Document Actions

IJEGE-11_BS-Scotton-et-alii

background image
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
595
DOI: 10.4408/IJEGE.2011-03.B-065
THE DEBRIS-FLOWS MONITORING SYSTEM OF ACQUABONA TORRENT
(CORTINA D’AMPEZZO, BELLUNO, ITALY)
P. SCOTTON
(*)
, R. GENEVOIS
(*)
, f. MORO
(*)
, l. ZORZI
(*)
,
G. GIRARDI
(*)
& n. PRATICELLI
(*)
(*)
University of Padua - Department of Geosciences - Padua, Italy
second one has been realized in the flowing zone, near
the deposition area. It has been equipped with an ul-
trasonic level meter, a video-camera served by a sys-
tem of night lighting and a tipping bucket rain gauge.
Geophones have been used for the activation of the
monitoring system and for measuring front velocities.
Substantial changes have been introduced, in
comparison with the previous installation, in the pow-
er supply of downstream station that will be reached
by the main electricity grid. The power supply of the
upstream weather station will be, instead, ensured by
solar panels. The data coming from the two stations
are collected at the downstream station (a radio link
connects the upstream meteorological station with the
downstream station) and are available for the down-
load from the Department of Geosciences of Padua
via mobile Internet.
K
ey
words
: debris-flows monitoring, field survey, debris
flows, hydrologic measurement
INTRODUCTION
The Acquabona catchment (Dolomites, Eastern
Italian Alps) has an upper rock basin, with a drain-
age area of 0.3 km
2
formed of upper Triassic to Lower
Jurassic massive dolomites and limestones. In the
lower basin these rocks and the underlying red marls
are covered by very thick talus deposits including het-
erogeneous scree, alluvium and debris flow deposits
containing boulders up to 3-4 m in diameter.
ABSTRACT
The article presents a debris-flow monitoring sys-
tem installed in the site of Acquabona near Cortina
d’Ampezzo, in the province of Belluno, Italy.
The site, whose activity is almost annual, was
equipped in the second half of the 90
s
, with the aim of
characterizing the phase of initiation, flow and depo-
sition of debris-flows typical of the Dolomitic areas.
Three measuring stations were been realized. The
power of the equipment was provided by solar pan-
els. The field data were stored on site and recovered
through inspections to the station.
The monitoring activity has proven to be, over the
years, of great difficulty as a result, firstly, of the need
for frequent visits to the site, sometimes long after
the events occurrence, and, secondly, of the morpho-
logical changes taking place in the water course un-
der study. In particular it was observed a progressive
regression of the deposition area that was and still is
affecting the two downstream stations.
The monitoring system has been, therefore, re-
designed taking into account the need to move old
downstream stations at a higher elevation and the will
to remotely control the activity of the basin. At the
moment two new stations have been realized. The
first one is a weather station that collects rain, wind,
temperature and humidity data. It is located further
upstream than the previous upstream station and in
a more apical position in the basin, to better charac-
terize initial conditions that trigger debris flows. The
background image
P. SCOTTON, R. GENEVOIS, F. MORO, L. ZORZI, G. GIRARDI & N. PRATICELLI
596
5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
THE JULY 18
TH
, 2009 DEBRIS FLOW
Resting on the local inhabitants and drivers, early
in the morning (5:00 and 7:00 a.m.) of July 18
th
2009,
a debris flow happened on the Acquabona basin, trig-
gered by a heavy pluviometric event affecting the en-
tire Dolomites area.
Two different surges have characterized the event:
a first one, with a total volume of about 2.000-3.000
m
3
, reached the retention basin at the channel outlet,
depositing part of its solid loading in the lower part of
the channel. A second surge, with an estimated vol-
ume of about 20.000-22.000 m
3
, overflowed both left
and right banks at an elevation of 1150-1160 m a.s.l.
where they had their minimum height (Fig. 1). Most
likely, the deposit of the first surge raising the channel
bed facilitates the lateral overflows.
The deposits on the hydrological right extend
from 1160 m a.s.l. to the n. 51 State Highway below
that has been completely overflowed.
