The Kanto Plain is the biggest and deepest groundwater basin on the Japanese Islands. The water in the basin has been used in various purposes, and the volume of use is estimated to be the greatest in the country. Consequently, severe problems have emerged in the history of water development and water environment protection. The study show two stories in the groundwater basin of the Kanto Plain, corresponding to depth. The deeper one emphasizes salt water containing natural gas, and the shallow one is characterized by the largest groundwater flow system in the country. The paper reviews the geological features of the basin. Groundwater condition, especially deep groundwater, is also reviewed to understand the next stage of activities to develop and protect the environment.
It is important to understand the history of water development and the water environment to solve problems related to water and plan its effective future use. First, surface water and groundwater from shallow areas where groundwater flow was controlled by geomorphology provided sources of water in Tokyo. Following the Edo period, the development of water resources accelerated, and groundwater controlled by geology was used by industries. The expansion of water use in Tokyo led to major problems such as land subsidence in the 1970s. Many studies have been undertaken on water use, which extend to the fields of pollution, land subsidence, and flow systems, etc. Development and management of the total groundwater environment in the near future requires an understanding of issues including water level, water quality, and water temperature.
Tokyo—one of the largest cities in the world—exhibits intensive urban land use, urban sprawl, and high anthropogenic heat exhaustion, which produce characteristic urban temperature distributions. Typical features of the nocturnal temperature distribution from November to February under conditions of clear skies and weak winds were analyzed for the Tokyo metropolitan-ward area using data from spatially high-density observations from the Automated Meteorological Data Acquisition System (AMeDAS) of the Japan Meteorological Agency (JMA), municipal air pollution monitoring systems, and Extended-METROS from 2006/2007 to 2009/2010. To analyze the structure of temperature distributions in the Tokyo-ward area, hourly temperature data at 124 stations were interpolated into grid points with 1-km intervals. When high temperatures in central Tokyo were expressed as a difference in AMeDAS temperature between central Tokyo (Otemachi) and an average of four points outside the Tokyo-ward area, the weather conditions most strongly affecting this temperature difference at 06:00 Japan Standard Time (JST), prior to sunrise, were cloud amount followed by wind speed. The temperature difference at night under clear-sky and weak-wind conditions (average cloud amount of 2/10 or less and average wind speed of 3m/s or less) generally showed an abrupt increase during the several hours before and after sunset followed by a gradual increase, reaching maximum levels before sunrise (06:00 JST). When the temperature difference before sunrise was large, the difference would evidently increase even after midnight; however, if this difference was small, it would tend to decrease after midnight. The high temperatures in the metropolitan area were concentrated throughout the night near the southern area of Chuo ward. In particular, it is noted that several zones of steep horizontal temperature gradients were detected in the metropolitan-ward area. These zones (e.g. starting from the southern part of Saitama Prefecture, it appeared through the border between Nerima and Itabashi wards, Toshima, Shinjuku, and the area stretching from western Setagaya to the southwest) appeared during the period several hours before and after sunset, and gradually became more noticeable near sunrise. The distribution of temperature-decrease rate around sunset also showed steep horizontal gradient zones, which corresponded to regions exhibiting steep horizontal temperature gradient zones between the inner city and outer area.
Present vegetation, changes in green spaces, and present status of their management in Tokyo are reviewed to introduce adequate management conditions in three areas of Tokyo 23 special wards, Tama, and Okutama, with special reference to the Tama area. The present natural vegetation in each of the three areas is as follows. The 23 special wards have a scarcity of green spaces, but there are major remnants of such evergreen broad-leaved forests as Machilus thunbergii forest, Castanopsis cuspidata forest, and Quercus myrsinaefolia forest. The Tama area is traditionally thought to be climatically an area dominated by evergreen broad-leaved forests of Quercus myrsinaefolia, with deciduous broad-leaved oak forest in the Tama area being secondary. However, this review takes a new view contrasting with the traditional interpretation that Castanea crenata-deciduous Quercus species forests also constitute important parts of the natural forest of the Tama area. These forests originate from remnants of forests of the Late Glacial in the Kanto district. The Okutama area is dominated by Cryptomeria japonica and Chamae-cyparis obtusa plantations. The natural forests of the area consist of cool temperate Quercus serrara, Quercus crispula, Fagus japonica forest, and subalpine Tsuga diversifolica forest. Regarding changes in green spaces, increments of such unique plant species as Trachycarpus fortunei, Neolistea aciculata, and Idesia polycarpa are obvious, especially in remnant forests in the 23 special wards. In the Tama area, forest fragmentation is serious and results in a decline of plant species diversity. Bamboo invasion destroys secondary Castanea crenata-deciduous Quercus species forests. In the Okutama area, increases in the Sika deer population cause long-term destruction of plant communities. Regarding green-space management, green spaces in the 23 special wards, which play an important role as fire shelters, should maintain fire-resistant tree species such as evergreen broad-leaved species. In the Tama area, a moderately strong forest management was proposed to maintain the plant species diversity of Quercus secondary forests. To conserve the diversity of species in forests through non-traditional management, it is necessary to manage forests continuously without long periods of neglect. It is concluded that to manage Quercus secondary forests appropriately, long-term changes in species composition need to be monitored. In the Okutama area, the Tokyo government is attempting a forest reconstruction enterprise to recover declining forests through forest management.
