Determination of Groundwater System by Using Hydroisotope Method of Sei Bingei and Surrounding Areas, Langkat Regency, North Sumatra

Journal of Applied Geology, vol. 5(1), 2020, pp. 13–24 DOI: http://dx.doi.org/10.22146/jag.51627

Azmin Nuha1, Heru Hendrayana*1, Agus Budhie Wiyatna2, Doni Prakasa Eka Putra1, and Azwar Satrya Muhammad3

1Department of Geological Engineering, Faculty of Engineering, Universitas Gadjah Mada, Yogyakarta, Indonesia 2Department of Nuclear Engineering and Engineering Physics, Universitas Gadjah Mada, Indonesia 3Water Resources and Process Department, Aqua Danone, Indonesia

ABSTRACT. Groundwater plays an essential role in the supply of water for various purposes, so the use of groundwater must also pay attention to the balance and preservation of the resource itself. The formation of springs can be used as a reference to evaluate the quantity, quality, and continuity of the ﬂow of water coming out of the spring. The shape and size of the spring recharge area are signiﬁcant for determining the spring protection area, both in quantity and quality. Comprehensive research into the hydrogeological system is carried out through geological, hydrogeological, and hydroisotope studies. The purposes of this study are (1) to determine the LMWL (Local Meteoric Water Line) of the Sei Bingei Region, (2) to determine the recharge area for the Sei Bingei area and (3) to determine the genesis or origin of groundwater that appears in the Sei Bingei area. To answer the objectives, the campaign of water sampling of 23 groundwater and 15 rainwater samples were taken during different months and measure for the 2H/1H(δD) and 18O/16O (δ18O) isotope ratios. Isotopic ratios are used to assess the origin and recharge elevation of water. The results of the study are (1) the LMWL (Local Meteoric Water Line) equation in the Langkat area is δD = 8.052 × δ18O + 14.162, (2) the main groundwater recharge area is located above 883 masl and (3) based on its isotopic ratios, groundwater in the study area can be differentiated into 3 genesis group: (a) Genesis-A Groundwater Group representing shallow-local groundwater system originated from local direct rainfall, (b) Genesis-B Groundwater Group is the main deep groundwater system in the research with the lowest value of the isotopic ratio of δ18O and δD, and (c) Genesis-C Groundwater Group is groundwater which it may come from the intermediate system between shallow and deeper groundwater system. Keywords: Groundwater genesis · Hydroisotope · Groundwater recharge area.

1B ACKGROUND concrete steps to minimize the negative impacts Groundwater is a resource that has an essen- caused by groundwater exploitation activities. tial role in providing water needs for various Research on springs is fundamental to explain purposes, so the use of groundwater must pay the origin of groundwater formation in springs. attention to the balance and its preservation. The genesis of a spring can be used as a refer- Groundwater is one of the water resources that ence to evaluate the quantity, quality, and conti- has now become a national problem, so it needs nuity of water ﬂow at a spring. Besides, know- ing the shape and extent of the recharge area

*Corresponding author: H. HENDRAYANA, Depart- of spring is essential to determine the conserva- ment of Geological Engineering, Universitas Gadjah tion area for the spring. Mada. Jl. Graﬁka 2 Yogyakarta, Indonesia. E-mail: The application of hydroisotope technology [email protected]

