Abstract—Sand mining activities at the Lake Ciseupan area was

started in 1980. The activity is currently in form of man-made lake

with 300 meters of diameter. The lake water is utilized by the

surrounding residential and industries. The volcanic aquifer consists

of tuff and volcanic sand as part of Formasi Cibeureum, underlaid by

impermeabel breccias, and bordered by intrusion at the southern part.

This paper identifies the hydrodynamic interaction between surface

water and groundwater around the lake, using finite difference

modeling. The total modeled area is 810,000 m2 with dimensions of

900 m x 900 m. The modeling is based on geoelectric-resistivity

measurement coupled with groundwater level observation and

hydrochemical data. The result shows that the groundwater flows

westward with radial pattern and 0.05 hydraulic gradient. Based on

the modeling and hydrochemical analysis, showing bicarbonate

dominations and small quantities of amonium, there are similarity

between lake water and groundwater. The truncated volcanic aquifer

by the previous excavation have exposed the groundwater to fill in all

the abandoned openings and have diversed the groundwater flow.

Therefore the exploitation of the lake water will convincingly affect

the groundwater level at the surrounding areas, as reflected by cone

depressions at the settlement area, southern part of the lake.

Keywords—Cimahi, groundwater modeling, groundwater-lake

interaction, West Java

I. INTRODUCTION

ISEUPAN Lake was a sand mining area that run from 1980

to 1990, leaving two large holes with 300 meters in

diameter. , surrounded by hills with a height. It lies at the

elevation between 690 to 720 meters above sea level (masl).

The water from the lake has been utilized by the surrounding

residential and industries. The volcanic aquifer consists of tuff

and volcanic sand as part of Cibeureum Formation, underlaid

by impermeabel breccias, and bordered by intrusion at the

southern part. The objective of this research is to analyzed the

hydrodynamic relationship between Ciseupan lake water (lake

water) with the surrounding water well. The first prediction

relates to the truncated aquifer case. Once we have decided the

relation then we have to calculate how much lake water can be

pumped without interferring with the water wells.

This situation is due to the lack of water infrastructures that

at some point force the locals to have alternative ways to find

water sources. For example, according to the most recent data,

D.E. Irawan is with the Applied Geology Research Group, Faculty of Earth

Sciences and Technology, Institut Teknologi Bandung, INDONESIA (phone: +62-22-2514990; fax: +62-22-2514837; e-mail: erwin@fitb.itb.ac.id).

D.J. Puradimaja and H. Silaen are with the Applied Geology Research

Group, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung, INDONESIA.

the amount of clean water that the state-owned local water

supply company (PDAM) supplied to the industrial sector was

only about 3.5 million m3 in 2003, which is just 1% of the

volume required by industry. Groundwater use was found to

continue to increase until 2004, reaching almost 70% of the

total clean water required by the industrial sector in the

Bandung Basin [1].

Fig. 1 The study site, Ciseupan man-made lake, Cimahi, Bandung,

West Java

II. METHODS

We combined two major methods to identify the

hydrodynamics relationship between lake water and the

surrounding wells at the Ciseupan lake: resistivity mapping

campaign using conventional sounding technique and floating

techniques, and groundwater modeling based on actual water

table and finite difference technique. The above mentioned

methods were successfully conducted in similar situation by

Hydrodynamic Relationship between Man-

Made Lake and Surrounding Aquifer, Cimahi,

Bandung, Indonesia Dasapta E. Irawan, Deny J. Puradimaja, and Hendri Silaen

C

World Academy of Science, Engineering and Technology 58 2011

100

Woessner (2000), Townley and Trefry (2000), Nield (1994),

and well discussed by Freeze and Cherry (1979).

A. Floating Resistivity Mapping

The analysis and interpretations were conducted, involving

two techniques floating geo-electric arrays across the lake and

six sounding points at lake’s vicinity. A 100 m long floating

geo-electric array was towed across the lake to measure the

vertical profile of electrical conductivity (Fig 2). A particular

focus was to investigate the depth and layers of Ciseupan’s

lake bottom. Both results were correlated to identify the

geological layers on the investigation site.

Fig. 2 The schematic drawing of floating resistivity mapping

techniques

B. Groundwater Modeling

A finite difference modeling with Visual ModFlow was

done to identify the groundwater flow and how it was

connected with lake water. We were also simulating the lake

water drawdown and its influence to groundwater level. The

total modeled area was 810,000 m2. The model was built

based on conceptual geological model from resistivity

measurements.

III. HYDROGEOLOGICAL BACKGROUND

Lembang Fault is part of depression chain in West Java,

which is called the Bandung Zone. The Bandung Zone can be

regarded as a graben-like longitudinal belt of intramontane

depressions, extending through the central part of West Java

(Fig. 4). In the central part of this zone, Bandung Basin and

Batujajar Basin are located. Bandung Basin is located in West

Java Province; the basin is a plateau encircled by mountains

forming a basin (Delinom, 2009).