The main fan has a principal axis of about 300 m
in length, and a maximum width of about 70 m. The
thickness of the deposit is variable along the fan, with
a mean value of about 1 m, also considering the mud
- film covering the foot of the tree trunks (Fig. 2). The
volume of the flooding mass relative to this sector is
about 20.000 m
3
.
The channel is mostly incised into the talus, ex-
cept for a 150 m long reach where it cuts through the
marls bedrock. The channel has been cut by debris
flows to 30 meters maximum depth. A detailed geo-
morphological description of the site is available in
b
eRti
et alii (1999) and G
enevois
et alii (2000a).
The Acquabona catchment and the debris flows
events have been studied since 1997 on the basis of a
field monitoring system that changed in the years. The
data collected led to a considerable amount of scien-
tific publications.
Hydrological conditions leading to the forma-
tion of debris flows, also using collected rainfall and
water pressure data, have been analyzed (G
enevois
et alii, 2000b; b
eRti
& s
imoni
, 2003; s
imoni
& b
eR
-
ti
, 2005; a
Rmento
et alii, 2007 and G
ReGoRetti
&
d
alla
f
ontana
, 2008). Front velocities, particles
size and velocities distribution on the debris flow
top surface, using data from induced ground vibra-
tion and recorded images have been obtained (G
e
-
nevois
et alii, 2000c; t
eCCa
et alii, 2003; G
enevois
et alii, 2001). Relationships between flow depth,
flow induced vibrations and front velocity and esti-
mation of debris flow volumes based on the integral
of measured ground vibrations have been proposed
(G
alGaRo
et alii, 2005). The debris-flow material has
been used to perform laboratory tests in order to ana-
lyze deposition processes (d
eGanutti
et alii, 2003).
Events detected at the site have been used to test
one-dimensional numerical models (P
aPa
& l
ambeR
-
ti
, 1999; f
RaCCaRollo
& P
aPa
, 2000) and to simu-
late the dynamic behaviour using one-dimensional
(DAN-W) and two-dimensional (FLO-2D) models
(a
Rmento
, 2007; a
Rmento
et alii, 2008). Debris-
flow hazard analysis has been carried out based on
the combination of field data and numerical applica-
tions (G
enevois
et alii, 2009).
The installed monitoring system, that underwent
numerous modifications during the years, has been
completely torn up by the 2009 debris flow and, then,
designed again and rebuilt.
The aim of this paper is to: i) summarize the his-
tory of the monitoring system installed in the debris-
flow prone basin of Acquabona (Cortina d’Ampezzo)
in Eastern Italian Alps, from the original one (1997);
ii) illustrate the new system installed after the 2009
disastrous debris flow.
Fig. 1 - Geomorphological map of the July 18
th
2009 debris
background image
THE DEBRIS-FLOWS MONITORING SYSTEM OF ACQUABONA TORRENT (CORTINA D’AMPEZZO, BL, ITALY)
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
597
THE FIRST MONITORING SYSTEM, 1997
The first monitoring system was designed in the
late 90s (Fig. 4), in collaboration with the USGS -
Cascades Volcano Observatory. Three measurement
stations have been realized (s
imoni
, 1998).
The upstream station was located in the initiation
area of the debris flow phenomena at the elevation of
approximately 1565 m a.s.l. This station was equipped
with a tipping bucket rain gauge, a geophone for the
activation of the monitoring system at the events, four
water pressure transducers distributed in the surface
layer of the bottom, a water pressure transducer located
at a larger distance from the surface, two cameras and
two VHS video recorders that were activated in case of
overcoming of the trigger threshold of the geophone.
The second fan, on the left side, is smaller. Grain
size distribution and texture of the deposit are similar
to those of the main fan, except for a lower percentage
of fines which are concentrated only on the upper part
of the fan. Unlike the main deposit, there is a decrease
in the grain size heterogeneity from the apical part to
the toe of the fan: in fact, close to the toe of the fan the
deposit is made only by gravel and pebbles, with only
a local presence of the fine debris.
