Greater Tokyo, Japan

THIS CASE STUDY PRESENTS the example of river basins that serve one of the world’s most populous areas, a region of 27 million people. In addition to its extremely high density, Tokyo metropolitan is subject to seasonal floods and other hazards such as droughts and earthquakes. However, because it is a rich and industrialized country, Japan has the means – and the skills – to manage these risks using infrastructure such as dams, levees and underground floodways. There is also great emphasis placed on public awareness and disaster preparedness. The authorities have developed early warning systems that rely on the Internet, Geographic Information Systems (GIS) and hazard mapping, and there are shelters where people can take refuge. Such continuous efforts have ensured that one of the world’s largest economic developments has been able to safeguard its population in the high-risks region. Other concerns include a degraded natural environment and pollution of groundwater, and many efforts, such as river restoration works, are being implemented with wide public participation.

Sustainable Development Goals:

Clean Water and Sanitation