The study site is dominated by Cibeureum Formation (Upper

Pleistocene-Holocene), composed of volcanic breccias and

tuff. Grey colored volcanic breccias are consist of scoria and

andesite-basalt fragments. Tuff layers are in brownish white,

sand to gravel grain size. This formation, with maximum

thickness of 180 m, is distributed southward in form of

alluvium fan (Koesoemadinata and Hartono, 1981). Another

researcher, Silitonga (1973), has mentioned that the productive

aquifer was called Tuffaceous Sands (Qyd), brown in color,

high porosity and permeability. He was also mentioned Scoria

Tuff (Qyt) and Tuffaceous Breccias, Andesite Lava, and

Conglomerate from Mt. Tangkubanparahu (Fig. 3).

IWACO-WASECO (1991), an Netherland based consulting

company, reported the hydrogeological condition of were

composed of moderate to high productivity aquifers consist of

Cibeureum formation (fm), Cikapundung fm, and Kosambi

fm. The transmisivity values (T) ranged from 100 to 900

m2/day (PLG, 2000). The Cibereum fm’s T value were

averagely the highest (900 m2/day), then the Cikapundung fm

(averagely 174 m2/day), and the Kosambi fm (150 m

2/day)

(Fig. 3). The recharge area of the system were located on the

northern part of Cimahi, known as the Lembang area.

Puradimaja (1995) and Sunarwan (1998) has mentioned that

the oldest water based on isotopic measurement were 50

years old. It flew from the north part (Lembang fault) to south

(Cibabat area). Delinom (2009) has noted that the north

groundwater system boundary is the Lembang Fault, an east-

west normal tectono-volcanic fault. Groundwater springs were

found mainly at the north of Cimahi, which was also the hilly

part, with noted maximum discharge of 10 L/sec. At south part

of Cimahi, there were many groundwater tapping in form of

dug wells and borehole. The recorded discharge from a

PDAM (State Owned Drinking Water Company of Cimahi)

well were up to 40 L/sec in late 1990’s.

Fig. 3 The stratigraphical units of Bandung Basin

Current

electrodesReceiver

electrodesBoat

Lake bottom

Water surface

Age

Stratigraphical Unit

Hydro-

strati-

graphy

Producti-

vity

(IWACO,

1991)

Silitonga

(1973)

Kusumadinata

and Hartono

(1981)

Quar

tenar

y

Holo-

cene

Lake Deposit

(Ql)

Kosambi Fm.

(Clay, sand)

Upper

aquifer Moderate

Pleisto-

cene

Tuffaceous

sand (Qyd)

Cibeureum Fm.

(Tuff, sand)

Middle

aquifer High

Tuff

Scoria

(Qyt)

Old Volc.

(Qob)

Cikapundung

Fm. (Breccias,

lahars, lavas)

Lower

aquifer High

Andesit,

Basalt Basement None

Ter

tiar

y

Plio-

cene

Tuffaceous

breccias,

sandstone,

conglomerate

(Pb)

Basement None

Mio-

cene Cilanang Fm. Basement None

World Academy of Science, Engineering and Technology 58 2011

101

IV. RESULTS

A. Resistivity Mapping

The dominant unconfined aquifer system is composed of tuff

and volcanic sands. All layers are underlaid by impermeable

volcanic breccias. The southern part is bounded by instrusion

body. Based on this measurement, the depth of the lake are up

to 20 m. It truncates the surrounding aquifers (Fig. 4). From

this result, our first interpretation is that the lake water and the

surrounding groundwater are connected. Therefore our first

hypothesis is when the lake water is pumped will instantly

lower the water level at the surrounding wells. This prediction

will be further analysed in the modeling stage.

Fig. 4 The aquifer section of the Ciseupan man-made lake area based

on resistivity mapping

B. Groundwater Modeling

The result shows that the groundwater flows westward with

radial pattern and 0.05 hydraulic gradient. Based on the

modeling and hydrochemical analysis, showing bicarbonate

dominations and small quantities of amonium, there are

similarity between lake water and groundwater. The truncated

volcanic aquifer by the previous excavation have exposed the

groundwater to fill in all the abandoned openings and have

diversed the groundwater flow. Therefore the exploitation of

the lake water will convincingly affect the groundwater level

at the surrounding areas, as reflected by cone depressions at

the settlement area, southern part of the lake. Excessive

pumping of Ciseupan’s water is prone to lake water level drop.

