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76-829: The Hauraki Gulf / Tīkapa Moana is a coastal feature of the North Island of New Zealand . It has an area of 4000 km, and lies between, in anticlockwise order, the Auckland Region , the Hauraki Plains , the Coromandel Peninsula , and Great Barrier Island . Most of the gulf is part of the Hauraki Gulf Marine Park. Hauraki is Māori for north wind . In 2014, the gulf was officially named Hauraki Gulf / Tīkapa Moana. The New Zealand Ministry for Culture and Heritage gives

152-534: A navy and some form of coast guard . Coasts, especially those with beaches and warm water, attract tourists often leading to the development of seaside resort communities. In many island nations such as those of the Mediterranean , South Pacific Ocean and Caribbean , tourism is central to the economy . Coasts offer recreational activities such as swimming, fishing, surfing, boating, and sunbathing . Growth management and coastal management can be

228-478: A challenge for coastal local authorities who often struggle to provide the infrastructure required by new residents, and poor management practices of construction often leave these communities and infrastructure vulnerable to processes like coastal erosion and sea level rise . In many of these communities, management practices such as beach nourishment or when the coastal infrastructure is no longer financially sustainable, managed retreat to remove communities from

304-420: A fort at North Head and a military camp, Fort Cautley, at Narrow Neck . These were upgraded during World War II , and further gun emplacements were constructed at Castor Bay and other East Coast Bays areas to the north. The channel was last dredged from a depth of 11.2m to 12.5m in a two-stage process in 2004. The first stage involved the mechanical excavation of hard rock. Blasting was not required. This

380-655: A much higher capacity for carbon sequestration than many terrestrial ecosystems , and as such can play a critical role in the near-future to help mitigate climate change effects by uptake of atmospheric anthropogenic carbon dioxide . However, the economic importance of coasts makes many of these communities vulnerable to climate change , which causes increases in extreme weather and sea level rise, as well as related issues like coastal erosion , saltwater intrusion , and coastal flooding . Other coastal issues, such as marine pollution , marine debris , coastal development, and marine ecosystem destruction, further complicate

456-599: A number of (above-water) wildlife sanctuaries. Coastal feature Coasts are important zones in natural ecosystems , often home to a wide range of biodiversity . On land, they harbor important ecosystems such as freshwater or estuarine wetlands , which are important for bird populations and other terrestrial animals . In wave-protected areas, they harbor salt marshes , mangroves or seagrasses , all of which can provide nursery habitat for fin fish , shellfish , and other aquatic animals . Rocky shores are usually found along exposed coasts and provide habitat for

532-653: A proper name to the coast of the Ligurian Sea , in the form riviera ligure , then shortened to riviera . Historically, the Ligurian Riviera extended from Capo Corvo (Punta Bianca) south of Genoa , north and west into what is now French territory past Monaco and sometimes as far as Marseilles . Today, this coast is divided into the Italian Riviera and the French Riviera , although

608-435: A provider of sediment for coastlines of tropical islands. Like the ocean which shapes them, coasts are a dynamic environment with constant change. The Earth 's natural processes, particularly sea level rises , waves and various weather phenomena, have resulted in the erosion , accretion and reshaping of coasts as well as flooding and creation of continental shelves and drowned river valleys ( rias ). More and more of

684-607: A relatively common sight. There are approximately 25 species of marine mammals in the gulf. Nearly a third of the world's marine mammal species live in or visit the Marine Park. Among larger cetaceans , Bryde's whales are residents and relatively common in the Gulf, and their presence in these busily travelled waters leads to a large number of ship strikes, with sometimes several of the whales dying each year from collisions with shipping vessels or sport boats. The population remaining

760-456: A shoreline configuration. Swash is the shoreward flow after the break, backwash is the water flow back down the beach. The relative strength of flow in the swash and backwash determines what size grains are deposited or eroded. This is dependent on how the wave breaks and the slope of the shore. Depending on the form of the breaking wave, its energy can carry granular material up the beach and deposit it, or erode it by carrying more material down

836-425: A slightly different way in discussions of legal and economic boundaries (see territorial waters and international waters ) or when considering the geography of coastal landforms or the ecological systems operating through the continental shelf ( marine coastal ecosystems ). The research on coastal waters often divides into these separate areas too. The dynamic fluid nature of the ocean means that all components of

