Towns on plateaus and towns in the hills. Why are new towns up on hills?

Published: September 12, 2026 / About 12 min read

New towns up on hills, and those hills are of two kinds

Aerial photographs from the grading period of new towns show cut slopes and wide flat areas where the trees have just been felled. That raises the question "why are new towns up on hills?", but if you line up the elevation figures side by side, there is not just one answer. The land that has been called "up on a hill" splits into two groups with completely different bands of height.

Towns placed on land called hills have central elevations within a band from 66.6 m at Senri-Chuo to 115 m at Minami-Osawa. On the other hand, towns placed on plateaus in the Kanto region range from 16.8 m at Chiba New Town Chuo to 26.8 m at Tokiwadaira Danchi (housing complex), and the two bands do not overlap at all. Although both are talked about with the same words "up on a hill", if you compare the upper ends of the two bands, they are 115 m and 26.8 m, a gap of more than four times.

This article centers on the latter, that is, the six places on plateaus in the Kanto region. Why do they look "up on a hill" when they are low in the figures? If you line up the measured values at the center and in the four directions and step through the eras of the aerial photographs, the character of plateau land comes out of both the figures and the images.

The six locations in Kanto line up at around 20 m

First, look at the heights themselves. The six places spanning Chiba Prefecture and Ibaraki Prefecture have central elevations within a 10 m range, from 16.8 m to 26.8 m. Even including the measurement points in the four directions, all except the lowest, 7.6 m, are between 13.9 m and 28.3 m.

This band of around 20 m also fits well with what the local government says. The City of Inzai, where Chiba New Town Chuo is, explains in its overview of the city that the city area consists of "a flat plateau known as the Shimosa Plateau, about 20 to 30 meters in elevation" and low land along marshes and rivers. This means it was not a hill for gaining height but land where flat surfaces remained in one piece.

The five points of the center and the four directions measure how flat the surface is

After height, flatness matters next. The location pages have measured values for north, south, east, and west in addition to the center, so if you take the range of the five values together, you can express how level the surface under the town is as a single number. This is different from the elevation difference that looks at a whole cross section; it is a rough but easy-to-compare measure that looks only at the four nearby directions as seen from the center of the town.

Of the six places on plateaus, two are 3 m or less, and the 1.1 m of Nagareyama-Otakanomori is of the same order as the two places on low land. The four places in the hills range from 6.8 m to 19.1 m, and except for Senri-Chuo at the bottom end, they exceed 12 m. If you look at the order of the table, however, plateaus and hills mix partway through. The 12.3 m of Ryugasaki New Town is exactly the same value as Minami-Osawa, so even on a plateau, depending on the place chosen, the values can swing as much as in the hills. It is not the name of the landform class that decides flatness but where on the surface the town sits.

A center sitting in a yatsu valley and a center sitting on the surface

The figures for Chiba New Town Chuo are arranged the opposite way among these six places. The center is only 16.8 m, yet the four directions all exceed 22 m: 22.7 m in the north, 23.2 m in the south, 23.8 m in the east, and 24.9 m in the west. Only the center sits in a hollow, and a flat surface surrounds it.

The phrase "dissected by valleys called yatsu" in the City of Inzai's explanation accounts for these figures. The surface of the Shimosa Plateau is carved like branches by narrow valleys leading to marshes and rivers, and the center of the location falls on one of these valley lines. In the 1961-69 aerial photograph, square fields are gathered on the surface of the plateau, and the valleys branch and descend, edged by dense woods. In the photographs after the streets were laid out, the shape of the valleys is hidden, but it remains in the elevation figures.

Yukarigaoka can be read the same way. Against the center's 25.2 m, the south and west match at 27.4 m, but only the east drops to 19.4 m. This arrangement, low on one side only, is the pattern of a place close to the edge of a plateau. Tsukuba Science City, by contrast, has a center of 23.8 m and four directions from 23.6 m to 26.5 m, so the five points fit in a range of 3 m. These are the figures of a town placed in the very middle of the surface, touching neither a valley nor an edge.

The edge of a plateau can be found in the figures

Ryugasaki New Town, with the widest range among the six places, is an example of a town on an edge. Against the center's 18.5 m, the north is 19.9 m and the east 18.6 m, almost matching, but only the south drops to 7.6 m, and the west stays at 13.9 m. The step of a little over 10 m down to the south corresponds to the boundary with the low land where paddies spread.

This step is visible just as it is in the aerial photographs too. If you divide the frame into top and bottom, the upper half is the plateau surface with woods and fields intricately mixed, and the lower half is paddies divided into strips by straight paddy ridges, with the boundary running diagonally from northwest to southeast. If you go back and forth between the 1961-69 photograph and the photograph as of 2026, only the upper half changes into a town, and the shape of the paddy ridges in the lower half has hardly moved. The step in the figures and the boundary in the image point to the same line.

