Document Actions

ijege-13_bs-okamoto-et-alii.pdf

background image
Italian Journal of Engineering Geology and Environment - Book Series (6) www.ijege.uniroma1.it © 2013 Sapienza Università
Editrice
361
DOI: 10.4408/IJEGE.2013-06.B-34
POSSIBILITY OF EARLY WARNING FOR LARGE-SCALE LANDSLIDES
USING HYDROLOGICAL AND SEDIMENT TRANSPORT OBSERVATIONS
IN MOUNTAIN RIVERS
A
tsushi
OKAMOTO
(*)
, Taro UCHIDA
(*)
, s
hin
-
ichirou
HAYASHI
(*)
, t
Akuro
SUZUKI
(**)
,
s
hintAro
YAMASHITA
(***)
, s
Atoshi
TAGATA
(****)
,
A
kihisA
FUKUMOTO
(*****)
& J
un
'
ichi
.
KANBARA
(*)
(*)
National Institute for Land and Infrastructure Management - Ibaraki, Japan
(**)
Sabo & Landslide Technical Center - Tokyo, Japan
(***)
Chi-ken Sogo Consultants Co., Ltd. - Tokyo, Japan
(****)
Nippon Koei Co., Ltd. - Tokyo, Japan
(*****)
Tenryugawa-Jouryu River Office, Chubu Regional Development Bureau, MLIT - Nagano, Japan
INTRODUCTION
In steep mountainous regions, landslides may
include both soils and underlying weathered bed-
rock (e.g., u
chidA
et alii, 2010). The velocities and
volumes of these landslides are often very high, and
these large-scale landslides may form landslide dams
and have serious impacts on human lives and infra-
structure (e.g., c
ostA
& s
chuster
, 1988). Thus, such
landslides may cause serious damage. For example, a
huge landslide killed more than 400 people at Shaolin
Village, Taiwan, in 2009 (e.g., s
hieh
et alii, 2009).
Early warning systems for sediment disasters are
important tools for reducing disaster risk, achieving
sustainable development, and preserving livelihoods.
In 2005, the Japanese government initiated a new
nationwide early warning system for landslides dis-
asters. The main methodology of the system involves
the setting of a criterion for the occurrence of debris
flows and slope failures based on several rainfall indi-
ces (e.g., o
sAnAi
et alii, 2010). Moreover, many previ-
ous studies have been conducted to clarify an appro-
priate rainfall threshold for the prediction of landslide
occurrence (e.g., c
Aine
, 1980; G
uzzetti
et alii, 2008;
s
Aito
et alii, 2010). These efforts are novel and have
been proven to result in reduction of landslide disas-
ters. However, the use of these rainfall thresholds did
not always ensure early evacuation (e.g., s
hieh
et alii,
2009; F
uJitA
et alii, 2010). Therefore, other monitor-
ing systems have been proposed (e.g., u
chimurA
et
alii, 2010; F
uJitA
et alii, 2010).
ABSTRACT
Early-warning systems for sediment disasters are
important tools for disaster risk reduction, achieving
sustainable development, and ensuring livelihoods.
In 2005, the Japanese government initiated a new
nationwide early warning system for landslide disas-
ters. The main methodology of the system involves
setting a criterion for the occurrence of debris flows
and slope failures based on several rainfall indices.
However, these rainfall thresholds did not always
work well and could not ensure early evacuation.
We considered that the early detection of small-scale
sediment movement, likes sediment discharge from
streams, could be used effectively in early warning
systems for large-scale landslides; however, the diffi-
culties in directly monitoring traction processes, such
as bedload and mass movements, has been widely rec-
ognized. Here, we propose a new observation method
for monitoring bedload transport in mountain rivers
using an acoustic method: the use of hydrophones, as
proposed by m
izuyAmA
et alii (1996). Moreover, we
demonstrate the applicability of this method to clarify
bedload dynamics in Japanese mountain rivers. Then,
we argue that our new method offers the possibility
of improvements in early warning systems of large-
scale landslides using real-time monitoring systems
for bedloads in mountain rivers.
