Skip to main content

How to control a killer flood on the Sumida River

This is epic! It started with mild curiosity. Why doesn't Tokyo do more with its rivers? Instead of entombing them in concrete, why not more parks and boats and bridle paths?

Then it escalated. Where does the Sumida River start? Why is the Arakawa in Tokyo such a straight line? Surely that's not natural? Iwabuchi sluice. What's that? Great Kanto Flood 1910. Cripes, look!, Sensō-ji was under water. Why is there so little information in English? Wait, hang on, Wikipedia is wrong!

Thus idle speculation unleashed a growing fascination with Tokyo's flood control techniques: a complex system of rivers, canals, sluices, locks, controlled water levels, super levees, evacuation areas and a massive underground discharge channel in Saitama. Research proved interesting but frustrating, so I rejected academia in favor of empirical evidence: I walked along Tokyo's most important waterway, the Sumida, from its origin in Kita-ku to Tokyo Bay. I covered 25 km and passed over/under 26 bridges for cars and pedestrians.¹

The original red sluice gate, Akasuimon, at Iwabuchi

This is such a complex topic that it justifies its own blog – nay, book! – but I'll do my best to limit myself to three parts:
  • the upper section of the Sumida and the origin of its present-day flood control system;
  • the middle section in Taitō, where I live, undeniably the part with the most interesting history, sights and bridges;
  • the lower section where the river forks at Tsukudajima before flowing into Tokyo Bay.

Let's start at the top, shall we?

What we now call the Sumida River² (隅田川 Sumidagawa) starts in Kita-ku where the Arakawa (荒川) splits into two: a river that flows through the Iwabuchi sluice gate and follows a natural course (called the Sumida) and an entirely man-made canal that follows a straight course (called the Arakawa).

Yes. This was another surprise. The Arakawa in Tokyo itself is actually a massive artificial canal built with one single purpose: to prevent disasters in the shitamachi. We forget that Tokyo is a harbor city crisscrossed with rivers, and that the shitamachi deserves its name: a low-lying area that used to be a swampland and is still vulnerable to floods.

Japan's rivers are prone to flooding because they are relatively short and flow rapidly down steep slopes. The ratio of peak flow discharge³ to basin area is relatively large, ranging from 10 times to as much as 100 times that of major rivers in other countries. The water level rises and falls very quickly. The river regime coefficient – the ratio of the maximum discharge to minimum discharge – is between 200 and 400 times larger than that of continental rivers.

Yakumo Jinja (八雲神社in Iwabuchimachi  is one of the oldest shrines
in this area. Yes, of course I visited shrines, too!

Yakumo Jinja

Tokyo's main river is the Sumida. I couldn't determine the origin of the name, but early Heian literature refers to a ferry that transported travelers across the river at a settlement called Sumida Juku (near present-day Mukōjima). Old records indicate, for example, that Minamoto Yoritomo stationed many troops at Sumida Juku. 

The river – and life – trundled along until the arrival of Tokugawa Ieyasu, the man who created a new capital at a little fishing village called Edo in the early 1600s. Edo, which used to be a huddle of huts near the mouth of the Sumida, was transformed into a huge political city by aggressive public works including land reclamation, new canals and clean water supply systems.

The first bridge across the Sumida was Senju-Oohashi, originally built in 1594; the second was Ryōgokubashi, built in 1659. Ryōgoku means "two provinces", because it connected the old provinces Musashi and Shimōsa.

Life continued, the river flooded, people died. A turning point arrived in 1910, when a torrential downpour of 300–400 mm fell between 8 and 10 August. The Sumida swelled, broke through several embankments and turned the city from Iwabuchi to Kameido into a vast inland sea. The flood water took two weeks to subside, affecting 1,5 million people and leaving 270 000 homes flooded. Damage totaled more than ¥120 million yen, equivalent to 4,2% of the gross national income at the time.4

The government's response was to build an artificial channel to protect downtown Tokyo from further flood damage.5 The project involved construction of a sluice gate at Iwabuchi in Kita-ku and a massive diversion channel 500 meters wide and 22 km long.

This notice board indicates the old red sluice (赤水門), the new blue sluice
(青水門), the Sumidagawa (隅田川) and the Arakawa (荒川).

The old red sluice gate with a marker that indicates previous flood levels.

The first sluice gate, called Akasuimon, was completed in 1924, on the spot where the Shingashi River joins the Arakawa. It was designed by Aoyama Akira, an engineer who was an architectural consultant on the Panama Canal a decade earlier. When the river was in flood, the sluice gates would be closed, controlling flow volume in the river’s main course and dumping the flood waters through the wide channel directly into the sea. Construction, which took a total of twenty years, was completed in 1930. This channel is also called the Arakawa, but it's not a real river: the "real" Arakawa actually morphs into the Sumida.

