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Coastal Erosion and Shoreline Change
Published in Yeqiao Wang, Coastal and Marine Environments, 2020
Most beaches experience a longshore current, which for swimmers means drifting slowly down the beach away from their beach towel as they swim in the surf. The longshore current is caused by waves approaching from any direction other than directly ashore—the wave crests are not parallel to the beach. Also, if waves are higher along one stretch of beach compared to an adjacent beach, the longshore current will flow along the beach from where the waves are high to where they are lower. Sand eroded from one beach can be transported along the beach by the resulting longshore drift.
Introduction
Published in Vanesa Magar, Sediment Transport and Morphodynamics Modelling for Coasts and Shallow Environments, 2020
Other bedforms, such as sandbars or sandwaves, may migrate offshore under the action of sea storms and migrate shorewards during calmer sea state conditions. Nearshore currents may have a significant longshore component, or longshore drift, that causes sediments to move alongshore rather than cross-shore. As Cowell et al. (2003) highlight, the nearshore waves and currents drive local longshore and cross-shore sediment budgets, i.e. sediment gains and losses, and define the position of the shoreline.
Coastal Resources
Published in Robert M. Sanford, Environmental Site Plans and Development Review, 2017
Numerous coastal engineering projects exist. However, the long-term effects of coastal engineering projects include: disruption of longshore drift that distributes sand and sediment along beaches; erosion of beaches on the low-energy side of jetties; nurturing a false sense of protection; interrupting the natural responsiveness and adaptation of natural systems; and misleading the true cost of property and structures. Figure 17.3 is an example of the type of erosion control detail that should be specified on plans.
Impact of coastal structure on shorelines along the southeast and southwest coasts of india
Published in ISH Journal of Hydraulic Engineering, 2022
V. Sundar, S. A. Sannasiraj, K. Murali, Vasanthakumar Singaravelu
Due to the extremely dynamic environment, there is an endless battle in progress between land and sea along the coast leading to the sea being the winner. Coastal erosion is caused due to natural factors, such as the waves, tidal cycle, current, and wind, among which the waves are dominant. Extreme storm events, such as typhoons and tsunamis, amplify the above process exhibiting its devastating effects. The sea-level rise is another severe threat to beaches which tends to expose a significant portion of the vulnerable coastal berms to inundation and tidal flushing that finally tends water to intrude into the land. The overall net sediment drift trend is influenced by wave characteristics such as wave period, breaker height and direction of wave incidence (Wright et al. 1986). A study on the sea breeze effect on the nearshore coastal process showed that the along and cross-shore drift increases due to an increased effect of sea breeze (Pattiaratchi and Masselink 1997). Littoral or longshore drift plays an important role in evaluating coastal processes such as erosion, accretion, and shoreline morphology (Kunte et al. 2001).
Long distance kelp-rafting of rocks around southern New Zealand
Published in New Zealand Journal of Geology and Geophysics, 2018
The coast of southern New Zealand is affected by large-scale ocean currents, the most prominent of which is the Southland Current (Figure 1a; Chiswell et al. 2015). This current results in a general northeastward drift of water and floating material along the southern and southeastern coastlines (Figure 1a). This current, combined with prevailing westerly winds, results in general east to northeastward longshore drift of sediments along the coastlines (Carter et al. 1985; Garden et al. 2011; Craw et al. 2013). North of Dunedin, the Southland Current diverts offshore to the east at the southern edge of the shallow submarine Chatham Rise (Figure 1a).