Ministry of Land, Infrastructure, Transport and Tourism

Evolving approach

to river management in Japan

18 April 2016

Takafumi NAKUISenior Deputy Director, River Planning Division, Water and Disaster Management Bureau, MLIT

@ Kanto Regional Agricultural Administration Office

Characteristics of Rivers in Japan

1

Mountain area

Plain area

properties

population

Area

Flood –Prone Area(lower than river water level at the time of flood)

(%)

Other areas

Concentration of population and assets

in flood-prone area

Most of land in Japan are covered by mountains, and people and assets are focused in the

narrow plain area.

Characteristics of Rivers in Japan

Many rivers in Japan are very steep with a short distance from the source to sea, resulting in

rapid flow.

Length(km)

Tonega

wa

River River

Seine

Mekong

River

Joganji

RiverShinano River

Altitude(m)

Rhine

River

Colorado

River

Lorre

River

Rivers in Japan

2

History of River Management in Japan

Before 19 century

○Each community implement river

management and flood control in each

region.

○Each measure of flood control and water

use were conducted without coordinating

among communities.

After 20 century

○Integrated river management is

implemented to achieve well-balanced flood

control and water use throughout the basin.

○Responsibilities and roles of river managers

and other stakeholders are clearly defined.

●Urbanization and population

increase in Catchment area

●Increase of water demand

due to the economic growth

●Increase of dam construction

for developing electric power

Coordinating regional interests

is needed for the efficient river

management and flood control .

3

河川法River Law

･River manager(administrator) is designated in this Law.

･Class-A rivers are managed by MLIT, Class-B by Prefectural

Government.

･Water resource management including Flood Management is

conducted by River Managers (River Administrators).

・Human activities to protect lives and properties from flooding

and minimize damage when a flood disaster is occurring or

about to occur. (flood warning, flood-fighting, etc.)

・Municipalities bear responsibility of flood risk management

activity and direct the ‘Flood Fighting Corps’.

・’Flood Fighting Corps’ are formed by local residents living

near rivers and are active in when floods occur.

Flood Management Policy in Japan

Flood management policy in Japan is stipulated in ‘River Law’ and

‘Flood Risk Management Act’, both of which complement each other

to strengthen flood management.

水防法Flood Risk

Management Act

4

Outlines of River Law

Responsibilities of River Managers

Monitoring, Planning of water resource management, and Implementing※* ex; construction of flood control facilities, operation and maintenance of facilities, permission and maintenance of water

rights, implementation of projects on water resources development, etc.

When disaster occurs, River Managers are the first responders for early recovery and

reconstruction of river infrastructures.

5

6

Normal Discharges, Facilities for

preventing floods, Water rights

and Environment to keep the

river safe.

River Managers construct, improve, operate and maintain river atnormal times.

River Management at Normal Times in River Law

Monitoring and MaintenanceConstructing and OperatingSetting targets

Construction river management facilieties based on each river improvement plan

Operation of these facilieties to keep rivers normally

Early detection of abnormality

Routine monitoring

Maintenance

River improvement plan is

formulated through the opinion

of relatives in each river(residents, experts, municipalities etc)

6

Media OrganizationsResidents

Prefectures Municipalities

Evacuation advisory,

Evacuation directive

Flood forecast

Flood forecastFlood

Fighting

Organizations

Order for action

River Office

Countermeasures to mitigate damages

River patrol

Information collection

【Response in fields】

Controlling facilities

Assisting municipalities

Emergency recovery

Assisting flood fighting activities

River administrators provide flood information for the smooth flood fighting activities,

patrol rivers, control facilities and utilize sump pumps in order to prevent and

mitigate damages in the event of flooding.

River Management during Floods in River Law

MLIT (River Offices, Regional

Meteorological Observatory of

Japan Meteorological Agency)

【coordination

when flooding】

Warnings to prepare flood fighting

7

Outlines of Flood Risk Management Act

Dissemination of river information

【MLIT or prefectural governments】・Flood forecasts must be released.

(with Japan Meteorological Agency)

・Information of flood water levels must be announced

and disseminated so as to prompt residents

evacuation.

・A flood fighting warning must be issued to warn that it

is required to initiate flood fighting activities.

On-site flood fighting activities

【Administrators of Flood Fighting Corps】・Flood fighting engineering methods must be applied.

(e.g., sand bag piling up methods)

・Emergency response measures must be taken after

levee breaches (so as to prevent the spread of flood

damage)

In case of a flood disaster event

Sand bag piling up methods to respond to over topping

Hooping Method to deal with levee leakage 8

Outlines of the revised Flood Risk Management Act

Provision of flood information

【MLIT or prefectural governments】Expected inundation assumption zones must be

designated, announced and informed to related

municipalities, for ensuring smooth and prompt evacuation

from floods, and for reducing disaster damage.

In ordinary times

Support to emergency evacuation

【Municipalities】

･Methods to disseminate flood forecasts and the locations

of evacuation sites must be specified in regional disaster

prevention plans.

・Methods to disseminate flood forecasts to the users of

underground facilities must be specified in regional

disaster prevention plans.

･Flood Hazard Map must be developed and disseminated. 9

Thank you for your attention!

Annual Flood Fighting Drill held by MLIT, Prefectural Governments, Municipalities and Flood Fighting Corps.