长江三角洲的形成和演变

文章从地质构造背景、泥沙来源、动力条件和海底坡度四个方面阐述了长江三角洲的形成条件：长江三角洲主体位于构造下沉区；塑造长江三角洲的泥沙主要来自长江，少量来自废黄河三角洲和钱塘江；长江口门地区的波浪、潮流及沿岸流的作用比较适中、海底坡度平缓，有利于三角洲的保存。文章进而对不同历史时期三角洲岸线的变迁做了描述。最后，文章对本世纪三峡工程等流域人类活动将导致的河流来沙锐减对三角洲演变的影响做了初步的展望。

The Formation and Development of the Changjiang (Yangtze) River Delta

The formative condition of the Changjiang River Delta is discussed in the following aspects: the geological tectonic , the sediment source, the dynamical condition and the gradient of the sea bed. The result is described as follows: Changjiang River Delta lies in the tectonic sinking area; sediment mostly come from Changjiang River, partly come from the old Huanghe Delta and Qiantang River; the moderate wave, tidal currents and littoral currents in Changjiang River estuary and the flat gradient of the sea bed are benefit to keep the delta. Then the article introduces the coastal changes of the delta in different historical period. Lastly, the paper initially forecast the effects on the delta when the sediment coming from Changjiang River must be greatly decreased after the completion of the Three Gorges engineering et al. in this century.