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Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
1031
DOI: 10.4408/IJEGE.2011-03.B-112
FORMATION CONDITIONS AND RISK EVALUATION
OF GLACIAL DEBRIS FLOW DISASTERS
ALONG INTERNATIONAL KARAKORUM HIGHWAY (KKH)
z
Hi
Q
uan
YANG
(*)(**)(***)
, y
inG
y
an
ZHU
(*)(***)
& d.H. s
teve
ZOU
(*)(***)
(*)
Institute of Mountain Hazards & Environment, Chinese Academy of Sciences & Ministry of Water Conservancy, Chengdu, China
(
**
)
Graduate University of Chinese Academy of Sciences, Beijing, China
(***)
Key Laboratory of Mountain Hazards and Earth Surface Processes, Chinese Academy of Sciences, Chengdu, China.
the evaluation result shows a good correspond with
the practical situation, i.e. this method has a valuable
application foreground.
K
ey
words
: glacial debris flow, International karakorum
Highway (kkH), risk evaluation, the comprehensive fuzzy
evaluation method
INTRODUCTION
The International Karakorum Highway (KKH) is
the highest international road in the world, which lo-
cates in Pamirs plateau hinterland. It connects Kashgar
in the north, a city in the Xinjiang province of China,
through the Karakorum Mountain Range, Hindu Kush
Mountains, Pamirs Plateau and west of Himalayas,
south to Thakot, a city of northern Pakistan (Figg.1-
3). KKH runs approximately 1036 km with a section
of 616 km in Pakistan and 420 km in China. Due to
its great achievements in engineering and the incred-
ible difficulties in construction, it is also admired as
the"the eighth man-made miracle of the world."
The unique geology and geomorphology make
the KKH as the very complicated geo-hazard collec-
tion site. The geological background is determined by
special high-mountain glaciers geological environ-
ment, so glacial debris flow is as a key geological dis-
aster along KKH,especially the section from Raikot
to Khunjerab pass. The glacial debris flow disasters
dominated the International Karakorum Highway af-
ter it was built, so some roads, bridges and construc-
ABSTRACT
The area of International Karakorum Highway
(KKH), a mountain highway connecting northern
Pakistan with northwestward China, is an area with
dense and frequent glacial debris flow disasters due
to the special glacial geology and landform. In this
area the three basic conditions inducing glacial debris
flow have developed,namely the widely distributed
glacial till and ice-snow colluvium, which arise from
collapse and landslide, provide the main solid sources
of glacial debris flow; the very high and steep slopes,
take the landform of steps with a very big gradient,
to provide the moving way for glacial debris flow;
and the ice-snow melt water from high-mountain, the
melt water of glacier avalanche and glacial lake out-
burst flood provide glacial debris flow for the force to
move. The valley-type debris flow is the main type of
glacial debris flow occurred in the area, and it can be
classified into further three sub-types according to the
water source, namely glacierablation type debris flow,
glacier-avalanche type debris flow and glacial-lake-
outburst-flood type debris flow. Based on in situ in-
vestigation and analysis of seven controlling variables
of glacial debris flow, such as occurrence frequency,
catchment areas, volumes of alluvial fan, estimated
outflow of every time,vegetation coverage, slope
and altitude,to evaluate the risk degree of 8 chosen
representative glacier debris flows along KKH. The
comprehensive fuzzy evaluation method is applied to
evaluate the risk degree of glacier debris flow and then
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Z.Q. YANG, Y.Y. ZHU & D.H.S. ZOU
1032
5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
ly high and steep mount landform, the sufficient loose
solid material and sudden and heavy water source,
which are all provided in the area of International Ka-
rakorum Highway.
International Karakorum Highway goes through
four mountains which are so-called "bow wave" in
the Indian geology---the Karakorum Mountain Range,
Hindu Kush Mountains, Pamirs Plateau and Hima-
layas, which are at high altitudes and also larger rela-
tive height. With regard to the area of International
Karakorum Highway, not only the altitude consid-
erably change from 4733 meters (Khunjerab pass)
to 460 meters (Thakot), but also the average altitude
is over 3000m (z
Hao
, 2009).Therefore,the towering
mountains and high and steep slope provide a move-
ment condition for the glacial debris flow in the area.
