33

Bulletin of Glaciological Research ,- (,**0) --ῌ-3
ῌJapanese Society of Snow and Ice

Hydrological observations at July +st Glacier in northwest China from ,**, to ,**.
Akiko SAKAI+, Yoshihiro MATSUDA+, Koji FUJITA+, Keqin DUAN,, Jianchen PU,,
Satoru YAMAGUCHI-, Masayoshi NAKAWO. and Tandong YAO/
+ Graduate School of Environmental Studies, Nagoya University, HyARC, Chikusa-ku, Nagoya .0.ῌ20*+, Japan, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, ,0* Donggang West
Road, Lanzhou 1-****, China- Nagaoka Institute of Snow and Ice Studies, National Research Institute for Earth Science and Disaster Prevention, Nagaoka 3.*
ῌ*2,+, Japan. Research Institute for Humanity and Nature, --/ Takashima-cho, Kamigyo-ku, Kyoto 0*,ῌ*212, Japan/ Institute of Tibet Plateau Research, Chinese Academy of Sciences, +***2/, Beijing China(Received May -*, ,**/; Revised manuscript accepted September +., ,**/)

Abstract
Hydrological observation was carried out at the July +st Glacier in the Qilian mountains,
northwest China, during the glacier melting season from ,**, to ,**.. Water discharge was measured
using two methods, current meter and salt water. The results of these methods showed a goodcorrespondence. A logger for water level was settled at the glacier terminus in ,**,, and at the foot of
the end-moraine in ,**- and ,**.. Then, variations in discharge were evaluated based on therelationship between discharge and water level. Total observed runo# depth from the basin was 2-.
mm in ,**,. The average value of water budget components, such as precipitation, glacier massbalance, evaporation at the glacier and glacier-free area, were evaluated in ,**, from observation andmeteorological data. The results indicated that the discharge from the glacier area was 0 times larger
than that of the glacier-free area mainly due to glacier shrinkage.

+.

Introduction

Precipitation in the mountainous area is relatively high in the arid region of northwest China.
Glaciers in the mountain area store the precipitationand then have a role as the reservoir of precipitationin the mountain area (Fountain and Tangborn, +32/).
The water from the mountains has been important for
the water resources in the lower side of the basin,
oasis cities and desert. Therefore, variations in the
meltwater from the glaciers impact the human activity. For example, there had been oasis cities in thedesert long ago, but at present those ancient cities lie
in ruins and have become excavation sites. These
environmental changes were caused by changes inwater resources due to the reduction of discharge
from mountain areas. Therefore, the primary purposeof this study was to estimate the historical changes indischarge from glaciers in the Heihe River basin.
Water discharge from the glacier has been studied by many researchers from the viewpoint of model
calculations. Ye et al. (+333) and Collins (+321) haveinvestigated the long-term variation of discharge

from this glacier area analytically. Fountain andTangborn (+32/) discussed the relationship between
glacier discharge and glacier area ratio based on annual variations. Braun and Aellen (+33*) compared
two models for their observed discharge and massbalance of the glacier.
There are many observations and analyses on the
discharge from glaciers in the middle Tibetan Plateau
and Tien Shan Mountains, China. There is also an
observation report of the discharge from glaciers in
the Tibetan Plateau by Ohta et al. (+33.), regarding
seasonal variations in the discharge from glaciers inbasins of several sizes. Kang et al. (+33,) has evaluateddischarge from a glacier area from observed discharge, calibrated precipitation and estimated evaporation at the Urumqi River in the Tien Shan Mountains. Kang et al. (+333) have applied the HBV model tosome river basins in China, and estimated future discharge from glaciers. Ye et al. (,**-) also calculated
the discharge from the glacier in Tien Shan, China,
taking into account the glacier area change. Theysuggested that the timing of the peak discharge depends on glacier size. Liu et al. (,**-) have evaluatedthe variation of glaciers in northwest China since the34

Bulletin of Glaciological Research

Little Ice Age, and also estimated discharge from theglaciers. However, there are few analyses based on
observations of glacier mass balance and discharge
from glaciers in the Qilian Mountains.
In order to analyze the observed discharge fromthe glacier, we have here summarized the observations of its discharge, and evaluated each water budget component, such as precipitation, evaporation,and glacier mass balance.

