Keynote Lecture by His Majesty the Emperor of Japan The 6th Special Thematic Session on Water and Disasters(through Video)

“Water in Circulation” - Thinking of Social Development through the Water Cycle -

March 21, 2023

The United Nations Headquarters

New York City, the United States of America

(through Video)

Your Excellency Dr. Han Seung-soo, Chair of HELP,
Your Excellency Dr. Csaba Korosi, President of the 77th Session of the General Assembly,
Excellencies, Ladies and gentlemen,

1. Prologue

 I am pleased to give this keynote speech at the 6th Special Thematic Session on Water and Disasters entitled “Connecting Mid-term Reviews of Water and Disaster Risk Reduction under Climate Change”. I would first of all like to express my deep condolences to the victims and my sympathy to all people affected by the severe earthquake in Turkey and Syria last month, the severe floods in Pakistan last summer, the devastating cyclones and the earthquake in Vanuatu just this month, and all disasters world-wide.

 The UN Water Conference will be held here starting tomorrow for the first time in 46 years, to discuss achieving water-related SDGs. In this context, I would like to offer my reflections on social development through the water cycle, and also touch upon the links between water, disaster risk reduction, and climate change, which is the theme of this Special Session.

2. People, society, and the water cycle – Formation of a recycle-based society in Edo and water -

(1) Development of Edo and water

 I would like to start my speech by introducing the link a few hundred years ago between water and the social development of Edo, or present Tokyo in Japan. The city of Edo developed rapidly after the Shogun, Tokugawa Ieyasu, established the Shogunate there in 1603. The Edo Castle, the city center, stood in a low marshland adjacent to Hibiya Cove which was open to the ocean in the East, as shown in this picture (Fig.1). A hilly area spread to the West of the castle. The hill, an outskirt of the Musashino Plateau, was topographically complex with numerous ups and downs, as it had been eroded by a number of tributaries. Those topographic features have inspired the names of many locations in Tokyo (Fig.2) that are taken after plateaus and mountains, such as Mejirodai and Atagoyama. Some are named after valleys, such as Ichigaya and Yanaka, and yet others after slopes, such as Kudanzaka and Kagurazaka in Tokyo. Although Edo was obviously geopolitically critical for the nation in terms of politics, military and economics, it was an immense challenge to develop the new metropolis sustainably.

 Ieyasu, the first shogun, and succeeding shoguns utilized water in full to achieve the sustainable development of Edo. Ieyasu in fact built a well-known water distribution system in the city. The pristine water originated from the rich spring ponds of Inogashira and Zenpukuji, as well as from the Tama River to the West. The stone gutters and wood pipes totaling 150 kilometers were cleverly networked along the complicated topographic contours of the city (Fig.3). Through this network, water flowed into public storage wells for use by citizens all over the city (Fig.4). A water saving culture was also developed and nurtured. For example, once-used water was reused for washing clothes and sprinkling over gardens (Fig.5).

 With regard to sanitation, it is noteworthy that human excreta was valued economically, and considered as important fertilizers for agricultural products in the mid-Edo period. Feeding the growing population of the new metropolis was of the utmost importance. Fertilizers were carried to farming areas in the suburbs of Edo through navigation networks in the lowlands. In return, the same boats brought back to the center of Edo agricultural products that were grown with this night soil. Here, a recycle-society (Fig.6) was formed, which had rarely been seen in the world at that period. To enable this recycling of agricultural products, inland navigation played an important role.

(2) An inland navigation network supporting the recycle-society

 The inland navigation was an important means of transportation in that period when modes of transportation were limited. The Shogunate developed marsh lands to the East of Edo Castle and a dense network of canals was constructed in the lowlands (Fig.7). They also embarked upon a large-scale project that diverted the river flowing into the center of Edo to the Pacific Ocean in the East of the Kanto Plain. It seems that this project also had the effect of flood control to protect Edo and surrounding towns from flood damage. Those navigation networks were used for transportation, not only between Edo and various regions, but also between Edo and the suburbs and within the city. New types of flat-bottomed boats, called Takase-bune, were developed (Fig.8). They were effectively used to carry cargo between the East of Edo and inland, as well as to the coastal areas of the country through the Tone and other rivers. This closely woven network of inland navigation (Fig.9) also helped the formation of the recycle-society of Edo.

(3) Flood management measures in Edo

 Flood management was one of the most important challenges for the feudal lords of Japan as the country lies in the Asia-Pacific Monsoon Zone, in which heavy rain was the norm rather than the exception. The Nihonshoki, the oldest official record of history in Japan of the 8th Century A.D., provides an account that Emperor Nintoku directed the construction of the “Manda Levee" to mitigate flooding (Fig.10). Lord Takeda Shingen, a prominent warlord of the Medieval War Period, built various flood control facilities, such as levees called “Shingen Levees (Fig.11)”, in strategic locations of the Kamanashi River as I have elaborated in my previous lecture. This intractable river that recurrently flooded was held back by those flood control facilities, which turned barren flood-prone hinterlands into fertile agricultural fields.

