Bulletin of Glaciological Research ,0 (,**2) +ῌ2
ῌJapanese Society of Snow and Ice

1

Water balance and mass balance in a mountainous river basin, Northern Japan Alps
Keisuke SUZUKI+, ,, Takayuki KURAMOTO+, Motoki TANAKA, and Shailendra Kumar SHAH+ Department of Environmental Sciences, Faculty of Science, Shinshu University Matsumoto, -3*ῌ20,+ Japan, Institute of Mountain Science, Shinshu University, Matsumoto, -3*ῌ20,+ Japan- Interdisciplinary Graduate School of Science and Technology, Shinshu University Matsumoto, -3*ῌ20,+ Japan(Received April ., ,**2; Revised manuscript accepted May 1, ,**2)

Abstract
We have investigated the water balance and mass balance for four years in Maekawa River basinon the eastern slope of Mt. Norikura-dake. In this region, the precipitation frequency is high from therainy season to the autumn. The maximum base-ﬂow discharge occurs in the spring snowmelt
season. The pH and electric conductivity of the river water decline rapidly with the beginning of thesnowmelt runo# and temporarily decrease when the discharge increases temporarily in the rainyseason or during a typhoon event. The Clῌ concentration of the river water increases in the earlystage of snowmelt season since there is a considerable amount of sea salt in the snow. In addition, theNO-ῌ concentration of the river water increases when the rainfall increases the discharge. The major
ion concentration of the river water, except Clῌ and NO-ῌ almost synchronizes with the change in theelectric conductivity. In the mass balance of cations, the runo# rate from the river basin considerably exceeds the atmospheric deposition rate to the river basin. This is because there is extremelymuch elution of ions from new volcanic rocks and soils. Further, the atmospheric deposition rate ofNO-ῌ is larger bigger with the biological consumption in the river basin than the runo# rate from thebasin.

+.

Introduction

For heavy-snow regions such as Japan Sea-side
area, the quantity of water precipitated by a snowfall
is extremely more important than rainfall as a water
resource. Moreover, snow also plays a role of natural
dams since it accumulates in river basins during winter time. The snowfall in mountainous regions ismore than that in the lowlands; however, it is di$cult
to determine quantitatively. The snowfall measurement using a regular precipitation gauge requires aheater and therefore an electrical power supply.
Moreover, the measurement accuracy is low becauseof a low capture rate of snowfalls in windy mountainous regions (Yokoyama et al., ,**-). For these reasons, snowfall is rarely measured using a precipitation
gauge in mountainous regions during the winter season. Precipitation-gauge stations are set up by theJapan Meteorological Agency in mountainous regions
only during warm periods; moreover, the number ofstations is extremely small. It is crucial to elucidate
the water balance by quantitatively comprehending
the amount of precipitation and also including thesnow in mountainous regions from the aspect of wa-

ter resources.
Further there are reports that state that the snowfall in Japan decreases in accordance with global warming (Inoue and Yokoyama, ,**-). However, this result is from research based on data mainly from lowlands; therefore, it is uncertain whether this data applies to mountainous areas at high altitudes. In asnowy temperate area, where rain or temporary warming can cause frequent melting at the surface ofsnow cover, the snow melts due to an increase in the
air temperature and the temperature determines whether the precipitation will be in the form of snow orrain. At such places, the snow turns to rain or viceversa depending on increases and decreases in temperature. In addition, it is likely that the snowfall
decreases if the climate becomes warmer since snow
particles melt while falling and turn into rainfall;thus, the precipitation amount is the same. However,
it is also conceivable that the snowfall will increase inmountainous regions at high altitudes. This is because the saturation vapor pressure in the atmosphere
increases with temperature. Therefore, snowfall will
increase if the precipitable water is increased in amount and dose not turn into rain. Inoue and Yokoyama(+332) predicted that the snowfall will not increase for2Bulletin of Glaciological Research

