THEORETICAL FORMS OF SHORELINES
THEORETICAL FORMS OF SHORELINES
复制标题
海岸线的理论形式
DOI：
10.9753/icce.v7.11
复制
发表时间：
1964
期刊：
影响因子：
--
通讯作者：
W. Grijm
中科院分区：
文献类型：
--
作者：
Shoreline Processes;Walcheren Dike;W. Grijm
在以前的出版物中，Pelnard-Cocomdere、Bruun和Larras提出了理论上的岸形。在这样做的时候，必须理想化条件，如只靠波浪进行横向输送，不变的波浪特性，以及波浪进场角度与沿岸输送之间的简单关系。此外，还必须进行各种其他简化，以便能够处理这些方程。
可能会出现这样一个问题，即从这种理想化的情况下获得的结果对实际情况是否有任何价值，因为在实际情况下，条件要复杂得多，多变得多。当我们期望获得某一特定海岸的发展的真实和详细的图景时，答案是否定的。然而，这样的理论练习可能是真正有价值的，因为它们帮助我们理解某些地层为什么和如何形成，以及它们如何受到某些物理过程的影响。例如，三角洲、唾液和汤波罗等地层就是这种情况。
我们不能说我们真的知道决定沿海运输的功能。到目前为止，数学处理中的简化之一是限制停留在<；*的值所在的区域内。是如此之小，以至于输运可以被归类为与o<；值的增加成正比增加(c<；被定义为在所考虑的点上波浪方向与海岸法线方向之间的夹角)*然而，实验表明，当波角在45°和600之间时，沿岸输运很可能达到最大值。当接近这一最大值时，必然会出现有趣的现象。考虑到这一点，我们尝试引入传输功能T？A SIN 2EX，在OC？45°时达到最大。
In previous publications Pelnard-Considere, Bruun and larras have d.erived theoretical shore formations. When doing so, it is necessary to idealize the conditions, such as a lxttoral transport by waves only, unvarying wave characteristics and a simple relation between the angle of wave approach and the littoral transport. Moreover various other simplifications have to be made in order to make it possible to handle the equations.
The question may arise whether results, obtained from such an idealized situation, have any value for practical cases, where the conditions are much more complex and variable. The answer is no when we expect to obtain a true and detailed picture of the development of any particular stretch of coast. Such theoretical exercises can be of real value, however, because they help us to understand why and how certain formations come into being and how they are influenced by certain physical processes* This is the case for instance with such formations as deltas, spits and tombolos.
We cannot say that we really know the function which determines the littoral transport. Up to now one of the simplifications in the mathematical treatment has been the restriction to stay within an area in which the values of <*. are so small that the transport may be assaned to increase in direct proportion to the increase of the value of o< ( c< being defined as the angle between the wave direction and the direction of the normal on the coast in the point considered)* However, experiments indicate that the littoral transport very likely reaches a maximum for a wave angle between 45° and 600. Interesting phenomena are bound to occur when this maximum is approached. With this in mind we have tried to introduce a transport function T « A sin 2ex., having its maximum when oC « 45°.