FIELD IDENTIFICATION OF GROUNDWATER POTENTIAL ZONE BY VES METHOD IN SOUTH MALANG, INDONESIA

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 10, Issue 02, February 2019, pp , Article ID: IJCIET_10_02_097 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed FIELD IDENTIFICATION OF GROUNDWATER POTENTIAL ZONE BY VES METHOD IN SOUTH MALANG, INDONESIA Water Resources Engineering Department, Brawijaya University, Indonesia ABSTRACT In order to solve the water scarcity problem in South Malang, East Java, Indonesia, we have attempted to investigate groundwater by assessing the subsurface geology and groundwater potential zones. An attempt had been made to identify the subsurface lithology and aquifer zones by VES (Vertical Electrical Sounding) method in Pagak, Kepanjen, Kromengan and Gondanglegi district. The study area consists of major subsurface litho units like sand, silt, clay, tuff, limestone and andesit. In order to explore the groundwater resources of the study area with an aerial extent of 100 km2, electrical soundings have been conducted by adopting Schlumberger technique in 12 locations with AB/2 200 m and 5 resistivity profiles were acquired. The field data were interpreted and processed qualitatively and quantitatively by using computer software. Considering the geological, geomorphology and hydrogeological conditions the VES interpretation was done. The study has shown that the region is underlain by 5 geoelectric layers within the depth penetrated. The groundwater potential in South Malang reveals four distinct classes (zones) representing Very good, good, moderate and poor groundwater potential in the area. From the interpretation result the VES no. 7 (Pagak), and VES no. 9 (Kepanjen) are found to be prospective for groundwater. It s also identified that Groundwater occurs under water table conditions the depth of water table ranges from 5 to 30 m. Keywords: Identification, Groundwater and VES Method Cite this Article:, Field Identification of Groundwater Potential Zone by VES Method in South Malang, Indonesia, International Journal of Civil Engineering and Technology, 10(2), 2019, pp INTRODUCTION Ground water is one of the most essential natural resources to support human health, economic development and ecological diversity. Due to its several inherent qualities (e.g editor@iaeme.com

2 widespread and continuous availability, excellent natural quality, limited vulnerability, low development cost and drought reliability), it has become an important and dependable source of water supplies in all climatic regions including both urban and rural areas of developed and developing countries [1]. Study of groundwater geology is much useful for all the activities of human life. Groundwater is more advantageous than the surface water. Water scarcity problem affects the human chain and other living things. To meet out the demand of water, people are depending more on aquifers [2]. There are two end members in spectrum of types of aquifers; confined and unconfined (with semi confined aquifer being in between them) [3]. The study area is mainly covered by limestone and hard rock formations, and faces acute water scarcity problem. Occurrence of groundwater in this type of area is limited to fractured and weathered horizons and upper unconsolidated materials. For identifying the groundwater potential in the hard rock terrain, the main target is fractured zone. The present study focuses on identification of fracture zone and its thickness by using geoelectrical resistivity method. The electrical resistivity method is a geophysical method that has been successfully used by several researchers for groundwater investigations [4, 5, 6, 7]. Other geophysical methods used to delineate groundwater potential zones include geotechnical, hydrogeological, remote sensing, and geographical information systems (GIS) [8, 9]. However, some of these methods lack the precision of an insitu analysis. The electrical resistivity method is usually preferable because of the resistivity contrasts obtained when the groundwater zone is reached. Evidence show that this technique has been successfully employed for delineating/mapping of geomaterials in the subsurface that guides exploration of groundwater resources [10, 11, 12, 13]. Surface electrical resistivity surveys were conducted at different locations to obtain subsurface lithological information, identification of horizontal and vertical disposition of aquifer system [14]. The main objective of the investigation is to delineate the subsurface lithology and to assess the groundwater resources of the study location. It also aims to focus on the identification of fracture zone and its thickness by using VES (Vertical Electrical Sounding) method. It is therefore expected that the results obtained from this work would produce detailed groundwater condition and recommend areas within the observatory were deep tube wells could be located Study Area The present study area has falls in South Malang, East Java, Indonesia (Fig.1). The study area lies between the latitudes South ,8 to ,1 and the longitudes East ,5 to ,2. The present study area occupies an aerial extent of 100 sq.km and the relief ranges from 317 m to 531 m above MSL. The study area receives an average annual rainfall of 1950 mm and the average annual temperature is 26,9 C editor@iaeme.com

Field Identification of Groundwater Potential Zone by VES Method in South Malang, Indonesia Figure 1 Location Map of Study Area and Data Collection The study area is located in the southern slope

A volcanic arc was built upon basement rocks from the middle Eocene to the Miocene [15, 16].

