Swash zone sediment fluxes: Field observations
Swash zone sediment fluxes: Field observations
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DOI：
10.1016/j.coastaleng.2010.08.002
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发表时间：
2011-01-01
影响因子：
4.4
通讯作者：
Russell, P. E.
中科院分区：
文献类型：
--
作者：
Blenkinsopp, C. E.;Turner, I. L.;Russell, P. E.
本文介绍了新获得的，高频率的观测海滩面临的形态变化，在众多的潮汐周期的大潮汐桑迪海滩使用一个大阵列的超声波高度计。这些测量使净跨海岸沉积物通量与成千上万的个人冲事件进行量化。据透露，无论潮汐时间尺度上的净形态变化的方向，测量的净通量每个事件基本上是正态分布的，与几乎相同数量的陆上和离岸定向事件。大多数冲流事件导致的净跨岸沉积物通量小于+/- 50 kg m（-1），每次冲流事件的平均沉积物通量仅为0（+/- 1 kg m（-1）），导致总体形态变化有限。然而，更大的事件，存款或删除数百公斤的沙子每米宽的海滩发生在不规则的时间间隔在整个过程中的潮汐。有人发现，斜流-斜流的相互作用往往会增加一个斜流事件的运输潜力和大多数的斜流事件，导致这些较大的沉积物通量值包括一个或多个相互作用。因此，大多数较大的沉积物通量测量在较低的冲浪区，接近冲浪/冲浪的边界，冲浪-冲浪的相互作用是最常见的。尽管存在个别的冲刷事件，可能会导致沉积物的通量，相当于潮汐时间尺度上观察到的，在运输方向的频繁逆转的行为，以限制净运输，使海滩面体积保持在动态平衡状态，并没有迅速侵蚀或增生。(C)2010 Elsevier B. V.保留所有权利。
This paper describes newly obtained, high-frequency observations of beach face morphological change over numerous tidal cycles on a macrotidal sandy beach made using a large array of ultrasonic altimeters. These measurements enable the net cross-shore sediment fluxes associated with many thousands of individual swash events to be quantified. It is revealed that regardless of the direction of net morphological change on a tidal time scale, measured net fluxes per event are essentially normally distributed, with nearly equal numbers of onshore and offshore-directed events. The majority of swash events cause net cross-shore sediment fluxes smaller than +/- 50 kg m(-1) and the mean sediment flux per swash event is only 0(+/- 1 kg m(-1)) leading to limited overall morphological change. However, much larger events which deposit or remove hundreds of kilograms of sand per meter width of beach occur at irregular intervals throughout the course of a tide. It was found that swash-swash interactions tend to increase the transport potential of a swash event and the majority of the swash events that cause these larger values of sediment flux include one or more interactions. The majority of the larger sediment fluxes were therefore measured in the lower swash zone, close to the surf/swash boundary where swash-swash interactions are most common. Despite the existence of individual swash events that can cause fluxes of sediment that are comparable to those observed on a tidal time scale, frequent reversals in transport direction act to limit net transport such that the beach face volume remains in a state of dynamic equilibrium and does not rapidly erode or accrete. (C) 2010 Elsevier B.V. All rights reserved.