Read the elevation along the Tama River: Tonomachi, Kawasaki, Musashi-Kosugi, and Futako-Tamagawa

Published: September 14, 2026 / About 15 min read

From the river mouth upstream, the height rises 12 m

If you open the four locations along the lower Tama River in order from the river-mouth side, the elevation at the center of each location rises step by step: 0.8 m, 2.8 m, 8.3 m, and 12.9 m. Ukishima / Tonomachi King Skyfront at the river mouth is 0.8 m, Lazona Kawasaki, next to the town that grew from a post town on the Tokaido, is 2.8 m, Musashi-Kosugi, where the Nakahara Kaido runs, is 8.3 m, and Futako-Tamagawa, which stands on the edge where the river cut into the terrace, is 12.9 m.

If you join the four with straight lines, the distance from end to end is about 13.9 km and the rise over it is 12.1 m, so on average it does not reach 1 m per km. It is a slope you do not notice as a hill, whether you walk or ride a bicycle. Even so, the difference between 0.8 m and 12.9 m appears clearly as a difference in what the photographs show.

This article lines up the shape of the cross-sections at the four locations and what the aerial photographs from around 1936-42 to 1987-90 show, in order from the river-mouth side upstream. The story of towns across the country lined up by elevation is in An elevation comparison. Read low towns and high towns from the terrain, so here we follow only the profile along one river.

Measure the distance to the river before calling it "riverside"

All four are towns on the Tama River, but they divide into places where you can see the water and places where you cannot. A rough estimate of the distance from the center coordinates of each location to the river channel gives about 0.3 km at Futako-Tamagawa and about 0.5 km at Tonomachi, close enough that the riverbed is a few minutes' walk from the blocks. On the other hand, Musashi-Kosugi is about 0.9 km away and Lazona Kawasaki about 1.2 km, and even if you stand in front of the station, the water is not in sight. If you call all four "riverside", this difference is the first thing to disappear.

Moreover, the order is not that the closer to the river, the lower the land. Lazona Kawasaki, about 1.2 km from the river channel, is 2.8 m, and Musashi-Kosugi, about 0.9 km away, is 8.3 m, so the order is that the one farther from the river is lower. The height is decided by how far upstream from the mouth you are, not by the distance to the river. On the river-mouth side the towns sit on a thin layer of sand and mud that the river carried, and on the upstream side they sit on surfaces that the river left uncut.

One flat surface, or a step

At each location, the height is measured at five points: the center and the four directions. The spread of these five shows the shape of the surface the town sits on. Tonomachi stays within 0.9 m, from 0.8 m to 1.7 m in the east, and at any of the five points there is almost no difference from the water surface. Lazona Kawasaki spans 2.9 m, from 1.6 m in the east to 4.5 m in the north, and it is the only one of the four whose highest point is on the river side. At Musashi-Kosugi, the center at 8.3 m is the highest, and the measuring point to the east, facing the river, drops to 6.5 m, a spread of 1.8 m; it is a single surface that tilts gently toward the river.

Only Futako-Tamagawa has a different shape. The points to the north at 13.6 m, at the center at 12.9 m, and to the east at 12.7 m stand shoulder to shoulder, and from there the land drops to 9.0 m in the south and 7.6 m in the west, a spread of 6.0 m. The two low points are both on the side facing the riverbed. In other words, only Futako-Tamagawa has a step, which means that the trace of the river cutting into the terrace reaches inside the location. While the three on the river-mouth side stay within less than 3 m, at the one upstream two levels sit together inside the same location.

How to read old aerial photographs: how to use Kakomap summarizes how to read the measuring points in four directions and the cross-sections themselves.

The oldest photographs show white riverbeds and levees

Of the four, three have a photograph from around 1936-42: Tonomachi, Musashi-Kosugi, and Futako-Tamagawa. Lazona Kawasaki has no photograph from this era and starts from 1945-50.

The three have one thing in common: the river itself is the brightest part of the frame. At Futako-Tamagawa the Tama River cuts diagonally across the frame from the upper left to the lower right, and on both sides of the thin stream of water, a white, shining gravel riverbed opens surprisingly wide. The flow does not gather into one channel; it divides inside the riverbed and goes around sandbanks. At Musashi-Kosugi, too, the river is a dark, thin line, with a white riverbed on both sides. At Tonomachi the river crosses the middle of the frame diagonally, and a bright sandbar lies in the flow.