Pluviometric data, registered at the Mt. Faloria
meteorologic station (no more than 1 km away and
more or less at the same elevation), show a series of
rainfall peaks between midnight and 7:00 a.m. (Fig.
3), three of which within the above mentioned time
- interval. One of these certainly triggered the second
main surge, but it is possible that the first small surge
was triggered by one of the rainfall peaks between the
0:00 a.m. and 1:30 a.m.
The lithology and grain size of the whole 18
th
July’s deposits indicates that the debris flow was not
generated as usual at the closure of the rock basin, just
upstream of station S1 M1 (Fig. 4), as it is confirmed
by the lack of Raibl Formation debris and the absence
of boulders larger than 1 m
3
, present almost only at
higher elevation, let presume that the event was trig-
gered below an altitude of 1440 m. The debris flow
was then triggered at the elevation of Station S2 M1
(Fig. 4) or just a little above.
As a consequence of the critical stability condi-
tions of the right side of the channel in this area, it can
be assumed that a series of small slides could have
happened, damming the channel and increasing the
available debris subsequently mobilized.
Fig. 2 - Debris flow deposits with transported
trees and mud on tree trunks
Fig. 3 - 5 minutes rainfall and cumulative 5 minutes rainfall at Mt. Faloria meteorological station (source: ARPA Veneto - Italy)
background image
P. SCOTTON, R. GENEVOIS, F. MORO, L. ZORZI, G. GIRARDI & N. PRATICELLI
598
5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
into account the relatively low data rates provided by
radio link and the required electrical power to activate
the equipment, in particular the large absorption sen-
sors: camcorders and ultrasonic meter. To reduce the
amount of data to transmit, the acquisition frequency
varied from normal conditions to event mode as de-
scribed and video data were stored locally on video
tapes. To reduce the energy required to operate all
the equipment, instrumentation with high power con-
sumption was only activated in event mode.
Important information about events of Acquabona
catchment were obtained from the event of June 12
th
,
1997 (estimated volume of 6.000 m
3
), when the moni-
toring system had not yet been activated. The moni-
toring system was active instead at the events of July
25
th
and 27
th
, 1998 (estimated volume of deposit of
less than 1000 m
3
) and August 17
th
, 1998 (estimated
volume of deposit of the order of 10.000 m
3
).
Alongside the wealth of information gathered,
the system also showed some drawbacks. The use
of geophones as sensors for the activation of event
mode was effective at the upstream and downstream
station and ineffective at the middle station, despite
the lowering of the threshold consequently the non-
activation after the events of July 1998. The system
for the measuring of the total pressure located at the
downstream station operated during the first event in
July 2008 and was swept downstream during the sec-
ond event, showing the considerable difficulties of
designing this type of instrumentation.
The middle station was positioned in the flowing
zone, at the altitude of about 1310 m a.s.l. The station
was equipped with three geophones separated from
each other about 100 m, the first of which acted as
recording trigger at the events, and an anemometer.
The downstream station was located at the end
of the sliding zone, at the altitude of about 1175
m a.s.l.. This station was equipped with three geo-
phones, separated from each other about 100 m. As
in the previous station the upstream geophone have
the function to trigger the fast data acquisition mode.
An ultrasonic sensor was mounted for measuring the
distance from the bed surface, a total pressure meas-
urement system was located in the channel (surface
dimension of 0.2 m x 0.3 m, measuring range from 0
to 300 kPa), a water pressure transducer and a VHS
camcorder were installed.
Each station was powered by a 12 V solar panel
battery and was equipped with a data logger and a
radio receiver and-transmitter. The radios allow con-
nection to a data collection station located in Socol
area, located about 1.3 km from Acquabona village.
The radio connection also allowed the remote con-
trol of the proper functioning of instrumentation and
possible modification of the instrumentation setting.
The data from the stations were collected continu-
ously at a frequency of 0.0033 Hz (one acquisition
every five minutes) in normal conditions, and at the
frequency of 5 Hz at event mode.