the next hundred years with the hypothesis of global
warming in Hokkaido (northern Island of Japan)
above .+./῍ north latitude. However, from the map
provided in this paper, it can be observed that thesnowfall along the coast of Hokkaido has decreased,
while that in the mountainous regions of Hokkaido
has increased.
In mountainous regions at high altitudes, even thesnow depth is rarely measured and the amount of snow
is entirely unknown. Only recently, National Research Institute for Earth Science and Disaster Prevention of Japan started the snow depth observation in
mountainous areas (Shimizu and Abe, ,**+; Yamaguchi
et al., ,**1). However, the highest altitude is +,-+* m
for this measurement. For the snow, as the water
resources of Japan and natural dams, it is essential topromptly build the network of meteorological observations including the snowfall and accumulation ofsnow in high altitudes regions in order to predict thesnowfall ﬂuctuation.
Further, to some extent, it is possible to evaluate
the amount of snow by hydrologically reviewing thewater balance based on even deﬁcient data of precipitation amount at the basins of mountains. Therefore,
we can report on the research results regarding thehydrological cycle and material cycle of the mountainous watershed on the eastern slope of Mt. Norikuradake, Northern Japan Alps.

,.

Methods

The study basin is the alpine watershed area thatspreads out on the eastern slope of Mt. Norikura-dake(Fig. +). The surface geology of this basin mainly
consists of granite. Mt. Norikura-dake is a Konide
volcano with scattered crater lakes and it is the quaternary volcano that constitutes the Norikura volcanic chain distributed along the Northern Japan
Alps. The Norikura volcano is a compound volcano
with six volcanic bodies, which were formed by volcanic activities that have been occurring since ap-

proximately +***** years, and it has a gentle shape as
young stage with the plateau formed by the objects of
volcanic eruptions. At the study location on the eastern slope, there is a lava plateau of a novel volcanic
body. The climate in this region is normal: a precipitation amount of ,***.2 mm, an annual mean temperature of 2.+῎, the mean temperature in the coldest
months (January and February) of ῌ-./῎, and themean temperature in the warmest month (August) of,*.-῎ according to the data from the neighborhood of
Nagawa where the Automated Meteorological Data
Acquisition System (AMeDAS) substation is set up by
the Japan Meteorological Agency.
The observation was started in May ,**, and thedata until June ,**0 was used. The measurement
point was at an altitude of +.1* m in Maekawa Riverbasin, which runs through the eastern slope of Mt.
Norikura-dake, and a water level gauge was setup at
this point to continuously measure the water level ofthe river. The measurement of discharge was conducted at di#erent water levels and the runo# rate
was calculated by using a discharge rating curve.
Further, an automatic water sampler was set up andthe river water was collected periodically. In addition, meteorological observations were conducted andthe atmospheric deposition amounts (wet and dry)were measured at a point located at an altitude of +./*
m from Norikura station of Institute of Mountain
Science, Shinshu University. Its location was approximately , km north of the lower end of this basin.
The atmospheric deposits were collected approximately once a week in a bulk sampler using a funnelof ,* cm diameter, a ﬁlter, and polyethylene bottle.
Then, the volume of the collected water was calculated from its weight and the sample was brought tothe laboratory. After ﬁltering the sampled river water and atmospheric deposits, its electrical conductivity and pH were measured and ionic concentration
was measured using ion chromatography. Also the
HCO-ῌ concentration was measured by the sulfuric
acid titration method on the river water.

-.
-.+

Fig. +.

Maekawa River basin and related points.

Results and discussion

Seasonal change of precipitation and runo#
The daily amount of precipitation at the Norikura
station and daily runo# at Maekawa River basin during the period of observation are shown in Fig. ,.
Every year, the amount of precipitation and its frequency are increasing between the rainy season (Baiu)
and autumn. The runo# is increasing in response tothese precipitations; however, the maximum baseﬂow discharge occurs during the snowmelt season.
On July ., ,**/, the largest daily runo# of /3./ mm wasrecorded; however, it was the result of both rainfalls
associated with the passage of a warm front and snow
melt caused by the increase in temperature on that

Suzuki et al.