 It is easy to imagine that Edo, which developed on low, coastal marshlands, was vulnerable to high tides and floods. The central parts of the city were indeed severely flooded. The Sumida Levee and other levees were constructed in the early Edo period to mitigate flood impacts. Together with these levees, the network of canals and waterways functioned as temporary storage of flood waters. Cherry blossom trees were planted on the Sumida Levee (Fig.12) so that visitors who came to view the cherry blossoms would tread on the levee, and hence strengthen the structure. When large floods occurred, the Shogunate dispatched relief ships called 'Otasukebune' to carry out rescue activities, and built evacuation sheds and supplied food to the victims. It is also said that many ships anchored in the city of Edo went to rescue the victims, suggesting that flood response operations were conducted, to some extent, systematically and swiftly in the city of Edo.

(4) The water cycle of Edo that promoted the social development of the city.

 I have demonstrated that water was central to the social development of Edo and for shaping its unique recycle-society. The city’s development adapted to its natural, topographical, and geographical conditions. Multi-faceted works on large-scale water cycle infrastructure, in and around Edo, enabled rapid progress of the society. Edo, supported by the water cycle, grew into a megalopolis and one of the largest cities of the world (Fig.13). The city made progress in directly addressing its water challenges as if it were climbing step by step up a spiral stairwell.

(5) From Edo to Tokyo - modern society and water.-

 The various water factors that supported the development of Edo are still current in the modern society of Tokyo. Tokyo, with a population of 14 million, is supported by an extensive and integrated water supply network. The Tama River still provides water to the Western part of Tokyo (Fig.14), as it did to Edo. Sewage water in Tokyo is valued as an economic and a social resource. For example, I visited this sewage treatment plant in Shinagawa(Fig.15). The plant produces recycled water and energy from the sewerage water. An innovative system for recycle-society can be formed in this way, and replicated.

 Efforts to mitigate flood impacts have also been ongoing since the Edo Period. The completion of the Ara River Diversion Channel before World War II, a series of dams on the Tone River in the period of fast economic growth, the Metropolitan Outer Area Underground Discharge Channel in 2006 (Fig.16), and so forth, have all effectively reduced flood impacts to the capital area.

 And new light has been shed on the concept of using inland navigation for carrying relief goods to disaster affected areas, as was performed in Edo. They were positioned as today’s advanced disaster risk reduction measures. Plans to build emergency ports and other facilities to transport casualties and relief goods to and from isolated areas during disasters are under implementation in the Ara River and elsewhere in Tokyo. As we commemorate this year the 100 years since the Kanto Earthquake, in which more than 100,000 people were estimated to have died due to the earthquakes and fires, it would be meaningful to think over disaster countermeasures in the Tokyo metropolitan area, learning from the history and from the perspective of water use.

3. Water that cycles on earth and through human beings – Our Common Future seen through the lens of the water cycle -

 The unique recycle-society of Edo has, with the support of modern technology, continued to make progress today. The prototype laid down in the Edo Period still yields numerous lessons and good practices for the future, when we think of the sustainable development of our society in terms of economy, food, energy, transport, and disaster risk reduction.

 As we turn our eyes to cases around the world, there are also various water uses that have adapted to natural and geographical conditions, leading to a diverse water culture. On the other hand, the water cycle has been deformed due to progressing climate change in the recent decades, which has led to unusual natural phenomena such as frequent floods and droughts. The greenhouse gas level has reached its historical high, and atmospheric temperatures have kept rising (Fig.17). I have been informed that the total oceanic heat has reached the historically highest levels, and retreats of glaciers are accelerating.

 It is said that 80% of climate change is felt through water. Challenges of climate change cannot be addressed without water, and vice versa. How can we approach these twin challenges? The hint can be found in the water cycle. Our society has acquired food and energy through the water cycle. We have protected our society from too much water, and shared too little water by adapting ourselves to water cycles.

 As we can appreciate through the story of Edo, human beings have allied themselves with nature, coped with disasters, and were bestowed with water blessings throughout their history. We can learn from this legacy, and meet our common challenges, by addressing them by adopting broader perspectives on the whole water cycle. It is hoped that water, disaster risk reduction, and climate change issues will be fully connected, leading to comprehensive solutions to meet our challenges.

4. Epilogue

 The first United Nations Water Conference in 46 years will start tomorrow. I have been told that the subjects discussed today, namely the climate change, resilience, and environment, will be addressed in the third interactive dialogue of the conference. I sincerely hope that many meaningful discussions will be made today, as well as during the conference, and that they will lead us to a global acceleration of the actions needed for the full achievement of water-related SDGs.

 Thank you.