2502-2822/© 2020 The Authors. Open Access and published under the CC-BY license. NUHA et al. has been used to determine groundwater con- tion of surface water. While the infiltrated wa- servation areas with high accuracy for the bene- ter is shielded by the aquifer from evaporation, fit of environmental protection at the Wonosobo thus preserving the isotopic composition of the Region (Wijatna et al., 2017). Hendrayana et al. rainwater. The Groundwater flows in aquifers (2019) used a similar technique to determine the as shallow groundwater and deep groundwa- origin of groundwater in springs for spring pro- ter. Shallow groundwater has the short cir- tection at Mambal Region. The Sei Bingei area culating with a near exit through a locally-fed is a new area for the development of residential groundwater system. and industrial areas. The food and beverage in- Meanwhile, the deeply-circulating ground- dustry is developing in this area, it is necessary water system has exit points in regionally-fed to protect water resources to ensure the conti- spring (Mazor, 2004). The isotopic composition nuity of the industrial activities. Comprehen- of the deep groundwater type is typically cal- sive research on the hydrogeological system of culated using the rainwater data. The derived the Sei Bingei area through hydro-isotope stud- isotopic values, in terms of Deuterium (2H) and ies is used to determine the recharge area for Oxygen-18 (18O), are collectively called the Me- water sources, including the shape and extent teoric Water Index (MWI) (Salonga, 2015) or accurately so that the water conservation pro- Meteoric Water Line (Crawford et al., 2014). gram can be optimally achieved. IAEA (2014) defined that the Global Meteoric Based on the above facts, the purpose of this Water Line (GMWL) used to δ2H = 8 δ18O + study is to determine the groundwater flow sys- 10. The primary source δ2H and δ18O data for tem and the origin of groundwater in the Sei GMWL is the Global Network of Isotope in Pre- Bingei and surrounding areas. The research ob- cipitation (GNIP) globally. The local precipita- jectives were (1) to determine the LMWL (Local tion data is called Local Meteoric Water Line Meteoric Water Line) of the Sei Bingei Region, (LMWL), (Clark and Fritz,1997). (2) to determine the groundwater recharge area Local Meteoric Water Line (LMWL) is a lin- for the Sei Bingei Region and (3) to determine ear correlation of δ2H and δ18O contents ob- the genesis or origin of groundwater that ap- served in the specific area. LMWL is useful pears in the Sei Bingei Region. for the evaluation of the origin of waters. If the values of a pair of isotopes ratio determine 2L OCATION from groundwater samples plot in the range of The research area was in the Sei Bingei area, the Meteoric Water Line (MWL), it means that Langkat Regency, North Sumatra Province (Fig- the groundwater was recharged by local pre- ure 1). The delineation of sub-watersheds bor- cipitations and come from meteoric water. Lo- ders the study area by considering local geolog- cal Meteoric Water Line (LMWL) is obtained ical conditions. The study area is volcanic hills from the analysis of monthly rainwater sam- with gentle slopes to steep slopes and in the ples in a specific area. The LMWL is com- form of gently sloping terrain and steep slopes monly used to determine the relationship of in the south. Elevation between 25–2,200 masl. surface/groundwater to a potential precipita- Geologically, the upstream area consists of mas- tion source or to determine the degree of water sive volcanic rocks in the form of andesite and evaporation enrichment (Crawford et al., 2014). dacite intrusion which are covered by autoclas- The determination of the groundwater tic breccia and lava flows, whereas in the down- recharge area is closely related to the calcu- stream areas dominated by lahar deposits in the lation of LMWL because of LMWL as a basis form of pebbly sand and pebbly clay. for whether the water comes from rainwater/ surface water or groundwater. LMWL equation 3T HEORETICAL BACKGROUND can be applied as a reference in natural iso- According to the hydrological cycle, ground- tope research to study groundwater dynamics water comes from the infiltration of rainwater in the hydrology cycle and to determine the towards the subsurface. The surface water is groundwater recharge area (Mook and Rozan- susceptible to be evaporation, which degree of ski, 2000). evaporation will change the isotopic composi- To determine the effect of elevation and rain-

14 Journal of Applied Geology DETERMINATION OF GROUNDWATER SYSTEMBY USING HYDROISOTOPE METHODOF SEI BINGEI

430000 435000 440000 445000 450000 MAP OF 0 0 0 0

0 TUNGGURONO 0 5 PADANG BRAHRANG PUJI DADI 5 RESEARCH AREA AND

9 LAU MULGAP SUKA MAJU 9 3 KUTA PARIT TANJUNG MERAHE NAMO RUBE JULU 3 WATER SAMPLING POINTS TANAH SERIBU SELESAI SEI MENCIRIM TANAH MERAH EMPLASMEN KWALA MENCIRIM SEI BINGEI, LANGKAT, SUMUT PADANG CERMIN BHAKTI KARYA MA 8 SUKA RAYA BINJAI SELATAN !( BEKIUN PERKEBUNAN BEKIUN SAWIT REJO 0 0

