【摘要】 <正> 海底沉积物运动可由重力作用引起,它常以水下滑坡的形式出现,对高含水量的细颗粒物质尤其是如此(林振宏等,1990);在陆架和陆坡区,水下滑坡可由于地震等事件而诱发。此外,海底稳定性还与水流作用引起的沉积物运动有关,沉积物输运造成相应的堆积和冲刷,从而改变海底的形态。在许多环境中,沉积物输运是控制海底稳定性的主要因素。海底某处高程在一定时段内的变化系由活动层厚度、冲淤量和底部地貌形更多还原

【Abstract】 Sediment movement patterns control the stability of sandy seabed in three aspects: (i) the sediment erodibility time and the thickness of the moving layer; (ii) seabed accretion/erosion and their rate; and (iii) seabed elevation changes in response to bedform (e.g.underwater dunes and tidal ridges) migration. These problems can be solved by the following procedures. Firstly, the sediment erodibility time and the rate of bed-load transport are calculated using an appropriate equation which takes into account the combined effect of waves and tidal currents. Secondly, the moving layer thickness and the accretion/ erosion rate are estimated using the transport rate data. Finally, the information on the migration velocity of dunes/ridges and the resultant seabed elevation changes is obtained using the transport data and the geomorphic data of the bedform. As an example for its usage, we applied the method to the assessment of seabed stability over an area to the west of Hainan Island. The results show that the seabed material is highly mobile, with active sediment movement. The rate and amplitude of seabed elevation changes are both relatively large, in response to rapid bedform migration. These characteristics must be taken into account in the development of the natural resources of the region.更多还原