K
ey
words
: large-scale landslide, bedload monitoring,
hydrophone, early warning system
background image
A. OKAMOTO, T. UCHIDA, S. HAYASHI, T. SUZUKI, S. YAMASHITA, S. TAGATA, A. FUKUMOTO & J. KANBARA
362
International Conference Vajont 1963-2013. Thoughts and analyses after 50 years since the catastrophic landslide Padua, Italy - 8-10 October 2013
observations in Japanese mountain rivers to examine
the applicability of hydrophones to (1) measuring the
bedload transport rate, and (2) detecting small-scale
sediment movements just after their occurrence.
LESSONS FROM PAST DISASTERS
First, we compiled documentations of recent two
disasters to test our hypothesis that if we were able to
detect these small-scale movements early, the infor-
mation could prove useful in ensuring effective early
warning systems for large-scale landslides.
SHIAOLIN VILLEAGE, TAIWAN
Typhoon Morakot landed Taiwan at 7-Aug.,
2009 and brought the heaviest rainfall in southern
part of Taiwan. Cumulative rainfall amounts of this
event exceed 2,500 mm. This heavy rainfall trig-
gered many sediment disasters. Especially, in Shiao-
lin village, Kaoshung, County had a serious damaged
by deep-seated catastrophic landslide. Many studies
documented this disaster in detail (e.g., s
hieh
et alii,
2009; F
uJitA
, 2010).
On 17:00LT and 21:00LT, 7-Aug., cumulative
rainfall amount exceeded threshold values for the cau-
tion and warning of sediment disasters, respectively.
However, the heavy rainfall was continued and the
peak rainfall intensity. At 19:00LT, 8-Aug. the bridge
No.8 was broken by sediment discharge from a tribu-
tary (Fig. 1). Moreover, at 6:00LT, 9 Aug. the bridge
No.9 was broken by sediment discharge from another
tributary. Then, huge deep-catastrophic landslide oc-
Recently, several researchers have argued that sev-
eral small-scale sediment movements can occur before
large-scale landslide occurrence (e.g., F
uJitA
et alii,
2010). Therefore, if we were able to detect these small-
scale movements early, the information could prove
useful in ensuring effective early warning systems for
large-scale landslides. However, the difficulties in di-
rectly monitoring traction processes, such as bedload
and mass movements, have been widely recognized.
Over the last few decades, research has been
conducted into surrogate monitoring technologies,
including acoustic (e.g., geophones, hydrophones)
and seismic methods, for the monitoring of bedload
transport (e.g., r
ickenmAnn
& m
c
A
rdell
, 2007;
G
rAy
et alii, 2010; r
ickenmAnn
et alii, 2012). Over
the last decade in Japan, hydrophones (m
izuyAmA
et
alii, 2010); also referred to as “Japanese pipe sys-
tem”) have been applied widely to monitor bedload
in mountainous rivers (e.g., m
izuyAmA
et alii, 1996,
2003; k
Anno
et alii, 2010). Thus, the abundance of
monitoring data has increased dramatically in recent
years. However, since the results of acoustic meas-
urements must be converted to bedload using em-
pirical and/or theoretical relationships, calibration is
still a key issue in the application of acoustic bed-
load measurements (e.g., n
AkAyA
, 2009; m
izuyAmA
et alii, 2010, 2011; s
uzuki
et alii, 2010). Recently,
we proposed a new method for conversion of sound
pressure data, collected by hydrophones, to rates
of bedload transport (s
uzuki
et alii, 2010). In the
present study, we conducted field bedload transport
Fig. 1 - Schematic map of Shiaolin village, Taiwan de-
scribing locations and timing of deep-seated cata-
strophic landslide and sediment discharge trig-
gered by typhoon Morakot, 2009. Location s and
timings were compiled from S
hieh
et alii (2009)
and F
ujita
(2010)
F
ig. 2 - Schematic map of Totsugawa village, Japan de-
scribing locations and timing of large-scale land-
slide, debris flow and sediment discharge trig-
gered by typhoon Tales, 20011. Location s and
timings were compiled from the survey by Nara
Prefecture and Y
amada
et alii (2012)
background image
POSSIBILITY OF EARLY WARNING FOR LARGE-SCALE LANDSLIDES
USING HYDROLOGICAL AND SEDIMENT TRANSPORT OBSERVATIONS IN MOUNTAIN RIVERS
Italian Journal of Engineering Geology and Environment - Book Series (6) www.ijege.uniroma1.it © 2013 Sapienza Università
Editrice
363
(1) There were relatively long time lags (i.e., around
one and half days in Shiaolin and Totsugawa vil-
lages) between the warning based on the rainfall
thresholds and the occurrence of large scale lan-
dslide. It can be thought that since the current
rainfall threshold for the warning against sedi-
ment disasters mostly determined by past ordi-
nal-scale landslides and debris flows (o
sAnAi
et
alii, 2010), the warning was much earlier than
the occurrence of large-scale landslide.
