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IJEGE-11_BS-Cardoso Landa

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Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
23
DOI: 10.4408/IJEGE.2011-03.B-003
GCL MODEL BY THE DETERMINATION OF THE CHARACTERISTICS IN
THE BEGINNING ZONE OF THE DEBRIS FLOWS USING A GIS
G
uilleRmo
CaRdoso-landa (*)
(*) Chilpancingo Institute of Technology, Land Sciences Department - Av. Guerrero # 81, Col. Ruffo Figueroa,
Chilpancingo, Gro., 39020, México - E-mail: gclanda@prodigy.net.mx
droughts, live in countries whose human development
is medium or low. In absolute terms, it has been dem-
onstrated that the economic cost of disasters has been
increasing during the last decades.
The data base EMDAT offers a very precise view
of the total losses by disasters with a suitable level of
national detail. The period of time chosen is sufficient
to represent the fluctuations of the most of natural dis-
asters. Figure 1 shows the total number of disasters
registered by the EMDAT between 1900 and 2000.
One of these natural disasters are the debris flows,
which have increased in prevalence in recent years
and in most regions of the world. For this reason, it is
is important to study their behavior, in order to reduce
the serious economic damage and loss of life caused
by these natural hazards.
ABSTRACT
In recent years an increase in the prevalence of
debris flows has been observed in various regions of
the world. These events, which have caused a signifi-
cant amount of damage to cities, infrastructure and
ecosystems; emphasize the importance of developing
early warning systems to alert residents of the danger
in advance. A model to determine the probability of
occurrence of a debris flow through the development
of a geographic information system that combines a
digital elevation model and a distributed hydrological
model is described.
K
ey
words
: debris flow, geographic information system,
digital elevation model
INTRODUCTION
Natural disasters are a serious obstacle to hu-
man development and the fulfillment of the Millen-
nium development goals such as poverty reduction.
Natural disasters have resulted in annual economic
losses ranging from 75,500 billion USD in the 1960s,
138,400 million in the 1970s, 213,900 million in the
1980s and 659,900 million in the 1990s, mostly in the
developed world. However, the economic estimates
fail to capture adequately the impact of disasters in
the poorest countries, where in terms of human lives,
means of subsistence and reconstruction of infrastruc-
ture the costs are higher. Currently, 85 percent of those
exposed to earthquakes, tropical cyclones, floods and
Fig 1 - Disasters registered by the EMDAT
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G. cArDoSo-lANDA
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5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
are particularly dangerous to life and property due
to their high speeds and their houses, roads, bridges,
trees and crops, as well as natural watershed areas and
ecosystems along the length of the flow. Debris flows
are generally associated with periods of high rainfall
intensities or heavy rainfall-snowfall mixtures.
DEBRIS FLOwS AT wORLD LEVEL
Debris flows disasters are not registered separate-
ly from landslide disasters in the EM-DAT database.
Therefore, figure 2 presents the total number of land-
slides collated in the EM-DAT database.
Figure 2 shows that the reported incidence of land-
slides has increased for 100 years, from 1903 until 2003,
and especially during the period from 1990 to 2002.
Figure 3 shows the countries that in 100 years have
suffered the most frequent landslide disasters. The fig-
ure does not include recent landslide occurrences in
other countries that have occurred since 2003.
DISASTERS ASSOCIATED WITH DEBRIS
FLOWS
Debris flow disasters have occurred in numerous
countries in recent years, including: United States,
China, Japan, Italy, Taiwan, Central Asia, Germany,
Switzerland, Russia, the Philippines, Ukraine, Cana-
da, Brazil, Ecuador and Venezuela. Numerous debris
flows have impacted the country of Mexico recent
years, mainly in the Mexican trans-volcanic axis and
coastal mountain ranges. Recent debris flows have oc-
curred at Popocatepetl volcano, the volcano Pico de
Orizaba, the volcano Nevado de Toluca, mountains of
Puebla, in Acapulco, Gro., in the city of Tijuana, B.C.
and in the coastal mountain of Chiapas and Oaxaca.