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912-594: A translation of "the mournful sea" for Tīkapa Moana . In traditional legend, the Hauraki Gulf is protected by a taniwha named Ureia, who takes the form of a whale. The gulf is part of the Pacific Ocean , which it joins to the north and east. It is largely protected from the Pacific by Great Barrier Island and Little Barrier Island to the north, and by the 80-kilometre-long Coromandel Peninsula to

988-529: A wide range of sessile animals (e.g. mussels , starfish , barnacles ) and various kinds of seaweeds . In physical oceanography , a shore is the wider fringe that is geologically modified by the action of the body of water past and present, while the beach is at the edge of the shore, representing the intertidal zone where there is one. Along tropical coasts with clear, nutrient-poor water, coral reefs can often be found between depths of 1–50 m (3.3–164.0 ft). According to an atlas prepared by

1064-541: Is a coastline that has experienced a fall in sea level, because of either a global sea-level change, or local uplift. Emergent coastlines are identifiable by the coastal landforms , which are above the high tide mark, such as raised beaches . In contrast, a submergent coastline is one where the sea level has risen, due to a global sea-level change, local subsidence , or isostatic rebound . Submergent coastlines are identifiable by their submerged, or "drowned" landforms, such as rias (drowned valleys) and fjords According to

1140-704: Is an area of the Hauraki Gulf in the Auckland Region of New Zealand 's North Island . The channel is north-east of the Waitematā Harbour , and is located between the North Shore and Rangitoto Island . The channel's traditional Ngāi Tai name is Te Awanui o Peretū , and is an important deep water shipping channel to reach the Ports of Auckland . The Rangitoto Channel is located in Auckland, between

1216-528: Is connected to marine pollution which can occur from a number of sources: Marine debris (garbage and industrial debris); the transportation of petroleum in tankers , increasing the probability of large oil spills ; small oil spills created by large and small vessels, which flush bilge water into the ocean. Marine pollution occurs when substances used or spread by humans, such as industrial , agricultural and residential waste , particles , noise , excess carbon dioxide or invasive organisms enter

1292-496: Is connected to the much older Motutapu Island by a causeway. The islands are separated from the mainland by the Tamaki Strait and Rangitoto Channel . Other islands in the gulf include Browns Island , Motuihe Island , Pakihi Island , Pakatoa Island , Rakino Island , and Rotoroa Island in the inner gulf, around Waiheke and Rangitoto; Tarahiki Island just east of Waiheke; Motukawao Islands and Whanganui Island in

1368-404: Is estimated to be between 100-200. In recent years, increases in numbers of migrating baleen whales are confirmed long after the end of hunting era. These are humpback whales , southern blue whales , pygmy blue whales , and southern minke whales . Less frequently, fin whales and sei whales are seen as well. For southern right whales , these whales will possibly become seasonal residents in

1444-415: Is extremely important to geologists. These provide vital clues for reconstructing the geography of ancient continents ( paleogeography ). The locations of these beds show the extent of ancient seas at particular points in geological time, and provide clues to the magnitudes of tides in the distant past. Sediments deposited in the shoreface are preserved as lenses of sandstone in which the upper part of

1520-408: Is more important. Macrotidal coasts lack barrier islands and lagoons , and are characterized by funnel-shaped estuaries containing sand ridges aligned with tidal currents. Wave action is much more important for determining bedforms of sediments deposited along mesotidal and microtidal coasts than in macrotidal coasts. Waves erode coastline as they break on shore releasing their energy; the larger

1596-423: Is moved along the coastline by the waves. This forms an abrasion or cliffed coast . Sediment deposited by rivers is the dominant influence on the amount of sediment located in the case of coastlines that have estuaries. Today, riverine deposition at the coast is often blocked by dams and other human regulatory devices, which remove the sediment from the stream by causing it to be deposited inland. Coral reefs are

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1672-412: Is the counterintuitive observation that the coastline of a landmass does not have a well-defined length. This results from the fractal curve –like properties of coastlines; i.e., the fact that a coastline typically has a fractal dimension . Although the "paradox of length" was previously noted by Hugo Steinhaus , the first systematic study of this phenomenon was by Lewis Fry Richardson , and it