This sculpture on Nakanoshima, a small island near the red sluice gate,
is called "piercing the moon".

Tokyo's only sake brewery, Koyama Shuzō, can be found in Iwabuchimachi.
It's said to be the only place in Tokyo with water pure enough for sake.

Above, the sake brewery; below, markers that
indicate the distance to the ocean and water levels

It wasn't the last of the floods. Typhoon Isewan in 1959, the strongest ever to hit Japan, killed 5098 people in Japan. Nagoya was the worst affected, but the typhoon also caused massive damage in Tokyo. Read about Isewan here and here (PDF).

Isewan won't be the last typhoon, but next time, perhaps, Tokyo will be better prepared. A bigger sluice gate, this time blue, was constructed slightly lower down the Sumida in 1982. Super levees and evacuation centres have been built along the river (the biggest evacuation centre, between Senju-Oohashi and Senju-Shiori-Oohashi in Minami-Senju, can accommodate 120 000 people), sluice gates and pumping systems have been added to various rivers in the shitamachi, and water levels in especially Kōtō-ku's rivers have been lowered. Finally, a massive underground discharge system called G-cans has been constructed in Kasukabe, Saitama. I haven't visited it yet, but you can read more about it here and here.

The new blue sluice gate

Here you can see the old and the new sluice gates in one shot.

You're wondering about tsunami damage in Tokyo? Uh-oh. If there's a quake right underneath Tokyo, or if it's so near that a tsunami comes funneling through Tokyo Bay … let's just say I hope this apartment building survives and I hope the 11th floor is high enough.

If not, shōganai.

If you'd like to walk along the Sumida yourself, I suggest you skip the upper part except for Iwabuchi. If you walk across the old red sluice gate, you'll reach a small, quiet island called Nakanoshima, where you can relax under a tree, have a picnic, watch the mighty angry river (Arakawa means angry river) as it divides into two.

The rest of the upper Sumida is really not that attractive. The Hero graciously offered to be my chauffeur, so we covered the section from Iwabuchi to Senju-Oohashi on a motorbike. I returned to walk from Adachiodai Station along the river, but had to take a shortcut via Kita-Senju Station to Horikiri Station, because there's no paved walkway along the river in that area.

I'll highlight two areas.

Firstly, Adachiodai Station on the Nippori-Toneri Liner is situated on the narrowest strip between the Sumida and the Arakawa. It's wide enough for a station, a row of apartment buildings, a road … and that's that. I tried to find a high spot where I could get both rivers into one shot, but didn't succeed.

If both rivers flood at the same time, that's it, bye-bye station.

This is the Sumida seen from Adachiodai Station.

Here's the Arakawa on the other side of the station.

The Nippori-Toneri Liner bridge across the Arakawa


See that apartment building? On its right is the Sumida, on its left is the Arakawa.





Secondly, Horikiri Station, which is near the only canal that connects the two rivers downstream. It's a fairly bleak industrial area, but I wanted to see the sluice, the canal and the super levee on the Sumida in that area.

Sluice gate on a canal between the Sumida and the Arakawa, near Horikiri Station

The Arakawa, with the canal leading to the Sumida

The canal leading towards the Sumida

The canal flowing into the Sumida

Levee on the Sumida

Horikiri Station

Coming up, Part 2, from Shirahigebashi to Ryōgokubashi.


A Companion to Japanese History, edited by William M. Tsutsui
Flood Prevention and Remediation, edited by F. C. B. Mascarenhas
Inland Flood Hazards: Human, Riparian, and Aquatic Communities, edited by Ellen E. Wohl
River Basin Management IV, edited by C.A. Brebbia


1) There are 26 bridges for cars and pedestrians across the Sumida; several more for railways and water supply pipes. Once I've done all three Sumida posts, I'll publish a list of all bridges with their names and photos.

2) River is kawa in Japanese, but it's pronounced gawa when it's combined with certain words. Sumidagawa would be translated as Sumida River; Arakawa as Ara River. It's usually translated as Arakawa River, but that means Ara River River, which is silly. My imperfect solution is to refer to them as the Sumida and the Arakawa.

3) Data provided by the Ministry of Land, Infrastructure, Transport and Tourism

4) Data provided by the Arakawa Downstream River Office (荒川下流河川事務所) in the Ministry of Land, Infrastructure, Transport and Tourism

5) One wishes this government were in charge right now, to provide an adequate response to the lingering after-effect of the Great Tōhoku Earthquake.

