Hydrogeological Features of Mount Fuji and the Surrounding Area, Central Japan: An Overview

Abstract

Mount Fuji (3776 m), Japan's highest mountain and one of the world's most picturesque stratovolcano was studied to give an overview of its hydrogeological features. The mountain was made from voluminous lava flows and pyroclastic materials produced through three generations of volcanic activities. The volcanic products, characterized by abundant pore spaces and fractures, play a role as productive aquifers by absorbing and storing rain and snow melt as groundwater and releasing it over a long period. Its foot slopes contain abundant water with Fuji-Five-Lakes in the north and hundreds of springs with enormous discharge to the south, leaving the upper slopes dry. Approximately 2.2 billion tons of rain and snow fall annually at Mt. Fuji, and ~4.5 million tons of groundwater is stored each day in average. The total amount of spring or groundwater discharge from Mt. Fuji is estimated at 6.55 x 106 m3/day and that in its southwestern slopes is ~1.76 x 106 m3/day. Rain and snow falling above the altitude of ~1,000 m is their main source of recharge. The water provides vital resources for the people living around it; however, over exploitation of this resource have already caused some decline in its quality and quantity.Journal of Institute of Science and Technology, 2014, 19(1): 96-105

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96
cultural icon to the people of Japan and its images are
held in high regard. The foot of the Volcano is densely
populated with about a half million people living around.
The mountain’s magnicent view and wilderness of the
area attracts more than 30 million domestic and foreign
visitors every year and about 0.40 million of them climb
it during June-August (Personal communication to local
people).
Mt. Fuji is a large composite volcano (stratovolcano),
which consists of alternating pyroclastic materials
and lava ows (Fig. 4). Pyroclastic materials include
fragmented particles of different diameters, such as dust
(<0.25 mm), ash (0.25-2 mm), lapilli or small stone (2-
64 mm), cinders, and block/bomb (>64 mm). Magma
contains gases and when it comes on the surface they
expand several times in response to the reduced pressure
producing highly porous vesicular rocks. Owing to their
nature and structure, volcanic materials can be good
reservoirs that absorb and store rain and snow melt
water as groundwater and release it over a long period.
Hydrologic knowledge involving mode of occurrence of
water, storage capacity, and water balance in a volcanic
terrain makes it possible to evaluate the water potential
of such reservoirs.
INTRODUCTION
Mount Fuji (Fuji-San) is the highest volcanic mountain
(3,776 m above sea level) in Japan. It is located about
110 km west of Tokyo close to the Pacic coast at the
border between Yamanashi and Sizuoka Prefectures
(35º21' N, 138º43' E) in southern Honshu Island (Fig.
1). The mountain rises above the Pacic coast in the
south and the summit part stands about 2,900 m above
the surrounding plain in the north. It has a diameter of
about 50 km and circumference of 153 km at the base,
and it displays gracefully curving slopes (Figs. 2 & 3)
diminishing from 32
0
near the summit to 25-27
0
in the
middle to almost level at the base (Tsuya, 1971). Its body
surface area is about 960 km
2
and volume about 1,400
km
3
. The summit of the mountain has a circular crater of
~500 m across and ~250 m deep below the highest point
(Fig. 3). The upper slope of the mountain is virtually dry,
whereas lower slopes contain abundant water of good
quality.
Mt. Fuji’s height and volume, eminent snow-capped
peak, and symmetrical beauty of ank lines (Figs. 2 &
3) has become a symbol of Japan, and is designated as
the UNESCO World Heritage Site. Besides its scenic
beauty and geological importance, the mountain is a
Hydrogeological Features of Mount Fuji and the Surrounding Area,
Central Japan: An Overview
Danda Pani Adhikari
Department of Geology, Tri-Chandra Campus
Tribhuvan University, Nepal
E-mail: adhikaridp@ntc.net.np
ABSTRACT
Mount Fuji (3776 m), Japan's highest mountain and one of the world's most picturesque stratovolcano was studied to
give an overview of its hydrogeological features. The mountain was made from voluminous lava ows and pyroclastic
materials produced through three generations of volcanic activities. The volcanic products, characterized by abundant
pore spaces and fractures, play a role as productive aquifers by absorbing and storing rain and snow melt as groundwater
and releasing it over a long period. Its foot slopes contain abundant water with Fuji-Five-Lakes in the north and
hundreds of springs with enormous discharge to the south, leaving the upper slopes dry. Approximately 2.2 billion tons
of rain and snow fall annually at Mt. Fuji, and ~4.5 million tons of groundwater is stored each day in average. The total
amount of spring or groundwater discharge from Mt. Fuji is estimated at 6.55 x 106 m
3
/day and that in its southwestern
slopes is ~1.76 x 106 m
3
/day. Rain and snow falling above the altitude of ~1,000 m is their main source of recharge. The
water provides vital resources for the people living around it; however, over exploitation of this resource have already
caused some decline in its quality and quantity.
