Damage from typhoon No.9 in the Sayo River in 2009

## Overseas flood control safety

Country name	Safety level of flood control	Implementation rate
United States $ ^{(Note1)} $ (Downstream of the Mississippi River)	1/500	About 94%
United Kingdom $ ^{(Note2)} $ (The Thames River)	1/1,000	100%
Netherlands $ ^{(Note3)} $ Coastal areas including the center of the country	1/10,000	About 94%
Japan (the Ara River)	1/200	About 40%

Note: 1 · Sharing the Challenge : Floodplain Management into the 21st Century, Report of the Interagency Floodplain Management Review Committee to the Administration Floodplain Management Task Force, 1993

• Annual Report Fiscal Year 2005, Department of the Army

2 Management Guidance for the Thames Estuary, Thames Estuary Partnership

3 · Flood Risks and Safety in the Netherlands (Floris) Floris Study – Full report, 2005

· Water in Focus 2004 Annual report on water management in the Netherlands

## 1 ) Preventive flood control measures

Whenever flood disasters happen, much human life and property will be lost. It brings great consequences not only on the regional economic activities but also the time and cost for recovering and reconstructing disaster areas. Therefore, according to the fundamental river management policy and the river improvement plan, the planned flood control facility development is carried out, such as the construction of embankments, river course digging, flood control basins and underground reservoirs. Moreover, the existing facilities are being utilized effectively through redevelopment of existing dams and the reorganization of dam capacity. Moreover, for existing embankments, a regular examination is implemented for checking the safeness against the seepage failure during flooding and earthquakes. Improvement measures are being taken for if the strength of facilities is insufficient.

## 2 ) Measures for preventing the reoccurrence of flood disasters

In these few years, in order to avoid suffering from the floods of the same scale again, short-term intensive measures are being implemented in regions that have suffered from huge floods for eliminating the anxiety of flood occurrences. Measures include river course digging for increasing flow capacity, the embankment enhancement of rivers and the construction of drainage pump stations for preventing inland flood.

## 3 ) Measures for reducing damage during flooding

In order to push forward measures for minimizing damage during river flooding, various structural and non-structural measures are being worked out with the cooperation of regional public organizations. Measures include the development of circle levee and secondary embankments, the preparation of hazard maps, the sophistication of damage prevention information such as water level and flood forecasting.

## 4 ) Appropriate river management

For enabling the developed river management facilities to perform their functionalities during flooding, the conditions of rivers and facilities are monitored and the appropriate management is implemented according to the changes in conditions. Additionally, there will be an increase in decrepit dams or water gates and drainage pump station from now on, so the planned maintenance and renewal of facilities are being pushed forward according to the Maintenance Management Plan in order to lengthen the durable period of facilities.

## (2) Measures against floods in urban area

## 1 ) Promotion of comprehensive and common flood control measures in drainage pump stations

In order to prevent the suspension of urban functionalities and damage of underground shopping arcades during flooding in urban areas, river administrators, sewerage administrators and regional public organizations are cooperating to push forward measures against drainage basin flooding based on the “Specified Urban River Flooding Damage Countermeasures Act”.