Shin-Yokohama Park and the Tsurumi River Multi-Use Retarding Basin

Climate change impacts

The highly urbanized Tsurumi River Basin has a class-1 river designation, and is susceptible to increased water hazards as a result of climate change.

Adaptation activity

The Shin-Yokohama Park, in the Tsurumi River basin, has been constructed within the Tsurumi River multi-use runoff retardation area. It is routinely used by many people as a park, but it also serves as a flood mitigation facility. The aim is to reduce downstream flood damage by diverting rising waters from the Tsurumi river and providing temporary containment. The Nissan Stadium in Shin-Yokohama Park is built on more than one thousand pillars, thus providing a flood water retention basin (Fig.).

Outputs / Expected benefits

The Tsurumi River multi-use retarding basin has been created where there were originally natural flood control functions; it artificially improves these functions to protect adjacent and downstream areas from flood hazards.

During the heavy rains caused by Typhoon No. 19 on October 12, 2019, the retardation area filled with approximately 940,000 cubic meters* of flood water. The water level at the recently installed Kamenoko Bridge hydrological station, reached 6.58 meters*. Without the retarding basin it is estimated that the water level would have been 0.3 meters (see Note) higher, exceeding the flood risk level. On October 13, the day after the typhoon, the final play-off game of the 2019 Rugby World Cup was successfully held at the Nissan Stadium.

Note: Preliminary estimates subject to change.