The west part of the lake is simulated to be the most prone to

this situation, due to the control of impermeable bodies,

intrusion of igneous rock and tertiary layers. West ward

groundwater flow is not enough to compensate the pumping at

this area. However, from the modeling, we found that there are

no significant drop at the north, east, and south area as there

are no impermeable layer to control the groundwater flow.

We have simulated four modeling scenarios on the pumping

situation with 1 m allowed groundwater level drop as

limitation. A scenarios shows that when the lake water drop by

1.3 m, which is equivalent with lake water pumping of 21,000

m3/day, will cause the depletion of groundwater level by 1 m

at the nearest well 10 m from the lake. We also recommend to

deepen these well 1.5 m to allow the optimum groundwater

thickness to be pumped (Fig. 5).

Fig. 5 The result of computer simulation in 4 scenarios

V. CONCLUSION

The methods can be used to answer the mentioned problems

related to the interaction between surface water and

groundwater in the area. The combination between surface and

subsurface mapping, coupled with hydrochemical approach

show both the aquifer setting and groundwater flow. Moreover

the groundwater modeling can compute the maximum lake

water exploitation without significantly lower the lake water

level.

Ciseupan lake Fishing ponds

Nearby

A B

C D

A

B

C

D

B T S U

pemukiman R

R

R

R

World Academy of Science, Engineering and Technology 58 2011

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The dominant unconfined aquifer system is composed of

tuff and volcanic sands. All layers are underlaid by

impermeable volcanic breccias. The southern part is bounded

by instrusion body.

The isopotentiometric map shows radial flow with low

gradient 0.05 with cone depression lies at southern part of the

lake. It flows towards the south municipalities.

Excessive pumping of Ciseupan’s water is prone to lake

water level drop. The west part of the lake is simulated to be

the most prone to this situation, due to the control of

impermeable bodies, intrusion of igneous rock and tertiary

layers. West ward groundwater flow is not enough to

compensate the pumping at this area. However, from the

modeling, we found that there are no significant drop at the

north, east, and south area as there are no impermeable layer

to control the groundwater flow.

We have simulated the pumping situation with limit of 1 m

allowed groundwater level drop. We have computed that if the

lake water pumping reaches ± 21,000 m3/day – which was

unlikely to be the case – then the lake water will drop 1.3 m.

This drop will cause 1 m drop of groundwater level.

However the addition of pumping test data at the

surrounding housings is needed to confirm the simulation,

especially recovery test.

ACKNOWLEDGMENT

The Authors thank The Built Environment Agency of

Cimahi Regency for their financial support to this research.

We also thanks Dr. Bagus Endar Nurhandoko for his review

on the resistivity method. We also give the highest

appreciation to the students for their contribution on the field

campaign.

REFERENCES

[1] Delinom, R.M., 2009, Structural Geology Controls on Groundwater Flow: Lembang Fault Case Study, West Java, Indonesia, Hydrogeology

Journal, DOI 10.1007/s10040-009-0453-z. [2] Freeze, R.A. dan Cherry, J.A, 1979, Groundwater, Prentice Hall.

[3] IWACO WASECO, 1991, Bandung Groundwater Supplies Report,

unpublished report. [4] Koesoemadinata, R.P. and Hartono, D., 1981, Stratigrafi dan

Sedimentasi Daerah Bandung (The Stratigraphy and Sedimentation of

Bandung Basin), Prosiding Ikatan Ahli Geologi Indonesia (Proceedings of The Annual Meeting of Indonesian Association of Geologist),

Bandung.

[5] Nield, S. P., Townley, L. R., and Barr, A. D., 1994, A framework for quantitative analysis of surface water-groundwater interaction: Flow

geometry in a vertical section, Water Resource Research, 30(8), 2461–

2475. [6] Puradimaja, D.J., 1995, Kajian Atas Hasil-Hasil Penelitian Geologi dan

Hidrogeologi dalam Kaitan dengan Deliniasi Geometri Akuifer

Cekungan Bandung (Overview of Hydrogeological Setting of Bandung Basin), Prosiding Seminar Air tanah Cekungan Bandung (Proceeding of

Seminar on Bandung Basin Groundwater).

[7] Silitonga, P.H., 1973, Peta Geologi Lembar Bandung (Geological Map, Bandung Sheet), Pusat Penelitian dan Pengembangan Geologi

(Geological Research and Development Center), Bandung. [8] Townley, L. R. and Trefry, M. G., 2000, Surface Water–Groundwater

Interaction Near Shallow Circular Lakes: Flow Geometry in Three

Dimensions, Water Resource Research, 36(4), 935–948.

[9] Woessner, W.W., 2000, Stream and Fluvial Plain Ground Water Interactions; Rescaling Hydrogeologic Thought, Ground Water, vol. 38,

no. 3, pp 423-429.

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