(2) In both disasters, sediment discharge from relati-
vely small tributaries occurred before the large-
scale landslide occurrence. Moreover, the time lag
between the occurrence of sediment discharge and
large-scale landslide was relatively short, compa-
red to the time lag between the warning and lan-
dslide occurrence.
These two issues supported our hypothesis sug-
gesting that the information about small-scale sedi-
ment discharge could prove useful in ensuring effec-
tive early warning systems for large-scale landslides.
SEDIMENT DISCHARGE MONITORING
METHODS
DEVICES
We used the type of hydrophone developed by
m
izuyAmA
et alii (1996, 2003, 2010), which consists
of a pipe deployed across a riverbed (Fig. 3). The di-
ameter of the pipe used was 48.6 mm, its length was
50 cm, and its thickness was 3 mm (Fig. 4). The pipe
was fixed using a mortar mound. The height of the
pipe from the surface of mortar mound was 12 mm,
as shown in Fig. 4.
Vibrations of the air, generated by the collision
of a sediment particle with the pipe, are detected by
a microphone; these are amplified by a preamplifier
and transmitted to a converter. The microphone and
preamplifier were installed inside the pipe (m
izuyAmA
et alii, 2010). The output of the preamplifier is a wave-
form, and we sampled output data at 100 kHz.
curred at 6:20LT, 9-Aug. A part of this landslide direct-
ly attacked Shiaolin village and induced landslide dam.
Finally, the landslide dam breeched by overtopping
erosion and triggered a flash flood. The Shiaolin village
was completely destroyed by landslide and landslide
dam and most of local people who lived in the village
were killed by this disaster.
TOTSUGAWA VILLEAGE, JAPAN
Typhoon Tales landed Japan at 3 Sep., 2011 and
brought the heaviest rainfall in central part of Japan.
Cumulative rainfall amounts of this event exceed 1,500
mm. This heavy rainfall triggered many sediment dis-
asters. Especially, in Kii Peninsula, including Totsug-
awa village, many deep-seated rapid landslides were
occurred. Based on satellite image survey, we detected
more than 50 large landslides, means that landslide ar-
eas were larger than 1.0 ha.
On 12:35LT, 2-Sep., local government and Japan
Metrological Agency alerted the special warning of
sediment disasters based on the rainfall threshold de-
scribed by o
sAnAi
et alii (2010). However, the heavy
rainfall was continued until the morning of 4-Sep.
Around 23:00LT 2-Sep., national road was closed by
rockfalls and sediment discharges from tributaries
of Totsugawa river (Fig. 2). From 18:45LT 3-Sep. to
16:20LT 4- Sep. several deep-seated rapid landslides
occurred and triggered serious damages in Totsugawa
village, Japan (Fig. 2).
LESSONS FROM THE DISASTERS
Based on these two disasters, we can point our
two issues about early-warning system for large-
scale landslides.