The ground at all three is fields. At Tonomachi the levee and the road on it trace the bend of the river exactly and draw a white arc, and inside the arc short rows of houses and fields in long, narrow lots continue. Musashi-Kosugi is filled with small field lots, and among them corners of factories, with long, narrow buildings facing the same direction, are scattered. At Futako-Tamagawa the rows of houses are dense only on both sides of the road that runs northeast from the foot of the bridge, and paddies and fields lie outside it. In the three photographs of this era, neither straight streets nor large blocks appear. Note that the photographs from around 1936-42 contain missing parts: at Tonomachi about 30% of the lower side of the image, and at Musashi-Kosugi the left third, are blank gray.

1945-50: all four locations line up

In 1945-50 all four have photographs, and for the first time they can be compared side by side. In this photograph, the outlines of large sites that have already appeared at the two on the river-mouth side catch the eye. At Tonomachi many long, narrow buildings stand in parallel along the levee, and a mass of large roofs with thin stripes in a row sits to the south of them. At Lazona Kawasaki, west of the station, there is a lot where rectangular buildings are lined up in good order, with a texture entirely different from the dense small buildings around it.

The two upstream, on the other hand, still divide their land loosely. At Musashi-Kosugi the tracks that run diagonally through the center draw a large arc and join, and the area held inside that arc is a factory district, but the left half is a spread of fields in a grid of lots. At Futako-Tamagawa the white of the gravel is even wider, a long, narrow sandbank remains like an island inside the riverbed, and there is only one bridge across the river.

Along a section of the same river about 14 km long, the river-mouth side took shape first as factory sites, while on the upstream side fields and the riverbed were still the main features.

1961-69: rows of houses reach the edge of the riverbed

1961-69 is the era when the area of town grows all at once at the four locations. At Musashi-Kosugi the field lots are pushed to the left edge and the corners of the frame, and rows of houses fill most of the view. At Lazona Kawasaki the farmland that had remained in the upper left is almost all replaced by town, and the lines that bundle together in the station grounds become even thicker. At Futako-Tamagawa, too, both banks fill with houses, and buildings come up to the inside of the levee line. At Tonomachi the inside of the levee is densely filled with factories under bright large roofs, and on the far bank the runways of Haneda appear as straight, bright bands. The composition of an airport and factories facing each other across the river can be read clearly from this era.

One more thing starts in this era: the way the riverbed is used. At Musashi-Kosugi and Futako-Tamagawa, faint grid-like lots are drawn on the sand, which until then had been simply white. This is the riverbed beginning to be laid out as sports grounds.

What becomes readable once color arrives

At all four, the photographs are in color from 1974-78. With color, land use becomes much easier to read. At Tonomachi you can see that almost the whole of the blocks is covered by a single factory under large roofs with long, narrow parallel stripes. At Musashi-Kosugi the large factory roofs shine white, and the black circular structure that had been in the same position since 1945-50 appears as a dark green circle. At Futako-Tamagawa the true nature of the round lots on the riverbed becomes visible, and the soil of the infields lines up as brown circles.

The 1979-83 photograph shows another face of the same river. At both Musashi-Kosugi and Futako-Tamagawa the water has turned a muddy yellowish brown and spreads across the full width of the riverbed, covering the sandbars. If you step to 1984-86, the water returns to a thin line, and the sandbars and grassland appear again. The photograph shows only the width that the water covered on the day it was taken, and nothing more than that can be read from one photograph.

The outline of the large roofs at Tonomachi hardly moves from 1974-78 to 1987-90, and only the color and brightness of the roofs change. It can be read as a time when the same factory went on being used while its roofs were replaced. In 1987-90 at Lazona Kawasaki, on the other hand, a building that rises above the surrounding roofs stands east of the station, and the dark shadow it casts at its foot can be seen even in the photograph.

The buildings, not the ground, changed in height

Even if you zoom in on the station areas of Musashi-Kosugi and Futako-Tamagawa in 1987-90, nothing tall appears. At Musashi-Kosugi the large white roofs, the blue roofs, and the black circular structure stand in the same arrangement, and the area around them is filled without gaps by low buildings. At Futako-Tamagawa the east side of the station is taken up by low buildings and white, empty lots that look like parking.

If you step from there to the photograph as of 2026, the same area looks different. At Musashi-Kosugi tall, deep navy buildings stand in a cluster from the north of the station to the center, the long, narrow shadows the buildings cast on the ground overlap one another, and only that area of the frame sinks into darkness. At Futako-Tamagawa only one block east of the station has a different roof tone, several long, narrow rectangular buildings stand facing the same direction, and a green plaza sits on top of the large flat roof to their southeast.

