梅家州形成、演化及其对鄱阳湖的影响

根据鄱阳湖口梅家洲东南缘钻孔（ZK2）沉积物环境指标特征，结合历史资料对梅家洲的形成与发展及其在历史时期对鄱阳湖的影响进行了探讨。随着古长江不断南迁，在长江与古赣江的共同作用下，2.3ka BP前后，在长江南岸湖口地区形成天然堤，即梅家洲。它的出现对古赣江来水产生阻水，导致了鄱阳湖形成并向南扩张。对比1970年和1980年湖口地区水下地形图，发现梅家洲仍在不断加积，其对鄱阳湖的阻水作用更加明显，将引起鄱阳湖湖区沉积环境的改变，给鄱阳湖带来生态环境等多方面的影响。

FORMATION AND DEVELOPMENT OF MEIJIAZHOU AND ITS SIGNIFICANCE IN POYANGHU LAKE

Based on features of environmental indexes of sediments from ZK2core located in Meijiazhou (116°12′50″E,29°04′30″N),the formation and development of Meijiazhou and its historic significance in Poyanghu Lake has been discussed.Meanwhile,based on hydrological and silt characteristics obtained in recent years in Hukou area,submerged topographic data of 1970 and 1980 and the growing trend of Meijiazhou has been noticed.Around 2.3 ka B.P.,with the joint action of Yangtze River and ancient Ganjiang River,the Meijiazhou was formed as the levee to the south bank of Yangtze River.It resisted the water from ancient Ganjiang River to flow into Yangtze River,resulted in the formation of Poyanghu Lake and its enlargement southward.After comparing submerged topographic data of 1970 with that of 1980,we found that the Meijiazhou is growing 0.031 m high annually and to the right bank and lower reaches continuously.The continuous growth of the Meijiazhou intensifies the resistant effect to water from Poyanghu Lake,and it will change the hydrological and geological condition of Poyang Lake further,bringing a series of environmental changes.