3 Field Identification of Groundwater Potential Zone by VES Method in South Malang, Indonesia Figure 1 Location Map of Study Area and Data Collection The study area is located in the southern slope regional uplift, also known as the southern mountains. Based upon this limited evidence, the basement has been interpreted to be arc and ophiolitic rocks of Cretaceous age. A volcanic arc was built upon basement rocks from the middle Eocene to the Miocene [15, 16]. It constitutes of the old andesite volcanic and volcaniclastic suite, initially interbedded with and then more completely overlain by Miocene limestones [16. 17]. These limestones often develop as reefal facies. The limestones show different depth of weathered zone. In the study area groundwater occurs under water table conditions in the joints, fractures and weathered rocks. Generally, the limestones of the study area are highly massive and compact and devoid of joints and fractures making it impervious, which in turn result in poor potential. 2. MATERIALS & METHODS Geophysical prospecting of groundwater comes under both surface and subsurface exploration. Under geophysical prospecting, one of the electrical methods is Schlumberger array of electrical resistivity method. The Schlumberger array was used to ensure deep penetration and for logistics of limited man power in the field [2]. Schlumberger configuration using microprocessor based signal stacking digital resistivity meter of Martiel Geophysics, Type MGG Both the survey procedures resistivity profiling and resistivity sounding (VES) have been carried out. VES has been conducted at 12 locations with AB/2 200 m and 5 resistivity profiles were acquired. The resistivity data have been qualitatively and quantitatively interpreted and analyzed by software packages Resistivity Method The electrical resistivity is the resistance offered by the opposite faces of a unit cube of material to direct current is called as resistivity. In geophysical literature the unit of resistivity is taken as the ohm. m. The resistance (R) of the material having a resistivity (ρ) over a length (L) and surface area of current flow (A) is given by R = ρ L/A. This is governed by Ohms law. The inverse of resistance is termed as conductance [18] editor@iaeme.com

4 2.2. Measurement of Resistivity In general for measuring the resistivity of the sub surface formation four electrodes are required. The current of electrical intensity (I) is introduced between one pair of electrodes called current electrodes which can be identified as A & B. The potential difference produced as a result of current flow is measured with help of another pair of electrodes called potential electrodes represented as M & N. Let Δr represent the potential difference. The apparent resistivity measure is K x Δv/I, where K represents geometrical constant, which can be calculated if we know the electrode arrangements. The basic needs for the resistivity survey are the power source, meter to measure current and potential, electrodes and cables Schlumberger Configuration In schlumberger configuration all the four electrodes are kept in a line similar to that of Wenner but the outer electrode spacing is kept large compared to inner electrode spacing usually more than five times. For each measurement only the current electrodes are moved keeping the potential electrodes at the same locations. The potential electrodes are moved only when the signal become too weak to be measured. The apparent resistivity for this configuration is computed with the formula: Ρ = {[(AB/2)2 (MN/2)2)/MN] x πr} Figure 2 Schlumberger Configuration 2.4. Vertical Electrical Sounding (VES) A series of measurements of resistivity are made by increasing the electrode spacing in successive steps about a fixed point. This method of vertical exploration is known as the expanding electrode method, resistivity sounding or depth probing or vertical electrical sounding (VES). The apparent resistivity values obtained with increasing values of electrode separation are used to estimate the thickness and resistivities of the subsurface formations. VES mainly employed in groundwater exploration to determine the disposition of the aquifers Geoelectrical Parameters The main objective of the quantitative interpretation of VES curve is to obtain the geoelectrical parameters. A geoelectric layer is called by its fundamental characters, resistivity ρ and thickness h. These two parameters are called the primary geoelectrical parameters. The secondary geoelectrical are also important to describe the geoelectric section consisting of several layers. The longitudinal (S) and the total transverse (T), transverse resistivity (T/h) an isotropy (λ) are called the secondary geoelectrical parameters editor@iaeme.com