Key words: Mount Fuji, stratovolcano, lava ow, pyroclastic materials, aquifer, hydrogeology, spring, groundwater.
Journal of Institute of Science and Technology, 2014, 19(1): 96-105, © Institute of Science and Technology, T.U.

97
Fig. 1. Location and topographical map of Mt. Fuji and the surrounding area, central Japan. Fuji-Five Lakes,
Aokigahara Jukai Forest, Shiraito Water Falls, and the boundary between the Yamanashi and Sizuoka Prefectures
are shown. Topographic contours are at 100 m intervals (adopted from the topographic map, Geographical
Survey Institute of Japan, Fuji-San, 1:25,000).
Fig. 2. Photograph of Mt. Fuji with Lake Kawaguchi
on background (approximately 15 km to the north).
KV: Komitake Volcano (seen separate from the main
body in the frontal part). Geographical position of
Lake Kawaguchi in relation to other Fuji-Five Lakes
is shown in Fig. 1.
Fig. 3. Arial view of Mt. Fuji (3,776 m) & the
surrounding area. The Hoei crater created by the last
eruption of Mt. Fuji (AD 1707-08) is visible on the
southeast side below the summit crater.
However, volcanic rocks have complex hydraulic features
due to their great textural and lithological variability,
different level of weathering, and their complex spatio-
temporal distribution (Vernier, 1993), which could
compartmentalize the regional hydogeologic system into
several domains (Gmati et al. 2011). The objective of
this article was to give a comprehensive overview of the
aquifer settings and movement and mode of occurrence
Danda Pani Adhikari

98
almost always below freezing and the annual average is
-7.10
o
C. At the summit, the highest and lowest recorded
temperatures were 17.80
o
C and -38.00
o
C in August 1942
and February 1981, respectively (Japan Meteorological
Agency, 2011).
Annual precipitation in the area varies from 2,750 to
3,000 mm on the wettest, east slope (sea facing slopes)
and from 1,500 to 2,000 mm on the north slopes (Kizawa
et al. 1969). Most of the moisture supply to the area is
derived from Sagami Bay and Suruga Bay in the south
through south-easterlies or southerlies or from both
winds. Much of the precipitation in the summit and upper
mountain slopes from October through April falls as
snow, and the average snow accumulation during 1958-
2004 was 188 cm (Tsuchi, 2007). The upper half of the
mountain is completely covered by snow in winter (Fig.
2), and small patches of permanent icy snow left on the
shady slopes in and around the summit crater are usually
seen even in midsummer (Adhikari, 2012). But, traces
of past glaciations are found nowhere on the mountain
(Tsuya, 1971). The evaporation rate ranges from 12 to
28 % of the annual precipitation for the north slopes and
from 11 to 24 % for the south. At a given elevation, the
evaporation rate from the north ank is 2 to 7 % higher
than that from the south ank, and is attributed to a longer
duration of sunshine and lower humidity in summer time
on the north ank than on the south ank (Yashuhara et.
al., 2007).
Mt. Fuji has an alpine timberline ecotone with vegetation
up to the altitude of about 2,400-2,500 m above sea level.
The timberline vegetation comprised three dwarf tree
species, viz., Alnus maximowiczii, Salix reinii and Larix
kaempferi (Sakio & Masuzawa, 2012). The common trees
in the lower slopes are species of pine, rhododendron
etc. The apical part above 3,000 m is virtually barren,
forming steep slopes and bluffs covered either with lava
ows or with ash fall deposits (Fig. 3).