0 BELA RAKYAT NAMBIKI PASAR VI KWALA MENCIRIM 0 0 0

0 PURWO BINANGUN SILEBO LEBO 0 9 9 0 1.25 2.5 5 7.5 10

3 DALAN NAMAN BALAI KASIH 3 AHL-5 Kilometers PEKAN KUALA ").! GUNUNG TINGGI PASAR IV NAMU TERASI SISTEM PROYEKSI...... DECIMAL DEGREE TUNTUNGAN I DATUM...... WGS 84 SEI PENJARA SG 4 NAMU UKUR UTARA Sumber : - Peta Rupa Bumi Indonesi, BIG !( [ - Survai Lapangan, 2018 SIDO MAKMUR RAJA TENGAH LAU BAKERI 0 MA 11 SB 2 0 0 MA 4 0 PASAR 8 NAMU TERASI 0 !( MA 7 !( 0 LEGEND : 5 SG 2 !( 5 8 BLANKAHAN !( 8 3 !( SUKA RENDE 3 NAMU UKUR SELATAN District Boundary SUKA DAMAI SG 1 SUKA DAMAI !( Village Boundary MEKAR JAYA SAMPE CITA BERUAM DURIAN LINGGA KUTALIMBARU National Road River GUNUNG AMBAT MA 9 SG 3 0 !( 0 Collector Road 0 !( SB 7SB 8 0 0 !( 0 0 !( 0 Local Road Elevation Countour 8 BESADI PARIT BINDU MA 10 8 3 AHL-4 !( !(SG 7 3 ") PEKAN SAWAH Hidrogeology SIMPANG KUTA BULUH PASAR X Sei Bingei Borehole MA 5 PERPANDEN Boundary .! MA 3 !( SB 1 SG 5 !(!( !( ") Rainwater Sampling

0 SUKA DAME 0

0 AHL-3 0

0 MA 2 NAMO MIRIK 0 5 !( 5 !( Groundwater Sampling 7 ") 7 3 3

PARANGGUAM BUAH NABAR MA 6 GARUNGGANG AHL-2 !( ")RUMAH GALUH TANJUNG GUNUNG 0 KUALA TANJUNG BERINGIN 0 0 SG 6 0 0 0

0 !( 0 7 7 3 3

BELINTENG PUANG AJA ADIN TENGAH MA 1 AHL-1!( SEI BINGAI UJUNG DELENG ") INDEX MAP

ACEH TENGAH 0 0 ACEH TIMUR NAGANRAYA ACEH TENGAH LANGKAT 0 0 ACEH TAMIANGLANGKAT

0 SUKA MAKMUR 0 5 5 GAYOLUES

6 UJUNG BANDAR 6 3 3 ACEH BARAT DAYA LANGKAT TELAGAH KOTA MEDAN KUTALIMBARU KOTA BINJAI DELISERDANG

ACEH TENGGARA SERDANG BEDAGAI SUKA MAKMUR KOTA TEBINGTINGGI KARO ACEH SELATAN KARO BANDAR BARU SIKEBEN SIMALUNGUNKOTA PEMATANGSIANTA 0 0 KOTA TANJUNGBALAI

0 0 DAIRI

0 0 WPNK ASAHAN SAMOSIR 0 SIBOLANGIT 0 SIMALUNGUN

6 MARTELU 6 SAMOSIR

3 3 PAKPAKBHARAT SAMOSIR ACEH SINGKIL SAMOSIR KUTA KEPAR TOBASAMOSIR TIGANDERKET LABUHANBATU HUMBANG HASUNDUTANTOBASAMOSIR TAPANULI UTARA BERASTAGI BUKUM KUTA GUGUNG NAMAN TERAN BELINTENG MERDEKA DAULU KUTA MBELIN MERDEKA DOLAT RAYAT KEBAYAKEN GUNG PINTO NDESKATI JARANGUDA

430000 435000 440000 445000 450000 DEPARTMENT OF GEOLOGICAL ENGINEERING FACULTY OF ENGINEERING UNIVERSITAS GADJAH MADA Gedung Teknik Geologi FT UGM, Jl. Grafika 2, Kampus UGM, Yogyakarta 55281 Tel.: 0274-513668, Fax.: 0274-546039, E-mail : [email protected]

FIGURE 1. Map of the research area and water sampling points.

