Approved Specified Nonprofit Corporation

【JWF News Vol.152】 2nd Stakeholders’ Consultation Meeting for the 8th World Water Forum


【JWF News Vol.152】 2nd Stakeholders’ Consultation Meeting for the 8th World Water Forum
May 17, 2017



・Foreword Transformation of Existing Dams: Towards Islands Rich in Energy

・Report from the Japan Water Forum
– 2nd Stakeholders’ Consultation Meeting for the 8th World Water Forum
– JWF Promotes Ex-ante Investment in Water at the ADB Annual Meeting
– Mission Statement of Water Conference for Future 2017
– JWF Fund 2016 Completed!


・Foreword Transformation of Existing Dams: Towards Islands Rich in Energy
By Kotaro Takemura, Chair of the Japan Water Forum


1957 Specified Multipurpose Dam Law
As Japanese rivers are fast-moving, their level suddenly increases when it rains, easily causing flood damage. When floodwaters recede, they run rapidly down to the sea. In contrast, after a week of dry weather, areas are stricken by droughts. Since the old days, Japan has suffered from either too much water or too little water. Therefore, flood control and water utilization is of particular importance for Japan.

After World Water II, dam construction was urgently needed to protect devastated land from flooding and to promote economic development. In 1957, the Specified Multipurpose Dam Law was enacted for the purposes of both flood control and water utilization. In such a small nation as Japan, there are few places suitable for dam construction. Therefore, it was necessary to build multipurpose dams for both protecting land from flooding and supplying water in times of drought.

However, it was technically very difficult to build such dams. For flood control, dams should be kept empty, so that they can store water during flooding. On the other hand, for water utilization, water should be stored in dams in preparation for droughts. Therefore, multipurpose dams had two contradictory purposes.

A Serious Accident
While officials in charge of river management were considering this law, a serious accident occurred. This was the Toya-Maru Accident of September 26, 1954. The Toya-maru, a railway ferry connecting Hakodate and Aomori, sank due to Typhoon Marie (No.15) and 1,155 lives were lost. It was Japan’s worst catastrophe at sea.

About sixty years ago, we could not detect where a typhoon was and where it was headed. The Toya-Maru accident had a crucial impact on enactment of the Multipurpose Dam Law. Officials in charge of river management in the Ministry of Construction were ready to create a new system, thinking that they would never make mistakes in the operation of new dams in order to prevent floods.

The Concept of a Multipurpose Dam
The overriding aim of a multipurpose dam was flood control. First, the height of the dam was determined by its location. It took into account the characteristics of the areas subject to flooding and the topography of the site. The volume required for flood control was determined such that it could store floodwaters even in case of the biggest flood of the century. Then the amount of sediment likely to be deposited over a hundred-year period was calculated. The capacity for water utilization was the capacity left after deducting the volume of sediment from the dam’s capacity

Here is the formula:
Capacity for water utilization equals dam capacity minus capacity of once in-a-century flood minus storage capacity of sediment

Unfortunately the usable water capacity was insufficient. Therefore, a new system was created whereby insufficient capacity could be compensated for with a new dam. The system of multipurpose dams worked well. Over a period of sixty years, more than 120 national and more than 300 prefectural multipurpose dams were constructed. These succeeded in storing flood water and protecting downstream areas from flooding, in a country which is subject to large typhoons and heavy rains.

New Dam Operations in the 21st Century
The planning and operation of multipurpose dams is based on sixty-year-old technology. We were not able to detect the location and the path of typhoons at that time, but weather prediction technology has significantly improved since then. Today, we are able to detect the formation of a new typhoon far away in the South Pacific. We know the location of a typhoon by the minute and can predict whether it will hit Japan or not within a week. The route of a typhoon can be predicted with great precision three days ahead of time. The improvement of weather forecasting technology will transform existing dams and improve their effectiveness. Specifically, we can now store water in spaces previously kept empty for flood control. When a typhoon is approaching, we can release the stored water beforehand while using it to generate electricity. This is referred to as a flood control release system, and has already been implemented in several dams.

For a Sustainable Japanese Society
Progress in weather forecasting and dam operation technology will increase the usefulness of existing dams. Multipurpose dams built for flood control and water utilization in the past should be transformed into new dams equipped with hydro-electricity generators. Japan’s self-sufficiency ratio of energy is currently only 6%. When we look 50 or 100 years into the future, when tighter supplies of fossil fuels are expected, Japanese society seems far from sustainable. The most serious challenge for Japan in the future is the issue of energy. Therefore, the many dams we’ve built across the nation must help increase our energy self-sufficiency.

Now we must move forward and make Japan a treasure Island of solar energy in the form of water.


・Report from the Japan Water Forum


2nd Stakeholders’ Consultation Meeting for the 8th World Water Forum

The Japan Water Forum (JWF) attended the 2nd Stakeholders’ Consultation Meeting, held on April 26 and 27 in Brasilia, the capital of Brazil.  The 8th Forum will be held under the overarching theme Sharing Water from March 18 to 23 in Brasilia in 2018.

▼Please visit the following website for details▼
(Reported by Kunihiro Moriyasu, Deputy Secretary General)


JWF Promotes Ex-ante Investment in Water at the ADB Annual Meeting

The ADB 50th Annual Meeting was held in Yokohama, Japan from May 4 to 7. JWF appealed to the government officials and financial institution representatives of ADB member countries to recognize the importance of increased ex-ante investment in water infrastructure at the exhibition booth and also introduced APWF activities including the preparation of the 3rd Asia-Pacific Water Summit.

▼Please visit the following website for details▼
(Reported by Shigenori Asai, Deputy Director)


Mission Statement of Water Conference for Future 2017

2017 is the year UN’s Sustainable Development Goals (SDGs) go into full swing. Therefore discussions on World Water Day focused on the roles of private companies, which will play an important part in solving environmental issues, including the SDGs. Discussions took place on how to establish sustainability from the perspectives of ESG investment, information disclosure and corporate value.
An outcome message was compiled and publicized.

▼Please visit the following website for details▼
(Reported by Sayoko Kuwahara, Manager)


JWF Fund 2016 Completed!

Japan Water Forum (JWF) Fund managed through fees from corporate and individual members and donations is the initiative that supports grass-roots organizations to address water-related issues in developing countries. 2016 is the 12th year since its establishment in 2005.
There were 560 applications from 45 countries for the JWF Fund 2016’s calling. As the result of selection, we have decided to provide grants for 6 projects from 5 countries. For detail of the results of the JWF Fund, please visit our website!

▼Please visit the following website for details▼
(Reported by Akie Gunji, Assistant Manager)


▼JWF News Achives▼

If you wish to post information on our bulletin board, or should you prefer not to receive further JWF News, please contact us. You can also get in touch regarding changes of address, or any other comments or requests.


JWF News Vol.152 May 17, 2017
Japan Water Forum

6th fl., 5-4 Nihonbashi-Hakozaki-cho, Chuo-ku, Tokyo, 103-0015
TEL: 03-5645-8040 FAX: 03-5645-8041
E-mail: news[at] URL:
※Please change [at] to @


This browser is no longer supported