1748-462: The Aegean Sea . The following articles describe some coastal landforms: "Coastal waters" (or "coastal seas") is a rather general term used differently in different contexts, ranging geographically from the waters within a few kilometers of the coast, through to the entire continental shelf which may stretch for more than a hundred kilometers from land. Thus the term coastal waters is used in

1824-510: The Coromandel Peninsula rise on either side of the Firth. Traditional Tāmaki Māori histories describe the naming of the gulf. The migratory canoes Tainui and Arawa left Raiatea at similar times, and both explored the Bay of Plenty area. The crew of both canoes met at Horuhoru Rock (Gannet Rock) , where a ceremony was held in memory for the relatives they had lost on the journey. During

1900-604: The North Shore and Rangitoto Island . During the Last Glacial Maximum (known locally as the Ōtira Glaciation), the area was a valley for the Waitematā River, which when sea levels rose between 12,000 and 7,000 years ago became the Waitematā Harbour . The channel is an important stretch of water as it is the only deep water approach to Auckland Port for large ships such as container cargo ships and passenger cruise liners. The traditional Ngāi Tai name for

1976-456: The US EPA considers this region to extend much further offshore. "Coastal waters" has specific meanings in the context of commercial coastal shipping , and somewhat different meanings in the context of naval littoral warfare . Oceanographers and marine biologists have yet other takes. Coastal waters have a wide range of marine habitats from enclosed estuaries to the open waters of

2052-617: The United Nations , about 44% of the human population lives within 150 km (93 mi) of the sea as of 2013 . Due to its importance in society and its high population concentrations, the coast is important for major parts of the global food and economic system, and they provide many ecosystem services to humankind. For example, important human activities happen in port cities. Coastal fisheries (commercial, recreational, and subsistence) and aquaculture are major economic activities and create jobs, livelihoods, and protein for

2128-686: The Western Interior Seaway , a shallow sea that flooded central North America during the late Cretaceous Period (about 100 to 66 million years ago). These are beautifully exposed along the Book Cliffs of Utah and Colorado . The following articles describe the various geologic processes that affect a coastal zone: Larger animals that live in coastal areas include puffins , sea turtles and rockhopper penguins , among many others. Sea snails and various kinds of barnacles live on rocky coasts and scavenge on food deposited by

2204-546: The Whangaparāoa Peninsula . Tiritiri Matangi Island is near the end of this peninsula. Further north, Kawau Island nestles under the Tawharanui Peninsula . Numerous beaches dot the shores of the gulf, many of them well known for swimming and surfing. During the last glaciation period the gulf was dry land, with the sea level being around 100–110 m (300 ft) lower than at present. The gulf

2280-469: The ocean and cause harmful effects there. The majority of this waste (80%) comes from land-based activity, although marine transportation significantly contributes as well. It is a combination of chemicals and trash, most of which comes from land sources and is washed or blown into the ocean. This pollution results in damage to the environment, to the health of all organisms, and to economic structures worldwide. Since most inputs come from land, either via

2356-596: The ocean . Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing aground, when it is known as beach litter or tidewrack. Deliberate disposal of wastes at sea is called ocean dumping . Naturally occurring debris, such as driftwood and drift seeds , are also present. With the increasing use of plastic , human influence has become an issue as many types of (petrochemical) plastics do not biodegrade quickly, as would natural or organic materials. The largest single type of plastic pollution (~10%) and majority of large plastic in

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2432-444: The rivers , sewage or the atmosphere, it means that continental shelves are more vulnerable to pollution. Air pollution is also a contributing factor by carrying off iron, carbonic acid, nitrogen , silicon, sulfur, pesticides or dust particles into the ocean. The pollution often comes from nonpoint sources such as agricultural runoff , wind-blown debris , and dust. These nonpoint sources are largely due to runoff that enters

2508-468: The 20th and early 21st century from human use. Although major study by the Hauraki Gulf Forum in 2011 found that all environmental indicators were still worsening or stable at problematic levels, voluntary coast clean-up groups have collected about 450,000 litres of litter collected from the shoreline, although further conservation efforts are required to maintain the environmental integrity of