Fig. ,. Daily precipitation at Norikura station anddaily runo# in Maekawa River basin.

Table +. Correlation matrix of river water chemistry(Q: discharge, EC: electric conductivity).

day. By the inﬂuence of low rainfall during summer
to autumn ,**,, the base ﬂow discharge was continuously decreasing after the snowmelt season in ,**,
until increasing again in the next snowmelt season in,**-. For other years, the runo# was temporarily
decreased after the increase in base ﬂow discharge inthe snowmelt season; however, it increased again in
the autumnal rainy season and the base ﬂow discharge in wintertime continuously decreased until thenext snowmelt season.
-., Seasonal change of river water chemistry
All samples of the river water were used during
the period of observation. For each sample, the correlation matrix between the chemical characteristics
and variables including the discharge at the samplingtime are shown in Table +. With an increase in discharge, the pH, electrical conductivity, and the concentrations of all the ions decreased. It can be observed that the NO-ῌ concentration barely shows apositive correlation with the concentrations of otherions and exhibits a peculiar variable trend. Further,
the Clῌ concentration exhibits no correlation with theconcentrations of other ions. It was discovered thatthe concentrations of ions excluding Clῌ and NO-ῌ
have an extremely high mutual correlation coe$cientand also show an almost analogous variable trend.
The pH, electrical conductivity, and ion concentrations in the river water during the period of obser-

3

vation along with the discharge at the time of sample
collection are shown in Fig. -. The concentrations of
only Clῌ, NO-ῌ, and SO.,ῌ anions are shown: Clῌ andNO-ῌ were selected because of their low correlation
coe$cient with the ﬂuctuation in the concentrationsof other ions and peculiar ﬂuctuation of Clῌ and NO-ῌconcentrations; SO.,ῌ was selected as a representative
for the variable trend exhibited by ions other than Clῌ
and NO-ῌ, because of a positive mutual correlation
excluding these two ions. In winter season, the discharge decreases and the recharge of river water by
the base ﬂow will be articulated. In this season, thepH and electrical conductivity of the river water indicated high values; they showed a gradual increase
until the snowmelt runo# started and drastically decreased thereafter. Then, if the trends are repeated,both pH and electrical conductivity gradually increased as a whole until the start of the next snowmelt
season and temporarily decreased with the ﬂow increase during rainy season (Baiu) and by typhoons.
It is known that there is a considerable amount of sea
salt in the snow at the snowy basins in Japan (Suzuki
and Endo, +33., +33/). It was also recognized that
there was an increase in the Clῌ concentration in theriver water at the beginning of a snow melt season(Suzuki and Kobayashi, +321; Suzuki, +33/; Yamazaki
et al., ,**/). As shown in Table +, the NO-ῌ concentration in the river water, which showed only a small
correlation coe$cient with the discharge of river water, was low at the time of the base ﬂow; however, it
was found to increase with an increase in the ﬂow
particularly caused by rainfalls. This increase is attributed to NO-ῌ that was produced in the soil bynitrobacteria and conveyed by shallow subsurface
ﬂows at the time of rainfall runo# (Suzuki, +330). Of
all the ion species in the river water, HCO-ῌ has the
maximum ion concentration, followed by SO.,ῌ.
From Fig. -, it is clear that the ﬂuctuation of the SO.,ῌ
concentration in the river water is simultaneous withthat of electrical conductivity.
-.- Mass balance in the study basin
We will discuss the water balance and mass balance for each month at the study basin. Regarding
the water balance, the monthly precipitation amountat the Norikura station and the monthly runo# atMaekawa River are reﬂected without modiﬁcation.
As for the atmospheric deposition amount of each ion
in the basin, the measurements of atmospheric deposition amount at the Norikura station will be used.
Since the measurement of atmospheric deposition
amount was implemented weekly, the deposition amount of each ion species per precipitation amount isprorated from the time of the measurements. The
runo# volume of each ion species from the MaekawaRiver basin is calculated as follows. First, the daily
average concentration of each ion species in the river