Fig. 3 - Hydrophone in Bouzudaira Sabo Dam, Yotagiri
River, Japan
Fig. 4 - Schematic illustration describing cross section of
hydrophone
background image
A. OKAMOTO, T. UCHIDA, S. HAYASHI, T. SUZUKI, S. YAMASHITA, S. TAGATA, A. FUKUMOTO & J. KANBARA
364
International Conference Vajont 1963-2013. Thoughts and analyses after 50 years since the catastrophic landslide Padua, Italy - 8-10 October 2013
mendous amount of data is necessary for experimental
accuracy. Therefore, s
uzuki
et alii (2010) proposed a
method for estimating the relationship between R and
N using numerical simulations, as follows (“Prepara-
tion” in Fig. 5).
In this method, a uniform random number, rd(t), is
given every one-millionth of a second, where t is the
elapsed time (s). The threshold value, Th, is set at Th =
N/100000 for a given value of N. When rd(t) is lower
than Th, an individual collision wave datum, which
is obtained by preliminary field experiments [Step (5)
in Fig. 5], is added to the wave data being produced.
R is calculated from the data computed in this way
using Eq. (1). The relationship between R and N is
obtained when N is varied over a wide range. Thus, R
decreases as N increases owing to the effects of sound
wave interference (“Collision frequency–Detection
rate relationship” in Fig. 5). Then, we determined the
relationship between collision frequency and relative
detection rate (Step (7) in Fig. 5).
Qs is expressed as
(3)
CALIBRATION METHOD
We used the integrated sound pressure method
proposed by s
uzuki
et alii (2010) to convert raw
hydro-phone data to bedload transport rate. First, to
reduce the electrical noise, we extracted circumfer-
ential frequency components using a band-pass filter
[Step (2) in Fig. 5]. Sound pressure data correspond to
the line connecting the local maximum points of the
extracted data (“Filtered wave data” in Fig. 5), and we
calculated the averaged sound pressures (Sp). s
uzuki
et alii (2010) confirmed the relationship between Sp
and bedload transport rate, Qs, as follows:
Sp = α Q sr
(1)
R = f (N)
(2)
where α is the proportionality coefficient, R is the de-
tection rate, and N is the collision frequency. Equation
(2) indicates that R is a function of N. The relationship
between R and N can be obtained from experimental
results under a wide range of conditions. However,
the relationship obtained is unrealistic, because a tre-
Fig. 5 - Schematic illustration describing the Integrated sound pressure method
background image
POSSIBILITY OF EARLY WARNING FOR LARGE-SCALE LANDSLIDES
USING HYDROLOGICAL AND SEDIMENT TRANSPORT OBSERVATIONS IN MOUNTAIN RIVERS
Italian Journal of Engineering Geology and Environment - Book Series (6) www.ijege.uniroma1.it © 2013 Sapienza Università
Editrice
365
Using the integrated wave data produced using
the observed preamplifier output and Eq. (6), we cal-
culated the average sound pressure under the assumed
k times larger bedload condition, Sp
k
, and the relative
detection rate, f(kN)/f(N) (=Spk /kSp) (Step (8) in Fig.
4). Based on the predermined relationship between
collision frequency and relative detection rate, we
were able to evaluate the bedload transport rate (Qs)
from the observed Sp and calculated Sp
k
(Step (9) in
Fig. 4). We also evaluated mean diameter of bedload
(d) based on this method.
INTENSIVE OBSERVATION
We conducted detailed measurements at Bou-
zudaira Sabo Dam in Yotagiri River in central Japan
(Figure 6). The river has a drainage area of 42.7 km
2
and mean riverbed angle of 5.4°. Debris flows occur
frequently at one particular tributary of Yotagiri River,
Onboro-sawa, where unstable sediments are deposited
on both the riverbed and surrounding hillslopes.
Bouzudaira Sabo Dam has a drainage area of
37.6 km
2
and is located at an altitude of 745 m a.s.l.