2584-773: The French use the term "Riviera" to refer to the Italian Riviera and call the French portion the "Côte d'Azur". As a result of the fame of the Ligurian rivieras, the term came into English to refer to any shoreline, especially one that is sunny, topographically diverse and popular with tourists. Such places using the term include the Australian Riviera in Queensland and the Turkish Riviera along

2660-659: The Rangitoto Channel is Te Awanui o Peretū or "The Great Channel of Peretū", named after an early ancestor in Tāmaki Makaurau, who lived at Narrow Neck and kept a kākā parrot reserve on Rangitoto Island . The channel was visited by the Tainui migratory canoe after arriving in Tāmaki Makaurau. During the Russian scare of the 1880s, coastal fortifications were built along the Rangitoto Channel, including

2736-546: The United Nations has declared 2021–2030 the UN Decade on Ecosystem Restoration , but restoration of coastal ecosystems has received insufficient attention. Since coasts are constantly changing, a coastline's exact perimeter cannot be determined; this measurement challenge is called the coastline paradox . The term coastal zone is used to refer to a region where interactions of sea and land processes occur. Both

2812-571: The average sea level rose by 15–25 cm (6–10 in), with an increase of 2.3 mm (0.091 in) per year since the 1970s. This was faster than the sea level had ever risen over at least the past 3,000 years. The rate accelerated to 4.62 mm (0.182 in)/yr for the decade 2013–2022. Climate change due to human activities is the main cause. Between 1993 and 2018, melting ice sheets and glaciers accounted for 44% of sea level rise , with another 42% resulting from thermal expansion of water . International attention to address

2888-417: The average wind wave and swell conditions are relatively mild. Low energy coasts typically change slowly, and tend to be depositional environments. High energy coasts are exposed to the direct impact of waves and storms, and are generally erosional environments. High energy storm events can make large changes to a coastline, and can move significant amounts of sediment over a short period, sometimes changing

2964-515: The beaches and restore their vitality. Sections 7 and 8 of the Hauraki Gulf Marine Park Act 2000 state: 7 Recognition of national significance of Hauraki Gulf 8 Management of Hauraki Gulf The park is distinctly different from other conservation areas of New Zealand not only by being a marine environment, but because it is home to more than one million people along its shores and on its islands. It also contains

3040-404: The ceremony, a mauri stone brought with them on their voyage named Tīkapa was placed on the island. The name Tīkapa Moana was adopted for the surrounding ocean, and became the name of the gulf. Some particular common or known animals include bottlenose and common dolphins , the latter sometimes seen in "super schools" of 300-500 animals or more, while various species of whales and orcas are

3116-461: The coast of Wales and other countries. Coastal fish , also called inshore fish or neritic fish, inhabit the sea between the shoreline and the edge of the continental shelf . Since the continental shelf is usually less than 200 metres (660 ft) deep, it follows that pelagic coastal fish are generally epipelagic fish , inhabiting the sunlit epipelagic zone . Coastal fish can be contrasted with oceanic fish or offshore fish , which inhabit

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3192-812: The coast. Estuarine and marine coastal ecosystems are both marine ecosystems . Together, these ecosystems perform the four categories of ecosystem services in a variety of ways: The provisioning services include forest products, marine products, fresh water , raw materials, biochemical and genetic resources. Regulating services include carbon sequestration (contributing to climate change mitigation ) as well as waste treatment and disease regulation and buffer zones. Supporting services of coastal ecosystems include nutrient cycling , biologically mediated habitats and primary production . Cultural services of coastal ecosystems include inspirational aspects, recreation and tourism , science and education. According to one principle of classification, an emergent coastline

3268-567: The continental shelf. Similarly, the term littoral zone has no single definition. It is the part of a sea , lake , or river that is close to the shore . In coastal environments, the littoral zone extends from the high water mark , which is rarely inundated, to shoreline areas that are permanently submerged . Coastal waters can be threatened by coastal eutrophication and harmful algal blooms . The identification of bodies of rock formed from sediments deposited in shoreline and nearshore environments (shoreline and nearshore facies )