Geology
Mt. Fuji’s present shape was created over three
generations of volcanic activities, namely, the Ko-Mitake
(literally meaning ‘small mountain volcano’), Ko-Fuji
(Older Fuji), and Shin-Fuji (Younger Fuji) volcanoes
(Miyaji et al. 1992). A generalized geologic map with
distribution of major categories of rock types around Fuji
Volcano is shown in Fig. 5. The Ko-Mitake volcano,
which was active between 700 and 200 thousands of
years before present (ka) (middle Pleistocene Epoch),
produced andesitic lava, agglomerate, and pyroclastic
materials (Tsuya, 1971). The Ko-Mitake can be seen in
of water around Mt. Fuji. Specically, the article aims at
providing better understanding of intricate relationships
of recharge, storage, groundwater ow, and discharge in
a volcanic terrain that manifests its hydrogeological work
as several lakes, springs, and provides quality water for
anthropogenic use.
Fig. 4. Schematic diagram illustrating the internal
structure of Mt. Fuji.
MATERIALS AND METHODS
The hydrogeological condition of a given area is the
results of interaction of two active agents- the solid and
the uid. The solid aspect comprises the material and
the geometry of an aquifer and the hydraulic properties
of the aquifer; the uid aspect involves the hydraulic
behavior of the groundwater. The solid and liquid aspects
of Fuji Volcano as a whole formed the material of this
study. Field excursions were undertaken in the northern
foot of Mt. Fuji in several occasions to understand the
geology and hydrology of the Fuji-Five Lakes area in
connection with paleolimnological investigation of Lake
Yamanaka (Fig. 1). The mountain was climbed up to the
top for more information on the upper mountain slopes,
and hydrogeological observations were made around
Fujinomiya, southwestern part of Mt. Fuji (Fig. 1) where
springs are abundant. In addition, relevant information
on Mt. Fuji, volcanic materials, and hydrogeology of the
area were collected from existing literatures.
RESULTS AND DISCUSSIONS
General Features
Climate
Mt. Fuji area has three climatic zones – humid temperate
below 1,600 m, subalpine in middle part, and alpine
above 2,500 m altitude. The temperature decreases by
0.60
o
C with each 100 m increase in elevation (Japan
Meteorological Agency, 2011). Excluding parts of
summer, the monthly average temperature at the peak is
Hydrogeological Features of Mount Fuji and the Surrounding Area, Central Japan: An Overview

99
the northern slope of Mt. Fuji at the Fifth Station (the
terminal parking lot of the highway called ‘Subaru Line’,
Figs. 2 & 6). The volcano then underwent dormant
(inactive) for some times and followed by another phase
of volcanic activities during 100 ka -11 ka which is
known by the Older Fuji Volcano (OFV) (Miyaji et al.
1992). The OFV released voluminous pyroclastic falls
(scoria and ash), lava ow, and large scale mudows
(‘Older Fuji mudows’ generated from pyroclastic-ows
and debris-avalanche deposits). The volcano formed a
separate, ~3,100 m high mountain in the southern side
of Mt. Ko-Mitake as illustrated in Fig. 6. Total volume
of ejecta from the OFV is estimated at 250 km
3
and it
formed the base of the current Mt. Fuji (Miyaji et al.
1992).
The Younger Fuji Volcano (YFV) started erupting basaltic
lava for the rst time in its history ~11 ka and exploded
Fig. 5. General geological map of Mt. Fuji area with location of Fuji-Five-Lakes and some of the springs and
waterfalls (modied from Machida, 1977; Yamamoto, 1970; Tsuya, 1968).
repeatedly for over 100 times (Miyaji, 2002) since then
creating the mountain's current shape and dimensions
(Figs. 2, 3 & 6). Its activities are characterized by
eruptions of different types and natures, such as summit
crater eruptions, summit and ank-ssure eruptions,
major lava ows and minor pyroclastic falls etc. The
last eruptions of December 1707-January 1708, known
by Hoei eruption (Hoei dai funka), is the largest of all
eruptions in recorded history of Fuji Volcano, and by
nature it was the largest scoriaceous Plinian eruption
(culminate in violent explosive eruptions) with a parasitic
crater in the southeastern part of the mountain (Fig. 3). It
released ~1.7 km
3
pyroclastic materials (Miyaji, 1988);
three meters of debris accumulated at the foot of Mt.
