Based on the data of high resolution seismic profiles, an ancient river channel system of the last glaciation occurred along the Zhedong and Xihu depression in the southeast of Hupijiao rise. The distribution of the channel fill system shows that the ancient Changjiang River went through the Changjiang depression into the low land plain of the outside continental shelf during the low sea level cycle of the last glaciation. The big channel fill into Okinawa trough is not found due to the depletion of the river kinetic energy in the low land plain. The river discharge dispersal was of an important role to the dilution of the northern Okinawa trough sea at that time. Six ancient river channel systems (A-F), which are main distributaries of ancient Changjiang in the East China Sea continental shelf during the last glaciation, may be buried off the modern Changjiang estuary. The distribution of these channels coincides with the zonal elevations in the sea floor.

Based on the measuring data of landforms, bigh-resolution seismic profiles, drilling cores, etc. a diapir body was found in the north of the modem Yellow River delta The diapir body with alength of 5 km and awidth of 1 km is distributed on the middle to low part of the slope of an abandoned delta lobe. Its formation is related to the deformity of the soft stratum which is deposited in the prodelta and covered by the stratum of the mouth bar sediments Research results show that its formation is very different from the Mississippi River delta's diapirs but related to the erosion of the seabed and occurs on the location with a large eroded quantity The soft stratum and its diapir body can result in a great hazard to marine buildings.

现场观测资料和卫星遥感校准图像计算表明，1855年以来，黄河三角洲新淤陆地3699km2，生长速率为26。8 km2/a，黄河输入三角洲1×108t泥沙形成3.144km2的陆地。进入河口区的泥沙约88.4%堆积在水下8km宽的三角洲前缘。研究表明，这一堆积比例是河口切变锋、异重流和潮流场相互作用的结果，异重流在黄河汛期一直存在，大约搬运黄河来沙的60%沉积在三角洲前缘；一个潮周期内，切变锋出现两次，它能够捕获异轻羽状流中的悬浮泥沙堆积，也能够限制异重流的远距离扩散。切变锋消失后，少量悬浮泥沙才能远距离扩散，随潮流离开三角洲水下斜坡。

根据黄河口卫星遥感数据和河口滨海区水文、泥沙实测资料，对河口区洪水的平面扩散和含沙水层特征进行分析， 结果表明：在洪水期，河口高高潮到低低潮线之间主河道两侧存在大范围漫流区，片状水流汇入网状汊沟入海，主河槽过流仍很明显，随着流量减小，漫流现象减弱乃至消失，推测口门区主河道的造床流量约1000m 3/s；TM 1～3 合成与TM6温度制图发现，在河口浅水区存在河海相互作用的混合带，混合带宽度与河流流量成正比，混合带中富集了大量悬浮泥沙，造成河口区快速沉积，黄河口滨海区切变锋常在此带中形成，实测锋带的总密度高于围域水体，表明切变锋具有二次发射异重流的能力。将实测获得的水体含沙量C、盐度S、流速V、水体剩余密度σt（与温度、盐度有关）、水体总剩余密度R 及水层厚度h进行聚类分析，对黄河口滨海区不同河流来水来沙条件下的水层进行分类，并对各种水层特征及水层垂向组合特征进行了分析，即洪水期滨海区属不均匀流体，成层性明显，河口来水来沙对其分层起重要作用，共区分出6种典型水层，三种异重羽状流层（高、中、低）在大水期经常发生，频率达42。5%。中水期区分出5种水层类型，明显反映出盐水的作用加强，河流作用表现在异轻羽状流层的存在；枯水期区分出4种类型水层，类型之间特征差异较小，成层性不明显；三角洲前缘水体底层，在3个阶段都判别出有低密度浮泥存在。

Historical bathymetry, satellite remote sensing and river discharge data have been used to examine the evolution of an abandoned delta lobe in the northern area of the modern Yellow River delta. Results show three stages of evolution in the subaqueous delta slope after lobe abandonment: (1) rapid erosion stage; (2) slow erosion stage; and (3) erosion

