Land Reclamation in Tokyo

The Tokyo Bay is the third largest closed-off bay in Japan with an area of 1380 square kilometers. Amazingly, as of 2012, a total of about 250 square kilometers of land has been reclaimed from the Tokyo Bay, roughly 15% of the original bay area (Koarai, 2013).

The origin of land reclamation activities in Tokyo can be traced as early as 1592, only two years after Tokugawa Ieyasu established himself in Edo, filling the northern part of the Hibiya Inlet (now near Marunouchi of the Chiyoda-ku) using dirt excavated from the moat of the Edo Castle (Endoh, 2004).

Historical trends of land reclamation in Tokyo is reflective of the city's political, social, and economic situations in different historical era. In the meanwhile, the action of making new physical space from reclaimed land also had its impact on urban planning, socioeconomic activities, and the environment. With 2020 Tokyo Olympics unveiling the "Tokyo Waterfront City" concept, certain aspects of contemporary development of reclaimed land such as waterfront sports and leisure, the building of a waste processing center, and disaster vulnerabilities are also worth to discuss.

Land reclamation is virtually ubiquitous in Japan, but history and scale of reclaimed land in the Tokyo Bay is unprecedented on a national level. According to the Ministry of Land, Infrastructure, Transport, and Tourism, Tokyo Bay is defined as the water body north of the connecting line between Tenzaki of the Miura Peninsula and Suzaki of the Bōsō Peninsula. Usually, it refers to the area in close proximity to Tokyo Metropolis (the 23 special wards) where reclaimed land can be seen in every one of the coastal wards, Ōta, Shinagawa, Minato, Chūō, Kōtō, and Edogawa. Other regions that have significant reclamation projects in Tokyo Bay include Kawasaki, Chiba, Urayasu, Ichihara, and Kisarazu.

Land reclamation projects at different historical periods have been motivated by different conditions so that the reclaimed land areas were built to satisfy different land use. The physical characteristics such as textual and composition of the reclaimed land also influenced the usage.

As mentioned previously, the first systematic land reclamation project was undertook by Tokugawa Ieyasu in 1592. The topography of Edo then was vastly different from the present: Tokugawa hoped to construct his castle in Hibiya which was then a beach near the Hibiya Inlet where the historical Hiragawa river entered Tokyo Bay; east of the castle was low-lying marshland dominated by an intricate web of river channels which included three major rivers Sumida, Tonegawa, Edogawa, and their tributaries; west of the castle was a terrain full of hills that stretched inland. Tokugawa's urgent goal was to find, or rather create a plain ground for agriculture and accommodation of his daimyos, samurais, and servants (Endoh, 2004).

Instead of clearing the hills, Tokugawa chose to tame the water by building reclaimed land. Very conveniently, materials to fill the river and ocean came from hills that were cleared for construction of the Edo Castle and other part of the city. A technique called cut-and-fill was employed which basically means clearing a highland while using the materials to fill a lowland that maximized the efficiency of work (Murphy, 2016). As a result of filling the Hibiya Inlet and the surrounding waters, the Edo Castle, the political center of the Tokugawa Shogunate, as well as the Shitamachi area, the urban center of Edo for commoners, were created by the mid-17th century. The houses of daimyos were concentrated on the plain/reclaimed land between Sumida and Nakagawa (a tributary of Tonegawa).

During the late Edo Period, accumulation of sediments at the river mouth of the Sumida shallowed the depth of water and caused trouble to the frequent passage of cargo ships. Given the importance of shipping along the Sumida to support the growing population of Tokyo materially, the Tokyo Perfecturate Government then initiated a project to dredge the river channel of Sumida while using the materials to reclaim new land at designated areas without interferencing the shipping routes. The 1st Sumida River Mouth Improvement Project started in 1906 which resulted in the consolidation of Tsukuda Island and the creation of Tsukishima No. 1 (now Tsukishima 1-chome) and No. 2 (now Kachidoki) Landfill.

Subsequent projects from 1911 to 1935 created and consolidated Shibaura and Tennozu in Shinagawa, Harumi, Toyosu, Shinonome in Kōtō (Endoh, 2004). After the completion of three projects, the passage of 2,000~3,000-tonnage level ships was made possible which significantly boosted shipping capacity of the Sumida. Another Edagawa Improvement Project from 1910 to 1923 created several other reclaimed areas in eastern part of Kōtō including Shiohama, Shiomi, and Edagawa (Endoh, 2004). Most of these aforementioned reclaimed land was designated as land for housing to accommodate the influx of population into Tokyo with the rapid development of Tokyo as the center of the new post-Meiji Japan.