Geologic structure and crustal movement in the area
are very available for the formation of sufficient loose
solid material,beacuse International Karakorum High-
way not only locates on the high intensity earthquake
zone,which belongs to Mediterranean- Himalayan seis-
mic zone, one of three seismic zones in the world, but
also lies on the subduction zone,interacted by the Indian
Ocean plate,the Eurasia plate and Arab plate.On the one
hand,the weathering, the erosion, the denudation and
downcutting along KKH ,including cold aspic weather-
ing, Chemical weathering, rivers erosion, freeze-thaw
erosion and block movement and so on, have formed
loose texture,which becomes the origin material of ac-
cumulation of falling directly and in another way fail to
support upper hard rocks and inducing them in the state
of easy sliding.On the other hand, the developed and
developing original joints in the hard rock cut its body
into broken lump and the nearly horizontal the gently
declining joint and weak plane are also very easy to
bring about landslide and collapse, so the stratum and
structure assembly of frequently alternate weak and
hard layers in the area can afford the condition to the
destruction of rock body. It can be seen that the above
provided a very abundant solid material sources for
the glacier debris flow along KKH. The special water
source condition provide glacial debris flows for the
force to move in the area.Glaciers,which are distributed
widely along Karakorum Highway, such as Batura
glacier, Pasu glacier, Gulmit glacier, Ghulkin glaciers
and Momhil glaciers etc, supply rich water source in-
ducing glacial debris flows ,i.e., the icesnow melt water
from high-mountain, the melt water of glacier ava-
tions along KKH often are destroyed or damaged.
What is more serious, traffic conditions usually result
in the tragedy of car destroyed and person died.
FORMATION CONDITION OF GLACIER
DEBRISFLOW DISASTERS ALONG KKH
As an outcome of the co-action of
geology,atmosphere and landform etc, three basic
conditions control the formation of debris flow, name-
Fig. 1 .-karakorum Highway route map
Fig. 2. - karakorum Highway in China
Fig.3 - karakorum Highway in Pakistan
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FORMATION CONDITIONS AND RISK EVALUATION OF GLACIAL DEBRIS FLOW DISASTERS ALONG INTERNATIONAL KARAKO-
RUM HIGHWAY (KKH)
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
1033
debris flow disasters between Hasnabar (K623) and
Gosghil (K796). According to the landform of move-
ment, the debris flow along KKH, can be categorized
into two types, i.e. valley-type glacial debris flow and
mount-slope type glacial debris flow.
Valley-type glacial debris flow is the main type oc-
curring, whereas,mount-slope type glacial debris flow
happens comparatively rarely along KKH. Valley-type
glacial debris flow can be classified into further three
sub-types according to the water source of ice-snow
melt water, namely glacier-ablation type debris flow
(Figs.4) glacier-avalanche type debris flow (Fig.5) and
glacial-lake-outburst-flood type debris flow (Fig. 6).
RISK DEGREE EVALUATION OF GLA-
CIER DEBRIS FLOW DISASTERS ALONG
KKH
Two aspects need to analyze,which are the risk
historically happened and the potential risk,whenwe
evaluate debris flow risk in a certain area (l
iu
& t
anG
,
1995). In the paper the study is made on evaluate the
risk of potential glacial debris flow at the base of the
current formation conditions of glacial debris flow. The
follows describe the evaluation process of 8 chosen
representative glacialdebris flow along KKH, which
are represented by number 1 to 8.
THEORY AND MODEL OF RISk DEGREE EVAL-
UATION
The debris-flow potential risk evaluation, which
is focused on physical attributes of debris flow disas-
ter, is used to evaluate the probability of debris flow
occurrence in the region concerned in the future by
comprehensively analyzing some disaster-inducing ac-
tivity and formation variables of debris-flow disaster.
The comprehensive fuzzy evaluation method provides
a suitable disposal measures to some complicated prob-
lem due to the multifactor in the course of formation of
debris flow (l
uo
& C
Hen
, 2000; H
an
& l
iu
, 2007), so
now it is often used in a potential risk evaluation,
which is generally expressed as following:
where: R
p
is the potential risk index to debris flow
(0–1 or 0%– 100%); i
x
is activity and formation varia-
lanche and glacial lake outburst flood.So the above pro-
vide plenty of heavy and sudden water source condition
for the formation of glacier flow.