DEBRIS FLOWS
Debris flows consist of a mixture of fine materi-
als (sand, silt and clay), coarse material (gravel and
rocks) and a variable amount of water. Debris flows
move down slope under the action of gravity, usually
in waves following the sudden collapse of the mate-
rial in bank. The generally occur on slopes covered
by unconsolidated rock and soil, especially where the
vegetation cover has been removed by deforestation
or forest fires. All debris flows have three fundamen-
tal elements: the generation area, the main path and
deposit area.
These flows commonly traverse pre-existing
drainage runoff channels that have a “V”-shaped or
rectangular cross-section. Thick debris flows often
form lateral ridges. Debris flows are deposited where
the slope of the channel decreases or at the mountain
front. Repeated occurrences of debris flows create
landforms called debris fans. Some fluid debris flows
are exceptionally long and can travel great distances
from their generation area. Deposits of these flows of
low viscosity extend outside areas of decreased con-
finement to form alluvial fans.
Debris flows occur in most climatic environ-
ments, from deserts to Alpine regions and from the
Arctic to Mediterranean areas. These kinds of flows
are potentially very destructive in mountainous re-
gions, where the sudden appearance of water, usu-
ally from intense rainfall or snowmelt, can mobilize
debris covering the slopes and can be incorporated
into a coherent flow of debris.
Debris flows are rapid slope movements caused by
hyperconcentrated flows of water and sediments, oc-
curring in a wide variety of climates worldwide. They
Fig. 2 - Landslide globally per year from 1903 to 2003
Fig. 3 - Landslides country from 1903 to 2003
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GCL MODEL BY THE DETERMINATION OF THE CHARACTERISTICS IN THE BEGINNING ZONE OF THE DEBRIS FLOWS USING A GIS
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
25
tude and from 38°43’ N to 43°26’ N latitude, and is
divided in four regions.
On July 28, 1981 an extreme precipitation event
produced avalanches, rock sliding and debris flows in
more than 100 ravines and slopes of the Laomao moun-
tain in this province, resulting in damage to 115 villages
in 6 counties and affecting 556.000 people, destroying
38.517 houses, 60.000 hectares of agricultural land and
destroying 4, 9 kilometers of the Changchun-Dalian
railroad line. Losses to the Chinese economy losses
reached 547’ 000.000 yean (z
Hao
et alii, 1992).
JAPAN
In Japan during twenty years, between 1967 and
1987, 4598 people were killed by natural disasters,
of which 1257 passed away due to the debris flows,
which corresponds to 27, 3% of the total (t
akaHasHi
,
1991). This high percentage results from the tendency
of people tend to live in high risk zones, near the foot
of mountains where this type of hazard is concentrated.
In 1990 the Mount Unzen volcano erupted, trig-
gering 114 debris flows (lahars) that deposited nearly 8’
000.000 m
3
of debris that destroyed 1123 buildings. The
number of refuges required by this event was greater than
11.000 in August of 1991 (s
uwa
& y
amakosHi
, 1997).
ITALY
July 19, 1985 the failure of two dams in the Val-
ley of the Stava River, in northeastern Italy caused a
catastrophic debris flow, which destroyed 2 villages
and killed 270 people (b
eRti
et alii, 1997).
A debris flow also happened October 18, 1990 in
Pomonte Creek, below Monte Capanne, Elbe Island,
of Archipelago of Toscana, Italy, with approximately
34.000 m
3
of debris (i
otti
& s
imoni
, 1997).
TAIwAN
During the last decade, several disasters produced
by debris flows occurred in Taiwan, causing hundreds
of deaths, injuries, and damage to houses, schools,
highways, bridges and other public and private prop-
erties (Cheng et alii, 1997). In table 2 the characteris-
tics of 6 of these disasters are summarizes.
