●Research Trends and Results

Improving wide area disaster damage
monitoring/predicting technologies
ITO Hiroyuki, HeadIINO Mitsunori, Senior Researcher
HIRATSUKA Mariko, Researcher
Research Center for Disaster Risk Management, Flood Disaster Prevention Division(Key words) Monitoring/prediction system, ad hoc water level gauge, distributed flood prediction model
1. Introduction
In recent years concentrated torrential rainfall withhourly rainfall over 100mm has occurred frequently inJapan, causing disastrous floods and loss of human life.
This means that it is now necessary improve theprecision of flood discharge prediction methods, andto develop and build information transmission
methods to support appropriate flood fighting andevacuation activities, and take other measures tofurther improve technologies for the wide area
monitoring and prediction of flood damage.
This research was a study of real time observations
by ad hoc water level gauges and of a distributed flood
discharge prediction model in order to build flood
disaster monitoring and prediction systems for entire
river basins including medium and small rivers.

discharge on September 21, 2011 at the Ochiai Bridgeat the furthest downstream point of the object riverbasin. The wave forms at the start and near the peak of
a flood discharge can be generally reproduced, but inorder to further improve precision and reliability, weare studying a method of improving the applicabilityof a model to the characteristics of the flood dischargeof an entire river basin by setting new water level
observation points on a river system and reflecting theobservation results in the model.
4. Conclusion
This research has confirmed the applicability andusefulness of ad hoc water level gauges and thedistributed flood discharge prediction model, which
contribute to wide area monitoring and prediction offlood damage. In the future, we will continue to boost
precision and improve the system to advance flood
disaster monitoring and prediction systems.

2. Real time observations by ad hoc water level
gaugesAd hoc water level gauges permit low cost
simultaneous water level observations of multiple
locations, because the water level gauges themselves
are wireless communication units comprising part ofdata communication use networks. To verify theirapplicability to real time observation of river waterlevel, proving tests were carried out on the Onda River,which is a tributary of the Tsurumi River. Figure 1
shows the network which was built. The results of theproving testing, which took 4 months to perform,
confirmed that they are all fully applicable toobservations during flood discharge and for long term
observations.

LegendWater level gauges: observe the water level
Relaying systems: relay data transmitted
between water level gauges
Summarizing/relaying systems: transmit data tomonitoring systems
Monitoring
Monitoring systems: accumulate and displaysystem
dataTransmission byinternet circuits
Shiratori River
Summarizing/rel
aying system

Onda River

Water level gauge

Wireless
communication

Water levelgauge

Iwa River

Wireless
communication
Relay system

Figure 1. Ad Hoc Network
0600

3Q(m /s)

500

50

Calculated flow rate
計算流量
H-Q converted flow
H-Q換算流量rate
Floater observation
浮子観測流量flow rate

400
300

100
150

200

200

100

250

0
9/21 0:00

9/21 6:00

9/21 12:00

9/21 18:00

300
9/22 0:00

Figure 2. Results of Verification at the Ochiai
Bridge (Flood of Sept. 21, 2011)

R(mm/h)3. Building and verifying the precision of thedistributed flood discharge prediction model
In order to improve flood discharge predictions in
medium and small rivers, which are characterized by
the abrupt rise of the water level and short flood
discharge arrival times, a distributed flood discharge
prediction model capable of directly reflecting thespatial distribution of rainfall in the middle andupstream reaches of the Tsurumi River was built, andthe precision of the object model was verified by 7
flood discharges which occurred in recent years.
Figure 2 shows the results of verification of a flood