广州城下的珠江（广州至虎门）不属河成水道，而是潮道一潮成水道。论述了这一水道的成因和动力地貌特点，强调指出了这一潮道体系中潮滩和潮汐汉道存在的重要性。认为珠江的保护必须首先洼意保护好潮滩（潮道中的近岸浅滩），即不要再缩窄江而；其次是不能随意将潮道四周平原上的潮汐汊道堵塞或消灭。

珠江河口大系统主要由一正两负的亚系统构成。正亚系统指呈扇形向海凸伸的西、北江联合三角洲及其6个“河优型”分流河口；两负亚系统指分布于上述正亚系统两侧的、向陆凹入的虎门和崖门2个“潮优型”分流河口及其口内的潮汐水道。它们相向发展而具相依并存和耦合共生的特点，并且通过诸多的横向支汊进行沟通和联系。而每一单个河优型分流河口也同样存在河控和潮控耦合共生动力—沉积地貌体系，珠江三角洲沙田区的“潮灌潮排”农田水利体系与模式，是此种陆海耦合效应的生动表现。珠江河口治理应尊重、保护珠江河口系统大、小尺度的陆海架构关系及其有机联系，努力做到人与自然和谐共处。

The distlnctive characterlstlcs of the modem Pearl River delta formalion and develop-meat are divided phases, diversity and imbalance in spatial and temporal The delta was moving seaward gradually in a long period after the last Holocene glacial stage and the ancient drowned Pearl River estuary was predominated by tide The delta was expanding quickly since fluvial force was turned to be leading status about 2500 years ago. The sediment grain size was changing Ion-gitudinally from coarser to finer. As well as the finer sediment may be reworked and redistributed shoreward by tidal current nearby the river mouth And the fluvial-dominated delta is developed bv the mutual deposition reflected in the vertical direction According to the spatial difference of land-ocean interaction, the main body of the Pearl River delta which is the fluvial-dominated and protruding seaward is coupled with or concomitant with the estuaries and tide-dominated deltas which are adjoined to both sides of the main part like two wings.

This paper analysed the main factors of the coastal formation in South China, i.e. the geological structures, the geographical conditions of the mainland coast, the raise of the sea-level during Holocene, the tide, the wave, the longshore drift and so on. The coast in South China is characterized by the pattern of barrier-lagoon (or bay), because the tide range is small and the sediment transported by wave is rather strong. The mud-sand of most part of the barriers was derived from inner shelf, and moved landward with sea-level rise in Holocene. The author described in full details of the morphology about the two patterns of harbour-coasts (i. e. sub-merged valley and barrier-lagoon) The characteristics of the harbour of barrier-dagoon are as follows: 1. A harbour with the ha rrier-lagoon is commonly independent from the adjacent coastai systems; 2. Either the pluvial-alluvial terraces and the erosion platforms or the hills always lie at the back of the harrier-lagoon (or bay) systems; 3. During the Holocene, the barriers had evolved continuously by retreat, progradation and return. That correspondingly caused the changes of the other morphology, such as the area of lagoon. the mud flat, the tidal inlet and its sand bodies; 4. The foreshorelines of most barriers have tended to the logarithmic spiral plan shape; 5. The morphodynamics of beach may be divided into three sections; 6. The throat-position of the tidal inlet is always situated in the apexof Z-shaped headl-and-bay and is generally stable.

陆——海界面是海岸带陆海相互作用研究的重点与关键科学问题。应改变视角，将河口自身作为陆--海界面进行研究。以河口自身作为界面，研究河口界面对河流系统和海洋系统的适应性、可渗透性、稳定性、防御性等功能和行为。用河口自身就是界面的新视角、新思维，来感受河口问题，可加深对河口若干重要认识、概念及现象的了解与理解，进而有助于揭示河口过程的本质，解读河口陆海相互作用的真谛。