从广义上说,河口系指河流的出口段,包括支流汇入干流的支流河口,注入湖泊的入湖河口,以及入海的潮汐河口。这里讨论的限于后一种河口。潮汐河口是河流与海洋联接的地方,为河流与海洋两种力量相互消长的区域,兼有两者及其叠加后的动力因素,情况甚为复杂。其复杂性首先表现在动力因素的多样性 Broadly speaking, the estuary refers to the outlet section of the river, including the tributary estuary into which the tributaries flow into the mainstream, the lake inlet into the lake, and the tidal estuary into the sea. The discussion here is limited to the latter estuary. The tidal estuary is a place where the rivers connect with the ocean and is a region where the two rivers and oceans are experiencing mutual depletion and extinction. Both are the two factors and their superimposed dynamic factors. The situation is quite complicated. The complexity of the first manifestation of the diversity of dynamic factors