Dams · Rivers

The River, Her Bounty and Fury: The Sakura and Tokyo

GUEST BLOG BY: Aparna Datar

The cherry blossoms of Japan are a glorious seasonal spectacle, swathing the entire country into a gentle blanket of soft pink Sakura flowers. Tokyo’s rivers turn pink as the Sakura petals, float upon their surfaces.

Sakura is a genus of the Prunus, with a genetic name Prunus serrulata, or the Japanese Cherry.

Sakura floating on the Meguro River in Tokyo (Left)  Sakura on the Hozugawa River in Kyoto (Right) 

A completely organic part of Tokyo’s steel and glass jungle and its public life and psyche, Sakura is found everywhere particularly along Rivers and their embankments. These embankments are called the Sakura Tsutsumi or Sakura embankments. The story of the Sakura embankments is in all the stories of Tokyo!

And like anywhere in the world the story of a great city is always a story of a great river and her people!

Tokyo follows this script to perfection.

The Sakura embankment of the Meguro, River, Tokyo ( Left)  The Sakura Embankment of the Sumida (The Bokutei) (Right)  


It begins on Tokyo’s most beautiful river bank, the banks of the Sumidagawa River in the Edo Era (1600-1800). The Sumidagawa, is the lifeline of the Sumida and the Taito wards today, the heart of Shitamachi or downtown of Edo (and still referred to as Shitamachi today). It was the centre of a culture of painting, Haiku, Sumo wrestling, had many recreational traditions centerd around her. Amongst them, Boating and Fireworks still figure prominently amongst present day Sumida ward’s public events.

The Shitamachi is the low lying area on the eastern flank of the Sumida, consists of the Sumida ward, the Taito ward, the Arakawa ward, the Adachi, Chiyoda and the Edogawa ward.

The Shitamachi(Wikipedia) (Left) Shitamachi and the Sumidapresent day (Right)

The tradition of public fireworks in summer and boating are the gift of the Sumida. But her greatest gift to the Japanese people is the gift of the Hanami, or the public viewing of Sakura flowers in spring. Hanami is a much loved Japanese tradition. Every year a sea of tourists from all over the world descend upon Tokyo to partake in this venerated celebration of the Sakura flowers. Sakura is almost always planted in large numbers in Public spaces and rarely if so in a private home or a garden. From Edo era to the present Hanami is celebrated with family, loved ones, with lovers, dogs and buddies. People picnic under the Sakura trees with food and Sake (the rice wine of Japan).

The Sumida embankment  is lined with over 700[i] Sakura trees, of the Someiyoshinoo specie, the most ubiquitous of all Sakura specie. Reputed to be a distant hybrid of a Korean Sakura it very much is domestic to Edo, and Shitamachi, cultivated nearby in the present day Toshima ward of Tokyo (one of the 23 wards of Tokyo metro), a product of the work and industry of the Eddoko or the original residents of Edo.

Someiyoshino Sakura on the Meguro River Photo by Aparna Datar
Someiyoshino Sakura

The Hanami was born on the Sakura Embankments of the Sumida, also called Bokutei. This beautiful tradition celebrating life and beginning of the new and hope was actually rooted in much devastation at the hands of the river.

This area at the heart of the Shitamachi looked very different from the present day Sumida ward. It was a marshy low lying area thickly clad with a dense forest, where the Shogun came to practice falconry at the start of the Edo era. Thousands of streams originated in the mountains on the western flank of Tokyo, danced through the marshes into the Tokyo Bay. In the Edo era it became home to lower castes, merchants, laborers, painters, Haiku masters and rebels.

Edo era was an era of floods for Tokyo.[ii]

Normally considered to be the period between 1600-1800AD, this would be about the same time as Chatrapati Shivaji Maharaj set about creating the foundations of the Maratha Empire.

Typhoons conspired with unseasonal rains and Tsunamis, floods would surge through all of Tokyo and the Kanto Plains.