The monitoring system has been designed taking
Fig. 4 - The position of the stations of the monitoring systems for debris-flow events installed at the Acquabona basin. The first
monitoring system (1997, M1) was composed of three stations in-site (S1 M1, S2 M1, S3 M1) and a station off-site (SO-
COL). In the second (2000, M2), a new station was built in the deposit basin (S3 M2) and the intermediate station of the
previous system (S2 M1) no more activated. The nowadays system (m
3
) is composed of two stations (S1 m
3
, S2 m
3
)
background image
THE DEBRIS-FLOWS MONITORING SYSTEM OF ACQUABONA TORRENT (CORTINA D’AMPEZZO, BL, ITALY)
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
599
data transmission in order to increase the transmission
speed and to allow remote real time monitoring. Mon-
itoring stations under construction are two.
The upstream station is located upstream the sedi-
ment catchment feeding the debris flows (Fig. 5), at an
altitude of about 1715 m a.s.l., in an area not involved in
the slope erosion processes that are close to reaching the
location where the previous upstream station were placed.
The elevation is higher than the elevation of the
downstream station of the previous system to take into
account the processes of deposition and reduction of
the slope, in place in recent years, in the final reach of
the flowing zone.
At the upstream station (Fig. 7) a weather station is
installed that allows data acquisition of liquid precipi-
tation, wind speed and direction, air temperature, baro-
metric pressure and relative humidity, in order to char-
acterize some metheorological properties of the site.
The downstream station (Fig. 6) is located at the
altitude of about 1185 m a.s.l., on a big boulder on the
left bank.
The obtained data have the form of ASCII strings
through the RS232 port of the device. They are stored by
a Rabbit RCM4000 microcontroller which in turn routes
them, through its serial port, to a radio transmitter having
a power of 0.1 W and a carrier frequency of 2.4 GHz.
THE SECOND MONITORING SYSTEM, 2000
The second monitoring system has been developed
to the early 2000s (Fig. 4) in collaboration with a lo-
cal company for the design and the management of the
system of instrumentation control. Again three meas-
uring stations have been equipped (G
alGaRo
, 2002).
The position of the upstream station was the same
of the monitoring system described above. A rain gauge,
a geophone for the activation of the monitoring system
at the events, four surface water pressure transducers, a
VHS camcorder activated in case of overcoming of the
geophone trigger threshold, have been installed.
A second station was located, approximately, at
the position of the downstream station of the previ-
ous system. The station was equipped with four geo-
phones, an ultrasonic sensor, a measurement system of
the total load on the bottom of the channel (anchored
to a concrete structure embedded in the river bed), a
piezometer and a video camera with video recorder.
The third station was located at the altitude of
about 1120 m a.s.l., within the retention basin designed
to contain the solid volume mobilized by debris flows.
This station was equipped with an ultrasonic distance
meter, a total load measuring system, a water pressure
transducer and a VHS camcorder.
The stations were equipped, as before, with a local
power system and a local data collection system, with
a radio receiver - transmitter (transmission speed 1200
baud) connected with the Socol station. Here a radio
modem (data rate 56 kB) allowed remote data transfer.
THE NEW MONITORING SYSTEM, 2009
The current monitoring system (Fig. 4) has been
implemented by the Department of Geosciences, Uni-
versity of Padua, as a result of damage suffered by
the existing installation during the event in July 2009.
The quoted event has been particularly heavy and
interested the national road 51. During the same mete-
orological event other debris flows occurred on slopes
nearby. In Cancia Village, little far from Acquabona,
an immature debris flow caused some victims caught
in their sleep in the room invaded by the flow.
The structure of the monitoring system being de-
veloped is simpler than previous systems, even if the
possibility of expansion is assured. Some instruments
that have proved unreliable and difficult to manage
have not been included in this phase. Major changes
have been introduced in the power supply and in the
Fig. 5 - The upstream station of the new monitoring
system. From the left to the right: the Vaisala
metheorological station; the antenna for down-
stream data transmission; the solar panels
background image
P. SCOTTON, R. GENEVOIS, F. MORO, L. ZORZI, G. GIRARDI & N. PRATICELLI
600
5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
Power is supplied by three solar panels of 20W
each that charge a battery 12 V/24 Ah through a 3A
power regulator. All equipment is supported by galva-
nized steel poles.