THE DISTRIBUTION AND TYPES OF
GLACIER DEBRIS FLOW DISASTERS
ALONG KKH
The area along KKH distribute mostly the glacial
Fig. 4 - Glacial-ablation type debris flow (k676+450,
10- 20-2010, taken photograph by Dr. Zhu Ying
Yan)
Fig. 5 - Glacier-avalanche
type
debris
flow
(k653+900, 6- 27-2009 , taken photograph by
Dr. Zhu Ying Yan)
Fig. 6 - Glacial-lake-outburst-flood type debris flow
(k687+440,1- 6-2008 , taken photograph by
K
hAN
)
(1)
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Z.Q. YANG, Y.Y. ZHU & D.H.S. ZOU
1034
5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
variable(s) and auxiliary variables in this paper (l
iu
&
y
ue
, 2002).Give an example, there are four variables
Y
a
,Y
b
, Y
c
and Y
d
, then polt a map of the four corre-
sponding curves, if the Y
a
and Y
b
are least parallel, there
is the worst relationship between Y
a
and Y
b
, and their
relative degree Rab is the smallest; while if the Y
a
and
Y
d
are most parallel, the correlation of Y
a
and Y
d
is the
best, and their relative degree Rad is the largest. Ac-
cording to the above analysis, the relative degree order
R
aa
=1>R
ad
>R
ac
>R
ab
>0 can be determined, thus we may
select those most contributive variables for the compre-
hensive fuzzy evaluation model under an assigned sig-
nificance level.
In the study, as stated above we choose estimated
outflow of every time (x
4
) of the glacier debris flow
considered to be the leading variable,thus the other 6
suggested variables (x
1
- x
3
, x
5
- x
7
) are considered
to be auxiliary variables. The detailed mathematical
procedures to calculate the relative degree R have been
described in a Liu’s paper (l
iu
, 1992).In terms of cal-
culating the relative degrees (R), the relative order of 7
chosen variables is shown in formula (3).
We adopt an arithmetical and geometrical incor-
poration way to decide the weighted coefficients of
the evaluating variables in the study (l
iu
, 1996),the
weighted numbers and their weighted coefficients of
these variables could be shown in the table 2.
Using the suggested weighted coefficients, equa-
tion (2) could be given as:
DETERMINE TRANSFORMATION FUNCTIONS
FOR THE EVALUATING VARIABLES
Because the dimensions of selected evaluating var-
iables are different, it is not appropriate to directly use
their observed original datas to calculate the risk degree
of glacier debris flow, so to build transformed values
of the evaluating variables is necessary in the process
of evaluating the risk degree of the glacier debris flow
along KKH. The method is that having determined the
upper limit value and the mean value for each variable,
the variable can be transformed by taking the upper
limit value, the mean value, and the zero value as the
bles of debris-flow disaster; i
w
is weighting coefficient
for the corresponding variable.
Classifying potential risk of debris flow disaster
in terms of their threat is the first thing to proceed to
the classification of risk. At present, a reasonable and
recognized criterion for measuring risk degree of de-
bris flow does not reliable. Anyone has separate rule
to define degree between the value ranges of the po-
tential risk .In most cases, the traditional equidistant
value classification method makes potential risk values
ranged from 0 to 1and suggested equidistantly classi-
fied into the following five degrees: very low (0-0.2),
low (0.2-0.4), moderate(0.4-0.6), high (0.6-0.8), and
very high (0.8-1), which is still widely used (l
iu
, 2002).
DETERMINATION OF VARIABLES AND OB-
JECTIVE TO STUDY
To choose the variables that bring about the poten-
tial risk of glacial debris flow directly or importantly
into analysis and discard other unimportant or subor-
dinated variables.By means of in situ investigation,7
main variables,such as occurrence frequency (average
times/year, x
1
), catchment areas (km x
2
), volumes of
alluvial fan (m
3
, x
3
), estimated outflow of every time
(m
3
, x
4
), vegetation overage rate (%, x
5
), slope (°,
x
6
), altitude (m, x
7
),etc, are chosen, and the observed
original data of 8 chosen representative glacier debris
flows along KKH for analysis are shown in the table
1.Risk degree of glacier debris flows is calculated in
index-weight model (each variable times its weight
and then plus together),the formula(1) is as follows:
DETERMINE wEIGHTED COEFFICIENTS FOR
THE CORRESPONDING EVALUATING VARI-
ABLE
The weighted coefficients reflect the contributions
of these variables to the potential risk. The basis for the
determination of the weighted coefficients is the rela-
tive degrees of these variables (l
iu
& y
ue
, 2002).