Rapid deposition and suspended sediment dispersal off the modern Yellow River mouth has been examined from the data of topographic maps (1:25,000), suspension and bed sediments, current and salinity, which were measured in the field. The results show that the sedimentation rate of the mouth bar is the highest of all the environments of deposition inthe modern Yellow River delta. About 30-40% of the sediment that the river transports into the sea has been deposited within the mouth bar area. Rapid deposition of the mouth bar results mainly from kinetic energy dissipation of the riverunder the influence of three ambient mechanisms. These three mechanisms occur simultaneously as shear front movement, which obstructs the river's jet-like flow, small-scale circulations where large velocity gradients occur and the'bulldozer'effect of the tide sensitive zone in the estuary at ebb. Based on the analysis of morphologic changes, the mouth bar can be divided into two morphologic types: one is the double-lobe and single-channel type and the other double-channel and single-lobe type. Weak hyperpycnal plumes with small density differences between the river flow and ambient water dissipate rapidly and deposit about 20% of the river sediments on the delta front slope, while hyperpycnal underflows from the river mouth can go through the steep delta front slope to form a rise apron along the upper part of the prodelta. Grain size analysis of suspended sediment shows that the flow can be divided into three layers: a tide layer in the upper part, and a hyperpycnal layer in the lower part, (these two layers are normally graded), and a transition layer with inverse grading in the mid-part. The fine suspended sediments have been transported in the hypopycnal plume layer into the prodelta and deep sea, such as the North Huanghai Sea (North Yellow Sea). This study indicates that the tidal current field has dominated the distribution of deposition of sediment on the subaqueous delta and the movements of the river effluent and hyperpycnal underflows.

A 44-year data record measured by Lijin Hydraulic Station on the Yellow River shows that sediment concentration has been increasing while river discharge has been decreasing into the delta since the 1970s. These changes are important because flood waters of the Yellow River, which are heavily laden with sediment, must be used to supply Dongying City and Shengli Oil Company which are located on the delta. Based on the analyses of data of velocity, sediment concentration, salinity and sediment grain size from four cross-section measurements at Lijin Station and one 8-vessel simultaneous measurement cruise in the estuary, structural haracteristics of the river flow and suspended sediments throughout the upper distributary and the estuary have been studied and discussed. Results show that when sediment concentrations of the Yellow River exceed 100 kg=m3 in the lower layer of the river flow during the flood period, the river flow structure does not coincide with the logarithmic law of wall and becomes vertically layered, and the vertical distributions of suspended sediment do not coincide with the diffusion law. The channel length influenced by the tide wave is less than 15 km and there is no tidal intrusion flow; only weak osmosis of salinity occurs inside the river mouth during the flood period of the Yellow River. Simultaneous 8-vessel measurements and simulation using the method of Preissman show that there is a tidal sensitive zone inside the river mouth bar with a length of 6-7 km, when the discharge is as large as 1100 m3/s, and an area of very active sedimentation. The tidal sensitive region near the river mouth becomes a low-velocity zone that traps a large amount of river sediment which rapidly forms a 'plastic' bed at flood tide, and a high-velocity zone with a strong hydrodynamic action to erode the new bed and transport the sediments into the sea at ebb tide.

measurements and Landsat scanning images, spatial-temporal changes in the shear front and associated sedimentation in the subaqueous delta slope of the Yellow River have been studied. The results show that the shear front is an important dynamic factor in controlling rapid accretion at the Yellow River mouth. Suspended sediment converges and is deposited rapidly along the shear front zone; this is because a low-velocity zone is formed between two inverse flow bodies. Some small eddies occur in the shear front zone, shown on (method of concentration-temperature ratio) mapping; this is conducive to rapid convergence and accumulation of the suspended sediment in the shear front. At the same time, some hyperpycnal plumes and gravity-driven underflow may be formed; these move away from the shear front zone, due to the high sediment concentrations there. The shear front is formed firstly at the prodelta area; it then moves to the river mouth, in response to the flood or ebb tidal controls and deep sea influences. It moves along the subaqueous delta slope for 1 221 3 of the tidal cycle, during the river flood season. The shear front zone of low velocity forms a wall of water that prevents dispersal of the river outflow. The temperature image from TM6 shows that a river–sea interaction zone, a transition between the river and sea water temperatures, occurs around the mouth. The shear front is formed within this zone. A four-stage dynamic process, related to the shear front during the tidal cycle, is discussed. The results show that the shear front occurs twice during a tidal cycle.