Because of the considerable difficulties in access-
ing the site, the installation was achieved through the
use of the helicopter to transport the material a short
distance from the mounting area and through the crea-
tion of a path made safe for installation and mainte-
nance of equipment.
At the downstream station the equipment has been
mounted on a reticular structure anchored to a big
boulder (Fig. 8). The length of the arm of the support
structure is about six meters and can reach the central
area of the section. The instrumentation is mounted
at a distance from the bottom of the channel of about
3.5 m. In order to make the assembly, disassembly
and maintenance of the equipment easier, the support
structure can be rotated around the anchorage vertical
axis about ninety degrees to align with the left bank of
the channel. On the described support a tipping bucket
rain gauge, an ultrasonic distance meter, a digital vid-
eo camera with a nocturnal lighting system and a radio
receiver, compatible with the upstream radio transmit-
ter, have been mounted.
Upstream the station, along the left bank of the
watercourse, three geophones have been buried spaced
roughly 100 m each other. Downstream the station, at
the same distance, another geophone has been placed.
The station is powered by connection to the main
electricity grid. The power provided is 3 kW.
The measured data are collected by a single board
computer and stored locally. The processor and the lo-
cal mass storage can be managed remotely via access
to high speed internet (up to a maximum of 7.2 Mbps),
recently available.
THE INSTRUMENTATION
VAISALA wEATHER STATION
The Vaisala Weather Station WXT520 (Fig. 9), oper-
ates in the temperature range between -52 °C and +60 °C.
It can be powered in DC 5-32 V with a typical
power consumption of 3 mA when powered at 12 V.
The station allows the measurement of the follow-
ing physical quantities: the liquid precipitation, wind
speed and direction, air temperature, barometric pres-
sure and relative humidity.
The rainfall is measured as accumulated liquid
starting from a manual or automatic reset. The de-
clared output resolution is 0.1 mm, while the accuracy
is 5%. The instrument provides a value of cumulative
accumulation every 10 seconds in the presence of pre-
cipitation. The intensity of precipitation is provided
as an average over a minute. The measurement range
varies from 0 mm/h to 200 mm/h (for higher intensity
the accuracy decreases).
The wind speed is measured in the range 0-60
m/s. The response time is equal to 250 ms and the ac-
curacy is equal to 3% up to 35 m/s and 5% between
35 m/s and 60 m/s. The resolution is equal to 0.1 m/s.
The azimuth of the wind direction is measured. The
response time is 250 ms, the accuracy is ±3° and the
resolution is ±1°.
The air temperature is provided in the range from
-52 °C to +60 °C with an accuracy that varies with tem-
perature from ± 0.2% at -52 °C to ± 0.7% at +60 °C.
The resolution is equal to 0.1 °C.
Barometric pressure is measured in the range 600-
1100 hPa with an accuracy of ± 1.0 hPa between -52
°C to +60 °C; the resolution is equal to 0.1 hPa.
The relative humidity is measured in 0-100 %RH.
The accuracy is 3 %RH in 0-90 %RH and 5 %RH in 90-
100 %RH. The output resolution is equal to 0.1 %RH.
Fig. 6 - The support structure of the instrumentation of
the downstream station. The arm length is 6 m.
The current elevation over the bottom, at the
center of the section, is about 3.5 m
Fig. 7 - The scheme of the new upstream station
background image
THE DEBRIS-FLOWS MONITORING SYSTEM OF ACQUABONA TORRENT (CORTINA D’AMPEZZO, BL, ITALY)
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
601
Super HAD, 480TVL. It supports two modes of im-
age compression: MJPEG and MPEG4. The shutter
speed can vary from 1/50 to 1/100.000. Images are
captured at a maximum speed of 25 fps. The camera
is powered with 5 VDC/2A. The operating tempera-
ture ranges from 5 °C to 50 °C. The relative humidity
should be between 20% RH and 80% RH. The mini-
mum illumination is 0.5 lux @ F 1.2. At low light
conditions is put into operation the system of artificial
lighting. The weight is about 300 g.
