Tenured Professor at
The Open University of Japan

Clusters of Meshed Areas with Population Densities of 5,000 or more people/km2

Here at Tamano Lab we have developed a method for defining urban areas throughout Japan using applied meshed data based Urban Areas (mdbUA).

Firstly, based on our standard scale of 5,000 or more people/km2, qualifying local zones associated with the country’s urban areas were colored in black.

Nationwide map showing grid squares of ≥5,000 people/km2
※click on the map to open an enlarged version

The resulting maps are enlarged by region below.

In Hokkaido Prefecture, the cities of Sapporo, Asahikawa, Otaru, Tomakomai, Kushiro, and Hakodate all have local clusters of grids colored black.
　

In Aomori Prefecture, we can identify clusters in the cities of Aomori, Hirosaki, and Hachinohe.

In Akita and Iwate Prefectures, we can detect black grids in Akita and Morioka.

In Miyagi Prefecture, we can identify clusters in Sendai and Ishinomaki, and Yamagata is detectable as an urban area in Yamagata Prefecture. Clusters are observable in Fukushima, Aizuwakamatsu, and Koriyama in Fukushima Prefecture, as well as Niigata Nagaoka in Niigata Prefecture.

In the northern part of the Kanto area, clusters of at least 5,000 people/km2 are recognizable in Mito, Utsunomiya, Maebashi, and Takasaki. Other detectable areas such as Narita, Ushiku, and Tsukuba are linked to the Greater Tokyo area. Clusters can be identified at Nagano and Matsumoto in Nagano Prefecture, as well as Kofu in Yamanashi Prefecture.

Adjacent to Greater Tokyo in Kanagawa Prefecture, we see clusters at Kanazawa-Hakkei, Yokosuka, Kamakura, Hiratsuka, Atsugi, and Odawara.

In the Tokai region, we see that Mishima, Numazu, Fuji, Shimizu, Shizuoka, Hamamatsu, and Toyohashi have clusters of 5,000 or more people/km2．

In the Hokuriku region, we can identify clusters in Toyama, Takaoka, Kanazawa and Fukui.

Around Aichi Prefecture, clusters are visible in Toyota, Kariya, Anjyo, Okazaki, Ichinomiya, Gifu, and Yokkaichi．

In the Kansai region, Osaka, Kobe, Kyoto, Nara, Wakayama, Otsu, and Shiga appeared in clusters．

In the Chugoku region, we can recognize bare minimum clusters in Tottori and Matsue along the coast of the Sea of Japan. Along the Seto Inland Sea coast are the rather distinct clusters of Okayama, Kurashiki, and Fukuyama．

In Hiroshima Prefecture, we can see wide areas extending from Hiroshima, Higashi Hiroshima, and Kure．

In the Shikoku area, Tokushima, Takamatsu, and Matsuyama form distinct clusters．

In the northern part of the Kyushu area, the clusters of Kitakyushu and Fukuoka are expansive.

In other areas of Kyushu, we can identify clusters at Sasebo, Nagasaki, Kurume, Saga, Beppu, Oita, and Kumamoto．

In the southern part of the Kyushu area, Miyazaki and Kagoshima exhibit high population densities．

Notably, in Okinawa Prefecture we see expansive clusters of dense grids in Naha and Okinawa City．

Demarcation Method

The following rules were applied in defining urban areas from the distributions of meshes with the above-mentioned criteria:

(1) When four or more meshes are linked, they count as an urban area (UA)．
(2) Following the cut-off rule of “the case of other cities” set up in the previous study; following “the case of metropolitan areas” only in determining the three major metropolitan areas.

Cities not detected as urban areas

Many cities were excluded by rule (1), despite having large populations as official administrative units.Table 1 below shows the densities and populations of cities that were excluded．

Table 1. Populations and densities (people/km2) of excluded cities
※Created from the 2010 Census results

Ota, Isesaki, Hitachinaka, Tsuchiura, Omuta, Tajimi, and Toride are notable examples of cities not identified as urban areas due to having lower population densities despite their relatively large populations. Only three or fewer meshes of at least 5,000 people could be linked within these areas.

Table 2 below shows the list of cities that were detected as UA even though their respective gross populations were below 300,000.

Table 2. Low population UAs

※Created from the 2010 Census results

Cities such as Isehara and Ushiku have population below 100,000 and relatively higher densities. Significant population differences between cities are less detectable when comparing overall population densities; however, distinctions become clearer when examining population densities in specific areas within the cities. Therefore, it can be said that density in specific areas within cities matters more in identifying urban areas than does the overall population density．

Again, for now, the minimum number of criteria for identifying an urban area being four or more mesh linkages of ≥5,000 people per km2．