With the growth of industrial production in Tokyo and its surrounding industrial regions, the Tokyo Perfectuate Government planned a 10-year "Tokyo Harbor Construction Proposal" in 1931, hoping to further boost the shipping capacity by allowing larger cargo ships to enter the bay area (Bureau of Port, 1994). As new land reclamation projects were made to provide the space for planned docks and storage facilities. Expansion of the existing reclaimed land at Shiba, Takeshiba, Toyosu, and Tsukishima would make up the majority of docks, while new land at Kōtō and Shinagawa would be created for the storage warehouses. There was also plan for a new airport on the so-called "Yumenoshima" 「夢の島」in eastern part of Kōtō where the artificial foundation of reclaimed land was already laid in water (Endoh, 2004).

However, both plans for Tokyo harbor and airport fell short due to start of the Pacific War as war production was prioritized and soon there was a shortage of construction materials. Construction of reclaimed land for the harbor plan was complete before war broke out, while further construction of "Yumenoshima" was abandoned. After the war ended, the airport proposal was put to discussion again but rejected by the GHQ (of Allied Occupation of Japan) who instead insisted for the building of the Haneda Airport (Endoh, 2004). At the end, Yumenoshima used as a landfill until reaching its capacity and being converted into a park in 1981. As a result, 1930s and 1940s saw only minimal increase of reclaimed land.

• Water Pollution Caused by Materials Used in Reclamation

Not all land reclamation utilizes natural soil and dirt collected from river channels, mounds, or hills. As Tokyo has been on constant expansion since the Meiji Period, using wasted material from construction of infrastructure to fill the Tokyo Bay seems an ideal solution to both solve the waste disposal problem and growing land demand. In practice, many of the reclaimed land are built on the mixture of construction waste and natural soil and dirt. Later, domestic waste also began to fill in the waterfront area and landfill could also be converted into reclamation project. However, both construction and domestic waste contain chemicals and toxic contents that contribute to the pollution and eutrophication of the Tokyo Bay. It was estimated in 2003 that red tides occur 40~60 times annually in the major port areas (Bureau of Port, 2003)

• Water Pollution Caused by Relocation of Heavy Industries

While moving heavy industries to peripheral cities around the Tokyo Metropolis seems to effectively reduce the air and water pollution inside the central wards, it nevertheless exacerbated the pollution level in the entire Tokyo Bay area. Discharge of industrial wastewater peaked in the 1970s and made the Tokyo Bay the "sea of death" as levels of dissolved oxygen at bay bottom in many places were well below the 4.3mg/l minimum for any marine species to survive (Takao, 1999). Subsequent enforcement of tight water quality control has gradually improved the situation but as levels of dissolved oxygen still remain low, a return of marine species is very unlikely. Extinction of marine species also means the diminishing of fishery industry in the bay area which was once a common occupation.

• Soil Liquefaction

Soil liquefaction describes the phenomenon in which the strength of a body of soil is reduced by earthquake shaking or other rapid loading which would result in damage to the foundation of constructions built on it. The March 11 Tohoku Earthquake in 2011 caused serious damage to reclaimed land and in particular to Urayasu City in Chiba where Tokyo Disney is located. This might lead to the concerns of purchasing properties on reclaimed land in the future. Since most reclaimed land is built on soft artificial foundation, before decades of consolidation to complete, the threat of earthquake is almost unavoidable.

At the height of the bubble economy in 1989, a staggering amount of 4.9 million tons of trash was produced that year. Despite the total amount being reduced to 2.7 million tons in 2014, a huge capability to process astronomical amount of waste is still mandatory for Tokyo. The Clean Authority Tokyo 23 which consists of the 23 central wards is now in charge of dealing with the waste problem. The major processes of waste disposal goes as follows:

Apart from the 19 incineration plants that are spread all over the 23 wards, the Large-sized Waste Pulverization Processing Facilities, the Incombustible Waste Processing Center, the Incinerated Garbage Ash Processing Facility, and the landfills are all concentrated at the reclaimed land near the Central Water Break. Ironically, all the waste processing facilities are built on land reclaimed by domestic waste in the last century.

One of the by-product of incineration is the ash which by itself is another form of waste to be dealt with. The Shinagawa Incineration Plant alone produces 180 tons of bottom ash daily. While the bottom ash is often used as a substitute for clay in cement, another genius engineering solution turns the ash entirely into a new construction material by melting it at 1,200 degree celsius and then cooling it to remold into blocks that can be used to pave pedestrian sidewalks (Tim, 2017).

These blocks can also be the foundation of landfills to be laid on the ocean bed which a lot of them are already used in the Outer Landfill and New Surface Landfill. Because they are processed, they are also pollution-free which is more environmentally friendly than many other materials used to create reclaimed land such as construction and domestic waste. In the end, it seems like Tokyo has made garbage a valuable resource to gain another valuable resource for the city, reclaimed land. However, as 50 years later the two present landfills will reach full capacities and currently no alternative locations have been found, Tokyo still need to cut down its waste furthermore.