4

Bulletin of Glaciological Research

Fig. -. Electric conductivity (EC), pH, and anion concentration in river water and discharge (Q) when river water samples
are collected.

water was calculated. As clearly shown in Fig. -, theriver water was collected multiple times per day andanalyzed in a warm period during which the ﬂow
exhibits a large ﬂuctuation. The river water wascollected less frequently in a cold period during which
the ﬂow exhibits only a small ﬂuctuation, and hence
only a small ﬂuctuation of ion concentrations in theriver water. Next, the daily runo# volume of eachion species from the basin was calculated using its
daily average concentration and daily discharge.
The total daily runo# volume of each month wasdeemed as the monthly runo# volume of each ion
species from the basin. On some days in a month,such as December ,**,, no sample of the river water
was collected; for such days, the daily average runo#
volume of that month was used to calculate the daily
runo# volume of each ion species.
The water balance and mass balance at the MaekawaRiver basin, which were calculated as above, areshown in Fig. .. As for the water balance, runo#
exceeded the precipitation amount for most months.
This result is inconsistent with evapotranspiration.
This is because only values from the Norikura station
obtained at the altitude of +./* m were used for the
precipitation amount, although the runo# was fromthe entire basin at the altitudes from +.1* to -*,0 m.
Further, the above result also contradicts the general

expectation that the precipitation amount would increase with altitude. This problem will be consideredlater.
As for the mass balance of each ion species, theruno# value from the basin was overwhelmingly larger than the atmospheric deposition amount in thebasin. Regarding cations, the contribution made byan extremely large elution from new volcanic rocks
and soil was more than the atmospheric deposition
amount derived from precipitation and dry deposition. Similarly, the runo# volume of the river water
exceeded the atmospheric deposition amount withregard to SO.,῍ which is peculiar to volcanic bodies(Asai et al., ,**+). As for the cations, the runo# volume is extremely larger than the atmospheric deposition amount, particularly that of Ca,ῌ; however, theatmospheric deposition amount of Naῌ progressively
increased mainly in the winter season. Further, theatmospheric deposition amount of Kῌ was found toclearly increase in a warm season when the eluviation
volume from plant leaves also increases (Kuramotoand Suzuki, ,**/). On the other hand, the atmospheric deposition amount of Cl῍ in the basin and its
runo# volume from the river water were balanced;
Cl῍ is thought to be barely eluted from the basin rocks
and soils due to the geological condition of this basin,
considering the underestimation of the precipitation

Suzuki et al.

5

Fig. .. Monthly atmospheric deposition at Norikura station (white column) and monthly runo# of water and ions from
Maekawa River basin (gray column).

amount as stated above. The underestimation of theatmospheric deposition amount will be discussed
later. Further, the atmospheric deposition amount ofCl῍ was relatively large during the cold season, sameas Naῌ. Moreover, the atmospheric deposition amount of NO-῍ in the basin exceeded its runo# volume
from the river water. Among all the analyzed ion
species, only NO-῍ exhibited positive values in themass balance of the basin. This is attributed to thenitrogen accumulation and its elimination by the internal circulation of microorganisms and vegetationin the basin.
-..