THE GEOPHONES
Geophones of Sercel, model L10-AR, are used for
triggering the monitoring system and for determining
the travelling time of the event through a section of the
water course. The standard frequency range is equal
to 10 - 14 Hz. Their use has proved adequate to the
analysed phenomena during previous activity.
THE HELIOS PC BOARD
The monitoring system is controlled by Helios
board of Diamond Systems Corporation, model
HLV800-256AV, which integrates a complete em-
bedded PC plus a full analog and digital data acqui-
sition circuit into a single board. The processor speed
is 800 MHz, a math coprocessor is present. The in-
ternal memory consists of 256 MB DDR2 RAM. It is
available a 10/100 Mbps Ethernet circuit integrated
in the processor chip and a connector for direct ac-
cess to the Internet. There are 16 single-ended or 8
differential analog voltage inputs available, 16-bit
resolution, and up to 40 digital programmable lines.
It requires 5 V power supply.
THE RABBIT PC BOARD
The upstream monitoring station is controlled by the
board Rabbit ZWorldCorporation, Model RCM4000,
which integrates a processor Z180 8-bit and an 11 bit
A/D data acquisition circuitry. The processor speed is
29.5 MHz with math coprocessor emulation function.
RADIO MODEM
The connection between the upstream and the
downstream station is done by radio-modem. Its use
ensures access to data even in case of failure of di-
rect access to the internet at the upstream meteoro-
logical station. The model used is the Xstream-PKG
RF (2.4 GHz). The transmission range is up to 5 km.
There are several options for data interface: the inter-
face RS-232/422/485 serial, USB and telephone. The
data transmission rate is selectable at 9.600 bps or at
19.200 bps. 10 V power is supplied. The current con-
sumption is about 200 mA in transmission and about
100 mA in receive mode. The instrument works in the
temperature range between -40 °C and 85 °C.
LEVEL TRANSMITTER
The level transmitter is the model 522 Smart Ul-
trasonic of LTH Electronics Ltd. It allows to measure
distances up to 15 m under ideal conditions of perfectly
reflective surface. The analog output is in the interval 4 -
20 mA. It can be powered by 24 V DC or 230 V AC. The
dissipated power is 6 W. The minimum distance meas-
ured is equal to 0.7 m. The sensor is temperature com-
pensated through a thermal resistance sensor, PT100, in
the temperature range -30/+60 °C. The resolution of the
instrument is 3 mm. Its use has proved suitable for field
operating conditions in the previous installations.
TIPPING BUCkET RAIN GAUGE
The measurement of the precipitation at the
downstream station is performed by the use of a tip-
ping bucket rain gauge. The diameter of the funnel is
equal to 28 cm (area equal to 616 cm
2
). The overturn-
ing of the bucket occurs every 13.8 grams of water
(the value has been obtained by calibration) which
corresponds to 0.22 mm precipitation height.
CAMERA
The camera is a high resolution IP colour Cam-
era, model Videoline Ep-CC480M4, CCD 1/3” Sony
Fig. 8 - The scheme of the downstream station
Fig. 9 - The
Vaisala
weather station,
model wXT520
background image
P. SCOTTON, R. GENEVOIS, F. MORO, L. ZORZI, G. GIRARDI & N. PRATICELLI
602
5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
The internal memory consists of 512 kB of SRAM and
32 MB of flash memory. There is a 10/100 Mbps Eth-
ernet circuit integrated on the chip of the core module
and the RJ45 connector for direct access to the Internet.
SOFTWARE FOR THE MANAGEMENT
OF MONITORING SYSTEM
On the Helios board of the downstream station the
acquisition program is written in C language (Fig. 10).
The heart of the program consists of two nested infi-
nite loops. The internal one periodically records the
analog signals of the geophones and of the ultrasonic
distance meter for a period of 1 minute per hour.