Fuji and >6 cm of ash blanketed Tokyo area. Lava ow
did not occur during the YFV period, whereas the total
volume of all erupted products is estimated to be 47 km
3
(Miyaji, 2002).
Danda Pani Adhikari

100
Fig. 6. Schematic cross section showing hydrogeologic
structures and groundwater ow in Mt. Fuji (modied
from Tsuchi, 2007).
Aquifer setting and water movement
Bodies of rocks or soils, or both, which contain signicant
quantities of water that can be tapped by wells or springs
are aquifers. Both consolidated and unconsolidated
geological materials are important as aquifers. From the
perspective of hydrogeology the important characteristics
of rocks are how much open space is available in between
the crystals or fragments to hold water (porosity) and
how well the open spaces are connected to allow water to
ow (permeability). The spaces between mineral grains
of a rock are referred to as inter-granular porosity. Many
volcanic rocks are fractured because of their relatively
rapid cooling or violent formation and give rise to
fracture porosity too.
Most of the volcanic materials on the surface around
Mt. Fuji are composed of the YFV as materials from
OFV are covered by the thick deposits of the YFV. In
most localities the scoria-fall deposit is composed of
massive bed of reddish-brown lapilli. The tephra clasts
are dominantly angular to sub-angular and display a wide
range in vesicularity from frothy scoria to dense, fresh
fragments with few vesicles. The color of the tephra varies
between light reddish and dark-gray. The prevalence of
scoria fall deposits on the surface and fracturing in the
rocks around Mt. Fuji area, as shown in Fig. s 7a, b, &
c, have given rise to inter-granular and fracture porosity
high, making them as excellent aquifers.
The geological units that serve as aquifers in Fig. 5
include: 1) alluvial deposits in the lowland and volcanic
ash beds (pyroclastic materials) on the surface of the
mountain as supercial aquifer; 2) the lava ows of YFV
(older, middle, and younger lava ows) as main aquifer
(new Fuji aquifer); and 3) the pyroclastic mudow
deposits of the OFV as minor aquifer (old Fuji aquifer).
Tsuchi (2007) gave an explanation of the reason behind
Fig. 7 (a). Close up view of the scoria fallout deposits as it seen in the upper mountain slopes and summit part of
Mt. Fuji; (b). Outcrop of Aokigahara Lava Flow of Younger Fuji Volcano with vesicles and high fracture porosity
at Narusawa-Michinoeki (after Takahashi et al. 2007); (c). Thin part of the Aokigahara Lava Flow at the edge of
Lake Sai. The rock is mostly left uncovered with volcanic ash and other pyroclastics and groundwater in the lava
discharges directly into lake and form the predominant source of recharge (after Yasuhara et al. 2007).
Hydrogeological Features of Mount Fuji and the Surrounding Area, Central Japan: An Overview

101
groundwater systems in the southwestern foot of Mt. Fuji:
(1) Shallow ow system locally and recently recharged
and prevailing the supercial aquifer; (2) Deep ow
system of the Old Fuji Aquifer (groundwaters draining
this aquifer are of great residence time and recharged at
higher altitudes); and (3) the ow system draining the
New Fuji Lava layers acting as a connector between
the above mentioned systems. Previously, Yamamoto
(1970) proposed divisions on hydrologic structure of Mt.
Fuji, classifying volcano body into three zones as upper
recharging zone, middle recharging zone, and spring
zone (Fig.10).
Water distribution
The anks and lower mountain slopes of Mt. Fuji are
sculptured by a number of radial valleys and erosional
gullies, none of which however has usual surface stream
except during occasional torrential rain events in summer
and typhoon seasons and sudden snow melt in spring
(Tsuya, 1988). The lack of surface streams is due to the
fact that the pyroclastics and the lava ows of the YFV
are highly permeable and water on the surface easily
percolates through the porous media. Below the YFV,
the mudows and pyroclastic deposits of the OFV are
impermeable and the water percolating down from the
surface layer could not move further deep and stored
as groundwater, and appears, at the foot of Mt. Fuji
as springs or waterfalls where the boundary between
the OFV and YFV is exposed (Koshimizu & Tomura,
2000). Given the difference in topography and aquifer
distributions in the north and the south, water movement
and distribution in these two slopes differ in some ways
as summarized below.
