河口整治工程的实施效果与堤坝的结构型式密切相关，在河工模型上直接研究局部复杂结构对整治效果的影响有较大难度。

Effects of estuary regulation are related to the structural type of dykes, but it is difficult to study the effect of some local complex structures with physical models directly.

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长期以来，长江流域的工农业及城市生活排污一直没有得到有效的控制，这必将对下游河口地区的生态环境造成直接或潜在的威胁。

For a long period, the industrial and city sewage were over-discharged along the Yangtze River, which would no doubt have harmful effect in estuary environment either directly or indirectly.

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