The riverbed angle at Bouzudaira Sabo Dam is 2.3°;
the width of the surface water is 50 m, and the me-
dian grain diameters of the riverbed sediments are
around 3-5 cm.
A sediment flow observation system was installed
at Bouzudaira Sabo Dam in 2000 (u
rA
et alii, 2002).
Using this system, samples of river water can be ob-
tained at three different heights (on the riverbed, and
50 and 100 cm above the riverbed). Therefore, the
rates of bedload, suspended load, and washload can
be observed directly (u
rA
et alii, 2002). We assumed
that the rate of sediment transport at the riverbed was
the same as the bedload transport rate.
INTERSITE COMPARISON
In 2010, the Sabo Department and Sabo Offices
of the Ministry of Land, Infrastructure, Transport and
Tourism of Japan initiated extensive monitoring of
bedload transport in Japanese mountain rivers using
hydrophones. Here, we have compiled some of these
data, including data from seven observation stations in
six watersheds (Fig. 6).
We evaluated transport rate using the integrated
sound pressure method and hydrophone data. We cal-
culated the dimensionless bedload transport rate (q
s*
)
using the following equations:
where d is the mean diameter of the bedload. Substi-
tuting Eqs. (2) and (3) into Eq. (1), Eq. (4) is obtained:
(4)
It is impossible to obtain Qs from Sp using Eq.
(4) alone, because there are two unknown variables:
N and d. Here we imagined larger bedload condition.
We defined the ratio of observed bedload to imagined
bedload as k. So, according to Eqs. (1) and (4), if N
increases k times without any increase in d, the fol-
lowing equation can be obtained.
(5)
where Sp
k
is the average sound pressure under the im-
agined k times larger bedload condition. Thus, from
Eqs. (4) and (5), relative detection rate (f(kN)/f(N))
can be calculated by the following equation:
(6)
In the integrated sound pressure method, we di-
vided the original observed wave data of the preampli-
fier output into k data [Step (3) in Fig. 5]; then, these k
wave data were integrated into single wave data as the
wave data of k times larger bedload condition [Step
(4) in Fig. 5]. We assumed that the preamplifier out-
put under k times larger bedload transport condition
(vk(t)) can be described as follows.
(7)
where v
i
(t) is the preamplifier output of the i-th wave
data. s the preamplifier output of the i-th wave data.
Fig. 6 - Location of observation stations
background image
A. OKAMOTO, T. UCHIDA, S. HAYASHI, T. SUZUKI, S. YAMASHITA, S. TAGATA, A. FUKUMOTO & J. KANBARA
366
International Conference Vajont 1963-2013. Thoughts and analyses after 50 years since the catastrophic landslide Padua, Italy - 8-10 October 2013
(8)
where is σ the unit weight of sediment and ρ is the
unit weight of water, g is the gravitational accelera-
tion, and d
r
is the representative bedload diameter. We
defined d
r
as the grain sizes at which 60% of the sam-
ple is finer (d60). We used sample taken from riverbed
sediments to define d
r
.
We also calculated the dimensionless bed shear
stress (τ
*
) using the following equation:
(9)
where u
*
is friction velocity.
RESULTS
Here, we present the results of a storm triggered
by Typhoon Roke (Fig. 7). Generally, the bedload
transport rate evaluated by hydrophone agreed well
with that observed by direct sampling. This suggests
that the integrated sound pressure method is appli-
cable for calibrating the output data of hydrophone
preamplifiers to the volume of bedload transport.
Moreover, the bedload transport rate evaluated
using the hydrophone exhibited complex character-
istics of bedload transport. For example, the peak
bedload transport rate occurred several hours earlier
than the peak water level. Therefore, bedload trans-
port during periods of rising water level was greater
than that during periods of falling water level, as-
suming constant water level. Accordingly, we con-
sidered the hydrophone to be effective in clarifying
the detailed dynamics of bedload transport in moun-
tain rivers. Moreover, our results indicate that the
bedload transport rate cannot be fully described un-
der the assumption that sediment transport can be a
capacity-limited system.
