## 2 ) Promotion of rainwater storage and infiltration

In order to reduce the flood damage of urban areas, other than rainwater clearance, it is also important to work on the storage and infiltration for controlling the rainwater outflow for the whole region. Therefore, through the project on supporting the development of a strong city against rainfall and river-basin storage and infiltration projects, the related regional parties are unified and pushing forward the control of rainwater outflow as well as private measures for reducing damage.

## 3 ) Measures against local downpours exceeding the planned for scale

Because of the reduction of penetrable rainwater amount due to urbanization, the recent frequent local downpours that greatly exceed the planned sewerage scale and the sophistication of land usage such as the construction of underground shopping arcades or basements, the damage risk of inland floods in urban areas is increasing. Therefore, the comprehensive project on the damage reduction of sewerage flood was established in FY 2009. The related parties were working together and pushing forward comprehensive flood measures including rainwater storage and infiltration facilities for outflow control, the preparation and publication of inland hazard maps, etc.

## 4 ) Prevention of destructive damage to major urban areas

For the major rivers including the Arakawa (Tokyo) and the Yodogawa (Osaka) accumulating high population-density and property-density along the river basin, various measures are being implemented including the development of high-standard embankments (super embankments) for avoiding destructive damage in cases where the embankment is ruined, and embankment enhancement by expanding the scale of the embankment.

## (3) Flood control policy change

Japan is facing three demand constraints, namely, depopulation, declining birthrate and aging population, and severe financial conditions. Considering these constraints, “The Future Flood Management Advisory Board” was established in December 2009 to propel change in flood control policy. Board meetings have been held since then to set guidelines to develop flood control plans with a wide-range of measures, evaluation criteria and concepts for the overall assessment, thus establish and propose future flood control principles based on studies. An interim report, including new re-evaluation criteria for ongoing dam projects, is scheduled to be released in the summer of 2010 and individual dam construction plans will be reviewed based on this report. The Board will continue to deepen discussions on the future flood control principles to form a final report around the summer of 2011.

## (4) Measures against sediment disasters

In our country, debris flow, landslides and slope failure caused by torrential downpours and earthquakes has been occurring around 1,000 times on average yearly for the past 10 years (2000 - 2009) and has been causing severe damage. In addition, the victims of sediment disasters account for a significant proportion of the victims of natural disasters. Therefore, structural and non-structural measures against landslides for reducing the number of victims of sediment disasters are being pushed forward. The measures include the development of sabo facilities in major spots that need special measures and the development of a secure and accurate Warning and Evacuation System through self-help, mutual assistance and public support.

## 1 ) Fundamental measures against sediment disasters

The river, which has left mountain areas in the headstreams, pours sand out and causes great damage throughout the river basin. In order to preserve national land and protect human lives from such sediment disasters, the development of sabo facilities is being pushed forward.

## 2 ) Emergency disaster prevention measures for regions susceptible to sediment disasters

Recently, measures are being pushed forward for preventing disasters from occurring again in regions susceptible to severe sediment disasters, through the intensive development of sabo facilities carried out in locations susceptible to sediment disaster and surrounding areas.