• Annual rainfall: A negative correlation was demonstrated. Low rainfall meant
sources of water were limited, which lead to intensive and high-density inhabited
districts.
• Extent of annual fluctuation in monthly rainfall: A positive correlation was
demonstrated. There was some correlation between rainfall and a large extent in
fluctuation itself. However, having periods of high rainfall and therefore a large
fluctuation was thought to be a principal cause in limiting inhabited areas.
Specifically, in order to avoid flood damage in inhabited areas caused by huge
volumes of rainfall during short periods, there was a need to ensure areas with
channels and good water-retaining soil, which resulted in limited inhabited areas
and high-density living.
• Average topographical gradient inside the urban area: A positive correlation was
demonstrated. It is difficult for inhabited areas to form on land with a steep
gradient. Inside those urban areas that had high average topographical gradients,
inhabited areas at the neighborhood level were limited.
• Percentage of size of agricultural land (13) (areas containing a mix of farmland
and other vegetation): A negative correlation was demonstrated. “Areas
containing a mix of farmland and other vegetation” are basically areas with
extensive areas of grasslands. In these areas, it is easier than in forests or deserts
for inhabited areas to expand, and they are areas with low-density settlement due
to their low human carrying capacity.
• RPI: A negative correlation was demonstrated. Earlier I briefly described the
association between RPI and population density. Those environmental elements
that cause the shape of an urban area to be intensive are not necessarily the same
as the elements that raise population density in that area. The elements that relate
to population density are believed to be elements that relate to limitations on
habitable land in more “micro” neighborhood units. One of the factors that are
related to high population density in micro neighborhood is limitation of habitable land, and the limitations are caused by topographic features, vegetations,
other geographical features, and policies and rules in the cities.
6.3 Sustainable Managements of Megacities
6.3.1 The Association Between Urban Morphology
and the Ecological Environment for Each Region
In the previous section, we discussed correlations between RPI and population
density and the ecological environment. In order to investigate the applicability of
the compact city model in all regions around the world, we will now discuss the
association between urban morphology and the ecological environment on a regionby-region basis.
6 Generation of Urban Morphologies Through Long-Term Evolution of. . .
119
sources of water were limited, which lead to intensive and high-density inhabited
districts.
• Extent of annual fluctuation in monthly rainfall: A positive correlation was
demonstrated. There was some correlation between rainfall and a large extent in
fluctuation itself. However, having periods of high rainfall and therefore a large
fluctuation was thought to be a principal cause in limiting inhabited areas.
Specifically, in order to avoid flood damage in inhabited areas caused by huge
volumes of rainfall during short periods, there was a need to ensure areas with
channels and good water-retaining soil, which resulted in limited inhabited areas
and high-density living.
• Average topographical gradient inside the urban area: A positive correlation was
demonstrated. It is difficult for inhabited areas to form on land with a steep
gradient. Inside those urban areas that had high average topographical gradients,
inhabited areas at the neighborhood level were limited.
• Percentage of size of agricultural land (13) (areas containing a mix of farmland
and other vegetation): A negative correlation was demonstrated. “Areas
containing a mix of farmland and other vegetation” are basically areas with
extensive areas of grasslands. In these areas, it is easier than in forests or deserts
for inhabited areas to expand, and they are areas with low-density settlement due
to their low human carrying capacity.
• RPI: A negative correlation was demonstrated. Earlier I briefly described the
association between RPI and population density. Those environmental elements
that cause the shape of an urban area to be intensive are not necessarily the same
as the elements that raise population density in that area. The elements that relate
to population density are believed to be elements that relate to limitations on
habitable land in more “micro” neighborhood units. One of the factors that are
related to high population density in micro neighborhood is limitation of habitable land, and the limitations are caused by topographic features, vegetations,
other geographical features, and policies and rules in the cities.
6.3 Sustainable Managements of Megacities
6.3.1 The Association Between Urban Morphology
and the Ecological Environment for Each Region
In the previous section, we discussed correlations between RPI and population
density and the ecological environment. In order to investigate the applicability of
the compact city model in all regions around the world, we will now discuss the
association between urban morphology and the ecological environment on a regionby-region basis.
6 Generation of Urban Morphologies Through Long-Term Evolution of. . .
119