We evaluated temporal changes in mean bedload
diameter using the hydrophone data (Fig. 8). Our results
indicate that mean bedload diameter varied from around
1 mm to 10 mm, and increased with increasing bedload
transport rate. Temporal variability in bedload diameter
was particularly large during high-flow periods. We also
compared mean bedload diameter evaluated using hy-
drophone data with the grain size distribution of bed-
load evaluated by direct sampling (Fig. 8). The results
indicated that there was little difference in mean bedload
diameter estimated using these methods. Therefore, we
consider the hydrophone to be effective in clarifying the
detailed dynamics of bedload transport, i.e., transport
rate and particle diameters, in mountain rivers.
Various relationships have been determined (us-
Fig. 7 - Hyetograph, water flow depth, bedload transport rate per unit width observed by both hydrophone and direct sam-
pling, combined with temporal changes in bedload diameter evaluated by hydrophone during the storm triggered by
Typhoon Roke, 2011
background image
POSSIBILITY OF EARLY WARNING FOR LARGE-SCALE LANDSLIDES
USING HYDROLOGICAL AND SEDIMENT TRANSPORT OBSERVATIONS IN MOUNTAIN RIVERS
Italian Journal of Engineering Geology and Environment - Book Series (6) www.ijege.uniroma1.it © 2013 Sapienza Università
Editrice
367
poral variations in the relationship between bed shear
stress and bedload transport rate were generally small-
er than spatial variations.
At Abukuma #1 and Fuji #2, the relationship
between bed shear stress and bedload transport rate
ing hydrophones) between dimensionless bed shear
stress and dimensionless bedload transport rate in
mountain rivers (Fig. 9). Furthermore, these relation-
ships can vary temporally, even for the same station,
e.g., Joganji #1 and Fuji #2 in Fig. 9. However, tem-
Fig. 8 - Mean bedload diameter evaluated by hydrophone (black circles) and bedload grain size distribution observed by
direct sampling (solid lines) at (a) 18:00 LT Sep/ 20, (b) 21:00 LT, Sep/ 20,
(c) 2:00 LT Sep/ 21, 2011. Numbers in
italics represent mean bedload diameters (mm) evaluated by direct samplings
Fig. 9 - Relationship between dimensionless bedload transport rate evaluated by hydrophones and dimensionless bed share
stress in mountain rivers of Japan: (a) gentle channel (gradient less than 1/30) and (b) steep channel. MPM, AM, and
ATM indicate theoretical relationships between bedload transport rate and bed share stress proposed by m
eYer
-P
eter
&
m
üller
(1948), a
Shida
& m
ichiue
(1972), and a
Shida
et alii (1978), respectively
background image
A. OKAMOTO, T. UCHIDA, S. HAYASHI, T. SUZUKI, S. YAMASHITA, S. TAGATA, A. FUKUMOTO & J. KANBARA
368
International Conference Vajont 1963-2013. Thoughts and analyses after 50 years since the catastrophic landslide Padua, Italy - 8-10 October 2013
warning systems for large-scale landslides.
However, we feel that further research is nec-
essary before the deployment of an early warning
system that uses hydrophones. For example, it is
important to clarify the types of changes in bedload
transport that will occur owing to changes in sediment
supply in upstream areas. Additionally, it is important
to clarify the time lag between changes in sediment
supply upstream and changes in bedload characteris-
tics downstream.
was almost the same as theoretical relationships pro-
posed by m
eyer
-P
eter
& m
üller
(1948), A
shidA
&
m
ichiue
(1972), and A
shidA
et alii (1978). In contrast,
the bedload transport rate at Uono #2 and Fuji #1 was
more than three orders of magnitudes smaller than the
theoretical rate, assuming that representative bedload
diameters as d60 of riverbed materials. However, in
general, the bedload transport rate in gentle channels
was close to the appropriate theoretical value.