Journal of Applied Geology 15 NUHA et al. fall on the rainwater isotopes composition, Most water (other than seawater) has an iso- measurements, and analysis of 2H/1H and tope ratio δD and δ18O < 0 (negative value) 18O/16O isotope ratios were performed. The or based on Equations2 and3h will apply (Craig, equation resulting from the influence of ele- 1961): a) if Rsmpl > Rstd then the value of δsmpl vation on the isotope composition (δ18O, δD) > 0, means that the D or 18O in the water sam- of rainfall that falls in the Langkat region is ple is more productive (enriched) than SMOW; called the Local Meteoric Water Line (LMWL)– b) if Rsmpl < Rstd then the value of δsmpl < 0, Langkat. The origin of groundwater can be means that the D or 18O level in the water sam- predicted from the equation formed on the ple is more reduced (depleted) than SMOW; c) 18 influence of elevation on the O isotope ratio. if Rsmpl = Rstd, then δsmpl = 0, means that the Standard mean ocean water (SMOW) is a D or 18O in water = SMOW or also can be con- standard for calibrating the composition of iso- cluded that the water comes from seawater. tope ratio in the water sample. SMOW is from Rainwater sample has the ratio of δD and International Atomic Energy Agency (Mook δ18O depleted than ratio δD and δ18O of sea- and Rozanski, 2000). Based on the considera- water due to the higher of elevation, the lower tion that the largest evaporation process occurs of temperature, vapor will be condensed again. in the ocean, so the seawater is used as a refer- Rainwater that falls on the higher elevation has ence or SMOW. SMOW values according to in- a lower δD and δ18O isotope ratio. This phe- ternational standards are presented in Table 1. nomenon cause’s groundwater from higher el- 1 18 16 The value of D/ H and O/ O isotope ratio evation has δD and δ18O smaller than ground- from rainwater is expressed relative to SMOW water from the lower elevation (Craig, 1961). 18 and written with the notation (δD ) and (δ O Besides the elevation influence, δD and δ18O ) using Equations [2,3]. h value also depend on rainfall intensity. The h higher rainfall, δD and δ18O ratio of rainwater Rsmpl − Rstd δ = × 1000 (1) are getting depleted and the lower rainfall in- R std tensity will be more enriched. Due to the rainfall, pressure, and air temperature, and air hu- " # D D midity always fluctuated, so the value of δD − and δ18O in every sample location should be H smpl H SMOW D = × 1000 (2) calculated with this Equations [4,5]. D n H SMOW 18 ∑ Pi δi O = δ18O = i 1 (4) " # n 18O 18O − ∑Pi 16 16 i=1 O smpl O SMOW 18O = × 1000 18O n Pi δiD 16O ∑ SMOW = i=1 (3) δD n (5) with: ∑Pi 1 18 16 i=1 Rsmpl = isotope ratio (D/ H or O/ O) water sample with: 1 18 16 18 18 16 Rstd = isotope ratio (D/ H or O/ O) sea- δ O = average isotope ratio O/ O relative water to SMOW in rainwater, δ = isotope ratio (D or 18O) water sample rel- δD = average isotopeh ratio D/1H relative to ative to the SMOW, SMOW in rainwater, 1 18 18 16 δD = isotope ratioh D/ H water sample rela- δi O = isotope rationh O/ O relative to tive to SMOW, SMOW in rainfall to (i), 18 18 16 1 δ O = isotopeh ratio O/ O water sample δiD = isotope ration D/h H relative to SMOW relative to SMOW, in rainfall to (i), h h

16 Journal of Applied Geology DETERMINATION OF GROUNDWATER SYSTEMBY USING HYDROISOTOPE METHODOF SEI BINGEI

TABLE 1. Isotope ratio of SMOW (Craig, 1961).

