Talk:Longshore drift

Spelling

Someone spelt Prevailing (as in prevailing wind) wrong in the diagram at the top of the page

Longshore Drift is mainly the act of Transportation of sediments of sand and stone down a beach. — Preceding unsigned comment added by Gabriel54321 (talk • contribs) 20:32, 1 October 2011 (UTC)

I have been researching updated material to add to this information. I do see majority is a but out of date. However, I did run across a journal with ten years of study. I will continue to search. If there is anything anyone would like to collaborate on, please let know. — Preceding unsigned comment added by ~2026-58340-9 (talk) 04:25, 27 January 2026 (UTC)

Request for verifiable references

Although the article reads and looks pleasantly, there are no references to the various claims made regarding the processes producing longshore drift.

• References to cross-shore drift effects are missing.
• The article mainly focuses on the effects of waves in the swash zone, from a linear point of view.
• (Tidal) current effects are hardly mentioned.
• There is little emphasis on the different relevant processes in the swash zone and in the rest of the surf zone.
• The terms constructive process and destructive process are misleading, since they suggest these are processes, while they only point to the net effects of several competing processes.

Since I am not an expert on sediment transport, I feel uncomfortable with adapting the article myself. Crowsnest (talk) 10:39, 4 March 2008 (UTC)

Londshore drift doesn't actually exist! It is merely a simplification for GCSE geography pupils. Longshore Current (which does exist) should be added to the article, with this explained. —Preceding unsigned comment added by 128.243.220.41 (talk) 18:38, 20 May 2008 (UTC)

Human Interaction

Humans in their need for costal real-estate often create structures to slow or stop natural processes such as long shore drift. The most common way that humans attempt to stop long shore drift is with a system of Groynes. The problem with groins is that they often accelerate erosion of the down-drift (the part of the beach closest to the groyne that has the waves coming from that same direction) beech. The groyne will create a side with very little sand and the other side will fill with the sand from the side that is loosing its mass. However the sand will eventually reach the top of the groyne and start the natural prosecies of longshore drift all over again. This leaves the beaches looking like the blades of a saw with deep depressions and long points. Groynes cause accelerated erosion the the beach and are not a viable way to stop beach erosion. —Preceding unsigned comment added by Acejohnson15678 (talk • contribs) 18:09, 16 May 2008 (UTC)

I agree I have also found information on the significant influence human activities have on natural shoreline processes, often times disrupting the longshore sediment transport and coastal equilibrium. Coastal structures are created to protect property from erosion like seawalls, but they can also alter wave action, and reduce sediment production and exacerbate erosion in other areas, Groynes and Jetties have been built perpendicular to the beaches shoreline to entrap sand, and interrupt the natural Longshore Drift; this leads to sediment accumulation on one side and erosion on the other. Lgorman0812 (talk) 00:58, 14 February 2026 (UTC)

beach drift vs. longshore drift

This article explains "beach drift" rather than "longshore drift". Longshore drift occurs off the beach, in the surf zone. It is simply the parallel-to-shore movement of sand carried by longshore current. Anyone who has felt their body being pushed by longshore current has also had their cut-off jean or swim suit pockets filled with sand carried by that current. Nelsonrockefeller64 (talk) 17:47, 8 November 2009 (UTC)nelsonrockefeller 8 Nov, 2009

Town created by LS Drift?

"Provincetown, Massachusetts, was formed by longshore drift after the end of the last Ice Age. It is still growing today"

What the town itself created by Longshore drift? I propose we change this to: "The land of which the town of Provincetown, Massachusetts,was build upon was formed by longshore drift after the end of the last Ice Age. And It is still growing today.

or something simular. —Preceding unsigned comment added by 92.14.251.11 (talk) 20:28, 16 November 2009 (UTC)

I've made an adjustment. Is that better? Feline Hymnic (talk) 21:03, 17 November 2009 (UTC)

The original statement correctly asserts that the entire town was indeed created exclusively by littoral drift, and is unique amongst the Cape towns in that regard. To wit:

The portion of Truro north of High Head and all of the Provincetown land area are not glacially derived. These areas consist of material derived from coastal erosion of the glacial outwash plains, transported northward, and redeposited by marine and eolian action as a series of recurved sand spits and dunes during the last 6,000 years (Ziegler et al., 1965).
— Cape Cod National Seashore, http://www2.nature.nps.gov/geology/parks/caco/#geology

 —Grollτech (talk) 18:29, 13 August 2014 (UTC)

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Concentration of examples

There are an inordinate number of examples of longshore drift from New Zealand in the article, and virtually none from anywhere else. Can we get some sourced examples from a few other places? Acroterion (talk) 12:03, 28 March 2018 (UTC)

Wiki Education assignment: Global Environmental Science

This article was the subject of a Wiki Education Foundation-supported course assignment, between 9 January 2026 and 7 March 2026. Further details are available on the course page. Student editor(s): Lgorman0812 (article contribs). Peer reviewers: Kristopa.

