpan River basin were analyzed based on the counted number of drought in recent 30 years in the time scale of five months. Moreover, the space distribution features of drought were analyzed through spatial in- terpolation by taking the average value of SPI in the time scale of five months from November to the next March as the indicator. The results indicated that SPI generally showed a downward trend during 30 years （1980- 2009）, and the meteorological drought was aggravated in annual variation~ the drought became more serious in inter-annual variation since 1995. The meteorological drought happened across all areas to different degrees around the Nanpan River basin. In general, the degree of meteorological drought in the Nanpan River basin increased from the south to the north,and reached the worst degree in the northeast. The proportion of precipitation in the northeast was relatively small during November to the next March within one year. The continuing drought from winter to spring was relatively serious in the Nanpan River basin so that the construction of water conservancy projects should be strengthened to control drought.