Fig. 9. Conceptual diagram illustrating the aquifers
interactions around Fuji Volcano area (modied after
Gmati et al. 2011).
YFV lava becoming the main aquifer - basaltic lava during
eruption attains ca. 1,200
o
C and the surface and bottom
parts of the lava ow are cooled rapidly and crushed,
becoming clinker as illustrated in Fig. 8, whereas the
lava in the inner part cools slowly and solidies densely.
The lava in the steeper parts of the cone in high altitude,
on the other hand, becomes thin and crushed. The
crushed and permeable parts (clinkers) existing between
the lava layers (Fig. 8) present the “route” through
which the groundwater ow and they may constitute
“the water-bearing horizons”. The precipitation stored as
groundwater in the crushed parts between the lava layers
in the foot area is pushed out on the surface because of
the water pressure from higher elevation.
Fig. 8. Schematic diagram showing the unpressured
underground waters in surface volcanic ash beds and
pressured groundwater within overlapping basaltic
lava ow beds (after Tsuchi, 2007).
Basaltic rocks constitute many overlapping lava ows
with various length and width, and they are well known for
their abundant joints and fractures and high permeability
resulting from that (Demlie et al. 2007; Koh et al. 2005).
Based on the identical features seen around Mt. Fuji,
Gmati et al. (2011) hypothesized vertical interconnection
between the water-bearing horizons of the New Fuji
Lava as the mechanism of aquifers interaction (Fig. 9).
The diagram shows that besides the horizontal clinkers
responsible for the horizontal groundwater ow, lateral
clinkers separating the lava blocks of different and
limited lateral extents could play an important role
in the percolation of groundwater downward causing
groundwater mixing (Gmati et al. 2011). Gmati et al.
(2011), using groundwater geochemical signatures and
hierarchical cluster analysis, highlighted three interacting
Danda Pani Adhikari

102
Fig. 10. Mt. Fuji ank slopes divided into three zones
on the basis of water availability (modied after
Yamamoto, 1970).
Northern Slope
Northern foot of Mt. Fuji is popularly known as Fuji-
Five Lakes (Fuji Goko in Japanese) as it hosts ve lakes,
namely, Lake Yamanaka, Lake Kawaguchi, Lake Sai,
Lake Shōji, and Lake Motosu from east to west (Fig. 1).
The lakes were formed by damming of preexisting streams
by lava ows from Mt. Fuji (Adhikari, 2011; Koshimizu
& Uchiyama, 2002). In the catchments of the Fuji-Five
Lakes, the boundary between the OFV and YFV is rarely
exposed on the surface and due to this hydrogeological
character most of the percolating water and snow melts
directly contribute to the lake internally, at some depths
below the lake surface, rather than appearing as overland
ow or streams (Koshimizu & Tomura, 2000) (Fig. 6).
Table 1 summarizes some of the physical characteristics
of the Fuji-Five Lakes.
Among the Five-Lakes, Lake Yamanaka is closest (12
km) to Mt. Fuji and located at the highest elevation (982
m) (Fig. 1). The lake is the largest in terms of surface area
and the shallowest with a maximum water depth of 14.00
m (Table 1). Lake Yamanaka is drained by the Sagami
River, and it is the only of the Fuji-Five Lakes to have a
natural outow. Lake Kawaguchi, on the other hand, is
at the lowest elevation (832 m), second largest (surface
area, 6.13 km²), and has the longest shoreline (Fig. 1). The
lake has no natural outlet. Lake Sai is the fourth largest
in surface area and second deepest (maximum water
depth: 71.10 m). Surface elevation and shore length of
Lake Sai are 900 m and 9.85 km, respectively (Table 1).
