川中丘陵地区近46年来气候变化及旱涝动态特征

旱涝是川中丘陵区一种主要的自然灾害.根据四川省盐亭县近46年来(1960—2005)的气候资料,在分析该区气候变化特征的基础上,运用Z指数法对该区近46年来年际、季节和月份旱涝的动态特征进行了计算和分析.结果表明,近46年来该区气候变化存在较为明显的降温、趋干和太阳辐射相对稳定的特征.近46年来该区年际旱涝具有交替变动的特征,且干旱等级明显高于洪涝等级.春、冬两季旱涝频率前期下降,后期增加,春季洪涝等级下降,干旱等级上升,冬季旱涝等级少变;夏季旱涝频率下降,但等级上升;秋季旱涝频率和等级明显减缓.该区偏旱月份主要集中在1、3和12月等月份,偏涝月份主要集中在1、4、5和9月等月份;而6、7、8、10和11月等月份则旱涝均比较多,各月旱涝的动态变化复杂.

Dynamic Characteristics of Drought and Waterlogging and Climate Change in Hilly Area of Central Sichuan During Last 46 Years

Drought and waterlogging are one of main natural disasters in hilly area of central Sichuan.Taking Yanting County,Sichuan Province as a case,climatic change characteristics in the area are analyzed in the light of climate data over the last 46 years(1960—2005).And then the dynamic characteristics of perennial,seasonal and inter-monthly drought and waterlogging in the county are calculated and analyzed by Z index method.The result shows that the climate in the area has been becoming cold,dry and stable solar radiation since 1960s.There is an perennial interchange of drought and waterlogging over the last 46 years,and drought is obviously more serious than waterlogging.As for the seasonal change of drought and waterlogging over the last 46 years in the county,the frequency of drought and waterlogging in spring and winter decreases during the early period,and ascends in the later period.In spring,the grade of waterlogging decreases and the grade of drought ascends,while in winter the grades are relatively stable.The frequency of drought and waterlogging in summer decreases,but its grade ascends;both the frequency and grade of drought and waterlogging in autumn has obviously decreased.In the county,January,May and December are main drought months,January,April,March and September are main waterlogging months,and both drought and waterlogging occur in June,July,August,September,October and November.There are complex inter-monthly changes of drought and waterlogging over the last 46 years in this area.