5 Field Identification of Groundwater Potential Zone by VES Method in South Malang, Indonesia 3. RESULT AND DISCUSSION The field data were interpreted and processed qualitatively and quantitatively by using computer software to obtain the resistivity values of different subsurface layers and their corresponding thickness (Table 1) Interpretation of Resistivity Data The interpretation of resistivity data is done in two stages, 1. Processing of data to get the geoelectric parameters, and 2. These parameters are used to infer the nature of surface lithology on the basis of the local geological knowledge and correlation studies Quantitative Approach The quantitative approach is to get the geoelectric parameters i.e., the true resistivity, layer thickness, etc. The VES data of the study area have been qualitatively and quantitatively analyzed and interpreted using software IPI2WINTM version 2.6.3, a Russian software package of Moscow University. By using Surfer 10TM, resistivity contour maps have been generated for different depth ranges to identify and demarcate the anomaly zones. The IPI2WIN software is used to prepare the VES curves, pseudo sections, geoelectric profiles and geoelectric sections [15]. Table 1 Summary of VES data interpretations with positions VES Location ρ1 ρ2 ρ3 ρ4 ρ5 h1 h2 h3 h4 Error (Ωm) (Ωm) (Ωm) (Ωm) (Ωm) (m) (m) (m) (m) (%) 1 Pagak Pagak Pagak Pagak Kepanjen Kepanjen Kromengan Kromengan Gondanglegi Gondanglegi editor@iaeme.com

Figure 3 Interpretation of Vertical Electrical Sounding Field Curves 3.3. Isoresistivity Maps The isoresistivity maps are the resistivity contour maps.

6 Figure 3 Interpretation of Vertical Electrical Sounding Field Curves 3.3. Isoresistivity Maps The isoresistivity maps are the resistivity contour maps. Accordingly the layer thickness contour maps of the study area have been generated incorporating all the 30 VES data for different formation with their co-ordinates, joining equal layer thickness of the depth of editor@iaeme.com

Field Identification of Groundwater Potential Zone by VES Method in South Malang, Indonesia

The resistivity contour map for first layer, second layer, third layer, fourth layer and fifth

The difference between two consecutive contour lines is termed the contour interval.

The isoresistivity maps can be used for qualitative interpretation of the groundwater and by

The method of qualitative and quantitative interpretations helps us identify good ground water

7 Field Identification of Groundwater Potential Zone by VES Method in South Malang, Indonesia investigation. The resistivity contour map for first layer, second layer, third layer, fourth layer and fifth layer were generated (Fig. 5-9). The difference between two consecutive contour lines is termed the contour interval. The contour maps can be generated using Surfer 10TM software packages. The isoresistivity maps can be used for qualitative interpretation of the groundwater and by quantity by demarcating the low and high layer thickness anomalous zones. The method of qualitative and quantitative interpretations helps us identify good ground water potential zones. a b c d e Figure 4 a. Isoresistivity Map of The 1st layer, b. Isoresistivity Map of The 2nd layer, c. Isoresistivity Map of The 3rd layer, d. Isoresistivity Map of The 4th layer, e. Isoresistivity Map of the 5th layer editor@iaeme.com

3.4. Geoelectrical Profiles All the 12 VES locations studied were made into 5 profiles covering the entire study area (Fig A-E) with definite orientations, traversing different geological formations

8 3.4. Geoelectrical Profiles All the 12 VES locations studied were made into 5 profiles covering the entire study area (Fig A-E) with definite orientations, traversing different geological formations to project a two dimensional subsurface geoelectric section along that profile. All these geoelectric profiles have been generated by IPI2WINTM software package. The geoelectric profiles are the geoelectrical section of each VES locations united into one profile with a definite directional orientation. Each geoelectric profile has two profiles namely Pseudo section displaying the apparent resistivities at different depths below ground level from surface to 200 m depth and the other section with thickness of different geoelectric layers below ground level. The resistivity sections only reflect the interpreted subsurface lithology. The ordinate X axis represent the distance of traverse and the abscissa Y axis represent the depth in meters below ground level. Figure 5 VES Profile Map of The Study Area Profile I The profile-i located in south side of Brantas River. It belongs to Sumberbening groundwater basin. The location considered for this profile is Pagak district. The traverse of the profile is west to eastern part of the study area (Figure 5). Profile II The profile-ii located in south side of Sengguruh Reservoir and south side of Lesti River. It belongs to Sumberbening groundwater basin. The location of this profile includes Pagak and Bantur district. The traverse of the profile is south to northern part of the study area (Figure 5) editor@iaeme.com

