一前言大小河流在世界各国人民的生产及社会经济生活中占有极重要的地位。从远古时代起,河流就成为历史上的人类定居和垦殖土地的生活条件。弥海的大河在人类社会历史的发展中起着很显要的作用。因为海口是海运与内河航运的衔接点,对发展航运、渔业都有很大的意义。对这种 I. Introduction Rivers and rivers occupy a very important place in the production, social and economic life of people of all countries in the world. Since ancient times, rivers have become the living conditions of human settlements and reclamation land in history. The vast sea of ​​Mihai plays an important role in the development of the history of human society. Because Haikou is the connecting point of shipping and inland shipping, it is of great significance to the development of shipping and fisheries. Right for this