Human Capacity Building for Natural Resources Development ... · 9-AM 8 Ordinary weather radars Use...
16
[LANDSLIDE] 9-AM Realtime Monitoring of Shallow-landslide Potential Area Using Multi-parameter Radar Ryohei MISUMI National Research Institute for Earth Science and Disaster Prevention Abstract In this lecture, we introduce recent rainfall-induced disasters in Japan and our researches for reducing them with the use of the multi-parameter radar system. As for the heavy rainfall in Japan, precipitation extremely concentrates on narrow regions by peculiar behavior of the convective clouds that is called "back-building". Forecasting of such phenomena is still difficult at present, thus real-time monitoring of rainfall area with meteorological radars and providing information are important for disaster reduction. In National Research Institute for Earth Science and Disaster Prevention, the multi-parameter radar system, which is able to estimate rainfall accurately with 500m mesh, is operated to detect heavy rainfall area in real time and provide information on the WEB. This technology is expected to reduce disasters caused by urban floods and rainfall-induced landslides.
Transcript of Human Capacity Building for Natural Resources Development ... · 9-AM 8 Ordinary weather radars Use...
[LANDSLIDE] 9-AM
Realtime Monitoring of Shallow-landslide Potential Area
Using Multi-parameter Radar
Ryohei MISUMI
National Research Institute for Earth Science and Disaster Prevention
Abstract
In this lecture, we introduce recent rainfall-induced disasters in Japan and our
researches for reducing them with the use of the multi-parameter radar system. As for
the heavy rainfall in Japan, precipitation extremely concentrates on narrow regions by
peculiar behavior of the convective clouds that is called "back-building". Forecasting of
such phenomena is still difficult at present, thus real-time monitoring of rainfall area
with meteorological radars and providing information are important for disaster
reduction. In National Research Institute for Earth Science and Disaster Prevention, the
multi-parameter radar system, which is able to estimate rainfall accurately with 500m
mesh, is operated to detect heavy rainfall area in real time and provide information on
the WEB. This technology is expected to reduce disasters caused by urban floods and
rainfall-induced landslides.
9-AM
1
REALTIME MONITORING OF SHALLOW-
LANDSLIDE POTENTIAL AREA USING
MULTI-PARAMETER RADAR
Ryohei Misumi
National Research Institute for Earth Science and Disaster Prevention, Japan
Recent rainfall disasters in Japan
9-AM
2
"Back-building" of convective cells
Formation
of new cell
"Organized" storm
Repeat
Dissipation
of cellHeavy rainfall
Loss of lives
476mm
9-AM
3
Shallow landslide（Tochio City）
Debris flow（Izumozaki Town）
9-AM
4
Typhoon Man-Yi on 14-15 July 2007
Isumi City
9-AM
5
Landslide（Isumi City）
A car carried by debris flow（Isumi city）
9-AM
6
防災白書より
WeightWeightWeightWeightBed rock
Soil layer
Slip surface
Sliding force
Shear resistance
Normal situationNormal situationNormal situationNormal situation
What is shallow
landslide ?
9-AM
7
Bed rock
Soil layer
Saturated ZoneSaturated ZoneSaturated ZoneSaturated Zone
Soil
particlesWater During heavy During heavy During heavy During heavy
rainfallrainfallrainfallrainfall
Increase of pore pressure
Decrease of normal stress
Rain
Why do rainfall induced disaster occur ?
�Problems in rainfall forecasting
�Difficulty in making appropriate warning
�Problems of "aging society" etc.
Monitoring heavy rainfall using
Multi-parameter radar
9-AM
8
Ordinary weather radars
Use of reflectivity
・・・・Large errors for strong rainfall・・・・Hard to distinguish between ground echo and rain
・・・・Strong attenuation
Multi-parameter radar
Use of ““““phase shift””””
・・・・Small errors for strong rainfall
・・・・Possible to estimate rainfall over
mountains
・・・・Not affected by attenuation
・・・・Small errors for strong rainfall
・・・・Possible to estimate rainfall over
mountains
・・・・Not affected by attenuation
Polarized waves
9-AM
9
RaindropVertically polarized wave
Horizontally polarized wave
Because the shape of raindrop is flat, some phase shift is
made between the back-scattered radio waves
9-AM
10
Estimation of rainfall intensity using the Estimation of rainfall intensity using the Estimation of rainfall intensity using the Estimation of rainfall intensity using the
specific differential phase (Kspecific differential phase (Kspecific differential phase (Kspecific differential phase (KDPDPDPDP) ) ) )
� not affected by rain attenuation
� immune to beam blockage
� less sensitive to beam filling and drop size distribution
＋＋
Z KDP
Disdrometer
+
R-KDP
R-Z
R-Z (corrected)
9-AM
11
MP-X radar
JMA radar (corrected with rain-gauges)JMA radar
Rainfall on 15 July 2006 (with hail）
青梅：22mm
13:23＠Tokyo
相模湖：0
府中：20
世田谷：32
X-band radar network (X-NET)
NUED1 NIED2 (2008-)
(To be installed) Chuo Univ
NDA
9-AM
12
Estimation of landslide area using radar-derived rainfall
"Effective" rainfall
⋅⋅⋅⋅+×+×+= 22110E RRRR αα
T/nn )
2
1(=α
T: Half-life period
(like radioactive decay)
t=0 t=-1 t=-2
0
10
20
30
40
50
60
70
0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00
Time (JST)
Rai
nfa
ll (m
m)
Rainfall
T=1.5 hours
T=72 hours
Strategy for landslide prediction
A realtime monitoring system for landslide
Radar-derived rainfall Observation at
slopes
WarningSoil moisture and slope movement
9-AM
13
6 hour rainfall (0000JST-0600JST)
Miura
Raingauge
MP-X
Slope failure (shallow landslide) at 0530 JST
9-AM
14
Effective rainfall (T=72 hours)
at 0500 JST on 12 September 2007
Slope failure
Deep-seated landslide
Effective rainfall (T=1.5 hours)
at 0500 JST on 12 September 2007
Slope failure
Deep-seated landslide
9-AM
15
Landslide Prediction Support System (LAPSUS)
http://lapsus.bosai.go.jp