9 Field Identification of Groundwater Potential Zone by VES Method in South Malang, Indonesia Profile III The profile-iii located in north side of Sengguruh Reservoir and north side of Brantas River. It belongs to Brantas groundwater basin. The location considered for this profile is Kepanjen district. The traverse of the profile is south to northern part of the study area (Figure 5). Profile IV The profile-iii located in north side of Sutami Reservoir and north side of Brantas River. It belongs to Brantas groundwater basin. The location considered for this profile is Kromengan district. The traverse of the profile is west to eastern part part of the study area (Figure 5). Profile V The profile-iii located in east side of Brantas River. It belongs to Brantas groundwater basin. The location considered for this profile is Gondanglegi district. The traverse of the profile is east to western part of the study area (Figure 5). 4. CONCLUSION Vertical Electrical Sounding using Schlumberger electrode configuration was conducted in South Malang, East Java, Indonesia to determine the underground water potential and the lithological setting in terms of aquifer distribution. The study has shown that the region is underlain by 5 Geo-electric layers within the depth penetrated. The groundwater potential in South Malang reveals four distinct classes (zones) representing Very good, good, moderate and poor groundwater potential in the area. The very good groundwater potential zone mainly encompasses good be recharged along the river alluvium. The good groundwater potential zone mainly covered by regions with groundwater in joints & some quantity of ground water will be recharged held in the weathered zone subsequently fractured planes. It s also identified that Groundwater occurs under water table conditions the depth of water table ranges from 5 to 30 m. Groundwater recharge takes place through precipitation of rain water aided by morphological features of ground surface around the major river systems. It s also demarcated that the areas in the upper part of the study area is not suitable for groundwater storage and also indicates the deep availability of water very below the ground. The poor groundwater potential is due to the higher slope and unfavorable geology and geomorphology in this zone. These prospective groundwater zones can provide a basis for the detailed hydro-geologic and/or geophysical investigations needed for well sitting and proper management of scarce groundwater resources. ACKNOWLEDGEMENTS I would like to express my appreciation to University of Brawijaya and Malang Regency officer for providing secondary data and interview season with local community. REFERENCES [1] Todd D.K. and Mays, L.W Groundwater Hydrology, 3rd ed. New York: John Wiley & Sons.Srinivasan K, Poongothai S, and Chidambaram S Identification of Groundwater Potential Zone by Using GIS and Electrical Resistivity Techniques in and around the Wellington Reservoir, Cuddalore District, Tamilnadu, India. European Scientific Journal, Vol. 9 No. 17, pp [2] Srinivasan K, Poongothai S, and Chidambaram S Identification of Groundwater Potential Zone by Using GIS and Electrical Resistivity Techniques in and around the Wellington Reservoir, Cuddalore District, Tamilnadu, India. European Scientific Journal, Vol. 9 No. 17, pp editor@iaeme.com