Lake Sai has no natural drainage, but an articial channel
now connects it to Lake Kawaguchi. Located at 900 m
elevation, Lake Shōji is the smallest in area (0.50 km
2
)
but the third deepest (maximum water depth: 15.20 m)
lake. Lake Motosu is the deepest among the Five-Lakes
(140 m) and the ninth deepest lake of Japan (Koshimizu
& Tomura, 2000). Like Lake Sai and Lake Shōji, Lake
Motosu is 900 m high in elevation and it holds the
largest volume of water. Lake Sai, Lake Yamanaka, Lake
Kawaguchi, and Lake Shōji are in descending order in
terms of water volume in the lakes (Table 1).
The western three lakes, Lake Motosu, Lake Sai and
Lake Shōji experience similar seasonal rise and fall in
water levels. Their similar surface elevation and similar
uctuations indicate that these three lakes remain
connected by underground waterways. Research ndings
(e. g. Rafferty, 2010; Takahashi et. al. 2007) suggest that
these three lakes were originally a single, big lake which
was later divided by enormous (~1.40 km
3
) lava ows
of Aokigahara Lava from Mt. Fuji during AD 864-868.
Seen as thousands of ow lobes, the Aokigahara Lava
(characterized by high fracture porosity, Fig. 7b & c)
widely covers the northwestern foot of the volcano and
the remnants of which are seen in the Aokigahara Jukai
Forest (Fig. 1). The Aokigahara Lava is the largest lava
ow of the YFV (Takahashi et al. 2007). Besides the Fuji-
Five Lakes, few springs emerge in some places in the
mountain between Lake Yamanaka and Lake Kawaguchi
where the boundary between the OFV and YFV exposes
(Fig. 5), and the Oshinomura Spring with discharge of
2,223 liters/second (L/s) (Yamamoto, 2070) is the largest
spring in the northern foot of Mt. Fuji.
The relative rate of direct ow of groundwater to the Fuji-
Five Lakes is not well known, but the lack of perennial
surface inlets and relatively high lake discharges
suggest that water budget is entirely the contribution of
groundwater ow (Koshimizu & Tomura, 2000). There
has been no large changes in lake level in response to
extended periods of drought or high rainfall, but few
centimeters of water level rise occurs each year during
rainy and snowmelt seasons (personal communication to
local people in Fuji-Five Lakes area).
Southern slope
Unlike the northern part, the southern part of Mt. Fuji
hosts few lakes but large number of springs as the
boundary between the OFV and YFV is exposed on the
surface. Locations of some of the springs are shown in
Fig. 5, and some of them are big and geometrically high
enough to develop themselves as waterfalls. Shiraito Falls
(Shiraito means Silk thread in Japanese) in Fujinomiya
(Fig. 11a), for example, constitutes of over 200 small
waterfalls and each of them looks like a silk line, and in
group they make beautiful white water curtain. It is 20
Hydrogeological Features of Mount Fuji and the Surrounding Area, Central Japan: An Overview

103
m high and 200 m wide, and is the largest of all in the
area. Additional unique feature of Shiraito Falls is it does
not have river run into the fall. The water volume from
Shiraito Falls is estimated at ~1,382 L/s (Yamamoto,
1970), and it discharges to Shiba River. Sometimes
Shiraito Falls is called as Japanese Niagara Fall. It has
been protected as a Japanese Natural Monument and in
2013 the waterfall was added to the World Heritage List
as part of the Fujisan Cultural Site.
Otodome Falls is right next to the Shiraito Falls, and is
CONCLUSIONS
Geology of Mt. Fuji plays an important role in the
hydrological processes, including the occurrence and
movement of groundwater in the area. This volcanic
terrain with multi-layered lava ows and pyroclastic fall
deposits make the Mt. Fuji a productive aquifer system.
The Fuji-Five-Lakes (Lake Yamanaka, Lake Kawaguchi,
Lake Sai, Lake Shōji, and Lake Motosu) in the northern
side and hundreds of springs with enormous discharge in
the southern side of the Mt. Fuji are the manifestation of
excellent hydrogeological conditions in the area.
The Mt. Fuji aquifer systems result from pore spaces as
well as the fractures in the rocks. The pyroclastic deposits
are porous, and development of clinkers at the basal parts
of the overlapping lava ow layers through crushing
during rapid cooling of the Younger Fuji Volcano gave
rise to additional pore spaces conducive for horizontal
and vertical water movement. The aquifer setting in Mt.