,.

al. (,**0) calibrated the observed precipitation.
Discharge observation was carried out from June++ to September +* in ,**,, from August +0 to September ,+ in ,**- and from May ,2 to September +, in ,**..
We could not carry out observations at the beginningof the melting season in ,**- because of the outbreak ofsevere acute respiratory syndrome (SARS).

Location and features of the glacier

The July +st Glacier is located in the Qilian Mountains in northwest China (Fig. +), 1* km south from
Jiquan, one of the oasis cities along the Western Corridor of the Yellow River. Figure , shows the topographical map of the July +st Glacier, which was madeby Shi (+322) in +312. The glacier is located on thenorthern slope of the Qilian Mountains.
Sakai et al. (,**.) indicated that the shrinkage of
the July +st Glacier has accelerated in recent years.
This belongs to the polar type of glaciers (Huang,+33*), and the ice temperature was quite low (ῌ0῍ inAugust in the +31*s) (Xie et al., +32/). Therefore, some
portion of the meltwater refreezes in the snow layer,
and it is necessary to take into account the refrozen
amount in order to estimate the mass balance of a
glacier (Fujita et al., +330; Fujita and Ageta, ,***).

-.

Observations

An automatic Weather Station (AWS) was set up
and started measurements near the glacier terminus
as of June +*, ,**,, and data were collected until
September ,**.. Matsuda et al. (,**.) and Sakai et al.
(,**0) reported the meteorological data, while Sakai etFig. ,. Observed basin in ,**, and ,**-ῌ,**.. Sites A
and B indicate discharge measurement sites in ,**,and in ,**-, ,**., respectively. Empty circles show
location of Automatic Weather Station. Lysimeters
were set up at AWS site and Base camp in ,**..

Fig. +. Location of July +st Glacier in Qilian Mountains, and Urumqi No. + Glacierin Tian Shan Mountains. Thick lines represent mountain ranges. Chain lines
indicate country borders.

Sakai et al.

Water level was measured at site A from June ++to September +* in ,**,, and at site B from August +0
to September ,+ in ,**-, from May ,2 to July +3 in ,**.
and from August +, to September +, in ,**. as shownin Fig. ,. The drainage area of these basins is summarized in Table +. Water level was measured at -*minute intervals by water level sensor using the pressure transducer with a resolution of + cm. The waterlevel was also measured manually using a pole with ascale when the discharge was measured.
In July ,., ,**., the water level sensor and thewater level pole were carried away by heavy discharge. A cross section of the river was also changed
dramatically. Therefore, a new water level pole wasset in place again on ,2 July +,, and the water levelsensor was also replaced on +, August ,**..
Discharge was measured by two methods, one
velocity-area method using the water current meter,
and the other a salt water dilution gauging method.
By the water current meter method, mean ﬂow velocity was measured as the 0*ῌ water depth velocity
was obtained by a Price-type current meter (Sanei
Co.). The cross section was measured by a scale with

Table +. Summary of glacier, glacier-free and totalbasin area in ,**,, ,**-, and ,**..
GlacierYear,**,,**-, ,**.

Area km,(Area ῌ)Area km,(Area ῌ)Glacier

free

Total

,4.0
ῌ00῍
,42/
ῌ.0῍

+4,3
ῌ-.῍
-4-0
ῌ/.῍

-41/
ῌ+**῍
04,+
ῌ+**῍

35

an interval +* to ,* cm in width.
The method using salt water and electric conductivity referred to by Hayakawa (+332) is as follows.
First, salt-rich water is made in a bucket, and thewater volume (: Vs) and electric conductivity (: Co) of
the salt-rich water are measured. The salt-rich water isthen dumped into the upper stream and electric conductivity is measured downstream (about -* m downfrom the dumping point) at intervals of / seconds (: C).
If the distance between the dumping point and theelectric conductivity measurement point is too short,the mixing length of the salt-rich water would not beenough to mix with the river water. On the contrary,
if the distance is too long, the distribution of measured electric conductivity would not be unclear. We
selected the distance to be -* m from the above twolimitations. The discharge level can then be derived
from the following equation by measuring the conservation of its salt mass:Q῏