Tokyo and the Kanto Plains

The largest flood of the Edo era hit the area around mid 1700 causing much death and misery. Mountains collapsed, landslides flattened communities, land was devastated and towns washed away. Bodies floated in swollen rivers all the way from Oasaka to Nagano, a distance of around 405 km, four hours today on the Shinkansen. This was the Great Kanto Flood of 1742.

Hanami is an inheritance of destruction wrought by such floods.


Edo was founded by Ieyasu Tokugawa (1543-1616), the founder of the Tokugawa Dynasty and the Kingmaker who built Tokyo. He moved mountains, had deltas shifted away and got the rivers to flow the direction he pleased, choosing to prevail over nature. He built Edo into a thriving trading agricultural, and manufacturing center.

By the time his great grandson Yoshimune Tokugawa started the Hanami tradition on the Bokutei, which was now the nerve of the Shitamachi, Edo was a bustling, prosperous commercial center, constantly at the risk of floods.

The Tokugawa Shogunate, it is believed began the tradition of Hanami as a part of the Shogunate’s large scale economic reform[iii] that spanned measures from taxation to western technology for flood control, trade reforms and of course the beloved tradition of Hanami. It was started as a measure of frugality in flood control, on the banks of the Sumidagawa where a thousand or more trees were planted, on the Bokutei.

Many of the Japanese rivers are born in steep mountains, flow furiously from the source and flood easy. Their lengths are shorter and catchments smaller than ones in India and they flood easy. Tokyo was built by the Tokugawa on the Kanto plains[iv] the low lying flood plains of five big rivers (the Tone, the Watarase, the Kinu,  the Ara, etc.)


Source: Wikiwand http://www.wikiwand.com/en/Tone_River

Japan’s extreme topography includes the Fuji, which is at almost 3800 meters above the sea level and the lowest elevation is located at Hachinoe in Aomori Prefecture to the extreme north of Tokyo. A mine in Hachinoe is at minus 585 m.         

    The Fuji San  Hachinoe, Aomori prefecture Photo: Aparna Datar

The Tokugawa’s position politically was similar to that of the Peshwas. Though all of political, economic and military might rested with them, they chose to bound themselves to, serve and protect the Emperor, who even today is revered and respected as having descended from God.  

The Daimyos or the local rulers who served the Tokugawa shouldered almost all the flood control public works. Building embankments and roads and castles and other public infrastructure, they were stretched to the limit, often to bankruptcy. The Tokugawa[v] was facing deep financial solvency issues around the time Yoshimune wanted to bring relief to his Daimyos[vi].

The Shogunate planted thousands of Sakura trees on the Sumidagawa embankments as a part of flood control reform. It was believed that the droves of people who would come in for Hanami on the embankments would help to firm  the embankments… by merely walking[vii] upon them for free! saving  the exchequer a fortune[viii].  This is reputed to be a part of a wider ranging economic reform that spanned taxation, public works, formalizing trading bodies, western tech. for flood control and… of course Hanami. This is one of the fondest public memories about Sakura passed on from one generation of Eddoko to the next into the present.

Yoshimune[ix] himself went out lobbying his people to Hanami away in scores, it  is widely held that this maybe  far more than just an old Edo lore. Like anywhere else in the world I suppose It was believed: “He who rules the rivers, rules the nation[x].

Yoshimune, and his descendants had a great love for the Sakura and curated large varieties of Sakura species from all over Japan. The Sakura embankment at Sumidagawa, all of it being Someyoshino specie Sakura, the most abundantly found specie within Tokyo even today, were reportedly the first big public Sakura in Edo for the Edokko.

This was the start of the tradition of building the Sakura Tsutsumi or the Sakura embankments. These continued to be built throughout the Edo era, the Meji Era, the pre war and post war eras in Japan. As times and technology changed these embankments also had an additional role of beautifying public spaces. Scores of rivers across Japan sport thousands of these spectacular embankments and the Japanese people have the Sumida to thank for this spectacular addition to their public lives.