Fuji makes it a big reservoir which absorbs and store rain
water in its body as groundwater and releases it over a
long enough periods. Rainwater and snow falling above
the altitude of ca. 1,000 m is their main source of recharge.
About 2.2 billion tons of rain and snow fall annually at
Mt. Fuji, and excluding evapotranspiration, ~ 4.5 million
tons of groundwater is stored each day in average. The
total amount of springs or groundwater discharge from
Table 1: Physical characteristics of Fuji-Five Lakes
13
Name of Lake Lake Yamanaka Lake Kawaguchi Lake Sai Lake Shoji Lake Motosu
Surface elevation (masl) 981 832 900 900 900
Maximum depth (m) 13.50 15.20 71.10 15.20 140 (67.3)
Surface area (km
2
) 6.46 6.13 2.10 0.50 4.70
Shore length (km) 13.87 19.00 9.85 6.80 11.82
Water volume (x10
6
m
3
) 65 53 130 7 400
Distance from Mt. Fuji
summit
(km)
12 15 13 15 13
(Sources: Adhikari, 2011; Koshimizu & Tomura, 2002; Yamamoto, 1970)
~25 m high and 5 m wide (Fig. 11b). These two falls are
listed as two of the 100 best waterfalls in Japan. Jimba
Falls is located just north of Lake Tanuki, which has
a surface area of 0.312 km
2
with 1 km length, 0.5 km
width, and 8 m average depth. Wakutama and Kohama
are spring ponds in Mishima. There are 13 springs,
among hundreds, with variable discharge from 80 L/sec
to over 1000 L/sec (Yamamoto, 1970).
Based on the oxygen and hydrogen isotope analysis
of spring waters, rainwater and snow falling above the
altitude of ca. 1,000 m is their main source of recharge
and its underground residence time is 15 years (Yasuhara
et al. 2007). Approximately 2.2 billion tons of rain
and snow fall annually at Mt. Fuji, and excluding
evapotranspiration, ~ 4.5 million tons of groundwater is
stored each day in average (Yasuhara et al. 2007). Kakita
River, which ows through the town of Shimizu in the
Shizuoka Prefecture, Japan, alone receives over one
million tons of water a day coming from the springs at
the southern foot of Mt. Fuji. The total amount of springs
or groundwater discharge from Fuji Volcano is estimated
at 6.55 x 106 m
3
/day or 24 x 108 m
3
/year, and that in the
west side of Mt. Fuji is ~1.76 x 106 m
3
/day (Yasuhara et
al. 2007).
The area’s abundant groundwater and streams facilitate
the operation of paper and chemical industries and
farming. Cultivation of rainbow trout and dairy farming
are other activities. In the last few years, groundwater has
been developed or is about to be developed in quantities
ranging from 1, 400, 000 m
3
per day on southern part to
24, 000 m
3
per day on northern part (Gmati et al. 2011).
An extensive development of groundwater for industrial
use as well as for agricultural activities has caused abrupt
decline of groundwater pressure, stopping or decreasing
of spring discharge, and groundwater contamination by
sea water invasion.
Danda Pani Adhikari

104
Fuji Volcano is estimated at 6.55 x 106 m
3
/day or 24 x
108 m
3
/year, and that in the west side of Mt. Fuji is ~1.76
x 106 m
3
/day.
Hydrogeologic knowledge involving mode of occurrence
of water, storage capacity, and water balance make
it possible to evaluate the water potentiality of this
volcanic terrain as a groundwater reservoir. The
extensive development of groundwater for industrial and
agricultural uses around Mt. Fuji can change the existing
hydrogeological balance in the area with unintended
consequences such as decline in groundwater pressure,
discharge, and quality. Therefore, it is important
to understand the overall hydrogeological factors
controlling the Mt. Fuji aquifer system for a sustainable
use of this resource.
ACKNOWLEDGEMENTS
Field excursions and part of the literature review works
were performed during Japan Society for the Promotion
of Science (JSPS) fellowship during 2003-2005. The
author is thankful to S. Koshimizu, Yamanashi Institute
of Environmental Sciences, Japan for his supports in
various ways. Comments from anonymous referees
helped improve the manuscript.
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Danda Pani Adhikari