10 [3] Ogungbe A.S, J.A Olowofela, O.O Oresanya, and A.A Alabi Mapping of unconfined aquifer using vertical electrical sounding (VES) at Lagos State University (Lasu) Archives of Physics Research, Vol. 2 No. 2, pp [4] Niwas, S., and de Lima, O. A. L Aquifer parameter estimation from surface resistivity data. Groundwater, Vol. 41 No. 1, pp [5] Sultan, S. A., Santos, F. A. M., Alla, M. A. A., and Mekhemer, H. M Application of the resistivity/gravity joint inversion technique for Nubian sandstone aquifer assessment on the area located at the central part of Sinai, Egypt. Journal of Geophysics Engineering, Vol 7, pp [6] Adepelumi, A. A., Yi, M. J., Kim, J. H., Ako, B. D., and Son, J. S Integration of surface geophysical methods for fracture detection in crystalline bedrocks of southwestern Nigeria. Hydrogeology Journal, Vol. 14, pp [7] Seaton, W. J., and Burbey, T.J Evaluation of two-dimensional resistivity methods in a fractured crystalline-rock terrain. Journal of Applied Geophysics, Vol. 51, pp [8] Adiat, K. A. N., Nawawi, M. N. M., and Abdullah, K Assessing the accuracy of GIS-based elementary multi criteria decision analysis as spatial prediction tool: a case of predicting potential zones of sustainable groundwater resources. Journal of Hydrology, Vol , pp , [9] Madrucci, V., Taioli, F., and De Araujo, C. C Groundwater favorability map using GIS multicriteria data analysis on crystalline terrain, Sao Paulo State, Brazil. Journal of Hydrology, Vol. 357, pp [10] Anudu, G. K., Onwuemesi, A. G., Ajaegwu, N. E., Onuba, L. N., and Omali, A. O Electrical resistivity investigation for groundwater in the basement complex terrain: a case study of Idi-Ayunre and its environs, Oyo state, southwestern Nigeria. Natural and Applied Sciences Journal, Vol. 9 No. 2, pp [11] Metwaly, M., Elawadi, E., Sayed, S., Moustafal, R., Al Fouzan, F., Mogren, S., and Al Arifi, N Groundwater exploration using geoelectrical resistivity technique at Al- Quwy yia area central Saudi Arabia. International Journal of Physical Sciences, Vol. 7 No. 2, pp [12] Okhue, E. T., and Olorunfemi, M. O Electrical resistivity investigation of a typical basement complex area. Journal Mining Geology, Vol. 2, pp [13] Porsani, J. L., Elis, V. R., and Hiodo, F.Y Geophysical investigations for the characterization of fractured rock aquifers in Itu, S.E. Brazil. Journal of Applied Geophysics, Vol. 57, pp [14] Nagarajan N, Poongothai S, Badrinarayanan TS, Sridhar K Identification of Groundwater Potential in Contact zones by using GIS and Electrical Resistivity Analysis An International Journal (ESTIJ), Vol. 1 No. 1. [15] van Bemmelen, R.W The Geology of Indonesia. The Hague: Government Printing Office. [16] Smyth, H Eocene to Miocene basin history and volcanic activity in East Java, Indonesia [Ph.D. thesis]: University of London. [17] Soeria-Atmadja, R., Maury, R.C., Bellon, H., Pringgoprawiro, H., Polve, M., and Priadi, B Tertiary magmatic belts in Java. Journal of Southeast Asian Earth Sciences, Vol. 9, pp [18] Ramanuja chary K. R., and T. Gangadhra Rao A monograph on groundwater exploration by resistivity, S.P and well logging techniques. Hyderabad: The Integrated Geo Instruments & Services [19] Ali H. Al-Aboodi and Zaid N. Hashim, Estimation of Groundwater Vulnerability in Bahr Al-Najaf Area, Middle of Iraq, International Journal of Civil Engineering and Technology (IJCIET) 9(13), 2018, pp editor@iaeme.com

11 Field Identification of Groundwater Potential Zone by VES Method in South Malang, Indonesia [20] Sudhakar Singha and Soumya. S. Singha Groundwater Depletion Scenario in Balodabazar Block, Balodabazar, Chhattisgarh, India. International Journal of Civil [21] M. Satish Kumar, M.V.Raju, G.Venu Ratna Kumatr and Hepsibah Palivela, Evaluation of Groundwater Pattern in Black Cotton Soils Using Geo Spatial Technology A Model Study. International Journal of Civil Engineering and Technology, 8(5), 2017, pp [22] V.S.S.R. Gupta, R. Srinivasa Rao and K. Divya, Evaluation of Groundwater Quality using Multivariate Statistical Techniques and GIS - A Case Study. International Journal of Civil Engineering and Technology, 8(8), 2017, pp editor@iaeme.com

Identification of aquifer zones by VES method: A case study from Mangalore block, Tamil Nadu, S. India

Identification of aquifer zones by VES method: A case study from Mangalore block, Tamil Nadu, S. India Available online at www.scholarsresearchlibrary.com Scholars Research Library Archives of Applied Science Research, 011, 3 ():414-41 (http://scholarsresearchlibrary.com/archive.html) ISSN 0975-508X CODEN