The Japanese River Basin Authorities of every prefecture have developed an entire science of how to care for these embankments and there is a separate authority that looks after these. This model is called the Sakura Tsustsumi Model, or the Sakura Embankment Model[xi].

Why did Edo flood this much? Because of Tokugawa’s public works of river reengineering. The impact of floods was compounded to tragic consequences for Edo and all the way to modern day, that modern Tokyo is still struggling to neutralize.

The Tokugawa carried out large scale river diversion works on Tokyo’s rivers, drained swamps, dammed rivers, dredged river beds and marshes, flattened mountains, changed courses of rivers and built Edo where the river should have flown free.

In an ambitious 60 year project the course of the Tone was changed eastward to flow into the Pacific Ocean, away from the Tokyo Bay where it flowed into originally. The consequences were tragic as we will see.    

MAP OF EDO OF YORE Source: Ministry of Land Transport and Infrastructure

Thousands of streams crisscrossed and eventually made their way across Kanto Plains and the Sumida, the Tone were formed in the marshy lowlands of what is today Chiba a prefecture bordering Tokyo on the north. Tokugawa engineers had the mountain that stood in the place of Surugadai ward today leveled for filling the marsh near the Hibiya inlet near the castle, which is the present day imperial palace at Otemachi. These were all neighborhoods of modern day Nihonbashi, Kudanshita, Otemachi, Hibiya districts after the Hibiya Inlet was filled and, built quite literally on shaky grounds.

The Hibiya Inle-Hibiya is a commercial and a government district. The WW2 Tokyo trials were all held in Hibiya Source-Japan Property Central
Hibiya Inlet Source: Japan Property Central

The objective was often both flood control and clearing land for Edo to be built upon, ironically two conflicting objectives, viz. the methods adopted.

Tokugawa Shogunate split a large river that emptied not the Tokyo bay, and those rivers became the present day Tone, basically a huge river in Tokyo and indeed all of Japan and the Ara a slightly smaller one. He then went on to connect the Asma to the Watarase rivers and eventually made the Watarase a tributary of the Tone. A series of canals were built to link the Tone to other rivers like the Hitachi and the Kinu rivers. The entire Tone delta was shifted out of Edo. Levees were constructed all across Edo. The Tokyo metro government of the present day has split entire Tokyo metro into 7 categories of land, starting with the most “stable land” to the weakest, where land is reclaimed and easy prey to earthquakes and tsunamis and flooding,  an important factor that determines real estate  prices.

Almost all of Shitamachi has evolved from these cleared marshes, former river beds at zero elevation from sea level, encompassing almost all of eastern Tokyo, a massive present day problem, called the Zero Kaibatsu Chitai, which cannot be reversed. Giant portions of the city, the Edogawa ward, Adachi ward, Katsushika ward, besides the other parts of Shitamachi are all either at sea level zero or below. Some of Tokyo’s swankiest property can be found in the Zero kaibatsu chitai or the zero elevation from sea level.

Source: Nikkei Shinbun (newspaper) March 2018    Source: TMG Hazard Map

Today if the embankments of the Arakawa river (thousands of Sakura trees were planted on her embankment in the 1800, another river that is in the Shitamachi, again engineered upon remorselessly through the last 500 years), and the Sumida give away, almost all of this area and 90 percent of Tokyo gargantuan train and subway network will be completely destroyed. It ferries almost 100 percent of Tokyo’s population, with a very few folks even owning cars or driver’s licenses. Experts argue that in the face of climate change the city is ill-equipped with flood control, to deal with only half of any expected deluge/rainfall. The Shitamachi is still at threat, a cursory glance at the hazard maps of the wards may reveal.

