长江河口海岸演变长周期波动的初步研究

The Long Period Oscilation of the Yangtze River Estuarine and Coastal Evolution-A Preliminary Study

长周期波动作为一种地貌演变现象在河口海岸地区广泛存在。在长江河口。表现为长江河口水下三角洲及长江河口拦门沙地形的波动变化。而在杭州湾北岸，它又以“侵蚀波”的形式来影响岸滩的冲淤演变。本文试图通过揭示该现象内在的动力机制来综合分析其在典型河口海岸演变中的表现。同时，通过定量分析，为理论模式提供佐证。

The estuarine and coastal evolution is an important problem attracting many researchers, which rises a new concept 'long term oscilation'. The paper mainly discusses this phenomenon.By means of the study of the Yangtze River Estuarine evolution, the author puts forward the developing conceptional model of the estuarine channel system and puts it in the interaction of huge system of moon - earth and river - sea system. Using the theory of positive negative feedbacks and the mechanism of gradual and abrupt changes, the author explains the evolution of estuarine channel system. which is the internal mechanism of the long term oscilation in Yangtze River Estuary. In the North Shore of Hangzhou Bay, the long term oscilation could be defined as an accretional/erosional wave which is similar to a forced vibration exprssed by zero order Bessel function. and is the internal mechanism of the coastal evolution.Based on the above analysis, the author uses Grid Analysis Method (GAM) to compute the accretional/erosional quantity of the study area, and draws the resulting maps, by which the conceptional model is proved effectively.