Catchment changes play important roles in the development of river deltas. Under the influence of human activities, the estuary processes become more rapid, intense and complicated. The Yalu River is an important river in North China, its landscapes being largely changed in the resent hundred years. In order to investigate the mechanisms and controlling factors of the estuarine delta evolution under anthropogenic interference in the whole catchments, ten sediment cores were collected at the tidal flats on the west bank and in the western channel of the Yalu River Estuary in 2010 and 2011. In association with the morphodynamic and the historical hydrologic data of the Yalu River catchment, the evolution of sedimentary environment influenced by human activities were thereby studied through analyzing the variations of 210Pb specific activities and grain sizes of the sediment cores. The vertical distribution of 210Pb specific activity can be classified into three types :( 1 ) exponential distribution type;(2) surface mixed or inverted type; and ( 3 ) abnormal distribution type. The results indicate that, the deposition rates of the sediment cores on the west tidal flats were less than 2cm/a,while the core in the western channel has the highest deposition rate of 5. 84cm/a from 45cm to 285cm (1960 ~2000). The vertical distributions of the sediment grain sizes suggest that the sedimentary environment evolution of the tidal flats experienced four stages: stage 1 (before 1940) ,the estuary in natural development; stage 2(from 1940 to 1970) ,the estuarine morphology changed greatly due to the sharp reduction of river sediment load; stage 3(from 1970 ~ 1995) ,the river water discharge decreased rapidly, and consequently the deposition thickness attenuated; and stage 4 ( after 1995) , erosion is the dominant process at the this stage, because the river sediment load can not provide sufficient material for the growth of the tidal flats. The sediment of the tidal flats were sorted and redistributed, resulting in the formation of coarse or fine surface layers in some of the sediment cores. Furthermore, the grain size frequency distributions of the core sediments and the suspended sediments during 1962 ~ 1985 show that, the grain size variations of the river-born sediments were markedly controlled by human activities, e. g., deforestation, and the following forestation. These changes are preserved in the sediment records.%2010年和2011年于鸭绿江河口西岸潮滩及西水道采集柱状样10根,对柱状沉积物进行210pb比活度及粒度测试,结合河口地貌演化及流域历年水文资料,探讨人类活动对流域输沙变化造成的影响,以及沉积过程对环境变化的响应.结果表明,柱状样210pb纵向分布具3种类型:1)指数分布类型;2)表层混合或倒置类型;3)异常分布类型.西水道的沉积速率最快,1960 ～ 2000年间达到5.84cm/a;而西岸潮间带沉积速率存在差异,均小于2cm/a.根据测年结果及沉积物粒度特征,将潮滩演化划分为4个阶段:阶段1为1940年以前,处于自然发展状态;阶段2为1940 ～1970年,流域输沙锐减,河口地貌发生显著变化,西水道由主流道逐渐萎缩为潮汐汊道;阶段3为1970 ～1995年,径流量锐减,沉积厚度减薄,以及河口区采砂作业加剧,盐水楔入侵,潮滩沉积物变细;阶段4为1995～ 2010(2011年)年,输沙量逐年减少,潮滩开始遭受侵蚀,受侵蚀区域物质重新分选,致部分柱状样表层出现“粗化层”或“细化层”.通过对1962 ～1985年间柱状样和悬沙粒径相关性的分析发现,森林砍伐及后期的植树造林对流域输沙的粒度变化控制明显,而该变化在潮滩沉积中亦有记录.
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