The marine dynamics and changing trend off the modern Yellow River mouth

Topography around the Yellow River mouth has changed greatly in recent years, but studies on the current state of ma- rine dynamics off the Yellow River mouth are relatively scarce. This paper uses a two-dimension numerical model(MIKE 21) to reveal the tidal and wave dynamics in 2012, and conducts comparative analysis of the changes from 1996 to 2012. The results show that M2 amphidromic point moved southeastward by 11 km. It further reveals that the tides around the Yellow River mouth are relatively stable due to the small variations in the tidal constituents. Over the study period, there is no noticeable change in the distribution of tidal types and tidal range, and the mean tidal range off the river mouth during the period studied is 0.5–1.1 m. However, the tidal currents changed greatly due to large change in topography. It is observed that the area with strong tidal currents shifted from the old river mouth(1976–1996) to the modern river mouth(1996–present). While the tidal current speeds decreased continually off the old river mouth, they increased off the modern river mouth. The Maximum Tidal Current Speed(MTCS) reached 1.4 m s-1, and the maximum current speed of 50-year return period reached 2.8 m s-1. Waves also changed greatly due to change in topography. The significant wave height(H1/3) of 50-year return period changed proportionately with the water depth, and the ratio of H1/3 to depth being 0.4–0.6. H1/3 of the 50-year return period in erosion zone increased continually with increasing water depth, and the rate of change varied between 0.06 and 0.07 m yr-1. Based on the results of this study, we infer that in the future, the modern river mouth will protrude gradually northward, while the erosion zone, comprising the old river mouth and area between the modern river mouth and the old river mouth(Intermediate region) will continue to erode. As the modern river mouth protrudes towards the sea, there will be a gradual increase in the current speed and decrease in wave height. Conversely, the old river mouth will retreat, with gradual decrease in current speed and increase in wave height. As more coastal constructions spring up around the Yellow River mouth in the future, we recommend that variation in hydrodynamics over time should be taken into consideration when designing such coastal constructions.     

Seasonal suspended particles distribution patterns in Western South Yellow Sea based on Acoustic Doppler Current Profiler observation

An Acoustic Doppler Current Profiler (ADCP) observation site was set up in the Western South Yellow Sea from 2012 to 2013 to study the local suspended particle matters (SPM) distribution pattern. The S...     

海洋沉积物测年方法综述

海洋沉积物是研究古气候变化、海平面升降、地球化学循环等重大科学问题的载体之一,精确的测年结果是上述研究的重要前提.随着海洋沉积物测年理论、技术设备不断突破,测年方法如210pb法、137Cs法、AMS14C测年、光释光法、古地磁定年、天文轨道调谐法、氧同位素曲线对比、电子自旋共振法、铀系法等层出不穷.文章总结了海洋地质...     

Bedform evolution around a submarine pipeline and its effects on wave-induced forces under regular waves

The paper presents an experimental investigation of seabed evolution behavior around a submarine pipeline and the hydrodynamic forces on the pipeline under regular waves. Unlike the previous flume tests that have largely used beds with median sands, this study focuses on fine sediments such as sandy silt and silt. The primary objective of the study was to investigate: (i) the scour process under different wave conditions and with different sediments and (ii) the influence of the bedform evolution on the hydrodynamic forces experienced by the pipeline. In terms of scour and ripple formation, four distinct regimes of the near-field bed evolution behavior are identified which are: (I) no scour, (II) scour without ripples, (III) scour with small ripples and (IV) scour with large ripples. The influence of bedform evolution on wave forces was found to vary significantly in different regimes. In regime I, the wave forces were quite stable; in regime II and III, the wave forces underwent a gradual reduction before reaching their equilibrium values at fairly early stages of the scour process; in regime IV, the wave forces were significantly affected by the migrating ripples and can be rather unsteady throughout the testing period.