— Assignment last updated by User104416 (talk) 16:38, 10 February 2026 (UTC)

This is some information I would like to add/ change on the topic Longshore Drift. I will post the information I have gathered so far, and I will also post a bit of an outline I am going by to ensure I do not leave any information out that I would like to add to this page to get it a little more up to date, with tested data and a few topics that are not included in the current article.

Longshore Drift Outline

The existing article provides a basic definition on longshore drift but lacks depth in explanation, particularly regarding the physical processes that drive it (wave approach, angle swash/backwash dynamics). Shorelines are shaped by waves, currents, and tides, which drive most coastal processes. A major factor in forming coastal landforms is the movement of sand by longshore drift, along with long-term changes in sea level. The shoreline—where land meets water—is divided into five zones, and the processes occurring there are known as littoral processes.

Waves usually approach the shore at an angle, causing wave refraction, which bends waves toward the beach. This refraction creates longshore currents and longshore drift, transporting sand parallel to the coast. When this sand is deposited in calmer water, it can form features such as spits and baymouth bars that may block bays and harbors. Human structures like jetties and groins are often built to keep harbors open or retain beach sand, but they disrupt natural sediment movement.

Coasts can be emergent when sea level falls or submergent when sea level rises. Ocean circulation also plays a key role in coastal and global processes. Surface currents form large circular gyres, rotating clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. Deep-ocean circulation is driven by differences in temperature and salinity, creating dense water that sinks and flows as part of the global conveyor belt.

Tides are the daily rise and fall of sea level caused by the gravitational pull of the Moon and Sun. There are three tidal patterns—diurnal, semidiurnal, and mixed—with average tidal ranges around 1 meter and extreme ranges reaching up to 18 meters. (Nesser adapted by Laura).

Real-World Impacts (Coastal Erosion, Accretion, Human Infrastructure):

The study analyzed satellite data over 32 years (1984–2015) to measure how shorelines worldwide have changed. It found that about 28,000 km² of coastal land has been lost to the sea, nearly twice the amount of land gained through coastal accretion during the same period, leading to a net loss of about 14,000 km² of land that could otherwise support human settlements and ecosystems.

Key impacts include:

• Coastal erosion dominates over accretion in most regions, meaning more land is being permanently submerged or converted to active shoreline zones than is being built up.
• Human activities are major drivers of these changes. Coastal infrastructure such as ports, dams, irrigation networks, and mangrove removal alters sediment supply and movement, often worsening erosion. Examples include large losses in the Indus and Mekong river deltas where dam construction and reduced sediment flow have deepened erosion.
• Natural disasters intensify impacts. Extreme storms, tsunamis, and tropical cyclones cause dramatic, localized losses (e.g., over 1 km of shoreline retreat in some areas after major storm events).
• Rising sea levels (relative sea-level rise) increase vulnerability to erosion, especially in low-lying coastal cities and islands, sometimes forcing relocation of infrastructure and communities.
• Accretion still occurs in places where land is naturally uplifting (like Hudson Bay) or sediment supply remains high, but these gains are smaller and less widespread than erosive losses.

Overall, the paper shows that coastal erosion outpaces land gain globally—a trend linked to both human infrastructure and climate change—which stresses the need for improved coastal planning and adaptation strategies ( Mentashki, Lorenzo).  I would like to add this updated information to the Wikipedia page. The information seems outdated, and this was a very long study proving the information to be updated, true and accurate.

I want to add into the article how wave angles transport sediment to the shoreline. This study examines how wave action sorts beach sediment both across and along the shoreline, forming layers of finer and coarser material depending on wave climate, grain size, and beach slope. To simplify this complex process, the researchers focus on longshore sorting, which is controlled by the angle at which waves break relative to the coast.

Using three-dimensional wave-basin experiments with regular waves and different sand beds, the study measures how sediment grain sizes are redistributed along the shore and how beach profiles change. Results show that obliquely breaking waves create diagonal swash and seaward backwash, combined with longshore currents, which transport sediment parallel to the shoreline, a process known as longshore drift. Over time, this causes finer sediments to move downdrift, while coarser grains remain or accumulate updrift, forming armored beach sections.

The experiments demonstrate that non-uniform grain sizes strongly influence sediment transport rates, meaning that grain sorting plays a major role in how much and how fast sediment moves along a beach. This behavior is similar to sediment sorting in river channels and helps explain why grain size varies spatially along coastlines. Longshore transport is most effective when waves approach the shoreline at angles of roughly 45–50 degrees.

Overall, the study highlights that sediment sorting is a key control on longshore sediment transport, and that accounting for grain-size variability improves predictions of coastal change, especially for practical applications such as beach nourishment and coastal engineering. (Science Direct).

How Longshore Drift Interacts with Sediment Budgets and Coastal Equilibrium:

This article explains sediment budgets as a way to understand how landscapes evolve through the balance of sediment inputs, transport, storage, and outputs, a framework that applies directly to coastal systems influenced by longshore drift. At its core, a sediment budget is governed by mass conservation: sediment entering a system must either leave it or be stored within it. When this balance is disturbed, landforms adjust until a new equilibrium is reached.