Land reclamation undertaken continuously in Tokyo Bay since the Edo era can be regarded as important for advancing civil engineering projects in Tokyo. Haneda airport D-runway extension work (hereafter D-runway construction) was completed in October 2010, with a new 2,500 m runway, operating a 24-h service, built in a sea area having a water depth of 15-20 m. Part of the island airport was constructed with a pier structure to provide flood control for the Tama River and preserve the environment. This report summarizes the marine geological survey, environmental assessment, and groundwater management for D-runway construction on the basis of previous reports. The main characteristics of construction are: marine drilling was carried out about every 500m in the sea area for the marine geological survey; the effects of construction on ocean currents, bottom sediments, and submarine topography were considered in the environment impact assessment of land reclamation; and, a new underground station was constructed with groundwater control provided by a deep-well dewatering system without building a sealing body for groundwater.
This paper describes the history of regional and transport planning in the Tokyo Metropolitan Area, and considers the relationship between urban structure and transport planning. The network of major roads in Tokyo has been shaped by revitalization planning since the Great Kanto Earthquake of 1923 and the Pacific War. However, because of financial difficulties, some roads in the urban plan remain incomplete to this day. On the other hand, the Metropolitan Expressway network was planned around 1950, and about 940 thousand vehicles use the expressway every day. The railway companies around Tokyo, notably Japan National Railways, faced problems of overcrowding because the population of the Tokyo Metropolitan Area had increased and suburbs were created during the high economic growth period from the mid-1950s. Japan National Railways and Council for Transport Policy planned construction of new lines and the congestion rate of railways tended to decrease. Urban structure planning of Tokyo Metropolitan aimed to have a multipolar pattern during the tenures of former Tokyo Governors Shun-ichi SUZUKI and Yukio AOSHIMA. However, around a year after taking office, the former Tokyo Governor, Shintaro ISHIHARA, suggested the concept of a “ringed megalopolis,” which is invested in central Tokyo including subcenters for improving international competitiveness. Even with the different strategy for reconstructing an urban structure, road and railway planning has not changed. Transport planning in Tokyo metropolitan area has depended on urban planning that is designed not to interfere with the placement of urban functions, but follows and satisfies demand resulting from suburbanization. However, because an urban structure with a compact city has become more important, urban structure planning is required to be coordinated with transport planning.
This study examines the spatial patterns of population change in the 23 Special Wards of Tokyo after the period of the bubble economy in the late 1980s. To this end, we analyze grid square data suitable for time-series analysis between 1985, when the bubble economy started, and 2005, the latest year for which data are available, using the geographic information system (GIS). After selecting major indicators representing three dimensions of the social area analysis—family status, socioeconomic status, and ethnic status—we map each indicator and make quantitative comparisons of six zones, classified by distance from the city center, and of four sectors classified by direction from the city center. The indicators used in this study are three variables representing family status (ratio of young population, ratio of elderly population, and ratio of single-person families), three variables representing socioeconomic status (ratio of blue collar workers, ratio of managers and officials, and ratio of professional and technical workers), and one variable representing ethnic status (ratio of non-Japanese people). Before analyzing these data, we examine the spatial pattern of population change in the 23 Special Wards between 1985 and 2005. This analysis reveals that a population recovery has occurred since the latter half of the 1990s in central Tokyo, where a previous population decline had continued until 1995. On the basis of this trend of population change, we examine the spatial pattern of each indicator in the social atlas. Concerning age and household composition (representing family status), spatial distribution has gradually shifted from a zonal pattern to a sectoral pattern due to the migration of nuclear families to the area surrounding the city center. The spatial distribution of socioeconomic status represented by the occupational structure maintained a sectoral pattern characterized by a contrast between the eastern and western parts of Tokyo although this distinction has blurred. In particular, the number of managers and officials in the 23 Special Wards has decreased, and the distribution shifted to a zonal pattern, which indicates a polarization of white-collar workers. The distribution of non-Japanese shows a zonal pattern in which the highest value appears in the area surrounding the city center. However, spatial autocorrelation analysis of the distribution of four major ethnic groups by nationality reveals a clustered pattern, supporting the findings of previous studies in Western countries.
