Effects of varied lithology on soft-cliff recession rates
Effects of varied lithology on soft-cliff recession rates
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DOI：
10.1016/j.margeo.2014.04.009
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发表时间：
2014-08
期刊：
影响因子：
2.9
通讯作者：
N. Carpenter;M. Dickson;M. Walkden;R. Nicholls;W. Powrie
中科院分区：
文献类型：
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作者：
N. Carpenter;M. Dickson;M. Walkden;R. Nicholls;W. Powrie
地貌建模是了解软崖后退过程的关键方法，可以预测未来的后退速度和对气候变化的响应。已经使用了一系列基于过程的模型;然而，各种垂直岩性的影响尚未量化。本文介绍了修改的2D SCAPE（软悬崖和平台侵蚀）模型，进行了探讨悬崖阻力强度和现行海岸条件的垂直变化之间的相互作用。正如预期的那样，较弱（/更具抵抗力）的地层导致更多（/更少）的快速撤退。然而，这种效果受到这些层相对于平均海平面的位置的强烈影响，其中侵蚀潜力最大。此外，模型模拟显示，层的可变电阻给出了一个不对称的反应，在两个率的撤退和时间框架的效果实现。例如，平均海平面附近材料强度降低1/5（与悬崖的其余部分相比），与引入具有相同特性的五倍阻力层相比，后退速率快速增加130%。这种响应的变化可以归因于与岩性变化相关的控制剖面重塑的反馈的不同幅度。例如，较弱地层的引入通过其更大的侵蚀潜力与上覆部分的陡峭相结合来放大侵蚀。这些结果对管理呈现可变地层的沿海悬崖以及未来与海平面上升相互作用的潜力具有重要意义。
Geomorphic modelling is a key method to understand the soft cliff recession process to predict future rates of retreat and responses to climate change. A range of process-based models have been used; however the influence of varied vertical lithology has yet to be quantified. This paper describes modifications to the 2D SCAPE (Soft Cliff and Platform Erosion) model, carried out to explore such interactions between vertical changes in cliff resistive strength and prevailing coastal conditions. As expected, weaker (/more resistant) layers lead to more (/less) rapid retreat. However, this effect is strongly influenced by the position of such layers relative to mean sea level, where the erosive potential is greatest. Moreover, model simulations reveal that layers of variable resistance give an asymmetric response in terms of both rates of retreat and the timeframe for the effect to be realised. For example, a reduction of material strength of 1/5 (in comparison to the remainder of the cliff) about mean sea level results in a rapid 130% increase in the rate of retreat in comparison to the introduction of a five times more resistant layer of the same characteristics. This variation in response can be attributed to the different magnitudes of feedback governing profile reshaping associated with the change in lithology. For example, the introduction of a weaker layer amplifies erosion through its greater erosive potential combined with steepening of the overlying section. The results have important implications for the management of coastal cliffs exhibiting variable stratigraphy, combined with the potential for future interactions with sea-level rise.