XXXVIII IAH Congress Groundwater Quality Sustainability Krakow, 12–17 September 2010

Extended Abstracts

Editors: Andrzej Zuber Jarosław Kania Ewa Kmiecik

University of Silesia Press 2010

abstract id:

129

topic: 2

Groundwater and dependent ecosystems 2.3 Interactions of surface and ground waters title:

Hydrodynamic interaction between surface water and groundwater in volcanic aquifer system of Lake Ciseupan, Cimahi, West Java, Indonesia

author(s): Deny Puradimaja Applied Geology Research Division, Institut Teknologi Bandung, Indonesia, [email protected] Erwin Irawan Applied Geology Research Division, Institut Teknologi Bandung, Indonesia, [email protected] Hendri Silaen Freeport Indonesia, Indonesia, [email protected] keywords: groundwater-surface water interaction, volcanic aquifer system of Lake Ciseupan, Cimahi, West Java, Indonesia

Krakow, Poland 2010

2. Groundwater and dependent ecosystems

INTRODUCTION The Lake Ciseupan was a sand mining area which excavate sands and stones, that has been started from 1980 to 1990. The remains of the activities are dug holes turned in to man-made lake, with undulating depth and 300 meters in diameter. Such holes are surrounded by hills with a height between 690 to 720 meters above sea level (m a.s.l.) (Figure 1).

Figure 1. The location of Ciseupan Lake, Cimahi, West Java, Indonesia.

The lake water is utilized by the surrounding residential and industries. The volcanic aquifer consists of tuff and volcanic sand as part of Cibeureum formation, underlain by impermeable breccias, and bordered by intrusion at the southern part (Table 1 and Figure 2). Volcanic deposits are proven to have high productivity, than older sedimentary rocks. The volcanic aquifers are composed of combination between porous and fractured systems.

XXXVIII IAH Congress

2.3. Interactions of surface and ground waters

Table 1. Stratigraphical unit and aquifer productivity of the study area. Lithological unit

Quartenary

Holocene Pleistocene

Tertiary

Pliocene

Miocene

Silitonga (1973) Lake deposit (Ql)

Sandy Tuff (Qyd) Pumice-Tuff (Qyt)

Kusumadinata and Hartono (1981) Kosambi Fm.

Old volcanic deposit (Qob) Andesite (a), Basalt (b)

Tufaceous Breccia, Lava Sandstone, Conglomerate (Pb) Old sedimentary rock (Cilanang Fm.)

Litologi utama

Clay and sand

Satuan Produktivitas akifer hidrogeologi (IWACO, 1991) Shallow aquifer

Sandy Tuff Cibeureum Fm. Mid aquifer Tufaceous sand Breccias, lahar, Cikapundung Fm. Deep aquifer lava Andesite and basalt

Yoiung volcanics

Age

Breccias Marl

Bed rock

Intermediate High None Low

None

Figure 2. Aquifer section of the study area.

METHODS

A finite difference modelling with Visual ModFlow was used to identify the hydrodynamic interaction between surface water and groundwater around the lake. It was built based on surface geological observation, geophysical and hydrochemical measurements (Figure 3). Desk study (previous study)

Surface geological observation

Geophysical measurement

Hydrochemical measurement

Geological model

Simulation

Results

Figure 3. Aquifer section of the study area.

Krakow, Poland 2010

2. Groundwater and dependent ecosystems

The total area modelled is 810,000 m2, 900 m × 900 m. RESULTS

The result shows that the groundwater flows westward with radial pattern and 0.05 hydraulic gradient (Figure 4 and 5). A

C

Figure 4. Scenarios of groundwater modeling.

B

D

Based on the modelling and hydrochemical analysis, showing bicarbonate dominations and small quantities of ammonium, 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 diverted 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. Scenarios of lake XXXVIII IAH Congress

2.3. Interactions of surface and ground waters

water and groundwater level depletion modelling show 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. B

T

A

R

S

U

pemukiman

B R

C R

D R

Figure 5. Scenarios of groundwater modeling cont.

The conceptualization of hydrogeological model at the man-made lake area reveals a complex interaction between lake and groundwater systems, with also considering the layers of volcanic rocks. This research with various scenarios also shows that groundwater flow around a depressional form can be in divergent pattern rather than always in convergent. This condition is controlled by the slow dip of volcanic layers. REFERENCES

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. Freeze R.A., dan Cherry J.A., 1979: Groundwater. Prentice Hall.

Krakow, Poland 2010

2. Groundwater and dependent ecosystems

Irawan D.E., Puradimaja D.J., Notosiswoyo S., Soemintadiredja P., 2009: Hydrogeochemistry of volcanic hydrogeology based on cluster analysis of Mount Ciremai, West Java, Indonesia. Journal of Hydrology 376 (2009), 221–234, doi:10.1016/j.jhydrol.2009.07.033. IWACO WASECO, 1991: Bandung Groundwater Supplies Report. unpublished report.

Koesoemadinata R.P., 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.

Liang X., Xie Z., Huang M., 2003: A new parameterization for surface and groundwater interactions and its impact on water budgets with the variable infiltration capacity (VIC) land surface model. Journal of Geophysical Research, vol. 108, no. D16, 8613, doi:10.1029/2002JD003090.

Nield S.P., Townley L.R., Barr A.D., 1994: A framework for quantitative analysis of surface watergroundwater interaction: Flow geometry in a vertical section. Water Resource Research, 30(8), pp. 2461–2475.

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). Silitonga P.H., 1973: Peta Geologi Lembar Bandung (Geological Map, Bandung Sheet). Pusat Penelitian dan Pengembangan Geologi (Geological Research and Development Center), Bandung. Townley L.R., Trefry M.G., 2000: Surface Water–Groundwater Interaction Near Shallow Circular Lakes: Flow Geometry in Three Dimensions. Water Resource Research, 36(4), pp. 935–948.

Woessner W.W., 2000: Stream and Fluvial Plain Ground Water Interactions. Rescaling Hydrogeologic Thought, Ground Water, vol. 38, no. 3, pp 423–429.

XXXVIII IAH Congress

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2-vol. set + CD ISSN 0208-6336 ISBN 978-83-226-1979-0