华北平原地貌体系与环境演化趋势

LANDFORM SYSTEM OF THE GREAT PLAIN OF NORTH CHINA AHD ITS TENDENCY OF ENVIRONMENTAL EVOLUTION

本文系统讨论华北平原地貌体系的时空分布,与形成营力的内在联系及其演化历史,宏观评价平原环境演化的趋势。

Depending on continuous accumulation and construction of sediments coming from the Yellow R., Haihe R.and Huaihe R.under the fault subsidence background since Late Tertiary, the landform system of the Great Plain of North China mainly consists of four subsystems, alluvial-pluvial fan; alluvial plain, lacustrine-marsh low land and delta, successively shown from the pediment to the shore.As the channel of the Yellow R.frequently bursts open and changes its own course, sediments brought with it spread almost over the whole plain.The pal-eo-channel highland and depression formed by diversion of the Yellow R.are arranged with the shape like fingers, towards the north-east and the south east,reaching Haihe R.and Huaihe R.respectively.The genaral framework of the Great plain of North China is composed of this structure, including the modern Yellow R.There is very obvious Change of geomorphological environment in the Great Plain of North China, such as building land quickly in the area of the river mouth, the potential hazard environment caused by crevasse and diversion in the Lower Yellow R., changes of the river systems and decline of the lakes brought about with it, and change of the sea level etc.All of them make a great effect on mankind, and, of course, human activities have also feedback, consequently, changes of the geomorphological environment of the Great Plain of North China take place in different degree