SwITZERLAND
The debris flows are a common phenomenon
in the Swiss Alps, as well as in other mountainous
zones of the world. A tool important to understand the
UNITED STATES
Utah received national attention and in the spring
of the year 1983 due to the floods, earth sliding and
debris flow caused by severe snow storms in the re-
gion (w
ieCzoRek
et alii, 1987). The worst damages
caused by the debris flows occurred in Davis County,
in the opening of the Rudd stream. Some debris flows
happened in at least 600 tributaries of the Colorado
River in The Grand Canyon, between Lees Ferry and
Surprise Canyon, Arizona (m
elis
et alii, 1994;
GRif
-
fitHs
et alii, 1996). Most of the flows occurred during
convective summer storms with intensities of rain of
the order of 40 mm/h.
More than 1.000 debris flows occurred on wooded
slopes Madison County, Central Virginia, during an
intense storm on the 27 of June of 1995 (w
ieCzoRek
et alii, 1996).
Numerous occurrences of debris flows have af-
fected in the mountainous areas of southeastern of
British Columbia in the last decade. In November of
1995 two debris flows appeared in Pierce Creek, in
Valle Chilliwack, and in Hope Creek, with 50.000 m
3
of debris carried during two hours, near the city of
Hope (J
aCob
et alii, 1997).
A series of debris flows appeared in several can-
yons 35 miles to the east of Portland, Oregon, on the
days 7th and 8th of February of 1996, near the small
localities of Dodson and Warrendale, destroying the
interstate highway number 84 as well as the railroad
and necessitating the evacuation of residents from the
area (P
owell
et alii, 1996).
CHINA
The Liaoning province is located in the northeast
region of China between 118°53’ and 125°46’ longi-
Tab. 1 - Regions affected by debris flows in China
1976-1988
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5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
In 2000 four important debris flows were ob-
served in this area of Switzerland. These deposits var-
ied in volume from 5.000 m
3
up to 35.000 m
3
; aver-
age speeds ranged from 2, 0 m/s up to 5, 0 m/s, and
maximum flow ranged between 20 m
3
/s and 125 m
3
/s.
CENTRAL ASIA
Central Asia is an area with a high level of de-
bris flows risk; the most important areas include hills
of Valle Fergana, Valle Zerafshan, and the Issyk-Kul
river basin, the central and south part of Tdjikistan
and also the hills of Kopetdag. In all these areas the
destructive flows happen during the spring-summer
period in small rivers and ephemeral channels (s
a
-
likHova
& l
iaHovskata
, 1992).
GERMANY
The village of Tramin in the south of Tyrolia was
affected by a sudden debris flow on June 23, 1986,
during a severe storm. The debris flow completely
destroyed a new rest center and seriously damaged a
wine cooperative, with the total damage amounting to
6 million dollars (s
tRunk
, 1992).
RUSSIA
The areas in where greater amount of debris
flows has appeared in this country are three regions:
to the east of the Sayan mountains, the mountain to
the Southeastern of Baikal Lake and the northeast of
the Baikal region, with registries from 1871 to 1971
(m
akaRov
& a
Gafonov
, 1977).
THE PHILIPPINES
The eruption of Monte Pinatubo in June of 1991
deposited of 7 to 8 km
3
of pyroclastic material in
slopes of the volcano. These pyroclastic deposits
formed the sediment sources for the debris flows of
volcano (lahars) of a frequent and great scale, that ap-
pear each season of rains causing great morphologic
changes and massive devastation in the zone. To the
date more than 400.000 people they have been moved
and around 350 km
2
with territories of agricultural
culture they are covered with material of lahars.
The number of dead in a series of debris flows that
happened in the Philippines after six days of intense
rains can surpass the hundred, said the authorities of
the country, after 35 corpses were recovered and tens
of people disappeared; in December of 2003, 300 peo-
mechanics of this type of flows is the installation of
observation stations that allow data collection in real
time. This type of station has been installed in 3 river
basins of Switzerland. These stations are equipped
with ultrasonic video cameras, radars, geophones and
instruments for measurement of precipitation. Figure
4 shows the locations of these stations.
Graph 5 shows the number of debris flow events
per year that have been registered in two of these hy-
drological river basins of Switzerland.