In the inner loop there is a function checking the
trigger signal from a digital input. If the signal exceeds
a threshold value for an assigned duration the program
exits the inner loop and enters the event acquisition rou-
tine. The routine is the same as before except in dura-
tion: 15-20 minutes. At the same time the camera is also
turned on for recording images of the watercourse. At
the end of the event recording, the program returns into
the inner loop and resumes the periodic registration.
The program is also provided of a connection via
TCP/IP, so it is possible to continuously monitor the
proper functioning of the equipment installed and the
remote download of the recorded data.
In the Rabbit board of the upstream station is
mounted a code, also written in C language, which al-
lows the management of serial communications of the
Vaisala meteorological station and of the radio modem.
Data can be stored locally and sent subsequent-
ly to the downstream station, or sent directly to the
downstream station by the radio modem. The method
of collecting and managing data is determined from
the downstream station accessing a simple user inter-
face with a standard HyperTerminal at 9600 baud rate.
CONCLUDING REMARKS
This paper has presented an overview of new sen-
sors and system employed for debris-flow monitoring
at the Acquabona site (Eastern Alps), where debris
flows frequently occurred in the past. The need for field
monitoring of debris flow occurrence mainly follows
on the consideration that many researches, both theo-
retical and laboratory, have been undertaken to under-
stand debris-flow processes and the associated hazards.
However, confirmation of results needs for quantitative
data from natural debris flows. Despite the valuable re-
sults that can be obtained, monitoring debris flows in
instrumented areas had a rather limited development
mainly due to the great difficulties arising from both
the morphology of mountainous regions where they oc-
cur and the characteristics of this natural phenomenon.
Data collection at the Acquabona site supported
then researches on the hydrologic factors controlling
debris-flow initiation, entrainment, and flow dynamics.
The previous installed monitoring system, that
underwent numerous modifications during the years,
was completely torn up by the 2009 debris flow and
a completely new system has been planned and real-
ized. Sensors employed are mostly the same used for
warning systems that have an important role in the
frame of non-structural control measures for these
hazardous phenomena.
ACKNOWLEDGEMENTS
The research was funded by grant from Strategic
Project “GEO-RISK-Geological and Hydrological
Processes: Monitoring, Modelling and Impact in the
North-Eastern Italy” (2010-2012).
The installation has been carried out with the lo-
gistic support of the “Regole” of Cortina d’Ampezzo
(Mr Diego Ghedina and his colleagues) and of the
Municipality of Cortina d’Ampezzo (Mrs Emilia Tosi
and her colleagues).
Fig. 10 - The core of the software for the management of
th downstream station
background image
THE DEBRIS-FLOWS MONITORING SYSTEM OF ACQUABONA TORRENT (CORTINA D’AMPEZZO, BL, ITALY)
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
603
REFERENCES
a
Rmento
M.C. (2007) - Le colate detritiche della conca ampezzana. Meccanismi d’innesco e valutazione della pericolosità.
Ph.D. Thesis. Università degli Studi di Padova, 99 pp. (in italian).
a
Rmento
m.C., G
enevois
R. & t
eCCa
P.R. (2008) - Comparison of numerical models of two debris flows in the Cortina d’Ampezzo
area, Dolomites, Italy. Landslides, 5: 143-150.
a
Rmento
m.C., t
eCCa
P.R., d
eGanutti
a.m. & G
enevois
R. (2007) - Numerical modeling of two debris flows in the Dolomites
(North-Eastern Italian Alps). In: C
Hen
C. & m
aJoR
J.J. (2007, eds.) - Proc. 4th Int. DFHM Conference, Chengdu, China.
b
eRti
m., G
enevois
R., s
imoni
a. & t
eCCa
P.R. (1999) - Field observations of a debris flow event in the Dolomites. Geomorphology,
29: 265-274.
b
eRti
m. & s
imoni
a. (2003) - Debris flow initiation in a highly-conductive soil. In: Proc. Int. Conf. Fast Slope Movements-
Prediction and Prevention for Risk Mitigation, 1: 29-36, Naples, Italy.
d
eGanutti
a.m., t
eCCa
P.R., G
enevois
R. & G
alGaRo
a. (2003) - Field and laboratory study on the deposition features of a
debris flow. In: R
iCkenmann
d. & C
Hen
C.-i. (2003, eds.) - Proc. 3rd Int. DFHM Conference, 1: 833-841, Davos, Switzerland.
f
RaCCaRollo
l. & P
aPa
m. (2000) - Numerical simulation of real debris-flows events. J. Phys. Chem. Earth, 25 (9): 757-763.