Discussion for water balance
As already stated, the water balance will not beanalyzed since the runo# would be larger than the
precipitation amount if the runo# of the entire basin
at the altitudes of +.1* to -*,0 m was calculated, against the precipitation amount of only one level at thealtitude of +./* m. Monthly precipitation amounts at
the Norikura station and monthly runo# at the basin
are diagrammatically shown in Fig. /. The annual
mean precipitation amount over a . year period between June ,**, and May ,**0 was ,+20 mm and theannual mean of runo# was -.31 mm. Since it is said
that the annual evapotranspiration at mountainous
regions in the main island of Japan is /** mm or less,there will be a shortage of approximately ,*** mm inFig. /. Monthly runo# in Maekawa River basin (solidline) and monthly precipitation at Norikura station(gray column).

the annual precipitation amount. We will examine
whether it is possible to cover this underestimation of
precipitation amount by the elevation e#ect of precipitation amount and the relationship between winter monsoon and topography.
There is Nagawa substation where AMeDAS is
located, which is near the Maekawa River basin, andNorikura-dake where the precipitation is measured
only in warm periods. The measurements of the precipitation amounts at the Norikura station at the altitude of +./* m started in May ,**, and the precipitation in Norikura-dake has only been measured until

6Bulletin of Glaciological Research

Fig. 0. Relationship between monthly precipitation at
Norikura station and Nagawa (left) and thatbetween monthly precipitation at Norikura-dake
and at Nagawa (right).

September ,**.. Due to the limited available data, it
is not appropriate to directly compare the Norikura
station with Norikura-dake, which is located at analtitude of ,1-* m where the precipitation is recorded
only during warm periods. Therefore, each precipitation will be compared for the Norikura station,
Nagawa, and Norikura-dake. The relationships between the monthly precipitations are shown in Fig. 0
for the Norikura station and Nagawa (left) for Nagawa
and Norikura-dake (right). The relational equation(+) was obtained for the Norikura station (Nk) andNagawa (Ng) for .3 months between June ,**, andJune ,**0.
Ng῎*.3*,ῌNk῍,.2/ (r῎*.30)(+)

The monthly precipitation at the Norikura station at the altitude of +./* m is +*῍ larger than that at
Nagawa at the altitude of +*02 m throughout the year.
The relational equation (,) was obtained for Nagawa(Ng) and Norikura-dake (Nd) only for the warm periods of 3/ months between +313 to ,**..
Nd῎+..*ῌNg ῌ 22.2 (r῎*.2/)(,)

There were monthly precipitations that were extraordinarily high at Norikura-dake, such as in July+32-, July +331, and July ,**.. However, it is recognized as a positive correlation. Again, it is determined that the monthly precipitation at Norikuradake at the altitude of ,1-* m is more than .*῍ larger
than that at Nagawa at the altitude of +*02 m for thewarm periods only.
By comparing the relationships of the Norikura
station and Norikura-dake with Nagawa using therelational equations (+) and (,), the relational equation(-) was obtained:
Nd῎+.,0ῌNk ῌ 2..2(-)

This relational equation can only apply to thewarm periods; however, the annual mean precipitation
at Norikura-dake for . years between July ,**, andJune ,**0 is -1.0 mm that is comparable to -.31 mm of
the annual runo# at the study basin for the same