We want to confirm here that the numbers for the height of the ground have not moved. The center of Musashi-Kosugi is 8.3 m and the center of Futako-Tamagawa is 12.9 m, and both are survey values available as of 2026. While you stepped through the eras of the photographs, the increase was in the height piled up from the ground surface. As for the riverbed side, the sports ground lots at the upper left of Futako-Tamagawa have not changed place since 1974-78, and the shapes of the stadium and the ballpark next to Musashi-Kosugi have hardly moved since 1987-90. As the town has grown upward, the flatness of the riverbed stands out in the composition.

The roofs changed at the two locations on the river-mouth side

At Tonomachi, the outline of the striped roofs that did not move from 1974-78 to 1987-90 has vanished without a trace in today's photograph. Separate medium-sized buildings are placed here and there with wide streets and open ground between them, and paved areas with rows of white parking spaces and bands of lawn and trees fill the space between. The City of Kawasaki officially opened this area as King Skyfront in March 2013 and laid it out as a district where research facilities in fields such as life sciences and the environment gather. Even so, the road on the levee along the river still draws the same arc as around 1936-42, and it can be read as only the arc of the levee remains.

In March 2022 the Tamagawa Sky Bridge, about 840 m long, opened, linking Tonomachi with the Haneda Airport side. However, the bridge does not appear in the latest photograph as of 2026. You can tell from the absence of the bridge that the photograph was taken before the opening.

At Lazona Kawasaki, too, the rows of buildings that had occupied the same position across six eras disappear in the last photograph, and a large building enclosing a courtyard and buildings taller than their surroundings stand west of the station. Even so, the bundle of lines in the station grounds runs diagonally in the same direction as in the old eras, and the fan shape of the ballpark on the riverbank and the two oval tracks lined up to the east keep their outlines. One thing holds across the four locations: roofs and buildings disappeared from the photographs, and the lines of the river, the tracks, and the levees remain.

The order of elevation and the order of land values swap partway

Let us also look at how far the order of heights and the order of land values overlap. The values available are not for the locations themselves but for the official land price (Chika Koji) points for residential land near each of them. For Tonomachi it is in Daimachi, Kawasaki Ward, about 1.2 km inland; for Lazona Kawasaki it is in Saiwai-cho 2-chome, Saiwai Ward, about 520 m away; for Musashi-Kosugi it is in Kosugi-machi 2-chome, Nakahara Ward, about 590 m away; and for Futako-Tamagawa it is in Seta 1-chome, Setagaya Ward, about 560 m away. None of them is the value of the ground of factories or research facilities, and this has to be discounted when reading them.

The 2026 official land prices per square meter are 324,000 yen in Daimachi, 552,000 yen in Saiwai-cho 2-chome, 905,000 yen in Kosugi-machi 2-chome, and 871,000 yen in Seta 1-chome. The order of elevation rises upstream: 0.8 m, 2.8 m, 8.3 m, and 12.9 m, but in the order of values the third and fourth swap places. It is not a simple order in which the farther upstream you go, the higher the value.

The length of the records is not the same either. Only the point for Lazona Kawasaki can be followed from 565,000 yen in 1989; up to the 2026 publication, the highest is 590,000 yen in 1991, the lowest is 287,000 yen in 2005, and 2026 is 552,000 yen. Even in 2026 the value has not yet reached the 1991 value. The records for the remaining Tonomachi / Musashi-Kosugi / Futako-Tamagawa start in 2012 or 2016, and up to the 2026 publication, all of them follow an order in which the first year is the lowest and 2026 is the highest.

Step through the four locations from the river-mouth side

Lining up four locations along the same river shows that the height of the ground is roughly decided by the position from the river mouth, and that the change in what the photographs show moves forward for other reasons. As a way of reading, first check the whiteness of the riverbed and the arc of the levee in the photograph from around 1936-42 or the 1945-50 photograph, next look at how far the rows of houses reached in the 1961-69 photograph, and last go back and forth between the 1987-90 photograph and the photograph as of 2026; the differences among the four come out most clearly this way.

On the pages for Ukishima / Tonomachi, Lazona Kawasaki, Musashi-Kosugi, and Futako-Tamagawa, you can check the era slider, the elevation in four directions, and the values of the nearby land price point on the same screen. If you want to see the published assumptions for low land, the materials of each local government are gathered on the Hazard Map Portal Site of the Ministry of Land, Infrastructure, Transport and Tourism. The row of reclaimed land that continues beyond the river mouth is covered in 60 years of the Tokyo Bay shore: the changing purposes of reclamation.

The prices in this article are actual examples at each point in time and do not reflect market prices after the article was written.