Ratio, H/L (= Rstd) Value, H/L %H %L D/1H 0.00015576 0.015574 99.984426 Standard Mean Ocean 17O/16O 0.0003799 0.0379 99.76206 Water (SMOW) 18O/16O 0.0020052 0.0020052 99.76206 Note: H = Heavy isotopes and L = Light isotopes

Pi = amount of rainfall between the sample long dry season, rainwater sampling can only (i − 1) to (i), mm per month. be done starting at the beginning of the rainy The value of δD and δ18O in some rainwa- season. Rainwater sampling (AHL) was car- ter samples is linear and follow the Equation ried out at 5 locations, representing upstream 6. Equation6 depends on geographical factors, and downstream areas (high altitude to low particularly concerning temperature, humidity, altitude). Each location was taken three times thickness, and precipitation. From rainwater in December 2018, January and February 2019 samples taken globally through 91 rainfed sta- which have also different intensities of rain- tions worldwide, d = 10, so it can be written fall. The coordinates and elevation of rainwater as the Global Meteoric Water Line (GMWL) in sampling locations are presented in Table 2. the following formulas (Kresic and Stevanovic, The number of rainwater samples was 15 in 2010; Clark and Fritz, 1997; Craig, 1961). total. To use rainfall data from Meteorology, Climatology, and Geophysics Agency (BMKG), δD = a × δ18O + d (6) the location of rainwater sampling is strive to be within the coverage radius of BMKG nearest And for analysis of elevation inﬂuence to rainfall monitoring station. Laboratory anal- δ18O can be obtained from plotting graph of ysis of hydroisotope content was carried out δ18O ratio vs. elevation, that will allow this lin- at the Earth and Environmental Laboratory, ear Equation7; PATIR-BATAN Jakarta. All groundwater and rainwater samples were analyzed to determine δ18O = α × elevation − β (7) the isotope ratios δD and δ18O using the Liquid tool-Water Stable Isotope Analyzer (LWSIA)- E = c × δ18O + d (8) LGR DLT-100.

Based on Equation7, if the data show the ra- 5R ESULTS AND DISCUSSION tio of δ18O groundwater, then the elevation of the origin or groundwater recharge area can be 5.1 Local Meteoric Water Line estimated. Determination of Local Meteoric Water Line (LMWL) is done by analyzing rainwater sam- 4R ESEARCH METHOD ples in 5 locations having different elevations. The method to carry out this research is by Following international conventions, the aver- conducting a campaign of water sampling age mean ratio and the actual ratio of isotope 1 18 16 of groundwater and rainwater samples also D/ H and O/ O of rainwater samples in De- measure the 2H/1H and 18O/16O isotope ra- cember 2018, January and February 2019 must tios on the water samples. Isotopic ratios are be stated relative to the Standard Mean Ocean used to assess the origin and recharge ele- Water (SMOW), which can be seen in Table 3. vation of water. The groundwater sampling Every month rainfall is ﬂuctuating and this locations were carried out in existing springs phenomenon affects the isotope ratios δD and 18 and wells in the research area. Twenty-three δ O. These results can be seen in the results groundwater samples from dug wells (SG), of rainwater isotope ratio measurements at the deep well/borehole (SB), and springs (MA) same elevation and taken different months or were sampled in September 2019 during the different rainfall intensities, showing different dry season. In the beginning, it was planned values. Theoretically, the higher the rainfall, the 18 to take also rainwater sample but due to the smaller the isotope ratios δD and δ O. Con-

Journal of Applied Geology 17 NUHA et al.

TABLE 2. The coordinates and elevation of rainwater sampling locations in Langkat Regency, North Sumatra.

Coordinate (UTM) Elevation No Code Location X Y (masl)

1 AHL-1 Air Babarsari Pool Lau Kulap, Garunggang Village, 431232 366528 712 Kuala Sub District, Langkat Regency 2 AHL-2 (Open Field) Rumah Galuh Village, Sei Bingei 433987 371819 550 Sub-District, Langkat Regency 3 AHL-3 Tugu Juang 45 Rumah Galuh Village, Sei Bingei 434733 374890 425 Sub-District, Langkat Regency 4 AHL-4 Telagah Str, Simpang Kuta buluh Village, Sei Bingei 436388 378851 260 Sub-District, Langkat Regency 5 AHL-5 Namu Ukur Str, North Ukur Village, Sei Bingei 441444 388563 85 Sub-District, Langkat Regency