period. Therefore, hypothetically, equation (-) can beapplied throughout the year, and not only to warm
periods. However, it can be said that it is underestimated for the precipitation in a cold period, considering the annual evapotranspiration of /** mm or lessand a wide range of altitudes from +.1* to -*,0 m forthe entire basin.
In general, it is believed that the precipitation in
mountainous regions increases with altitude. Moreover, signiﬁcant snowdrift is expected on the leeward
side when it snows during the winter monsoon, since
this basin is located on the eastern side of the mountain range stretching north to south. This can becorroborated by the snow patch at the upper part ofthis basin after summer. Consequently, the survey
for water equivalent of snow cover was conductedwithin the basin in the winter season. This was apart of the snow chemical research of Japan Alps area;
thus, the snow survey was also conducted within thebasin. The details of the methods employed for snow
layers survey will be stated in the next paragraph;
here, only the water equivalent of snow cover is described. The water equivalent of the snow at thealtitude of ,*** m on February ,2, ,**0 was 2,, mm.
In addition, it is known that the snow started toaccumulate continuously in Norikura Plateau at analtitude of +/3* m from the ﬁrst of December, ,**/.
Furthermore, samples were weekly collected from theatmospheric deposition at the Norikura station at thealtitude of +./* m since December +, ,**/: the precipitation at this point from December +, ,**/ to February,2, ,**0 was -., mm. Ignoring the di#erence of start
time for the continuous accumulation of snow at analtitude of ,*** m and the basal snowmelt rate inwintertime, it is observed that the precipitation in acold period at the altitudes of ,*** m is ,.. times morethan that at +./* m.
The annual mean precipitation at the basin for .
years between July ,**, and June ,**0 was calculated
as -30+ mm on the basis of the following assumptions:(a) the monthly precipitation in the warm periods at
the altitude of ,1-* m (Nd) can be obtained using theabove relational equation (-),(b) the monthly precipitation of the basin in thewarm periods can be obtained by averaging the precipitations at +./* m (Nk) and ,1-* m (Nd),(c) by multiplying the monthly precipitation at +./* m(Nk) by ,.. yields the monthly precipitation at ,*** min the cold periods, and the monthly precipitation at,*** m (which was about in the middle of the basin)
can be regarded as the monthly precipitation in thebasin in the cold periods.
It is considered that the water balance was obtained reasonably since the annual mean runo# at thebasin for the same period was -.31 mm; thus, the annual evapotranspiration will be .0. mm.

Suzuki et al.

-./

Discussion for mass balance
It was stated that inexpediencies occur because of
the elevation e#ect of precipitation and underestimating the amount of snow in wintertime if the waterbalance of the basin was obtained in a wide range ofaltitudes from +.1* to -*,0 m by using the precipitation at the Norikura station at the altitude of +./* m.
This also applies to the mass balance which was previously described. In other words, the basin’s ion content that is deposited from the atmosphere is also
underestimated if the precipitation amount was underestimated even if the ion concentration was constant. Here, we will discuss the amount of ion deposition in the cold periods, which can be elucidated by
the snow survey.
As stated in the preceding paragraph, the snow
survey was conducted at the northern part of the basin
at the altitudes of ,*** m on February ,2, ,**0 as a partof the snow chemical research of Japan Alps area.
The snow layers were excavated until the groundsurface was reached and the snow temperature anddensity were measured after observing the snow layers. Then, snow layers were collected at every - cm
depth. Snow samples were put in spill-proof plasticbags and carried to the laboratory in a cooler and thenkept in a freezer until the chemical analysis that was
performed in a clean room. At the time of analysis,
the snow was melted and ﬁltered; then, pH and electrical conductivity were measured. Furthermore, theion concentrations were measured using ion chromatography. The water equivalent of snow could be
calculated from the density and depth and the ion
loadings of all the snow layers could be calculated
from the water equivalent of the snow cover at eachlayer and the ion concentrations. The anion loadingsin the snow obtained from the above analysis areshown in Table ,. The water equivalent of snow
cover and the precipitation at the altitude of +./* mmeasured from December +, ,**/ to February ,2, ,**0
are also shown. Additionally, the atmospheric deposition amount for each ion species at the altitude of+./* m for the same period is also shown. It wasobserved that the precipitation at the altitude of ,***
m is ,.. times more than the one at the altitude of +./*
m; however, more atmospheric deposition amount
was also recorded for each of the ion species: +./ times
more for Cl῍, +.1/ times more for NO-῍, and +.*3 times
more for SO.,῍. It was determined that the anion
concentrations at the altitude of ,*** m were lower
than that at the altitude of +./* m. It is thought that
this can be attributed to the di$culty in the transportation of snow particles at high altitudes, since thesnow particles become heavy as their ion content
increases.
The water balance results at the basin, considering the elevation e#ect of precipitation and the snow
distribution at the basin, as stated above. A similar

7

Table ,. Total atmospheric deposition at +./* m andsnowpack load at ,*** m.

