1960-2008年间洞庭湖流域降水变化时空特征分析

依据洞庭湖流域27个气象观测站1960—2008年逐月的降水量资料,综合运用气象统计方法和GIS空间分析技术,对洞庭湖流域近年来降水变化的时空特征进行了分析。结果表明:(1)在1960—2008年间,流域年降水量呈现出不显著的增加趋势,四季中春、秋两季表现为减少趋势,而夏、冬两季则表现为增加趋势,其中夏季的增加最为明显;但在1999—2008年的近10年间,流域年降水量表现为显著的减少趋势,四季中除冬季仍表现为增加的趋势外,其余三季均表现为减少的趋势。(2)在近10年间,流域内除个别站点年降水量仍表现为增加的趋势外,其余多数站点均表现出不同程度的减少。在时间分配上,夏、冬两季降水较流域多年平均值分别偏多2.85%和3.07%,而春、秋两季则偏少1.35%和11.43%。其中,秋季9、10月份偏少明显,而变差系数同期则明显增大,带来入湖水量大幅减少和区域干旱发生增加等不良影响。

Spatial-temporal characteristics of precipitation in the Lake Dongting Basin from 1960 to 2008

Based on the monthly data of 27 meteorological stations from 1960 to 2008 and with the synthetic usage of climatic statistics methods and GIS spatial analysis techniques,the spatial-temporal characteristics of precipitation changes in the Lake Dongting basin are analyzed.The results show that：（1） during the period of 1960-2008,the basin＇s annual precipitation takes on a slight increasing trend,while its seasonal precipitation during the same period presents a decline trend in the spring and autumn and an increasing trend in the summer and winter,especially with the most sigrificant increasing trend in the summer. But in the recent 10 years of 1999-2008,the basin＇s annual precipitation oppositely has a remarkable decreasing tendency.The seasonal orecipitations have an increasing trend in winter and a decreasing tendency in the other three seasons.（2） in the last 10 years of 1999-2008,over the Lake Dongting basin, except one meteorological station whose annual precipitation still has an increasing tendency,at other sites,the annual precipitations decreases to a certain degree.Meantime,the distribution of precipitation in each month has become more imbalanced.In summer and winter,the precipitations have been respectively 2.85%and 3.07%more than the average over previous years,whereas in spring and autumn,they have been 1.35%and 11.43%less than the normal.Among them,the decline in September and October are more significant,but at the same time,the variation coefficients of precipitation also have an obvious increasing. As a consequence,these changes will lead to some adverse effects,such as a substantial reduction of the amount of water that flows in the probability tha regional drought occurs.