This is the Arakawa just before the red sluice gate.
That's Saitama on the other side.


Taking a nap on Nakanoshima

Boats 'n stuff

He's playing a saxophone. This photo was taken near Adachiodai Station.

Suntanning next to the Sumida near Adachiodai Station


More fishing! The fishing shots were taken near Otakebashi.


There's The Hero, patiently waiting while Ru faffs with cameras.
He deserves a medal for his assistance.
(This is a bridge across the Shingashi River near the red sluice gate.)

Sunset on the Sumida, and time to say goodbye.

View Sumida River from Iwabuchi to Horikiri Station in a larger map

Popular posts from this blog

Higanbana, a flower of loss and longing

I love this flower. I love all flowers, but this one, ah, this one comes packaged with the most wonderful stories. Its scientific name is Lycoris radiata; in English it's red spider lily; in Japanese it has several names including higanbana (ヒガンバナ), in other words, autumn equinox flower.

It's also referred to as manjusaka (曼珠沙華), based on an old Chinese legend about two elves: Manju guarded the flowers and Saka the leaves, but they could never meet, because the plant never bears flowers and leaves at the same time. They were curious about each other, so they defied the gods' instructions and arranged a meeting. I assume it was not via Twitter. The gods promptly punished them, as gods are wont to do, and separated them for all eternity.
To this day, the red lily is associated with loss, longing, abandonment and lost memories in hanakotoba(花言葉), the language of flowers. It's believed that if you meet a person you'll never see again, these flowers will grow along your…

Happy birthday, Mum!

Here's an August flower for you.  Not your beloved cherry blossoms, but your favourite colour. I miss you.

This is what my language sounds like

A while ago I promised I would do a post about Afrikaans songs. Oh dear. It's more work than I thought it would be, and it's aggravated by the fact that I've lost touch with contemporary culture in South Africa. (Please don't ask me about Die Antwoord. I don't get it. I don't want to get it.) So for now, while I continue my research, I've selected two golden oldies that are very natsukashii (that's a Japanese word for "dear" or "missed") to me. You'll notice the central themes that unite these songs: an abiding love for Africa, as well as loss and longing.
Quick recap: Afrikaans, my mother tongue, is a South African language developed from 17th century Dutch. It has adopted words from Malay, Khoisan and Bantu languages, but 90% of its vocabulary is of Dutch origin. Yes, I understand Dutch (with a bit of effort) and Flemish (easily). Afrikaans has about 6 million native speakers.
Tomorrow we return our focus to Japan. Tonight, son…

The Princess Who Loved Insects (updated)

My blog gets so many search keyword hits about this particular topic that I've decided to update an old post about the Japenese story The Princess Who Loved Insects(虫めづる姫君Mushi Mezuru Himegimi).

It's contained in Tales of the Riverside Middle Counselor (堤中納言物語Tsutsumi Chūnagon Monogatari), a collection of short stories written in the late Heian period. It focuses on the adventures of a young girl who refuses to make herself beautiful and play the courtship game. She doesn't blacken her teeth and pluck her eyebrows (as refined ladies did in those days); instead, she spends her time outdoors, playing with bugs and caterpillars.

I refer to her as Ms Mushi (Ms Insect).  A girl this tough is definitely not a prim prissy Miss, she's a ballsy Ms. She's my favourite Japanese heroine. She's strong, she's rebellious, she refuses to pretend, she ignores society's stupid rules that fetter women. You go, girl! Long live caterpillar eyebrows!

Donald Keene mentions in hi…

The princess who loved insects

Edit added 8 May 2013: This post receives so many keyword search hits for "The Princess Who Loved Insects" that I've published an updated post (with extra information) that focuses on the book. Click here to read it.)

Blogging has been an interesting experiment. I initially started two blogs, Rurousha for personal musings and Sanpokatagata for factual stories accompanied by photos. I've now decided I'll do all stories on this blog, regardless of the content, and turn Sanpo into a supplementary photo blog. I'm not sure it's a good idea, since I'm not a good photographer at all, but let's see how it goes.
It occurred to me that "nomad" is not the ideal name for my blog. I don't wander anymore; I want to live in Japan forever and ever amen till death do us part. Then I remembered that I've already stayed in six different apartments in Tokyo and although most of my income is derived from one company, I've been based in three diff…

Edo wind chimes: air con for your soul

Have you noticed that Japan has a thing about bells?
Watch people's phones: every second phone charm has a little bell that jingles with the slightest movement. There are bells on doors and bells at shrines and bells at temples. There are bells on traditional hair ornaments called bira-bira kanzashi, bamboo chimes tuned DFGA for your garden, bells are a symbol of peace (link) and their sound echoes the impermanence of all things (link).
From which one could correctly deduce that peace is ever transient.
Now, before I get sidetracked down a thousand rabbit holes, let’s focus on the real topic: bells, yes, but specifically wind chimes or fūrin(風鈴).

