唐宋汴河的变迁及其对生态环境的影响

唐宋汴河经历了由盛转衰、废而复通、最终堙废的变迁过程。导致其变迁的因素包括自然和人为两方面，根本原因是黄河泥沙的长期侵袭和改道北流，战乱中以水代兵又加剧了它的淤废程度。汴河的变迁一方面阻遏了黄河的南泛，改变了淮北地貌，淤泥用以肥田改土，分洪排涝保障了黄河安流；另一方面又导致土地的沙化、盐碱化，破坏了正常水系，淤塞了湖泊，致使流域经济走向衰落。

Changes in the Bian River of Tang and Song Dynasties and Its Impact on Ecological Environment

The Bian River in Tang and Song Dynasties saw the changes from prosperity to decline, from discard to navigation, and finally into submergence. There are natural and human factors contributing to this consequence. The root causes are the Yellow River＇ s long-term silt recession and northward diversion, wars, etc. The changes of the Bian River prevented the Yellow River from flowing southwards, changing the landscapes of the north part of the Huai River. The silt was used to fertilize the field and water drainage secured peaceful discharge of the Yellow River. On the other hand, the changes led to land desertification, salinization, destroying the normal water system, silting up lakes, converting the basin economy into decline.