3344-555: The deep seas beyond the continental shelves. Many coastal areas are famous for their kelp beds. Kelp is a fast-growing seaweed that can grow up to half a meter a day in ideal conditions. Mangroves , seagrasses , macroalgal beds, and salt marsh are important coastal vegetation types in tropical and temperate environments respectively. Restinga is another type of coastal vegetation. Coasts also face many human-induced environmental impacts and coastal development hazards . The most important ones are: The pollution of coastlines

3420-560: The dredging having destroyed the seafloor, and sediment drainage from the agriculture in the Firth of Thames affecting the mussel's viability. Numerous beaches dot the shores of the gulf, many of them well known for swimming and surfing. Although environmental problems exist around urban areas, with 14 out of 52 beaches in the Auckland Region at least occasionally showing unsafe pollution levels (mostly because of untreated sewage ) for bathing, environmental groups are working to clean

3496-550: The east. It is thus well protected against all but northern winds. Three large channels join the gulf to the Pacific. Colville Channel lies between the Coromandel Peninsula and Great Barrier, Cradock Channel lies between the two islands, and Jellicoe Channel lies between Little Barrier and the North Auckland Peninsula . To the north of Auckland several peninsulas jut into the gulf, notably

3572-406: The food chain, led to further degradation, such as a widespread disappearance of kelp beds as they were overtaken by kina barrens. Trawler fishing in general is seen as severely damaging the gulf, and lobster stock are also reported as not rebuilding. It is estimated that today's fish stocks are around 25% of pre-European levels. Also particularly damaging are the results of nitrogen carried into

3648-436: The gulf as the populations recover (one of two of the first confirmed birth records on New Zealand's main islands since after commercial and illegal whalings were recorded at around Milford and Browns Bay in 2012). Sperm whales visit occasionally. Many of the islands are official or unofficial bird sanctuaries, holding important or critically endangered species like kiwi, takahe, brown teal and grey-faced petrel. Centred on

3724-464: The gulf from surrounding agricultural land, with almost 90% coming from the dairy-farming runoff into the Firth of Thames . Other exploitation such as the dredging of the mussel beds of the Firth of Thames, reaching its height in 1961 with an estimated 15 million mussels taken (shortly before collapse of the industry) have led to damage which has not been recovered from forty years later, possibly due to

3800-405: The gulf. Particularly damaging were the introduction of industrialised fishing , with for example snapper fishing peaking in the 1970s at more than 10,000 tonnes a year (though even in the 2000s, private fishing of this species is also a considerable factor, weighing in at 400–800 tonnes a year). This severe overfishing, which unbalanced the marine environment by the removal of a main predator in

3876-789: The human uses of the coast and threaten coastal ecosystems. The interactive effects of climate change, habitat destruction , overfishing , and water pollution (especially eutrophication ) have led to the demise of coastal ecosystem around the globe. This has resulted in population collapse of fisheries stocks, loss of biodiversity , increased invasion of alien species , and loss of healthy habitats. International attention to these issues has been captured in Sustainable Development Goal 14 "Life Below Water", which sets goals for international policy focused on preserving marine coastal ecosystems and supporting more sustainable economic practices for coastal communities. Likewise,

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3952-399: The lee of the Coromandel Peninsula; and Channel Island in the outer gulf. In March 2020, a small excavation was carried out in a large coastal midden on Otata Island. In January 2018, huge swells in the Hauraki Gulf caused widespread damage to its coastal areas and in only a few hours, the coastline or Otata had been reduced by up to 5 meters, exposing the midden. The aim of the excavation

4028-416: The main conservation island of Tiritiri Matangi and Little Barrier Island , numerous bird species that were locally extinct have been reintroduced in the last decades, while there have also been some naturally occurring bird "re-colonisations", especially after introduced pests were removed from breeding and nesting grounds. The gulf is a vibrant natural environment, which has seen significant damage during

4104-410: The majority of coastal human populations. Other coastal spaces like beaches and seaside resorts generate large revenues through tourism . Marine coastal ecosystems can also provide protection against sea level rise and tsunamis . In many countries, mangroves are the primary source of wood for fuel (e.g. charcoal ) and building material. Coastal ecosystems like mangroves and seagrasses have