Table -. Annual total atmospheric deposion, annual
outﬂow and estimated total deposition in river
basin.

estimation was made for the mass balance of ions. It
is believed that if the ion concentration at the altitudeof +./* m is used and the elevation correction is madeonly to the precipitation amount in the warm periods,
and if the volume of the atmospheric deposition at thealtitude of +./* m is multiplied by the proportion indicated in Table ,, the basin would be correctly characterized in the cold periods. The annual total atmospheric depositions of Ca,ῌ and anions were calculatedon the basis these hypotheses along with the annual
runo# from the basin are shown in Table -. Due tothe characteristics of the volcano basin, the runo#
volume from the basin overwhelmingly exceeds theatmospheric deposition amount for SO.,῍. However,
the runo# volume of NO-῍ from the basin is about half
the atmospheric deposition amount in the basin due
to the consumption and internal circulation inside thebasin. There is more runo# volume from the basinthan the atmospheric deposition amount of the Cl῍,
considering that there was no consumption inside thebasin and no elution from rocks and soils. However,this is on the agenda to be examined in the future
including the possibility of increased atmosphericdeposition in the past.

..

Conclusions

As the result of examining the water balance andmass balance at the Maekawa River basin, which is an
alpine watershed area and runs through the eastern
slope of Mt. Norikura-dake, the following was discussed:+) The precipitation frequency is high from the rainyseason to fall and the runo# temporarily increases in
response to this. However, the maximum base-ﬂow
discharge occur in the snowmelt season. The pH andelectrical conductivity of river water gradually in-8Bulletin of Glaciological Researchcrease in wintertime until the snowmelt runo# begins;
however, both drop suddenly with the start of thesnowmelt runo#. The pH and electrical conductivityof the river water temporarily decrease as the ﬂow
increases during the rainy season and during typhoons. At the beginning of snow melt, the Cl῍ concentration in the river water increases. Further, theNO-῍ concentration in the river water increases when
the ﬂow increases due to rainfall. The primal ion
concentrations in the river water, except these two,are nearly simultaneous with the ﬂuctuation of theelectrical conductivity.
,) As for the mass balance of cations at the study
basin, the runo# volume of the river water overwhelmingly increases compared to the atmosphericdeposition amount in the basin, which is caused by anextremely large elution from new volcanic rocks andsoils. Conversely, the atmospheric deposition amount and the runo# volume of the river water arebalanced reasonably for Cl῍ ions since it was notnecessary to consider the elution from rocks and soils.
Furthermore, the atmospheric deposition amount ofNO-῍ ions in the basin was higher than the runo#
volume of the river water, due to the consumption andinternal circulation inside the basin.
-) If the water balance at the study basin was obtained by only using the precipitation amount at the
low altitudes, the runo# would be excessive. Therefore, it would be balanced with a water balance with
evapotranspiration if the elevation correction is madeto the precipitation amount of the AMeDAS observation in the warm periods and a correction is made to
the precipitation amount from the water equivalent ofsnow survey in the cold periods.
From the above results, it is determined that thelack of observation of the amounts of precipitationand snow in the high altitude mountainous regions inJapan makes it very di$cult to accurately predict
increases or decreases in water resources; thus, it isimperative to promptly devise a measure to deal withthis problem.

Acknowledgements
The authors would like to thank Mr. K. Yokoyama,

Mr. H. Ichihara, Ms. M. Nara, Mr. Y. Yoshida, Ms. M.
Muramoto and Mr. M. Namba for their help on thesampling and analysis. This research was supported
by a Grant-in-aid for Scientiﬁc Research (No. +,.2**+2,+1-+***1) of Japan Society for the Promotion of Science. This research was supported by the Global
Environment Research Fund (C-0, C-*/,) of Japan
Ministry of the Environment.

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