DISCUSSION AND CONCLUSIONS
We have shown that use of a hydrophone and
adoption of the integrated sound pressure method can
evaluate bedload transport rate and bedload diameter
successfully. In Yotagiri River, we observed preampli-
fier output at one-minute intervals using a data logger,
and calibrated the data immediately after collection
using a personal computer. Calibration according to
the integrated sound pressure method took less than 1
min. Therefore, our system allows real-time monitor-
ing of bedload transport rate and diameter.
While, based on the past disasters, it can be con-
sidered sediment discharge occurring in rivers near
landslide areas just before the occurrence of large-scale
landsliding (see Figs 1 and 2). Therefore, it is possible
that our system could be used to obtain new informa-
tion about sediment discharge before the occurrence of
large-scale landslides (Fig. 10b). In the past disasters in
Japan and Taiwan, there were relatively long time-lag
between the waning based on the rainfall threshold and
the lare-scale landslide occurrences (Fig. 10a). While,
the time lags between sediment discharge and landslide
occurrence were relatively short. So, these suggest that
our system could contribute to improvements in early
REFERENCES
A
shidA
k., t
AkAhAshi
t. & m
izuyAmA
t. (1978) - Study on bed load formula for mountain streams. J. Jpn. Erosion Control
Engng., 30 (4): 9-17.
A
shidA
k. & m
ichiue
M. (1972) - Study on hydraulic resistance and bedload transport rate in alluvial streams. Trans. Jpn. Soc.
Civil Engng., 206: 59-64.
c
Aine
n. (1980) - The rainfall intensity–duration control of shallow landslides and debris flows. Geografiska Annaler. Series
A, 62: 23-27.
c
ostA
J.e. & s
chuster
r.l. (1988) - The formation and failure of natural dams. Geol. Soc. Am. Bull., 100: 1054-1068.
F
uJitA
m. (2010) - Sediment disasters and flood disasters in Taiwan: Triggered by typhoon Morakot. Annuals of Disaster
Prevention Research Institute, Kyoto University, 53A, 73-83.
F
uJitA
m., o
hshio
s. & t
sutsumi
d. (2010) - A prediction method for slope failure by means of monitoring of water content in
slope-soil layer. J. Disaster Res., 5: 296-306.
G
rAy
J.r., l
Aronne
J.B. & m
Arr
J.d.G. (2010) - Bedload-surrogate monitoring technologies. U.S. Geological Survey Scientific
Fig. 10 - Schematic illustration describing early-warning
system for large scale landslide
background image
POSSIBILITY OF EARLY WARNING FOR LARGE-SCALE LANDSLIDES
USING HYDROLOGICAL AND SEDIMENT TRANSPORT OBSERVATIONS IN MOUNTAIN RIVERS
Italian Journal of Engineering Geology and Environment - Book Series (6) www.ijege.uniroma1.it © 2013 Sapienza Università
Editrice
369
Investigations Report 2010–5091.
G
uzzetti
F., P
eruccAcci
s., r
ossi
m. & s
tArk
c. (2008) - The rainfall intensity–duration control of shallow landslides and
debris flows: an update. Landslides, 5: 3-17.
k
Anno
t., t
oshidA
t., m
iyAzAwA
k. & h
idA
y. (2010) - Bed-load detection with a pipe geophone: Field experiments at the
Gentaro sabo dam on the Hira River, Int. J. Erosion Control Engng., 3: 126-129.
m
eyer
-P
eter
e. & m
üller
, r. (1948) - Formula for bed-load transport. Proc. 2
nd
IAHR Meeting, 39-64.
m
izuyAmA
t., F
uJitA
m. & n
onAkA
m. (2003) - Measurement of bed load with the use of hydrophones in mountain rivers. IAHS
Publ., 283: 222-227.
m
izuyAmA
t., n
onAkA
m. & n
onAkA
n. (1996) - Observation of sediment discharge rate using hydrophone. J. Jpn. Erosion
Control Engng., 49 (4): 34-37.
