TURBIDITY CURRENTS GENERATED AT RIVER MOUTHS DURING EXCEPTIONAL DISCHARGES TO THE WORLD OCEANS
TURBIDITY CURRENTS GENERATED AT RIVER MOUTHS DURING EXCEPTIONAL DISCHARGES TO THE WORLD OCEANS
复制标题
DOI：
10.1086/629747
复制
发表时间：
1995-05-01
影响因子：
1.8
通讯作者：
SYVITSKI, JPM
中科院分区：
文献类型：
--
作者：
MULDER, T;SYVITSKI, JPM
海洋高旋流是一种特殊的浊流，发生在河口，当悬浮沉积物的浓度非常大，以至于河水的密度大于海水的密度。然后，羽流会向下俯冲，并可能侵蚀海底，在一段特定的时间内（几小时到几周）自我维持。通过对等级曲线特征的了解，特别是在洪水条件下，可以预测河流流量产生的高气旋羽流的频率。这些曲线的例子显示了北美中型河流。提出了平均流量、平均含沙量和汛期流量之间的半经验关系，并对150条世界河流进行了应用。结果表明，中小型河流在河口引发底流的能力方面具有重要意义。至少有九条“脏”河流在一年中的一个或多个时期可能引发洪水泛滥。其他大多数河流都比较干净，只有在洪水期间才会有超峰羽流。大河在河口处不会产生底流，因为在其广阔的沿海洪泛平原上泥沙的滞留有效地降低了悬浮浓度的上限。下流输运可能是海相三角洲构造的重要过程，在沉积盆地-充填模型中应予以考虑。所提出的方程和模态图可以帮助工程师进行河口向海的基础设施设计。
A marine hyperpycnal plume is a particular kind of turbidity current occurring at a river mouth when the concentration of suspended sediment is so large that the density of the river water is greater than the density of sea water. The plume can then plunge and possibly erode the seafloor to become self-maintained for a particular period of time (hours to weeks). Frequency of hyperpycnal plumes emanating from river discharge can be predicted with knowledge of rating curve characteristics, particularly during flood conditions. Examples of these curves are shown for middle-sized North American rivers. Semi-empirical relationships among average discharge, average sediment concentration, and the discharge during flood are proposed and applied to 150 world rivers. Results show the importance of small and medium sized rivers in their ability to trigger underflow at their mouth. There are at least nine ''dirty'' rivers that may trigger underflows during one or more periods of the year. Most other rivers are cleaner and have hyperpycnal plumes only during floods. Large rivers do not generate underflows at their mouth because sediment retention within their expansive coastal flood plains effectively reduces the upper limit of the suspended concentration. Underflow transport may be an important process in marine-delta construction and should be considered in sedimentary basin-fill modeling. Proposed equations and nomograms may assist engineers in infrastructure design seaward of a river mouth.