4180-673: The margins of the continental shelves , make up about 7 percent of the Earth's oceans, but at least 85% of commercially harvested fish depend on coastal environments during at least part of their life cycle. As of October 2010, about 2.86% of exclusive economic zones were part of marine protected areas . The definition of coasts varies. Marine scientists think of the "wet" (aquatic or intertidal ) vegetated habitats as being coastal ecosystems (including seagrass, salt marsh etc.) whilst some terrestrial scientists might only think of coastal ecosystems as purely terrestrial plants that live close to

4256-587: The microplastics go through the water filtration system and into the ocean, but because of their small size they are likely to escape capture by the preliminary treatment screens on wastewater plants. These beads are harmful to the organisms in the ocean, especially filter feeders, because they can easily ingest the plastic and become sick. The microplastics are such a concern because it is difficult to clean them up due to their size, so humans can try to avoid using these harmful plastics by purchasing products that use environmentally safe exfoliates. Between 1901 and 2018,

4332-507: The more resistant rocks erode more slowly, remaining as headlands or outcroppings . Parts of a coastline can be categorised as high energy coast or low energy coast. The distinguishing characteristics of a high energy coast are that the average wave energy is relatively high so that erosion of small grained material tends to exceed deposition, and consequently landforms like cliffs, headlands and wave-cut terraces develop. Low energy coasts are generally sheltered from waves, or in regions where

4408-441: The ocean through rivers, but wind-blown debris and dust can also play a role, as these pollutants can settle into waterways and oceans. Pathways of pollution include direct discharge, land runoff, ship pollution , bilge pollution , atmospheric pollution and, potentially, deep sea mining . Marine debris , also known as marine litter, is human-created solid material that has deliberately or accidentally been released in seas or

4484-485: The oceans is discarded and lost nets from the fishing industry. Waterborne plastic poses a serious threat to fish , seabirds , marine reptiles , and marine mammals , as well as to boats and coasts. A growing concern regarding plastic pollution in the marine ecosystem is the use of microplastics. Microplastics are beads of plastic less than 5 millimeters wide, and they are commonly found in hand soaps, face cleansers, and other exfoliators. When these products are used,

4560-493: The plains, turning east and exiting towards the Pacific Ocean along the modern-day Colville Channel between the Coromandel Peninsula and Great Barrier Island. In the west of the gulf lie a string of islands guarding the mouth of the Waitematā Harbour , one of Auckland's two harbours. These include Ponui Island , Waiheke Island , Tiritiri Matangi and the iconic dome of Rangitoto Island (a dormant volcano ), which

4636-416: The sandstone is coarser than the lower part (a coarsening upwards sequence ). Geologists refer to these are parasequences . Each records an episode of retreat of the ocean from the shoreline over a period of 10,000 to 1,000,000 years. These often show laminations reflecting various kinds of tidal cycles. Some of the best-studied shoreline deposits in the world are found along the former western shore of

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4712-579: The sea. Some coastal animals are used to humans in developed areas, such as dolphins and seagulls who eat food thrown for them by tourists. Since the coastal areas are all part of the littoral zone , there is a profusion of marine life found just off-coast, including sessile animals such as corals , sponges, starfish, mussels, seaweeds, fishes, and sea anemones . There are many kinds of seabirds on various coasts. These include pelicans and cormorants , who join up with terns and oystercatchers to forage for fish and shellfish. There are sea lions on

4788-401: The seashore (see also estuaries and coastal ecosystems ). While there is general agreement in the scientific community regarding the definition of coast, in the political sphere, the delineation of the extents of a coast differ according to jurisdiction . Government authorities in various countries may define coast differently for economic and social policy reasons. The coastline paradox

4864-427: The second principle of classification, a concordant coastline is a coastline where bands of different rock types run parallel to the shore. These rock types are usually of varying resistance , so the coastline forms distinctive landforms, such as coves. Discordant coastlines feature distinctive landforms because the rocks are eroded by the ocean waves . The less resistant rocks erode faster, creating inlets or bay ;

4940-404: The slope than up it. Steep waves that are close together and break with the surf plunging down onto the shore slope expend much of their energy lifting the sediment. The weak swash does not carry it far up the slope, and the strong backwash carries it further down the slope, where it either settles in deeper water or is carried along the shore by a longshore current induced by an angled approach of