m
izuyAmA
t., l
Aronne
J.B., n
onAkA
m., s
AwAdA
t., s
AtoFukA
y., m
AtsuokA
m., y
AmAshitA
s., s
Ako
y., t
AmAki
s., w
AtAri
m.,
y
AmAGuchi
s. & t
surutA
k. (2010) - Calibration of a passive acoustic bedload monitoring system in Japanese mountain
rivers. In: G
rAy
J.r., l
Aronne
J.B. & m
Arr
J.d.G. (
eds
.). Bedload-surrogate monitoring technologies. US Geological
Survey Scientific Investigations Report 2010–5091. US Geological Survey, Reston, VA: 296-318.
m
izuyAmA
t., h
irAsAwA
r., k
osuGi
k., t
sutsumi
d. & n
onAkA
m. (2011) - Sediment monitoring with a hydrophone in mountain
torrents. Int. J. Erosion Control Engng., 4: 43-47.
n
AkAyA
h. (2009) - Bimodal analysis of sediment transport in mountain torrents using hydrophones and sediment traps. Int. J.
Erosion Control Engng., 2: 54-66.
r
ickenmAnn
d. & m
c
A
rdell
B.w. (2007) - Continuous measurement of sediment transport in the Erlenbach stream using
piezoelectric bedload impact sensors. Earth Surf. Process. Landf., 32: 1362-1378.
r
ickenmAnn
d., t
urowski
J.m., F
ritschi
B., k
lAiBer
A. & l
udwiG
A. (2012) - Bedload transport measurements at the Erlenbach
stream with geophones and automated basket samplers. Earth Surf. Process. Landf., 37: 1000-1011.
o
sAnAi
n., s
himizu
t., k
urAmoto
k., k
oJimA
s. & n
oro
t. (2010) - Japanese early-warning for debris flows and slope failures
using rainfall indices with Radial Basis Function Network. Landslides, 7: 1-14.
s
Aito
h., n
AkAyAmA
d. & m
AtsuyAmA
h. (2010) - Relationship between the initiation of a shallow landslide and rainfall
intensity-duration threshold in Japan. Geomorphology, 118: 167-175.
s
hieh
c-l., w
AnG
c-m., l
Ai
w-c., t
sAnG
y-c. & l
ee
s-P. (2009) - The composite hazard resulted from Typhoon Morakot in
Taiwan. J. Jpn. Soc. Erosion Control Engng., 62 (4): 61-65.
s
uzuki
t., m
izuno
h., o
sAnAi
n., h
irAsAwA
r. & h
AseGAwA
y. (2010) - Basic study on sediment rate measurement with a
hydrophone on the basis of sound pressure data. J. Jpn. Erosion Control Engng., 62 (5): 18-26.
u
chimurA
t., t
owhAtA
i., t
rinh
t.l.A., F
ukudA
J., B
AutistA
c.J.B., w
AnG
l., s
eko
i., u
chidA
t., m
AtsuokA
A., i
to
y., o
ndA
y., i
wAGAmi
s., k
im
m.s. & s
AkAi
n. (2010) - Simple monitoring method for precaution of landslides watching tilting and
water contents on slopes surface. Landslides, 7: 351-358.
u
rA
m., F
ukAyA
t., i
rino
m., t
Akeuchi
h., n
AkAmurA
h., y
okoyAmA
k., h
AmAnA
s. & u
memurA
h. (2002) - Sediment yield
monitoring in Yodagiri River, central Japan. Development of sediment flow observation system and sediment transport
investigation.
Proceedings of INTERPA-REVENT 2002: 483-492.
y
AmAdA
m., m
Atsushi
y., c
hiGirA
m. & m
ori
J. (2012) - Seismic recordings of the Landslides caused by Typhoon Talas. Geophy.
Res. Lett. 39: L13301. doi:10.1029/2012GL052174
u
chidA
t., y
okoyAmA
o., s
uzuki
r., t
AmurA
k. & i
shizukA
t. (2011) - A new method for assessing deep catastrophic landslide
susceptibility. Int. J. Erosion Control Engng., 4: 32-42.
background image
Statistics