JR 5.png
Shitamachi in Edo 
The River Basin Source-Ministry of Land Infrastructure and Transport
Tokyo River Basin Source: Ministry of Land transport and infrastructure

Just like Edo used to be, again and again. The floods back then would win almost to a predetermined plan. The levees would fail, and the rivers would roar back with a ferocious vengeance, during floods down their original course, which was now the city of Edo. The reason was that the original course was the lowest point on the Edo topography, where now the city sprawled away.

The damage always worst in low lying areas near the Sumida where the Tone originally met the ocean before she was moved. Moving a river had only worsened the floods.

There was no estimating the death toll come a tsunami or a typhoon or an unseasonal rain. The Great Kanto Flood (1742) occurred on the backdrop of these works, ironically the purpose of which was flood control as much as shipping and agriculture and industry. The reclaimed areas, around the castle would be ravaged, bridges washed away.

There are scores of hidden subterranean rivers in Tokyo that were built upon post WW2 or during the Meiji and the pre war era. The canals of the Shitamachi, and parts of the moats, all had roads or train lines built upon them. Tokyo’s giant express way network also had their mammoth pillars built right into the rivers, impacting their flow. Tokyo is full of Old Sakura tree lined narrow stretches of curved alleys and street way all former rivers and canals, and most of all the Sakura on the edges often is a testament of a former river. A good but an inaccurate way to figure if a train line or a city part was built upon a former river or a canal is to spot Sakura in large numbers through the JR trains. That is likely to be a former embankment often enough.

JR 6.png
A former waterway in Tokyos Setagaya Ward Copyright: Aparna Datar

Says she: This is my neighborhood!

There’s near geometric cuts into the entire landscape of Tokyo. Tokyo continues to explode into former river beds and marshes and is now considered by insurance conglomerates as the world’s riskiest, flood prone city. The city kept following in the Tokugawa’s footsteps for 500 years right through and post ww2, through into the heady bubble economy days of the eighties and the nineties when valuations for these former river beds sky rocketed.

Ironically this brings to mind Japan’s other big problem, that of cities and villages in the mountains emptying as younger population moves to Tokyo causing Japan’s most intense economic and social problem, that of depopulation. Most of the population that now moves into Tokyo, is often spread in the Kibatsu Zero Chitai or city spread at sea level or zero where land is graded as the shakiest. Reason would compel us do the opposite in modern times!   

Life at Zero Kaibatsu Chitai 

JR 9

Source: Nagoya River Basin Authority public information service

Zero Kaibatsu Chitai

Experts urge the government to acquire riverside areas as they come into market at the market price, over a span of a century and turn it all into unused land that could be allowed to flood.

They warn Tokyoites themselves to simply not buy property in these areas.

Or if you did, live with the reality that if the Tone or the Arakawa decide to rage, all you can do is climb up to the second floor of your house and pray the river won’t follow suit.

Aparna Datar (aparnanitindatar@gmail.com)






Tae Moriyama, Tokyo Adventures (Glimpses of A City in Bygone Eras)

translation by Reiko Gavey ISBN4-07-975842


The homepage of the Sumida Ward detailing the Sumida embankment Sakura




Japanese Ministry for Land and Infrastructure Development








Katsushika ku ward office home page


[i] Tae Moriyama: Tokyo Adventures

[ii] https://soranews24.com/2016/03/10/edo-era-illustrated-records-show-the-disasters-that-have-plagued-japan-throughout-its-history/

[iii] https://en.wikipedia.org/wiki/Tokugawa_Yoshimune

[iv] https://en.wikipedia.org/wiki/Kantō_Plain

[v] https://en.wikipedia.org/wiki/Kyōhō_Reforms

[vi] https://en.wikipedia.org/wiki/Tokugawa_Yoshimunkaho no kaik

[vii] https://kojodan.jp/blog/story/182.html

[viii] https://kojodan.jp/blog/story/182.html

[ix] https://milt.go.jp 


[x] https://toyoeiwa.repo.nii.ac.jp/?action=repository_action…item

[xi] http://www.mlit.go.jp

One thought on “The River, Her Bounty and Fury: The Sakura and Tokyo

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.