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Expanding torrential rainfall monitoring regionswith X-band MP radar

TORII Kenichi, HeadKAWASAKI Masaki, Senior Researcher
TSUCHIYA Shuichi, Researcher
River Department, Water Management and Dam Division(Key words) X-band MP radar, torrential rainfall monitoring
1. Expanding torrential rainfall monitoring
regions
In recent years, drownings and flood disasters
caused by localized heavy rainfall and concentrated
torrential rainfall have occurred increasingly often.
So the Water and Disaster Management Bureau ofthe Ministry of Land, Infrastructure, Transport andTourism has introduced X-band MP radar,strengthened the resolution of radar rain information,and enhanced its real-time availability in order tostrengthen rainfall monitoring systems. The
National Institute for Land and InfrastructureManagement is building data processing andtransmission systems to realize more advanced
radar rainfall information, conducting technicalstudies of scan modes, parameter tuning etc. needed
for trial operations of X-band MP radar, and studies
to improve precision by advancing rainfall
observations, the correction of attenuation, andsynthesis methods. X-band MP radar started trial
operation in some regions in 2010, and new trial
operation regions will be added beginning in July
2011, expanding the area where torrential rainfall ismonitored (Fig. 1). This is extending theobservation range to all government ordnancedesignated cities except Sapporo to strengthen
torrential rainfall monitoring systems in cities. The
monitoring systems around Mt. Kurikoma andSakurajima Island, both regions at high risk of
sediment disasters, were strengthened.
In the Niigata Region, one more X-band MP
radar base will be established to start monitoring by
two bases beginning in 2012, in order to reduce theareas where monitoring is impossible during
torrential rainfall. Land subsided and river levees
were damaged as a result of the earthquake andtsunami caused by the Great East Japan Earthquake,so to strengthen torrential rainfall monitoring
systems in this disaster region, where safety fromflooding has declined, X-band MP radar will be
introduced in Tohoku and the Northern Kanto.
2. Examples of the use of X-band MP radar
rainfall information
In Niigata, where trial transmission started in2011, X-band MP radar based rainfall information

was used by regional governments as reference
information to order flood-fighting activities andevacuations during the Niigata/Fukushima torrential
rainfall of 2011. When typhoon No 12 of 2011
triggered the collapse of soil, blocking river courses,X-band MP radar rainfall information for the Kinki
Region was used as rainfall information to monitor
the collapse of the soil blocking the rivers.
3. Developing technologies using X-band MPradar
The National Institute for Land and InfrastructureManagement, regional development bureaus, anduniversities and research institutes, are developing
technologies using X-band MP radar to achieve
early detection of torrential rainfall, to improverainfall predictions, and to increase the precision ofinundation predictions.
The National Institute for Land and InfrastructureManagement is carrying out studies using X-band
MP radar rainfall information to improve inundation
simulations of urban regions, and advanceevacuation information systems in water parks. In
the future, the NILIM plans to perform research on
the detailed evaluation of precision of monitoringby X-band MP radar and on the precision ofcalculation of average river basin rainfall.

Niigata
新潟Toyama/Ishikawa
富山・石川Hiroshima
広島 Okayama

Mt.
Kurikoma region
栗駒山周辺岡山

Northern Kyushu
九州北部
Kanto
関東

Chubu
中部

Shizuoka
静岡Kinki
近畿
Sakurajima
桜島周辺Island

2010年度試験配信開始地域
2011年度試験配信開始地域

Area where trial transmission began in 2010
Area where trial transmission began in 2011

Figure 1. Regions where X-band MP Radar Trials
have Begun