In recent years, population recovery and gentrification have become increasingly common in the city centers of most developed countries. The emergence of relatively new gender relations has been observed in city centers, such as single female households and families having two incomes and no children. The purpose of my work is to examine the factors that enable working mothers who live in city centers to simultaneously manage their jobs and housekeeping, focusing especially on the impacts of the Internet. An activity diary survey conducted on working mothers living in central Tokyo revealed that they allocate more time to work than do working mothers who live in the suburbs. So, working mothers who live in the city center have tight time budgets. The survey also showed that reducing time devoted to housekeeping tasks is crucial to balance work with housekeeping. So, housekeeping time was scrutinized under different conditions to determine the factors that would contribute to reducing it. The results showed that Internet services such as e-commerce do not contribute to reducing housekeeping time over a single day. Therefore, whether Internet services reduce housekeeping time over longer periods such as one week or one month should be examined. Allocating housework to husbands definitely reduces housekeeping time. The share of housework shared by husbands living in the city center is greater than that shared by husbands living in suburban areas. Therefore, living in the city center leads to a reorganization of the time budgets of households. For husbands, living in the city center can reduce commuting time and increase time devoted to housekeeping. For working mothers, living in the city center can increase time devoted to work. This reorganization indicates that comparatively new gender relations are emerging in central Tokyo.
The Tokyo metropolitan area is the largest city-region in the world, and is a location where many of the advanced functions in Japan are centralized. This paper overviews changes and characteristics in Tokyo's industrial structure at the metropolitan level, as well as the inner city level. The restructuring of manufacturing industries under the pressures of globalization and a declining population in an aging society has had powerful impacts on the industrial structure of the Tokyo Metropolitan Area. Most sub-regions within the area are suffering from declining manufacturing industries and wholesale and retail sectors with a depressed construction industry. On the other hand, the number of employees of service industries, such as health care and welfare, has risen in suburban areas. Although the growth rate in Tokyo's inner city became weak during the recession of the 1990s, after the collapse of the asset inflation-led economy, the functions of information services have again become concentrated since the early 2000s. The competitive power of new cultural industries has also been demonstrated in recent years. To enhance creativity and strengthen the international competitiveness of cultural industries, it is important to convert the internal structures of urban areas and to accelerate connections among various industrial agglomerations in the metropolitan area.
The purpose of this paper is to clarify the history and the characteristics of electric utility companies in Tokyo. In 1887, the first electricity supply company in Japan was established in Tokyo. In 1933, there were 818 electric utility companies. Before World War II, two or more electricity supply companies supplied one region, and there was tough competition to supply electricity to the Tokyo area. In 1938, the principle of free competition was replaced by nationwide management by the pre-war military government. Tokyo Electric Power Company was established in Tokyo by the Potsdam government ordinance in 1951, and the right to supply electricity to a region was limited to one company. Disproportionate electricity demand and amount of power generated is a historical characteristic of electric utility companies operating in Tokyo. The rate of self-sufficiency of electricity in Tokyo was 15 percent in 1931, and it was three percent in January 2012. The power generation and electric supply system began to be discussed after the nuclear plant disaster caused by a major earthquake on March 11, 2011 at Fukushima. In August 2011, the Tokyo Metropolitan Government Office began to examine constructing a large-scale power plant fueled by natural gas．As the population of Japan decreases, revenues will decline. Before World War II, Tokyo City's managed electric utility obtained high earnings constantly. These high earnings were a very important and stable source of income for the local government. The system of the electric utility companies in Japan before World War II could provide a model for a reorganized electricity supply system in the future.
This paper evaluates the status of Tokyo among major cities of Japan and compares Tokyo with major cities of the world in terms of head and branch offices. First, the paper analyzes major cities of Japan from the standpoint of the head offices and branch offices of large private firms. The main focus of this analysis of Japan is the period from 1950 to 2010. Clearly, the largest number of head offices is found in Tokyo. This is followed by Osaka. However, it should be noted that in recent years, more and more firms have adopted the system of having multiple head offices. Including such firms, the number of private firms with head offices in Tokyo is steadily increasing. Tokyo houses the large number of branch offices, as well. As is the case for head offices, the city with the second largest number of branch offices is Osaka. The difference in status between Tokyo and other cities, particularly Osaka, has increased in recent times. The status of Tokyo has become more elevated with Osaka losing ground. Second, the paper compares the situation in Tokyo with major cities of Korea, France, the United Kingdom, Thailand, The United States of America, Germany, and India. Tokyo, Seoul, Paris, Bangkok, and London gravitate to the same category in that these capital cities are strong in terms of office locations. On the other hand, within The United States of America, Germany, and India, capital cities are not so strong in terms of numbers. The important factor affecting these results is the political system. Namely, in the cases of federated states, the status of capital cities is not as high. On the other hand, in the cases of non-federated states, the status of capital cities is very high.