近年来黄河下游断流的干旱背景分析

近年来黄河下游连年断流 ,引起社会的极大关注。文中根据全国 1 60个基本气象测站近47a的月降水量资料 ,应用旋转主分量分析等统计分析方法 ,分析了黄河流域平均降水量的年际变化 ,比较了全国各区域降水量异常及其累积程度 ,还与历史上著名的大旱灾荒和黄河下游断流事件作了对比分析。结果表明 ,近 2 0 a来 ,黄河流域尤其黄河下游山东省及其附近地区 ,遭遇到数百年一遇的气候上连续干旱阶段 ,近 1 0 a来累计少降的雨水总量 ,相当于黄河 4 a的径流量。黄河下游近 2 0 a里集中发生了 1 5 a明显的干旱年份 ,其中 5 a大旱 ,1 0 a干旱。其干旱的累积程度不仅是全国最严重的地区 ,而且超过了历史上著名的“崇贞大旱”(1 640年 )和 1 372年的大旱及黄河下游断流事件

CLIMATIC BACKGROUND ANALYSIS OF FLOW-BREAK EPISODE OF LOWER REACHES OF YELLOW RIVER IN RECENT YEARS

The successive dry episodes in the lower reaches of Yellow River in recent yearsari causing great concern of our society. On the basis of monthly precipitation data of nearly 47 years gained from 160 basic observatories of China and by means of rotating principal component annual variations of average precipitation along Yellow River are studied, and the anomalies of rainfall and their accumulation extent are compared with other regions of the country,and contrasting analysis is conducted with historic heavy droughts and dry episodes in the lower reaches.The results show that the past 20 years is a severe successive drought period encountered per hundred years, and the total amount of decreased rainfall in recent 10 years is equal to the runoff of 4 years of the river, 15 years out of the recent 20 years are dry, in which 5 years are severe and 10 years are moderate. The accumulating effect of these droughts is not only the heaviest in the coutry in recent one hundred years but also heavier than the historic "Chongzhen Catatrophe (1640)" and the drought and flow-break episode in 1372.