From the town's side, the edge of a plateau is where the town ends. The blocks of Ryugasaki New Town sit on the surface to the north and east and do not extend into the low side to the south. When you find a location whose elevation values do not match in the four directions, check in the aerial photographs what lies in the low direction. This is the quickest procedure for reading a plateau town.

The result of looking for land that was flat and not paddies

Why were towns placed on plateaus in Kanto and in the hills in Kansai? In the 1960s and 1970s, when large blocks of residential land became necessary in the metropolitan areas, the land among wide, flat surfaces that was not used as paddies remained on top of plateaus and hills. The low land of the Kanto Plain had long been opened up as paddies and could not easily be replaced. The order is this: it was not the height of the terrain that was chosen, but a gap in how land was used.

In the City of Inzai's explanation, too, the low land is treated separately from the plateau as land where sediment carried by rivers built up. The same difference appears on the aerial photograph side. In the 1961-69 frame of Chiba New Town Chuo, square fields on the plateau surface gather in pale gray, and long, narrow, bright lots line up only on the valley floors. Paddies are limited to the narrow bands of the valley floors, and most of the surface is fields and woods.

This difference in use also connects to how the stages of grading appear in the photographs. Lots, not houses, appear first in the 1974-78 photograph, and in 1984-86 the photograph shows a band of railway crossing an expanse of ocher bare ground, with only one long, narrow roof sitting partway along it. The station and the lots were built first, and the buildings filled the surface later. This is the order that was repeated in the plateau new towns.

Put them beside the new towns in the hills

On the hill side, too, the correspondence between the figures and the photographs can be read the same way. Senri-Chuo has a center of 66.6 m, Izumigaoka 71.5 m, Kozoji New Town 91.5 m, and Minami-Osawa 115 m, so the band of height differs from town to town. The range of the five points runs from 6.8 m at Senri-Chuo to 19.1 m at Kozoji New Town, swinging higher than at the six places on plateaus. This is because the traces of the work that rearranged ridges and valleys into terraces remain as differences in height between blocks.

The locations with small swings gather on the plateau side. If you choose a place that does not touch a valley, the five points fit in a range of 3 m, but all four places in the hills exceed 6 m. On the other hand, the towns in the hills gain views and stepped landscapes not seen in plateau towns. This is not a matter of which is better; it is a matter of the nature of the construction work showing in the framework of the town.

The progress of grading on the hill side and the years the towns opened are covered in Towns born by cutting away mountains and Sixty years of the three great new towns. This article leaves those topics to them and returns to how to read the plateau side.

In flatness, plateau towns line up with danchi on low land

If you look only at the flatness of the surface, plateau towns line up with unexpected partners. Takashimadaira Danchi along the Arakawa River has a five-point range of 1.0 m, and Takesato Danchi has 1.2 m, hardly different from the 1.1 m of Nagareyama-Otakanomori on a plateau. Only the band of height differs: the two places on low land have centers of 3.4 m and 5.2 m, and the six places on plateaus are 16.8 m or higher, so the ranges do not overlap. The condition of wanting a flat surface could be met on low land too, so the choice split along what the surface had been used for, not along flatness. The origins of danchi built on former paddies can be followed in Trace the danchi called the largest in the East through aerial photographs.

Three clues for telling plateaus apart in aerial photographs

You can also tell plateaus apart from the photographs alone, before looking at the elevation figures. There are three clues.

The third works especially well. Settlements on plateaus line up not in the middle of the flat surface but along roads by the valleys, so in the 1961-69 photograph the rows of houses look connected in a single line running down the valley. In the photographs after grading those lines disappear, and grid or ring-shaped blocks cover the surface. If you go back and forth between the two eras, you can estimate where the valleys hidden under the streets are.

In terms of the sequence of eras, too, these six places are an easy set to compare. All six have five eras, 1961-69, 1974-78, 1979-83, 1984-86, and 1987-90, and can be set side by side at the same time intervals. On the hill side, only Senri-Chuo goes back to around 1936-42 and 1945-50, and Kozoji New Town lacks 1984-86. The fact that the same five eras are complete means they can be used as they are as material for comparing the six plateau places side by side.

Put the elevations and the photographs side by side yourself

The procedure for reading a plateau town comes down to three steps. Look at the five points of the center and the four directions and take the range; if the range is wide, check which direction is low; then go and look at that direction in the 1961-69 photograph. If the low side shows the woods of a valley, it is a yatsu valley; if paddies spread there, it is the edge of the plateau.

The ordering by height and each town's cross section are summarized in An elevation comparison. Read low towns and high towns from the terrain, and the order in which stations and towns were built is in Places where a new station and a town were born at the same time, seen in aerial photographs. On the location pages of all six places taken up in this article, you can step through the eras and compare the photographs with the elevation values. For the expected flood areas and the landslide warning zones, you can follow each local government's published materials from the Hazard Map Portal Site of the Ministry of Land, Infrastructure, Transport and Tourism.