5016-758: The terms coast and coastal are often used to describe a geographic location or region located on a coastline (e.g., New Zealand's West Coast , or the East , West , and Gulf Coast of the United States .) Coasts with a narrow continental shelf that are close to the open ocean are called pelagic coast , while other coasts are more sheltered coast in a gulf or bay . A shore , on the other hand, may refer to parts of land adjoining any large body of water, including oceans (sea shore) and lakes (lake shore). The Earth has approximately 620,000 kilometres (390,000 mi) of coastline. Coastal habitats, which extend to

5092-491: The threats of coasts has been captured in Sustainable Development Goal 14 "Life Below Water" which sets goals for international policy focused on preserving marine coastal ecosystems and supporting more sustainable economic practices for coastal communities. Likewise, the United Nations has declared 2021–2030 the UN Decade on Ecosystem Restoration , but restoration of coastal ecosystems has received insufficient attention. Rangitoto Channel The Rangitoto Channel

5168-487: The wave the more energy it releases and the more sediment it moves. Coastlines with longer shores have more room for the waves to disperse their energy, while coasts with cliffs and short shore faces give little room for the wave energy to be dispersed. In these areas, the wave energy breaking against the cliffs is higher, and air and water are compressed into cracks in the rock, forcing the rock apart, breaking it down. Sediment deposited by waves comes from eroded cliff faces and

5244-476: The wave-front to the shore. These waves which erode the beach are called destructive waves. Low waves that are further apart and break by spilling , expend more of their energy in the swash which carries particles up the beach, leaving less energy for the backwash to transport them downslope, with a net constrictive influence on the beach. Riviera is an Italian word for "shoreline", ultimately derived from Latin ripa ("riverbank"). It came to be applied as

5320-407: The waves surge up the river estuaries from the ocean. Geologists classify coasts on the basis of tidal range into macrotidal coasts with a tidal range greater than 4 m (13 ft); mesotidal coasts with a tidal range of 2 to 4 m (6.6 to 13 ft); and microtidal coasts with a tidal range of less than 2 m (7 ft). The distinction between macrotidal and mesotidal coasts

5396-469: The whole ocean system are ultimately connected, although certain regional classifications are useful and relevant. The waters of the continental shelves represent such a region. The term "coastal waters" has been used in a wide variety of different ways in different contexts. In European Union environmental management it extends from the coast to just a few nautical miles while in the United States

5472-482: The world's people live in coastal regions. According to a United Nations atlas, 44% of all people live within 150 km (93 mi) of the sea. Many major cities are on or near good harbors and have port facilities. Some landlocked places have achieved port status by building canals . Nations defend their coasts against military invaders, smugglers and illegal migrants. Fixed coastal defenses have long been erected in many nations, and coastal countries typically have

5548-770: Was a stream formed by the major Hauraki Plains rivers: the Waihou River , Piako River and Waitakaruru River . Prior to the Oruanui eruption 27,000 years ago, the Waikato River also flowed into the Hauraki Gulf at the Firth of Thames . The Hauraki Plains rivers were met by two tributaries, the Wairoa River to the west from modern-day Clevedon and the Umangawha Stream to the east, at Colville , Coromandel Peninsula . This river flowed north, along

5624-441: Was expanded upon by Benoit Mandelbrot . Tides often determine the range over which sediment is deposited or eroded. Areas with high tidal ranges allow waves to reach farther up the shore, and areas with lower tidal ranges produce deposition at a smaller elevation interval. The tidal range is influenced by the size and shape of the coastline. Tides do not typically cause erosion by themselves; however, tidal bores can erode as

5700-518: Was submerged when the sea reached its current level around 7200 years ago. During this period, the area was home to two river systems. The first of these was a river formed by two tributaries, the Mahurangi River and Waitematā Harbour (then a river) acting as tributaries. This river flowed north-east between modern day Little Barrier Island and Great Barrier Island , and emptied into the Pacific Ocean north of Great Barrier Island. The second

5776-505: Was to record this information before it is lost to erosion and was carried out in partnership with Ngāi Tai ki Tāmaki , the landowners. An understanding the changing marine environment around the island will also form part of the work. At the southern end of the gulf is the wide, relatively shallow Firth of Thames . Beyond this lie the Hauraki Plains , drained by the Waihou River and the Piako River . The Hunua Ranges and hills of

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