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Land Reclamation

Kiran Swati, Architect

What Ails Us?

Around 70% of the earth's surface is water. Some interesting facts about the remaining 30% are: The total surface area of the earth, is 5.101x10⁸ Sq Km.Based on population estimates in 1900 the area per person (density) was 21 acres. By 2005 it had shrunk to 5 acres with 6.5 billion people inhabiting our planet. The world population by 2039 is predicted to be anywhere between 8.0 -13 billion which would bring down area per person to 2.81 acres per person. The calculation is based on all earth's land. However to get a realistic picture we have to leave out the poles and other inhospitable terrain.

Historically, humans have preferred to settle in areas close to water and land density in these areas becomes much higher. This is also the case when urban areas are contained due to geographical, commercial or other reasons.  Some urban centres show alarming statistics of 'humans per square kilometre' based on the area of the city: Singapore 8350; Mexico City 8400; Cairo 9400; Bangalore 10100; Manila 10550; Beijing 11500; Shenzhen 17150; Karachi 18900; Mumbai 26950.

With carbon emissions causing the greenhouse effect affecting world weather, the result is climatic changes that affect agriculture giving rise to food shortages; and rising sea levels requiring communities to shift inland as the coastline is over-run by the incoming water. Some crowded cities have barely enough infrastructures to sustain themselves and are choking with the resultant pollution and struggling with the poor quality of life.

The Panacea

One solution is land reclamation which is the process of creating land from water bodies like oceans and river beds. In some parts of the world it is also relevant to returning disturbed land such as mined areas to an improved or productive state. Often areas that are deforested or rendered inhospitable due to nuclear or chemical contamination are given a new lease of life and this process is also referred to as land rehabilitation. Some areas that have too many contours or have many internal cavities are unstable and are more useful if reclaimed by levelling.

Since reclaimed land is used for various purposes the methods to make it habitable used also differ. The most common ones are:

• Filling the submerged area with heavy rocks
• Using a mixture of rocks and cement and topping with clay and dirt.
• Draining off water from wetlands.
• Deep cement mixing involves injecting the land with cement to stabilize the base when topsoil cannot be excavated due to contamination.
• In some areas further denudation can be halted by planting trees that hold the topsoil and prevent erosion.
• Areas like sand and gravel pits which have been excavated for use in construction can be refilled with appropriate geologically complementary filling so that the covered pit can then be used.
• If a site is being re-contoured for vegetation it is critical to use a landfill that is organic and promotes re-growth by recognised Bioengineering methods.
• Cement mixed soil is often used with artificially produced Geotextiles with sufficient tensile strength to act as an intermediary layer between soils.
• Refuse, sludge and clay are often components of filler materials in areas where there is a shortage of other materials. These are used once they are treated, are environmentally stable and cost effective.
• A hydraulic filling using a marine source is a common method where suction dredgers can supply large amounts of materials. Densification is necessary to avoid settlement of the compacted area.

Concerns

Earthquakes cause soil liquefaction in reclaimed land. The saturated soil loses its stiffness and strength due to the tremors and behaves like quicksand. Landslides on slopes that have not been appropriately stabilised are an imminent danger. Geologists are also concerned if subsidence occurs to reclaimed land where by it settles or shifts downwards in relation to the surrounding area e.g.- sea level. This movement can happen by soil compaction which occurs when heavy weights push out the water between the land particles and make it dense. Land reclaimed by draining wetlands is protected by dikes but there is always a danger of the surrounding water levels rising above this area and eventually flooding it. Often ground water gets polluted by drainage or leaching of pollutants into it from industrial units. During coastal reclamation aquatic habitat is affected and shoreline changes occur. These are detrimental to the environment and should be kept in mind.

Artificial Islands

Most reclaimed lands are derelict areas that are already inland or areas that are added to a shoreline. Artificial islands as the name suggests are built up land that are stand alone, away from the mainland. Geologically speaking it is created by man rather than by natural means. However nature lends a helping hand as artificial islands are often constructed on reefs, islets or combining many smaller naturally occurring bits of land into one large island. When this concept was initially applied the artificial islands were floating structures. With time, technology and innovation land reclamation has allowed for creation of artificial islands with sizes that vary from supporting just one structure to housing complete communities.

Living Examples

Some examples of countries that have successfully reclaimed land are: The Netherlands has 1/6 of its area below sea level, in lakes, marshes and swamps and has reclaimed it to effective use; South Korea has reclaimed almost 40% of its coastal wetlands; Singapore - by 2009 already more than 22% of its original size had been reclaimed. Further reclamation is on-going in spite of a dispute with Malaysia over some issues pertaining to these projects; Hong Kong has added almost sixty acres that house the International airport, Disneyland as well as smaller new townships; Macau began as 2.78 square kilometres and was 29.7 square kilometres by 2009 due to reclamation; Mumbai developed as a harbour city by joining of several independent islands; New Zealand’s Wellington harbour has added several hectares to its shoreline to become the successful waterfront development that it is today. Inland rehabilitation is just as useful to countries that depend on arable land for successful agriculture. The story of Egypt is worth mentioning here. Once desert land was reclaimed it made a huge difference to not only food production but also to the new life it gave to settlers in the region with new opportunities in the social and economic sense.

International Acclaim

In the recent past the United Arab Emirate’s reclamation projects have been the cynosure of all eyes. It is home to several artificial islands as well as the famous Palm Islands, the World islands, the Dubai Marina and the Burj Al Arab. The Palm islands were proposed to generate revenue through tourism and the reclaimed land is built up only of rock and sand to make it natural. In fact the scale of the projects is understandable by the fact that the Palm Jumeirah is visible from the International Space Station! The Burj Al Arab meaning the Arabian Tower is constructed on artificial island 280 metres offshore. At 321metres, it is the world’s tallest seven star hotel. To make the sand and rock island stable the foundation comprises of 230 cement piles each 40 metres long that were driven into the sand. Since these piles do not reach bedrock they are held in place by the friction of the surrounding sand and silt with the piles. Large rocks were then put in place to counteract the sea's strong erosive forces. It took three years to reclaim this area from the sea before the construction of the hotel could commence.

The challenges of being a small nation have made it difficult for Singapore to meet the needs of its inhabitants. Even with the optimum use of the land there has been a requirement for more. Hence, this country has long since turned to land reclamation to resolve the problem of scarcity of space. The world renowned Changi airport occupies a part of this reclaimed land as do many useful housing and industrial projects. In fact over the last thirty years the area of this nation has increase by 100 square kilometres.

Bahrain Project

To end on an architecturally exciting note let us look at a project of the firm WKK one of whose partners is Tom Wright the designer of Burj Al Arab when he was with Atkins. This project in Bahrain is on a site of 20 square kilometres. The firm’s website further states:

"Durrat Al Bahrain is a sustainable residential, commercial and leisure resort, a necklace of pearls suspended from the southeast shoreline of Bahrain. Providing a water based island lifestyle, the 20 square kilometre masterplan comprises a broad arc of six man- made atoll shaped islands, each with an exclusive community of 172 villas that have either individual moorings or private beaches."

“From an early stage a hydrodynamic study to analyse the effect of the islands on the ecology of the area guided their development. The study also examined water flushing of the atoll beaches helping to reduce and control potentially strong current flows between the islands at spring tides.”

Designed by Wright; Khennouchi &Kuruvilla whilst working with Atkins

References

www.esa.un.org ;

www.lkyspp.nus.edu.sg;

www.wkkarchitects.com ;

www.weather.com