Land reclamation
Land reclamation, usually 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 or land fill. In some jurisdictions, including parts of the United States, the term "reclamation" can refer to returning disturbed lands to an improved state. In Alberta, Canada, for example, reclamation is defined by the provincial government as "The process of reconverting disturbed land to its former or other productive uses." In Oceania, it is frequently  referred to as land rehabilitation. Methods. 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. Notable instances. Oceania. One of the earliest large-scale projects was the Beemster Polder in the Netherlands, realized in 1612 adding of land. In Hong Kong the Praya Reclamation Scheme added of land in 1890 during the second phase of construction. It was one of the most ambitious projects ever taken during the Colonial Hong Kong  era. Some 20% of land in the Tokyo Bay area has been reclaimed, most notably Odaiba artificial island. Le Portier, Monaco and Gibraltar are also expanding due to land reclamation. The city of Rio de Janeiro was largely built on reclaimed land, as was Wellington, New Zealand. 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. Agriculture. 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 . Beach restoration. 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. Landfill. 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 will be used at a planned facility in St. Lucie County, Florida. Environmental impact. 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. Environmental legislation. 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. Dangers. 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.