G
alGaRo
A. (2002) - Studio sperimentale delle colate detritiche rapide mediante sistemi di monitoraggio: il bacino di Acquabona.
Ph.D. Thesis. Università degli Studi di Ferrara, 140 pp. (in italian).
G
alGaRo
a., t
eCCa
P.R., G
enevois
R. & d
eGanutti
a. (2005) - Acoustic module of the Acquabona (Italy) debris flow monitoring
system. Nat. Hazards Earth Syst. Sci., 5 (2): 211-215.
G
enevois
R., G
alGaRo
a. & t
eCCa
P.a. (2001) - Image analysis for debris flow properties estimation. Physics and Chemistry of
the Earth, 26: 623-631.
G
enevois
R., t
eCCa
P.R., b
eRti
m. & s
imoni
a. (2000a) - Debris flows in Dolomites: experimental data from a monitoring
system. In: w
ieCzoRek
G.f. & n
aeseR
n.d. (2000, eds.) - Proc. 2th Int. DFHM Conference: 283-292, Taipei, Taiwan.
G
enevois
R., t
eCCa
P.R., b
eRti
m. & s
imoni
a. (2000b) - Pore pressure distribution in the initiation area of a granular debris flow.
In: b
RomHead
e., d
ixon
n. & i
bsen
m.L. (2000, eds.) - Proc. 8th Int. Symposium on Landslides, 2: 615-620, Cardiff, England.
G
enevois
R., t
eCCa
P.R., b
eRti
m. & s
imoni
a. (2000c) - Debris flows in Dolomites: experimental data from a monitoring
system. In: w
ieCzoRek
G.f. & n
aeseR
n.d. (2000, eds.) - Proc. 2th Int. DFHM Conference: 283-291, Taipei, Taiwan.
G
enevois
R., t
eCCa
P.R., f
loRis
m., s
QuaRzoni
C. & d’a
lPaos
a. (2009) - Multi-step hazard assessment of debris lows in an
Alpine region. In: m
alet
J.-P., R
ema
Î
tRe
a. & b
oGaaRd
t. (2009, eds.) - Proc. Conference Landslide Processes: from
geomorphological mapping to dynamic modelling. A tribute to Dr. Theo van Asch: 291-296, Strasbourg, France.
G
ReGoRetti
C. & d
alla
f
ontana
G. (2008) - The triggering of debris flow due to channel-bed failure in some alpine headwater
basin of the Dolomites: analyses of critical runoff. Hydrological Processes, 22: 2248-2263.
P
aPa
m. & l
ambeRti
a. (1999) - Application of debris flow numerical modelling to Acquabona catchment. In: e
uRoPean
C
ommission
(1999, ed.) - Debris Flow Risk. Final Scientific Report, EC Research Programme - Environment and Climate
1994-98, Contract No. ENV4-CT96-0253, Brussels, 2, 20 pp.
s
imoni
a. (1998) - Innesco e Mobilitazione di Debris Flow. Il Bacino Sperimentale di Acquabona (Cortina d’Ampezzo, BL).
Ph.D. Thesis. Università degli Studi di Bologna - Università degli Studi di Modena, 162 pp. (in italian).
s
imoni
a. & b
eRti
m. (2005) - Hydrologic prediction and geologic reality in debris flow triggering. In: Proc. Int. Symposium
Landslide Hazards in Orogenic Zones: 185-196, Kathmandu, Nepal.
t
eCCa
P.R., G
alGaRo
a., G
enevois
R. & d
eGanutti
a.m. (2003) - Development of a remotely controlled debris flow monitoring
system in the Dolomites (Acquabona, Italy). Hydrological processes, 17: 1771-1784.
Statistics