I would not to mine own self be true if I didn't include a little history lesson. Here we go:
The oldest wind chimes found at archeological sites in South East Asia are 5000 years old. These early versions were made from wood, bones and shells; and were probably used to keep birds out of cultivated fields and/or to ward off evil spirits.

The ultimate guide to Kanda Myojin

I'm floundering. I don't know how to start a post about Kanda Myōjin (神田明神), because how do you choose a highlight from this collection below?
The decapitated head of a rebellious samurai who's still haunting Ōtemachi is buried in the vicinity, and his deified spirit is enshrined here.It's been called the world's geekiest shrine thanks to its proximity to otaku heaven Akihabara. The shrine has a Facebook, Twitter and LINE account.You can see some extremely generously endowed young ladies on the shrine's ema.It has a horse. A real horse. A tiny living breathing pony.Birds protect it against fire.
See my problem? Where do I start the ultimate guide to the ultimate shrine?

Why Kanda Myōjin?
Let's be boring and kick off with my own connection with Kanda Myōjin, which is very simple: I've always lived within walking distance of the shrine. My first four years in Tokyo were spent in Kanda, blissfully close to the book district Jinbōchō, and I frequently passed …

Hiking along the Mitake Valley in Okutama

I'm lying. Exaggerating. It's not hiking; it's walking.

As a matter of fact, the Mitake Valley Riverside Trail has given me a new definition of walking vs hiking: if you encounter vending machines along the way, it's walking, not hiking.
I've done several hikes in Okutama, but I'm going to start with this walk because anybody can do it. It's exceptionally beautiful, truly pleasant and very easy. You don't need to be an experienced hiker, you don't need hiking boots, you don't need energy drinks – or Scotch – to keep going.

It starts at Ikusabata Station on the Ōme Line, follows the Tama River and ends about 5 km upstream. It took me about two hours of slow walking, many photos, frequent diversions and arbitrary stops to enjoy the autumn colours.
Let's do this section by section. Warning: this post is photo-heavy!
Ikusabata to Sawai

It takes 90 minutes from Tokyo Station. Take the Chūō Line to Ōme, transfer to the Ōme Line and get off at Ikusab…

Yotsuya Kaidan, Japan's favourite ghost story

Kaidan! Ghost stories! You ready?
August is the month of Obon (お盆), a Buddhist festival that honours ancestral spirits, who are believed to return to their birthplaces in this week.  Since otherworldly beings are wandering about, it's also the perfect time for ghost stories or kaidan.
Kaidan (怪談) consists of two kanji: 怪 (kai) meaning "strange, mysterious or bewitching apparition" and 談 (dan) meaning"talk"or "recited narrative". It's a slightly old-fashioned word that conjures up tales from the Edo era, and we're going to start our August Kaidan Series with an old Edo tale of murder, betrayal and revenge that remains the most famous ghost story in Japan.
It's called Yotsuya Kadain (四谷怪談), and it proves that "heavenhas norage like love to hatred turned, norhellafury like a woman scorned".¹ It's roughly based on a real event: a woman called Oiwa² married a man called Tamiya Iuzaemon, but after their divorce, various misfortunes be…

Bush clover, the flower of autumn

It's a modest plant, easy to overlook, yet it used to be Japan's most beloved flower.

Bush clover (ハギ, hagi) is mentioned in 141* poems in the Manyōshū (万葉集, Collection of Ten Thousand Leaves), Japan's first anthology of poetry, compiled in the 8th century. That far exceeds the 119 poems about the second-most popular flower, plum blossoms. The latter was revered as an exotic import from China; the former was praised for its rustic simplicity.

Bush clover grows about 3 m in height and has long, slender branches that droop across paths. The branches represent feminine elegance, but it's also a symbol of vigour thanks to its ability to produce young shoots from old stock. It flowers in September, when summer's heat lingers, but it's believed that if you can see dew drops on the plant's small green leaves, you know that autumn is near.

Nowadays the flower attracts little attention. There aren't any good bush clover viewing spots in Tokyo that I know of, apart…