CoVsῐῌC῎Cw῍dt

or

Q῏

CoVs
,
ῌCave῎Cw῍ῑt(+)

where Cave῏average of electric conductivity measured
downstream.
ῑt῏period of electric conductivity measurement of dumped salt water.
Cw῏electric conductivity of the stream.
It is not necessary to measure the cross-sectional
area in order to calculate discharges by this method.
Therefore, this calculation is easy to apply to complicated river ﬂow such as in mountain areas. One example of diagrams of the observed electric conductivity
variations is shown in the Figure -. The observed

Fig. -. Example of ﬂuctuation of electric conductivity, when the discharge wasmeasured by salt water dilution gauging method. t, Cw, and Cave correspond withparameters in Eq. (+).

36

Bulletin of Glaciological Research

Fig. .. Relationships between water level and discharge observed from ,**, to ,**.. Discharge measurementby salt water dilution gauging method is shown by empty circles and velocity-area method using thewater current meter by solid circles.

value necessary to calculate discharge in Eq. (+) is
indicated in Fig. -.

..

Results of observations

The relationship between water level and discharge using the above two methods is shown in Fig.
.. All correlation coe$cients of the approximatedcurve were more than *.2/. The result of the dischargeusing the salt water method corresponded well to thatusing the current method as shown in Fig. .(c). The
daily averages of observed discharges calculated fromeach observed water level using the relationship between the water level and discharge (Fig. .) are shownin Fig. /. The values of the observed discharge obtained manually when there was no logger for thewater level in August ,**. are also shown in Fig. /.

/.

Discussion

Observed runo# depth at the basin (: Qd) was composed of runo# depths from the glacier area (: Qg) andglacier-free area (: Qf). The runo# depth can then be
expressed as follows:
QdῐQg῎Qf῍

(,)

Water balance equations at the glacier and at theglacier-free area can then be expressed as follows:
QgῐQgp῏Qge῏Qgm῏ῒSgῌ(-)

QfῐQfp῏Qfe῏ῒSf ῌ(.)

where Qgpῐprecipitation from glacier area,
Qgmῐmass balance at glacier,Qgeῐevaporation at glacier ice surface,ῒSgῐchanges of the stored water in the glacier,Qfpῐprecipitation at glacier-free area,
Qfeῐevaporation at glacier-free area, andῒSfῐchanges of the stored water in the glacierfree basin.
All units are in mm. Stored water in the glaciercan be assumed to be zero, since the July +st Glacier isa polar-type glacier (Huang, +33*), and the glacier ice
temperature was less than ῏/ῑ (Matsuda et al., ,**.).
Also, there are rocks, debris and little vegetation orsoil in the glacier-free area of this basin, making forlittle water storage capacity. Therefore, it can be assumed that the change in the stored water in theglacier-free basin is zero.
Precipitation measured and calibrated at the
AWS site during the observation period in ,**, was-*3 mm (Sakai et al. ,**0). Precipitation at the glacierand glacier-free areas during that period were ,*- mm
and +*0 mm, respectively, in the entire observed basin(-.1/ km,). Total glacier mass balance in ,**, during
the summer was ῏3++ mm in the glacier area (,..0km,) (῏/32 mm in the entire observed basin) which
was calculated from the data in Matsuda et al. (,**.).
Evaporation (: E) (mm sec῏+) at the glacier surface

Sakai et al.

