中文摘要：

东江下游博罗河段近几十年来受上游建库与大规模河床采沙等人类活动影响强烈,水沙动力条件与河床演变趋势出现了明显变异。一方面上游建库使得含沙量与输沙量明显减小,中枯水流量增大;另一方面大规模人工采沙造成河床大幅下切,水位严重下降,潮汐上溯明显,潮汐动力显著增强。本河段水沙动力过程的变异对通航条件、咸潮防护、取水供水、堤防安全和生态环境等都产生了较大影响。

英文摘要：

In the past 20 years,the hydrodynamic and fluvial processes of the Boluo reach of the East River were greatly affected by human activities,such as the large-scale sand digging from the riverbed and the construction of reservoirs.On the one hand,the reservoirs decreased the mean sediment concentration and the mean sediment discharge and increased the runoff in the dry seasons in the downstream channel.On the other hand,the large-scale sand mining had the great effect on the fluvial processes,including increasing of the channel capacity,lowering of the riverbed which caused severe drop of water level and obvious strengthening of tidal action.Therefore,human activities have become the dominant factor controlling the changes of the hydrodynamic and fluvial processes instead of natural processes.