Department of Civil Engineering

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Development of Disaster Prevention Technologyfor River Basin
Masato KITA
Lecturer, Dr. Eng.
Email : m-kita@gifu-nct.ac.jp
Research Fields
Keywords

Hydraulic, Hydrology
Rainfall and flood simulation, Climate change, Meteorological radar● Research Outline
Evaluation and Characteristics Analysis ofEnsemble Flood Prediction

Enhancement of Numerical Prediction forHeavy Rainfall Using Data Assimilation

To evacuate in plenty of time, the prediction
information having long lead time is important such as
rainfall and water level. Especially, water levelcalculated by numerical model is recommended
because it leads directly to river disaster. On the otherhands, predicted rainfall data for input of flood
prediction has the problem. The error grow large withduration. the ensemble prediction has the potential for
resolving this problem. Ensemble prediction can covera variety of prediction possibility because this method
adds slight perturbations to initial condition
meteorology numerical model. This study aim atdeveloping ensemble flood prediction system using
ensemble rainfall data and validate the performance ofthe system (Fig.1). Especially, we focus on probabilistic
characteristic of water level obtained from the system.

High accuracy prediction for rainband precipitation
system is important to prevent the water hazard.
Moreover, Numerical model can have longer lead timethan kinematic method. The model strongly depend oninitial condition. We focus on data assimilation method.
Data assimilation modify the initial condition using
observation data. In this study, we employ themeteorological radar data. Particularly, X-band MP
radar data operated by MLIT (Ministry of Land,Infrastructure, Transport and Tourism) can capture therain cloud in high temporal-spatial resolution. This
study aims at evaluation the accuracy of rainfall
prediction using numerical model with radar data
assimilation(Fig.2). Moreover, we discuss the effective
utilization for radar data.

Observation

Assimilation

Water level（m)Designated water level
Dangerous water level
Observation
Deterministic Pre

Warning water level
Design high water level
Ensemble Pre

181614121086420

No-assimilation
TimeFig.1 Ensemble water level hydrograph

Evaluation and Characteristics Analysis ofEnsemble Flood Prediction

MainRivarTributary
18.5

Peakピーク水位（m)water level (m)16.5

Peakピーク水位（m)water level (m)In the future, Climate change will affect thefrequency of flood and draught in the basin. We must
consider the deal with water resource near future. In
this study, we conduct the rainfall and flood numericalsimulation considering effect of climate change. With
respect to rainfall simulation, pseudo-global warming
method is employed. This study aims at evaluate theprobability of flood hazard (Fig.3) and discuss thesuitable operation of flood control and water utilization
facility(e.g., dam etc).

Fig.2 rainfall prediction using numerical model

15.5
14.5
13.5
12.5
11.5
10.5

Evacuation
decision
避難判断水位
WL

17.5
16.5

氾濫危険水位
DangerousWL

15.5
14.5

Designhigh WL
計画高水位

13.5

OBS
観測値

12.5

CTL
再現計算

Case_P2K
UP_2

11.5

CTL
再現計算

Case_P2
UP_2K

Fig.3 Box plot of peak water levelXX