Tab. 2 - Zones affected by debris flows in Taiwan
Fig. 4 - Location of the 3 debris flow observation sta-
tions in Switzerland
Fig. 5 - Historical registries of debris flows during the
XX Century in Schipfenbach and Illbach, Swit-
zerland
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GCL MODEL BY THE DETERMINATION OF THE CHARACTERISTICS IN THE BEGINNING ZONE OF THE DEBRIS FLOWS USING A GIS
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
27
including the debris flows, with greater dimensions in
recent years, is due to the storm from the 14
th
to the
16
th
of December of 1999 in the coasts of Venezuela,
particularly in slopes of the Mountain of Avila, at the
north of Caracas, Venezuela. The severe storm from
the 14th to the 16th of December of 1999 caused cata-
strophic sliding of earth and floods with debris flows
throughout 40 kilometers on the coast of Caracas, be-
tween the Guaira and Naiguita, located in the coastal
state of Vargas, Venezuela. The damages to the com-
munications and the infrastructure of this zone were
very high. In Vargas, more than 8.000 individual resi-
dences and 700 apartment buildings were destroyed
completely (s
alCedo
, 2000).
The highways, and the telephone services, elec-
tricity, water and sewage systems severely were dam-
aged. The total economic losses was calculated as
1, 79 Venezuelan pesos billion and preliminary esti-
mations established that between 5.000 and 50.000
people they passed away (b
Randes
, 2000; s
anCio
&
d
istRiCts
, 2000; s
alCedo
2000 and USAID; 2000).
The estimation of the number of inhabitants of Vargas
was approximately of 300.000 inhabitants before the
catastrophe, which means that approximately 10% or
more passed away by this event.
DEBRIS FLOWS INITIATION PROCCES
Knowledge of the mechanism in the debris flows
initiation process is fundamental to the mitigation of
risks associated with this type of hazards and a nec-
essary requirement to implement measures to reduce
the disastrous effects they produce. Understanding
this process can provide a guide to classify hazardous
areas and design protective structures. On the other
hand, it also can increase the understanding of criti-
cal situations of these areas and serve as a criterion
to send forecasts of hazardous events and people can
be evacuated from those places of high risk (H
onda
et alii, 1997).
However, investigations related to debris flows
until now, have essentially focused on the dynam-
ics of debris flows, its deposit mechanism, numeri-
cal modeling and computer measurement features.
The debris flows formation process is currently very
poorly understood. This is the fundamental reason
for this work, with the idea to help increase a little
understanding of the debris flows initiation process.
ple were evacuated towards safer zones after the sol-
diers got to the zone of disaster to rescue the victims
cached under mud and debris.
THE UkRAINE
The combination of natural conditions in the
mountains Carpathian, Crimean and along the rivers
Dnieper and Dniester is favorable for the formation of
the debris flows (y
ablonskiy
et alii, 1992).
CANADA
Howe Sound is a region prone to the presence of
debris flows, which extends from the Horseshoe Bay
(20 km to the northwest of Vancouver) to Squamish,
in Canada, where they have appeared a great number
of these events due to the type of ground, slopes in his
valleys as well as the deforestation and fires in the zone.
BRAZIL
At the beginning of August of 2000 great debris
flows took place caused by five days of torrential rains
in the northeast of Brazil, causing 28 died and 90.000
abandoned. Bad weather caused the most serious
damages in the states of Pernambuco and Halagaos,
affecting to 46 localities.
ECUADOR
At least 36 died people died, 11 disappeared and
212 families damaged were the balance who left to
the debris flows happened in Ecuador day 13 of June
of 2001, affecting the provinces of Papallacta, Amazo-
nia, Tungurahua and Zamora Chinchipe.
MEXICO
In this country, a great amount of debris flows
have appeared in recent years, many of them in the
Mexican trans-volcanic axis and coastal mountain
ranges, such as the happened ones in Popocatepetl
volcano, the volcano Pico of Orizaba, the Nevado
de Toluca volcano, in the mountains of Puebla, in
Acapulco, Gro., in the city of Tijuana, B.C. and in
the coastal mountain range of Chiapas and Oaxaca,
to only mention those that have produced important
disasters in recent times.
