Land reclamation

Land reclamation, often known as reclamation, and also known as land fill (not to be confused with a waste landfill), is the process of creating new land from oceans, seas, riverbeds or lake beds. The land reclaimed is known as reclamation ground, reclaimed land, or land fill.
In ancient Egypt, the rulers of the Twelfth Dynasty (c. 2000–1800 BC) undertook a far-sighted land reclamation scheme to increase agricultural output. They constructed levees and canals to connect the Faiyum with the Bahr Yussef waterway, diverting water that would have flowed into Lake Moeris and causing gradual evaporation around the lake's edges, creating new farmland from the reclaimed land. A similar land reclamation system using dams and drainage canals was used in the Greek Copaic Basin during the Middle Helladic Period (c. 1900–1600 BC). Another early large-scale project was the Beemster Polder in the Netherlands, realized in 1612 adding 70 square kilometres (27 sq mi) of land. In Hong Kong, the Praya Reclamation Scheme added 20 to 24 hectares (50 to 60 acres) of land in 1890 during the second phase of construction. It was one of the most ambitious projects ever taken during the era of colonial Hong Kong. Some 20% of land in the Tokyo Bay area has been reclaimed, most notably Odaiba artificial island. The city of Rio de Janeiro was largely built on reclaimed land, as was Wellington, New Zealand.
Land reclamation can be achieved by a number of different methods. The simplest method involves filling the area with large amounts of heavy rock and/or cement, then filling with clay and dirt until the desired height is reached. The process is called "infilling" and the material used to fill the space is generally called "infill". Draining of submerged wetlands is often used to reclaim land for agricultural use. Deep cement mixing is used typically in situations in which the material displaced by either dredging or draining may be contaminated and hence needs to be contained. Land dredging is also another method of land reclamation. It is the removal of sediments and debris from the bottom of a body of water. It is commonly used for maintaining reclaimed land masses as sedimentation, a natural process, fills channels and harbors.
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Agriculture was a driver of land reclamation before industrialisation. In South China, farmers reclaimed paddy fields by enclosing an area with a stone wall on the sea shore near a river mouth or river delta. The species of rice that are grown on these grounds are more salt tolerant. Another use of such enclosed land is the creation of fish ponds. It is commonly seen on the Pearl River Delta and Hong Kong. These reclaimed areas also attract species of migrating birds.
A related practice is the draining of swampy or seasonally submerged wetlands to convert them to farmland. While this does not create new land exactly, it allows commercially productive use of land that would otherwise be restricted to wildlife habitat. It is also an important method of mosquito control.
Even in the post-industrial age, there have been land reclamation projects intended for increasing available agricultural land. For example, the village of Ogata in Akita, Japan, was established on land reclaimed from Lake Hachirōgata (Japan's second largest lake at the time) starting in 1957. By 1977, the amount of land reclaimed totalled 172.03 square kilometres (66.42 sq mi).
Artificial islands are an example of land reclamation. Creating an artificial island is an expensive and risky undertaking. It is often considered in places with high population density and a scarcity of flat land. Kansai International Airport (in Osaka) and Hong Kong International Airport are examples where this process was deemed necessary. The Palm Islands, The World and hotel Burj al-Arab off Dubai in the United Arab Emirates are other examples of artificial islands (although there is yet no real "scarcity of land" in Dubai), as well as the Flevopolder in the Netherlands which is the largest artificial island in the world.
Beach rebuilding is the process of repairing beaches using materials such as sand or mud from inland. This can be used to build up beaches suffering from beach starvation or erosion from longshore drift. It stops the movement of the original beach material through longshore drift and retains a natural look to the beach. Although it is not a long-lasting solution, it is cheap compared to other types of coastal defences. An example of this is the city of Mumbai.
As human overcrowding of developed areas intensified during the 20th century, it has become important to develop land re-use strategies for completed landfills. Some of the most common usages are for parks, golf courses and other sports fields. Increasingly, however, office buildings and industrial uses are made on a completed landfill. In these latter uses, methane capture is customarily carried out to minimize explosive hazard within the building.
An example of a Class A office building constructed over a landfill is the Dakin Building at Sierra Point, Brisbane, California. The underlying fill was deposited from 1965 to 1985, mostly consisting of construction debris from San Francisco and some municipal wastes. Aerial photographs prior to 1965 show this area to be tidelands of the San Francisco Bay. A clay cap was constructed over the debris prior to building approval.
A notable example is Sydney Olympic Park, the primary venue for the 2000 Summer Olympic Games, which was built atop an industrial wasteland that included landfills.
Another strategy for landfill is the incineration of landfill trash at high temperature via the plasma-arc gasification process, which is currently used at two facilities in Japan, and was proposed to be used at a facility in St. Lucie County, Florida. The planned facility in Florida was later canceled.
Draining wetlands for ploughing, for example, is a form of habitat destruction. In some parts of the world, new reclamation projects are restricted or no longer allowed, due to environmental protection laws. Reclamation projects have strong negative impacts on coastal populations, although some species can take advantage of the newly created area. A 2022 global analysis estimated that 39% of losses (approximately 5,300 km or 2,000 sq mi) and 14% of gains (approximately 1,300 km or 500 sq mi) of tidal wetlands (mangroves, tidal flats, and tidal marshes) between 1999 and 2019 were due to direct human activities, including conversion to aquaculture, agriculture, plantations, coastal developments and other physical structures.
The State of California created a state commission, the San Francisco Bay Conservation and Development Commission, in 1965 to protect San Francisco Bay and regulate development near its shores. The commission was created in response to growing concern over the shrinking size of the bay.
Hong Kong legislators passed the Protection of the Harbour Ordinance, proposed by the Society for Protection of the Harbour, in 1997 in an effort to safeguard the increasingly threatened Victoria Harbour against encroaching land development. Several large reclamation schemes at Green Island, West Kowloon, and Kowloon Bay were subsequently shelved, and others reduced in size.
Reclaimed land is highly susceptible to soil liquefaction during earthquakes, which can amplify the amount of damage that occurs to buildings and infrastructure. Subsidence is another issue, both from soil compaction on filled land, and also when wetlands are enclosed by levees and drained to create polders. Drained marshes will eventually sink below the surrounding water level, increasing the danger from flooding.