37

Fig. /. Variation of discharge during melting season in ,**,, ,**- and ,**..
White circle shows instantaneous value (not daily) of observed discharge
calculated manually from observed water level.

can be calculated from bulk aerodynamic formulas asfollows:
Eῐ+***raCHU῍hq῍Ta῎῏q῍Ts῎῎ῌrw ῌ(/)

where raῐair density (ῐ*.2+3 kg m῏- at .*** m a.s.l),CHῐheat transfer coe$cient (ῐ*.**, (Kondo
and Yamazawa, +320), non-dimensional),Uῐ wind speed (m sec῏+),Taῐair temperature (ῑ),
Tsῐsurface temperature (ῑ),
q (T)ῐsaturated speciﬁc humidity at air temperature T (ῑ)(non-dimensional),hῐrelative humidity (*ῌ+) , andrwῐwater density (+*** kg m῏-).
The heat transfer coe$cient, *.**, (Kondo andYamazawa, +320), which was induced at the snow
surface, was applied. Surface temperature of the glacier can be assumed to be *ῑ during the melting
season. Evaporation at the glacier surface was calcu-

lated using meteorological data near the glacier terminus at an interval of one day. Total evaporation from
June ++ to September 0 in ,**, was .1 mm in the areaof the glacier (-+ mm in the whole drainage area) from
Eq. (,). Total discharge from the glacier (: Qg) during
the observation period can then be evaluated to be++1- mm in the glacier area from Eq. (-) and 103 mm in
the entire drainage. Discharge from the glacier-freearea can be calculated to be 0/ mm in the entire drainage area (+22 mm in the glacier-free area) as a residual
value between observed total discharge and discharge
from the glacier area from Eq. (,) by assuming that
there was no stored water change at the basin. Precipitation in the glacier-free area should be equal to thatin the glacier area, -*3 mm. Thus, evaporation shouldbe +,+ mm in the glacier-free area (., mm in the whole
drainage area).
The above elements of total discharge from thebasin have been summarized in Table ,. Discharge

38

Bulletin of Glaciological Research

Table ,. Summary of all components of runo# depth from totalbasin from ++ June to 0 September in ,**,. Precipitation
observed at AWS site. Evaporation from glacier calculated bybulk aerodynamic method. Evaporation from glacier-free area
observed by lysimeter. Mass balance evaluated from observation by staken method. Total runo# depth from glacier induced from each component.
Runo# fromeach area
(mm)

Area
(km,)

Runo# fromentire basin(mm)

Precipitation
Evaporation
Mass balance

-*3
.1
῍3++

,4.0

,*-+
῍/32

Runo#

++1-

Precipitation
Evaporation

-*3
+,-

Runo#

+20

From ++ June to 0 Sep.
in ,**,
Glacier

Glacier-free

Totalfrom the glacier area in the glacier area (++1- mm) was
more than 0 times that from the glacier-free area in
the glacier-free area (+22 mm) since the decreasing
glacier mass balance contributed to the discharge.

0.

ῌ

11*
+4,3

+*0
.,
0.

-41/

2-.

nology of Japan, and The Sumitomo Foundation. Thisis a contribution from the Oasis Project (Historicalevolution of adaptability in an oasis region to water
resource changes) being promoted by the ResearchInstitute for Humanity and Nature (RIHN).

Concluding remarks

Variation in the discharge from the basin during
the melting season from ,**, to ,**. has been evaluated on the basis of the relationship between waterlevel and discharge measurements.
In ,**,, each component of discharge from thebasin, such as precipitation, evaporation, and glaciermass balance was evaluated from observed data andcalculation from the residual value. In the ,**,, discharge from the glacier was more than 0 times thatfrom the glacier-free area because of the glacier shrinkage.
Unfortunately, there are not enough data on water levels, in other words, discharge to analyze thevariation of discharge in the basin from ,**, to ,**.,
because of many missing values. In further study, we
will have an applicable estimation of discharge after
analysis of the glacier-mass balance and evaporationin the glacier-free area.

Acknowledgments
We would like to express our thanks to Prof.
Yutaka Ageta of the Institute for HydrosphericAtmospheric Sciences, Nagoya University for his valuable suggestions on these analyses. We wish to
thank all of the members of the Project for theirvaluable support in the ﬁeld. The ﬁeld research anddata analyses were funded by a Grant-in-Aid for Scientiﬁc Research (Project No. +.,*3*,*) from the Ministry of Education, Culture, Sports, Science and Tech-

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