VENEZUELA
Probably one of the disasters produced by the
combination of diverse processes of removal in mass,
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5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
TRIGGERING FACTORS OF THE DEBRIS
FLOwS
The mass removal processes or field movements
(which include debris flows) occur due to two fun-
damental causes (t
eRzaGHi
, 1950; s
elby
, 1993). Ex-
ternal causes are all those that produce an increase
in loads, but not in the strength of materials; internal
forces are those which diminish the strength of materi-
als without changing the loads. This way, we can say
that mass removal processes are those movements of
soil, debris and rocks that occur in a slope as a result
of the direct influence of gravity and which can be
triggered by internal or external factors.
The most important external type changes include
geometric or weight changes facing slopes (as a result
of erosion, undermining, incision of a river, artificial
excavations, uploads and downloads), natural and ar-
tificial transitional loads that are exposed (earthquakes,
explosions or use heavy machinery vibration) and
changes to the hydrologic regime (intensity and dura-
tion of precipitation, etc.). The major internal changes
relate to the transformation of materials from progres-
sive movements (by lateral expansions, fissures, etc.),
processes of weathering and erosion. Mass removal
processes occur through a combination of factors, such
as all contribute in different degrees to their instability.
However, according to the circumstances, some
of these elements can be considered crucial, triggers
as for example, the presence of extraordinary rainfall
in permeable materials, reason why it is not only im-
portant to know the mechanisms and types of move-
ments, but also the factors that cause and control such
processes on defined spaces.
MODELS EMPLOYED TO DESCRIBE THE INI-
TIATION DEBRIS FLOwS
Analysis of the initiation of the movement of a de-
bris flow underlines that causal factors of this phase of
the process are the location of the trigger area and the
main triggering mechanism (hydrodynamic actions,
geotechnical causes and mechanical equilibrium).
At one level of outcome is difficult to identify
which of these mechanisms is the most likely makes
the largest contribution; in any case, any of these
types of mechanisms can include others, or rather, in
the same event different trigger mechanisms can occur
in different areas of the basin. In some studies con-
cerning the trigger not cohesive debris followed by a
flow of surface water flow conditions analysis focuses
on the study of the instability of the accumulation of
material that occurs below the saturation. A surface
flow drained in a slope from intense rainfall, primarily
saturated layers of debris, and then mobilizes them,
thus causing the dispersion of solid particles of the full
depth of surface runoff, which eventually becomes a
flow of debris accumulation.
With the purpose of identifying mechanisms in-
volving the solid material in a fluid, it is necessary to
analyze the roles played by various forces acting on
the genesis of the movement. Approaches developed
to date are as follows: model of infinite slope stabil-
ity, approximation of Shields, approach of Takahashi,
and recent developments, (l
oRenzini
& m
azza
, 2004).
GCL MODEL
The debris flows initiation process is influenced
by many factors: morphological, geological, hydro-
logical, plant coverage, topographic, and anthropo-
genic; it is necessary to establish a methodology that
takes into account most of these aspects.
Some researchers have intended to understand the
relationship between climate and geomorphologic proc-
esses, which trigger debris flows. These works have
analyzed the physical properties of the failed slope, the
effects of the angle of inclination and soil pore pres-
sure, mechanical movement debris flows and the result-
ing deposits properties (s
Cott
, 1972; w
illiams
& G
uy
,
1973; H
ollinGswoRtH
& k
ovaCs
, 1981; i
stok
& H
aR
-
waRd
, 1983; P
ieRson
& C
osta
, 1987; m
ontGomeRy
&
d
ietRiCH
, 1994; w
u
& s
idle
, 1995; P
aCk
, 1995; m
oR
-
Gan
et alii, 1997; R
eid
et alii, 1997; G
RiffitHs
et alii,
1997; w
ieCzoRek
et alii, 1997; t
oGnaCCa
& b
ezzola
,
1997; G
ReGoRetti
, 2000; i
veRson
, 2000; C
Hen
& J
an
,
2004; R
eid
et alii, 2003; s
avaGe
& b
aum
, 2003).
