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A basic role of sewerage is to eliminate
rainwater (so-called "internal water")
that has fallen in cities |
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Encouragement of hard and soft countermeasures
in order to protect people's lives, property,
and urban functions from frequent urban flood damage |
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Infrastructure target: percentage of achievement
of urban anti-flood measures: 52% (2004) >
54% (2007)
No. of households that need emergency resolution in case of flooding
to floor level: 74,000 households (2004) >
60,000 (2007) |
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Internal water countermeasures
are one role of the sewerage |
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Flood damage caused
by inability of sewerage and rivers to drain rain that has fallen
 internal
water flood damage |
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Proportion of damage
by internal water |
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| Total of decade from 1994
to 2003 (from flood damage statistics) |
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Tokyo flood damage
(2004) |
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Vicinity of a reservoir
intersection that caused road flooding
(Typhoon 22) |
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Factors that intensify
flood damage in cities |
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Increase of localized
torrential downpours in recent years |
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Change of rain runoff
before and after urban development |
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| Before development,
rainwater was seeping underground. Due to development, the earth's
surface was covered with concrete, etc., resulting in frequent flooding
when large quantities flow in a short timeFlood damage caused by |
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| (an example in a Tokyo
ward) |
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Increase of flood
damage in underground facilities |
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| 2003 Fukuoka City |
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| 1999 Tokyo |
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| 1999 Fukuoka City
(fatalities) |
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Comprehensive anti-flood
measure by sewerage |
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| Minimization
of damage by encouraging software and self-help |
| Goal
of minimizing damage by encouraging self-help
while limiting districts and time-periods and pushing forward
steadily with effective hardware countermeasures.
Moreover, reinforcing software countermeasures
paves the way for effective self-help. |
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| Effective hardware
countermeasures |
Installation and operation of efficient,
priority-focused facilities
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Active introduction of reservoir / infiltration
facilities |
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Effective use of existing facilities
Networking of main line pipes and drains
Real-time control |
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| Reinforcement of
software countermeasures |
Encouragement of information-gathering
and -provision in support of self-help
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Assistance to encourage self-help |
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Publication of internal waters hazard
maps |
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Promotion of provision of real-time information
Use of rain radar and fiber optic
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Carry out training regarding floods and
disseminate information |
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| Encouragement of
self-help |
Minimization of the damage by encouragement
of self-help
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Setup of water stops in underground facilities |
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Setup of sandbags when flooding occurs |
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Setup of storage infiltration facilities,
etc. |
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