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Future Modelling Applications
Published in Vanesa Magar, Sediment Transport and Morphodynamics Modelling for Coasts and Shallow Environments, 2020
Cliffs can suffer erosion at the foot from wave action, tides and storm surge, overall erosion from the effect of the wind, sliding of the cliff, and changes of cliff slope due to waterlogging. Cliff stabilisation can be achieved by placing revetments at the foot of cliffs to protect them from geotechnical instabilities by dewatering the soil at the top of the cliff to reduce waterlogging and the probability of sliding or collapsing of the cliff (Mangor et al. 2017) or by artificial smoothing of the slopes (as has been done, for instance, in Point Grey, see https://web.viu.ca/earle/pt-grey/gvrd-pg-document-full.pdf). Some cliffs may not need protection when they are composed of a noncohesive material and rocks; the cliff slope will naturally erode slowly, and the cliff material falling at the foot of the cliff will provide some natural protection against storm waves. Engineering works to protect a cliff are more necessary when the cliff material consists of a mixture of sand, clay, silt, and rock. Different aspects of coastal cliff modelling are addressed by Castedo et al. (2017) and references therein.
Romania
Published in Enzo Pranzini, Allan Williams, Coastal Erosion and Protection in Europe, 2013
Adrian Stãnicã, Nicolae Panin, Glicherie Caraivan
at a rate of about 2 m/yr after the building of the Mangalia Harbour protection jetties. Vama Veche, the southernmost beach, is stable. Cliff erosion has been an active process during the past century, with rates varying from 0.3 to 0.7 m/yr on average. Cliff erosion rates were obtained through comparison of topographic maps in 1924 and Ikonos satellite images taken in 2002 (Constantinescu, 2005). In the late 1950s, a widespread system of stabilizing cliff erosion was developed from Constanta South, Eforie North, Eforie South, Costinesti, Mangalia North (Olimp, Cape Aurora, Venus, Saturn) and Mangalia. Most of these coastal protection works (systems of drains combined with seawalls) have until recently been successful. The past decade started to witness failures of the cliff coastal defence systems, as no maintenance investment has been made for more than five decades. The rest of the cliffs have been left in a natural state, some (like the sections of Cape Tuzla-Costinesti and 2 Mai -Vama Veche) suffering from very active erosion, with retreat rates reaching even 1 m/yr.
Earthworks
Published in Barry G. Clarke, Engineering of Glacial Deposits, 2017
Clark and Fort (2009) undertook a review of techniques used to stabilise soft cliffs around the United Kingdom. This included glacial deposits along the east coast. Stabilisation measures included drainage, soil reinforcement retaining structures and slope support, as shown in Table 5.19. Erosion of coastal cliffs formed of glacial clay tills is prevented by a combination of drainage and slope reinforcement to stabilise the slope and toe protection including beach loading and retaining structures to prevent erosion.
Multi-scale approach to analyse the evolution of soft rock coastal cliffs and role of controlling factors: a case study in South-Eastern Italy
Published in Geomatics, Natural Hazards and Risk, 2021
Piernicola Lollino, Rossella Pagliarulo, Rosamaria Trizzino, Francesca Santaloia, Luca Pisano, Veronica Zumpano, Michele Perrotti, Nunzio Luciano Fazio
In order to investigate the coastal retreat of the study area over space and time, a detailed morphological analysis has been carried out for eight segments of the coastline portion examined. Rocky coast cliff retreat estimation based on multi-temporal analysis of maps and images has been carried out on multiple areas of the world, such as in Normandy (France) (Costa et al. 2004), in UK (Dornbusch et al. 2008) or in California (Hapke and Reid 2007; Hapke et al. 2009; Young 2018). A variety of techniques have been exploited to calculate recession rates (Sunamura 1992; Hapke 2004) usually as distance against time interval. The most common method is based on a multi-temporal analysis of aerial photographs and/or historic maps to trace the changes in the position of a cliff top or edge Sunamura (2015).
Origin, geomorphology and geoheritage potential of Australia’s longest coastal cliff lines
Published in Australian Journal of Earth Sciences, 2020
G. A. Wakelin-King, J. A. Webb
The limestones comprising the Zuytdorp Cliffs and Great Southern Scarp are sufficiently well cemented to maintain a steep vertical cliff face, but (owing to their grainsize, primary porosity and carbonate lithotype) are susceptible to disintegration under direct wave attack. As a result, cliff retreat occurs when the cliff base is undermined by wave erosion, causing sudden localised block failure or slumping (Bird, 2016) and maintaining the vertical face. Accumulation of fallen rock at the foot of the cliff temporarily protects it from further wave attack, but such debris crumbles relatively rapidly under the impact of the high energy swell along these coasts. As a result, the cliffs retreat relatively rapidly (∼30 mm/yr; Short, 2019). Cliff line continuity reflects regionally uniform scarp retreat rates, resulting from the broad spatial scale across which relatively homogenous lithologies have been uplifted to face wide expanses of ocean. In addition, the limestones of the Zuytdorp Cliffs and the Great Southern Scarp are mostly undeformed and jointing is poorly developed (contributing to the relatively minor development of karst features on and within the Nullarbor Plain; Webb & James, 2006). As a result, the cliff faces retreat more or less uniformly, rather than being segmented by preferential retreat along joint planes.
Numerical analysis on mining-induced fracture development around river valleys
Published in International Journal of Mining, Reclamation and Environment, 2018
C. Zhang, R. Mitra, J. Oh, I. Canbulat, B. Hebblewhite
The impacts of mine subsidence on these significant natural features have been extensively investigated [1–4]. The environmental consequences of these impacts mainly include loss of surface flows to the subsurface, loss of standing pool, adverse water quality impacts, development of iron bacterial mats, cliff falls and rock falls, impacts on aquatic ecology etc. [4], as illustrated in Figure 2(a) and (b). Field investigations have shown that mining-induced valley closure subsidence can lead to the formation of voids beneath watercourses, often in the form of open bedding planes which can act as underground flow paths for groundwater and stream water [5]. Therefore, there is significant potential for surface water to flow through the subsurface fracture network in the area that has been affected by valley closure subsidence. Figure 2(c) depicts the process of water flow through a mining induced fracture network in an area that was affected by valley closure.