Taking into consideration the prevailing factors
and models for known debris flows startup as well
as the analysis of the works of previous researchers,
distributed hydrologic models and using digital eleva-
tion models in combination with the model of infinite
slope stability and geographic information systems
technology, it was developed a model to estimate the
potential areas of startup in a debris flow.
DESCRIPTION OF THE GCL MODEL
The proposed model was realized by a compu-
ter program, which was developed using some sub-
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GCL MODEL BY THE DETERMINATION OF THE CHARACTERISTICS IN THE BEGINNING ZONE OF THE DEBRIS FLOWS USING A GIS
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
29
GEOGRAPHIC INFORMATION SYSTEM
According to the requirements necessary for the
determination of the initiation areas produced by de-
bris flows in a mountainous region, it was selected the
use of the software developed by ESRI to a geographi-
cal information system called Arc View GIS 3.3 due
its versatility and features, (Shamsi, 2002).
In response to the main factors which triggered
the debris flows it was proposed the topics listed be-
low as an integral part of the project of Arc View GIS
3.3, called zoinifluder.apr, and presented in Figure 6.
Layer 1 - Topography of the area of study
Layer 2 - Surficial hydraulics dates
Layer 3 - Soil internal friction angle
Layer 4 - Soil density
Layer 5 Soil cohesion
Layer 6 Plants cover (the root of the trees force)
Layer 7 Subsurficial hydraulics dates
FLOwCHART OF THE GCL MODEL
In order to display graphically the proposed mod-
el it presents a diagram of flow in Figure 7.
RESULTS
The proposed GCL model derives its ranking of
the ground stability from input as the topographic
slope, specific catchment area and the quantification
of the properties of the material (such as resistance)
and climate (mainly hydrological parameters such as
routines proposed by Pack, using Arc View GIS 3.3
with Arc View Spatial Analyst extension program, and
digital models of elevation. This model predicts the
potential stability of a debris flow, uses an equation
to the safety factor and Darcy’s law for flow-saturated
within the ground, in order to estimate the distribution
of pore pressures. The saturated flow refers to the flow
where the pores are completely filled with water.
The theory underlying the proposed model was
implemented in computerized form. The theory was
incorporated in a library of routines of computation
that can be called to perform computational tasks, in-
cluding the calculation of stability and saturation rates
(humidity index). In addition the library routines are
also available for many basic tasks for the manage-
ment of the mesh data in the digital elevation model
(DEM), model including topographic fill mines, cal-
culation of slopes, and determination of the directions
of the flow and definition of drainage area to a spe-
cific point. These different routines were written in C
programming language and are contained within a file
(DLL) dynamic link library.
The spatial or geographical nature of the analysis
carried out in the model, printed or on-screen maps
are required to play some computer outputs. Instead
of creating common routines to provide common geo-
graphical analysis skills, the model uses the of geo-
graphic information systems (GIS) software itself to
handle these tasks.
Fig. 6 - Themes or layers in the ‘zoinifluder’ project
Fig. 7 - Flowchart of proposed model
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G. cArDoSo-lANDA
30
5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
rain) parameters. Each of these parameters is outlined
on a numerical grid in the study area. The primary pro-
duction of this modeling approach is an index of sta-
bility, which is the numeric value which is classified
or categorizes the stability of the ground in each loca-
tion of the mesh within the study area. Topographic
variables are automatically calculated from the digital
elevation (DEM) model data. Other input parameters
are recognized as uncertain, so in the model are speci-
fied in terms of upper limits and lower ranges that they
can be taken.
FUTURE wORkS
It is necessary to apply the proposed model to a re-
cent debris flow to validate this model, which will take
place in a next stage of the investigation under way.
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HenG
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u
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Hen
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onda
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otti
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imoni
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veRson
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azza
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akaRov
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