In coastal environments, longshore drift functions as the primary transport mechanism within the sediment budget, redistributing sand parallel to the shoreline. Beaches remain in dynamic equilibrium when sediment supplied to a stretch of coast (from rivers, cliff erosion, offshore sources, or updrift transport) is balanced by sediment removed through downdrift transport or offshore losses. If longshore drift exports more sediment than is supplied, beaches experience erosion and shoreline retreat. If sediment input exceeds removal, accretion occurs, widening beaches or forming depositional features such as spits and barrier bars.

The article emphasizes that sediment storage is as important as transport. In coastal systems, sand can be temporarily stored in dunes, nearshore bars, or tidal shoals. Longshore drift may move sediment into or out of these storage zones, altering shoreline shape without immediate erosion or accretion. Changes in storage can therefore delay or amplify coastal responses to changes in wave climate or sediment supply.

A key insight is that imbalances in sediment budgets drive morphological change. Just as rivers aggrade or degrade when sediment supply and transport capacity are mismatched, coastlines adjust when longshore transport capacity exceeds or falls short of sediment availability. Human interventions, such as jetties, groins, dams that reduce river sediment supply, or beach nourishment, modify sediment inputs and pathways, often disrupting coastal equilibrium and shifting erosion downdrift.

Overall, the article highlights that sediment budgets provide a conceptual and practical framework for understanding coastal equilibrium. Longshore drift links different sections of the coast into an interconnected system, meaning changes in sediment supply or transport at one location can produce delayed but significant impacts elsewhere along the shoreline. (USDA)

Human Impacts and Coastal Management

Human activities significantly influence natural shoreline processes, often disrupting longshore sediment transport and coastal equilibrium. Coastal structures such as seawalls are designed to protect property from erosion, but they can alter wave action, reduce sediment production, and exacerbate erosion in adjacent areas. Groins and jetties, built perpendicular to the shore to trap sand, interrupt natural longshore drift, leading to sediment accumulation on one side and erosion on the downdrift side. Dams trap sediment that would normally replenish beaches, increasing coastal erosion and reducing the formation of depositional features like spits or baymouth bars. Beach nourishment, which involves adding sand from other locations, can temporarily widen beaches but may introduce foreign materials and disrupt local ecosystems. Breakwaters calm water for harbors but interfere with sediment transport, causing sediment build-up behind the structures and depriving nearby beaches of sand. Collectively, these interventions illustrate the challenge of managing coastlines to protect human interests while maintaining natural coastal processes. (R. Adam Dastrup, MA.)

Works Cited

Neser, adapted by Laura. “Coastlines.” Introduction to Earth Science, Virginia Tech Department of Geosciences in association with Virginia Tech Publishing, 13 Dec. 2022, pressbooks.lib.vt.edu/introearthscience/chapter/12-shorelines/?utm_source=chatgpt.com.

Mentaschi, Lorenzo, et al. “Global Long-Term Observations of Coastal Erosion and Accretion.” Nature News, Nature Publishing Group, 27 Aug. 2018, www.nature.com/articles/s41598-018-30904-w.

Https://Www.Sciencedirect.Com/Science/Article/Abs/Pii/S1051200421000968 | Request PDF, www.researchgate.net/publication/351163114_httpswwwsciencedirectcomsciencearticleabspiiS1051200421000968. Accessed 7 Feb. 2026.

USDA, www.fs.usda.gov/psw/publications/reid/psw_2016_reid001.pdf. Accessed 7 Feb. 2026.

R. Adam Dastrup, MA. “7.6 Human Interference with Shorelines.” Physical Geography and Natural Disasters, 1 June 2020, slcc.pressbooks.pub/physicalgeography/chapter/7-6/.

BRIEF OUTLINE ON WHAT CHANGES WILL BE MADE

I. I would like to Identify Content Gaps in the Depth of Explanation on the wave approach, angle, and swash/backwash), and also add into this article real world impacts such as coastal erosion, beach accretion, and effects of human infrastructure.

II. Planned Source Based Additions- Clarify how oblique wave angles generate sediment transport parallel to the shoreline. This addition fills the gap between a surface level explanation and scientifically accurate description.

I wouldd like to add sediment budgets and coastal equilibrium. Differences in sediment movement based on grain size and wave energy, this will help improve this articles quality by connecting longshore drift to broader coastal system concepts.

III. Human Impact and Coastal Management- This information will talk about the effects of groins, jetties and seawalls on longshore sediment transport. Case studies where interference with longshore drift caused increased erosion down drift. These topics address a major content gap linking the process to coastal engineering and environmental consequences .

My goal is to reorganize this article into clearer sections such as: Definition, Physical Processes, Sediment Transport, Human Interactions, and Environmental Impacts, to ensure a smoother transition between sections, to hopefully improve readability for general audience. Lgorman0812 (talk) 07:27, 7 February 2026 (UTC)