-32 800 LMWL-Langkat -34 GMWL 700 Elevation = -624.98 -36 600 -38 18 O + 14.162 × δ 500 × δ 18 -40 O - 3786, R 400 δD = 8.052 D (‰) -42 2 = 0.99 δ 300 -44 18 O + 10

× δ Elevation (masl) -46 200 δD = 8 -48 100 -50 0 -7.5 -7 -6.5 -6 -5.5 -5 -7.2 -7 -6.8 -6.6 -6.4 -6.2 δ18O (‰) δ18O (‰)

FIGURE 2. Langkat local meteoric water line FIGURE 3. Elevation versus isotope ratio δ18O of (LMWL) compare to global meteoric water line rainwater. (GMWL).

Rainwater on of AHL-5 (85 masl) has a more versely, the lower the rainfall, the value of the enriched isotope ratio, δD = -36.093 and δ18O 18 isotope ratios δD and δ O will be even higher. = -6.211 ; and vice versa rainwaterh at high el- 18 Therefore the isotope ratios δD and δ O for evation sites,h AHL-1 (712 masl) has more de- rainwater samples are averaged by taking into pleted isotope ratios, δD = -43.510 and δ18O account the influence of monthly average rain- = -7.165 (Table 4). The results ofh this mea- fall values at each elevation. The results of the surementh are following the theory which states 18 calculation of the isotope ratios δD and δ O in that the higher the elevation, the isotope ratios rainwater by taking into account the variation δD and δ18O in rainwater are depleted and vice in rainfall are presented in Table 4. versa. Based on rainwater isotope data of AHL-1, AHL-2, AHL-3, AHL-4, and AHL-5 as seen in 5.2 δ18O vs Recharge Elevation Table 4, the graph δ18O versus δD is made to If the data in Table 4 draw to a graph repre- obtain the LMWL curve in the Langkat region. senting the isotope ratio δ18O vs elevation (E), Figure Figure 2 displays the LMWL curve rela- the graph shows a linear relationship between tive to the Global Meteoric Water Line (GMWL) both parameters and it is clearly shown that on as a comparison. From Figure Figure 3 it is the higher elevation, the isotope ratio δ18O rain- found that the LMWL-Langkat equation is δD water is depleted (Figure 3), which can be cal- = 8.052 × δ18O + 14.162, with the coefficient of culated by the equation: Elevation = -624.98 × determination (R2) 0.9949 of the linear correla- δ18O − 3786, with the coefficient of determination. tion, R2 = 0.99905.

18 Journal of Applied Geology DETERMINATION OF GROUNDWATER SYSTEMBY USING HYDROISOTOPE METHODOF SEI BINGEI

TABLE 3. The isotope ratio value of δD and δ18O of Langkat rainwater relative to SMOW.

δD, δ18O, No Code Elevation (masl) Dec-18 Jan-19h Feb-19 Dec-18 Jan-19h Feb-19 1 AHL-1 712 -45.59 -43.16 -41.22 -7.32 -7.15 -6.98 2 AHL-2 550 -43.11 -42.37 -40.88 -7.82 -6.89 -6.02 3 AHL-3 425 -41.94 -39.54 -38.37 -7.49 -6.69 -5.91 4 AHL-4 260 -38.94 -36.89 -35.82 -6.99 -6.49 -5.63 5 AHL-5 85 -37.49 -35.99 -34.39 -6.76 -6.29 -5.39

TABLE 4. Langkat rainwater isotope ratio as a function of elevation.