In order to determine the significances of the aux-
iliary variables based on their parallel degrees to the
leading variable(s) of debrisflow disaster along KKH,
we adopt the theoretical principle for determining
the relative degree is a comparison of the geometric
curves of the sample sequences between the leading
(3)
(4)
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FORMATION CONDITIONS AND RISK EVALUATION OF GLACIAL DEBRIS FLOW DISASTERS ALONG INTERNATIONAL KARAKO-
RUM HIGHWAY (KKH)
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
1035
X
3
is the transformed value of volumes of alluvial fan
of glacier debris flow along KKH
X
4
is the transformed value of estimated outflow of
every time of glacier debris flow along KKH.
X
5
is the transformed value of vegetation coverage rate
of glacier debris flow along KKH
X
6
is the transformed value of slope of glacier debris
flow along KKH.
control points, which are transformed to 1, 0.5, and 0,
respectively; It is assumed that the transformed vari-
ables vary linearly between the control points, There-
fore, each variable can be represented by linear or bilin-
ear model (l
iu
, 1996). Based on the observed original
data of glacier debris flow along KKH and relevant
literatures (l
iu
, 1996; l
iu
, 2002), the upper limit value
is estimated,and the mean value for each variable.Then
the transformation functions for the evaluating vari-
ables might be as follows:
X
1
is the transformed value of occurrence frequency of
glacier debris flow along KKH.
X
2
is the transformed value of catchment areas of gla-
cier debris flow along KKH.
Tab. 1 - Observed original datas of evaluating variables of 8 chosen representative glacier debris flows along kkH
Tab. 2 - weighedt coefficients of evaluating variables of 8 chosen representative glacier debris flow along kkH
(5)
(6)
(8)
(9)
(7)
(10)
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Z.Q. YANG, Y.Y. ZHU & D.H.S. ZOU
1036
5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
X
7
is the transformed value of altitude of glacier debris
flow along KKH
The transformed values of evaluating variables
for 8 chosen representative glacier debris flow along
KKH can be get by equations (5-11),which are given
in the table 3.
EVALUATION OF RISk DEGREE
Based on equation (4) and table3, the risk degree
of 8 chosen representative glacier debris flow along
KKH are obtained as in the table 4.
From table 4, it can be seen that the risk degree
of both no. 4 of K676+450 and no. 8 of K765+200
glacier debris flow along KKH is very high, belonging
to extremely serious debris flow. The judgment got by
means of comprehensive fuzzy method evaluation re-
sults shows that the calculation correspond excellently
to the practical situation and then provide a effective
analysis method for prevention of the risk of glacier
debris flow at near situation.
CONCLUSION
- In the area of International Karakorum Highway
three basic conditions control the formation of gla-
cier debris flow are all serious, that is, high and
steep mount landform, the sufficient loose solid
material and rich water source. The development
of glacier debris flow influence the safe property
of International Karakorum Highway.
- The estimated outflow of every time of the glacier
debris flow is the most controlling variable to de-
termine the development and distribution regulari-
ty of glacier debris flow in the area of International
Karakorum Highway.Valley-type glacial debris
flow is the main type occurring and it can be clas-
sified in further three sub-types according to the
water source of meltwate of ice-snow, namely gla-
cier-ablation type debris flow, glacier-avalanche
type debris flow and glacial-lake-outburstflood
type debris flow.
(11)
Tab. 4 - The evaluation results and the risk degree of 8 chosen representative glacier debris flow along kkH
Tab. 3 - Transformed values of evaluating variables for 8 chosen representative glaciers debris flow along kkH
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FORMATION CONDITIONS AND RISK EVALUATION OF GLACIAL DEBRIS FLOW DISASTERS ALONG INTERNATIONAL KARAKO-
RUM HIGHWAY (KKH)
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
1037
ACKNOWLEDGEMENTS
This study was supported by the two western
traffic construction technology projects of Minis-
try of Communications of the People‘s Republic of
China(No. 09A3070070; No. 09A3190190). We also
thanks Wan Ke Yang & Jian Li for their assistance in
revising the paper.
The comprehensive fuzzy evaluation method are
applied to evaluate the risk degree of glacier debris
flow in the area of International Karakorum High-
way and then the evaluation result shows a good cor-
respond with the practical situation, i.e. this method
has a valuable application foreground, based on in
situ investigation and analysis of seven controlling
variables of glacial debris flow along KKH.
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