隋唐运河改建京杭大运河,跨海河、黄河、淮河、长江、钱塘江五大水系,成为贯通我国南北的交通大动脉。自北宋以来黄河夺淮,元明两代定都北京。从此,淮河流域失去以水脉联接京师,位居天中之势的优越区位。淮河入海口被黄河所夺,尾闾不畅。 The Sui and Tang Dynasties canal reconstruction Beijing-Hangzhou Grand Canal, across the river, the Yellow River, the Huaihe River, the Yangtze River, Qiantang River five major rivers, a major artery of communication through North and South of our country. Since the Northern Song Dynasty Huai Huai, Yuan and Ming dynasties capital Beijing. Since then, the Huaihe River Basin lost its connection to the capital of the capital, superior position in the sky. Huaihe River was taken to the sea by the Yellow River, tail poor.