Elevation Average isotope No. Location Code (masl) δD, δ18O, 1 Air Babarsari Pool Lau Kulap, Garunggang Village, AHL-1 712 -43.510h -7.165h Kuala Sub-District, Langkat Regency 2 (Open Field) Rumah Galuh Village, Sei Bingei AHL-2 550 -42.225 -6.988 Sub-District, Langkat Regency 3 Tugu Juang 45 Rumah Galuh Village, Sei Bingei AHL-3 425 -40.095 -6.766 Sub-District, Langkat Regency 4 Jalan Telagah, Simpang Kuta Buluh Village, Sei AHL-4 260 -37.344 -6.433 Bingei Sub-District, Langkat Regency 5 Namu Ukur Str, North Namu Ukur Village, Sei AHL-5 85 -36.093 -6.211 Bingei Sub-District, Langkat Regency

The above equation can be used to determine 5.3 Groundwater Genesis and Groups the recharge elevation of groundwater. As the Despite the above consideration, the isotope ra- 18 isotopic ratio of δ O assume to be similar af- tio data δD and δ18O of groundwater samples ter the water enters the groundwater system. at least can be used to determine the genesis 18 Based on the above equation and the value δ O group of each groundwater sample relative to on the groundwater samples listed in Table 5, LMWL-Langkat (see Figure 5 and Figure 6). it is concluded that on the case of springs and Based on Figure 5, the groundwater in the study deep well in the research area, the recharge ele- area can be differentiated into 3 groundwater vation comes mainly from an altitude above 883 genesis, namely: masl (Figure 4). There are two considerations regarding the a. Genesis-A group is a groundwater source result of the main recharge area. First, due to no with isotope ratios similar to the ratio of rainwater sample coming from or near the top rainwater isotopes that fall at the same el- of the mountain (higher than 900 masl), the re- evation. Members of this group are MA-1 lationship between isotopic ratio δ18O with ele- and SB-2. The groundwater of MA-1 and vation may be used with concern. Two, the dif- SB-2 does not come from the most recharge ference of sampling time and season between area elevation but comes directly from lo- groundwater and rainwater sample may affect cal rainwater. the result of the analysis. According to Clark b. Genesis-B group is a groundwater source (2015), there is an isotopic ratio sensitivity of with the commonly lowest value of iso- the groundwater system to recharge frequency topic ratios. There are 17 groundwater and drought. Groundwater near the water table sources including SB Sei Bingei; and other may still ﬂuctuate within 1 to 2 per mil for δ18O sources, such as MA-2, MA-3, MA-4, MA- during the rainy and dry season. 5, MA-6, MA-7, MA-8, MA-10, MA-11, SB- 1, SG- 1, SG-2, SG-3, SG-4, SG-5, and SG-6. Most of this groundwater originated from an elevation above 883 masl.

Journal of Applied Geology 19 NUHA et al.

430000 435000 440000 445000 450000

MENCIRIM MEDAN KRIO GROUNDWATER 0 BINJAI ESTATE 0

0 SUKA PULUNG 0 PADANG BRAHRANG TUNGGURONO TELAGA SARI 0 PUJI DADI 0 RECHARGE MAP 5 LAU MULGAP TANJUNG MERAHE 5

9 KUTA PARIT SUKA MAJU 9 3 NAMO RUBE JULU 3 OF SEI BINGEI BOREHOLE TANAH SERIBU SEI MENCIRIM SELESAI TANAH MERAH EMPLASMEN KWALA MENCIRIM LANGKAT, SUMATERA UTARA PADANG CERMIN BHAKTI KARYA SUKA RAYA

BINJAI SELATAN SAWIT REJO BEKIUN PERKEBUNAN BEKIUN 0 0

0 BELA RAKYAT NAMBIKI PASAR VI KWALA MENCIRIM 0 0 0 0 1.25 2.5 5 7.5 10 0 PURWO BINANGUN SILEBO LEBO 0 9 9 Kilometers

3 DALAN NAMAN BALAI KASIH 3 PEKAN KUALA GUNUNG TINGGI .! SISTEM PROYEKSI...... DECIMAL DEGREE PASAR IV NAMU TERASI TUNTUNGAN I DATUM...... WGS 84 SEI PENJARA NAMU UKUR UTARA [ SIDO MAKMUR RAJA TENGAH LAU BAKERI

0 NAMORIH 0 0 PASAR 8 NAMU TERASI 0 LEGEND : 0 0

5 BLANKAHAN 5 8 NAMU UKUR SELATAN SUKA RENDE 8 District Boundary 3 3 SUKA DAMAI Village Boundary SUKA DAMAI MEKAR JAYA SAMPE CITA BERUAM DURIAN LINGGA KUTALIMBARU National Road River GUNUNG AMBAT Collector Road 0 KWALA LAU BICIK 0 0 0

