The effect of coastal defences on cliff top retreat along the Holderness coastline
The effect of coastal defences on cliff top retreat along the Holderness coastline
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海岸防御对霍尔德内斯海岸线悬崖顶部退缩的影响
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
R. Nicholls
中科院分区：
文献类型：
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作者：
Sally Brown;M. Barton;R. Nicholls
摘要本研究调查软悬崖撤退的变化和沿海防御的影响，沿沿着55公里的霍尔木兹海峡海岸1845年和2005年之间。对三个大约50年的时期（1854-1905年、1905-1952年、1952-2005年）的分析得出，后退速度在0.8±0.4米/年和2.1±0.4米/年之间。由于自然原因和人类活动的影响，尤其是19世纪世纪的海滩开采和海防建设，海岸后退在空间和时间上都有很大的变化.防御减少了沉积物的输入，并改变了沉积物的收支，通常导致沉积物亏损向下漂移，导致发展的挫折。利用来自历史和现代地形测量地图、航空照片和差分地理定位系统（DGPS）测量的数据，悬崖顶部被选为参考特征。挫折由于国防建设在巴姆斯顿，霍恩西（两个时期），梅普尔顿和威森西（两个时期）进行了分析，给六个不同的时间段。由于测绘的不确定性和自然变异性很大，短时间是不可靠的。有两个例子显示，自防御工事建立以来，在很长一段时间内，过度后退了数万米到数千米。有两个案例表明撤退过度，但在建造防御工事之后需要更多的时间（在这些案例中，超过20年）才能得出明确的结论。有两个案件没有定论，但可能在防御工事建造后保持了恒定的撤退速度。因此，在大规模的侵蚀中，防御措施改变了侵蚀的模式，而不是阻止它。防御措施的加速后退会威胁到人类的基础设施和建筑物，并降低防御措施的效率。在海岸线管理规划中应认识到这一点。
Summary This study investigates variations in soft cliff retreat and the impact of coastal defences along 55 km of the Holderness coast between 1845 and 2005. The analysis of three approximately 50-year periods (1854–1905, 1905–1952, 1952–2005) gives a retreat rate of between 0.8±0.4 m/yr and 2.1±0.4 m/yr. Retreat varies spatially and temporally due to natural causes and human activity, especially 19 th century beach mining and coastal defence construction. Defences reduce sediment input and modify the sediment budget, usually resulting in a sediment deficit down-drift, leading to the development of a set-back. Using data from historical and modern Ordnance Survey maps, aerial photographs, and Differential Geographical Positioning System (DGPS) surveys, the cliff top was selected as a reference feature. Set-back due to defence construction at Barmston, Hornsea (two periods), Mappleton and Withernsea (two periods) was analysed, giving six different time periods. Short time periods are unreliable due to large mapping uncertainties and natural variability. Two cases showed excess retreat for tens to thousands of metres down-drift over a long time period since defence construction. Two cases were indicative of excess retreat, but require more time to elapse after defence construction (in these cases >20 years) to reach a definitive conclusion. Two cases were inconclusive, but possibly maintained a constant retreat rate post-defence construction. Hence, at the scale of Holderness, defences have changed the pattern of erosion rather than stopping it. Accelerated retreat down-drift of defences can threaten human infrastructure and buildings and reduce the efficiency of defences. This should be recognized in shoreline management planning.