0 BINTANG MERIAH 0 Elevation Countour 0 BESADI 0 Local Road

8 PARIT BINDU 8 3 3 PASAR X Hidrogeology SIMPANG KUTA BULUH .! Sei Bingei Borehole PEKAN SAWAH PERPANDEN Boundary

SUKA DAME 0 0 Groundwater Recharge Area of Sei Bingei 0 0

0 NAMO MIRIK 0 5 5 7 7 3 KUALA 3 Groundwater Recharge Area PARANGGUAM BUAH NABAR

GARUNGGANG RUMAH GALUH Groundwater Discharge Area

SUKA MAKMUR

0 TANJUNG GUNUNG 0

0 TANJUNG BERINGIN TAMBUNEN 0 0 0 0 0 7 7 3 3 BELINTENG PUANG AJA ADIN TENGAH DURIN SERUGUN SEI BINGAI UJUNG DELENG

0 0 INDEX MAP

0 0 ACEH TENGAH ACEH TIMUR

0 SUKA MAKMUR 0 NAGANRAYA ACEH TENGAH LANGKAT ACEH TAMIANG

5 5 LANGKAT

6 UJUNG BANDAR 6

3 3 GAYOLUES

TELAGAH ACEH BARAT DAYA LANGKAT KUTALIMBARU KOTA MEDAN KOTA BINJAI

DELISERDANG

ACEH TENGGARA SERDANG BEDAGAI KOTA TEBINGTINGGI SIKEBEN KARO BANDAR BARU ACEH SELATAN KARO 0 0 0 0 SIMALUNGUNKOTA PEMATANGSIANTA 0 0 KOTA TANJUNGBALAI

0 SIBOLANGIT MARTELU 0 DAIRI

6 6 WPNK ASAHAN SAMOSIR 3 3 SIMALUNGUN KUTA KEPAR SAMOSIR TIGANDERKET PAKPAKBHARAT SAMOSIR ACEH SINGKIL SAMOSIR TOBASAMOSIR LABUHANBATU BUKUM HUMBANG HASUNDUTANTOBASAMOSIR BERASTAGI TAPANULI UTARA NAMAN TERAN BELINTENG KUTA GUGUNG MERDEKA DAULU

0 KUTA MBELIN 0

0 KEBAYAKEN GUNG PINTO JARANGUDA DOLAT RAYAT 0 0 NDESKATI 0 5 KUTA RAYAT MERDEKA SEMPAJAYA 5 5 5 3 3 430000 435000 440000 445000 450000 DEPARTMENT OF GEOLOGICAL ENGINEERING FACULTY OF ENGINEERING UNIVERSITAS GADJAH MADA Gedung Teknik Geologi FT UGM, Jl. Grafika 2, Kampus UGM, Yogyakarta 55281 Tel.: 0274-513668, Fax.: 0274-546039, E-mail : [email protected]

FIGURE 4. The main groundwater recharge area according to isotope ratio δ18O of rainwater.

20 Journal of Applied Geology DETERMINATION OF GROUNDWATER SYSTEMBY USING HYDROISOTOPE METHODOF SEI BINGEI

TABLE 5. Isotope ratio δD and δ18O Langkat groundwater samples.

No. Location Code Elevation δ18O( ) δD( ) (masl) h h 1 Garunggang Village, Kuala MA-1 705 -7.31 ± 0.21 -44.73 ± 1.91 Sub-District Tanjung Gunung Village, Sei Bingei 2 SG-6 445 -8.17 ± 0.22 -50.99 ± 1.32 Sub-District Rumah Galuh Village, Sei Bingei 3 MA-2 365 -8.13 ± 0.02 -50.99 ± 0.92 Sub-District Rumah Galuh Village, Sei Bingei 4 MA-3 339 -7.99 ± 0.12 -49.56 ± 1.22 Sub-District Rumah Galuh Village, Sei Bingei 5 SB-1 327 -8.18 ± 0.52 -50.62 ± 1.23 Sub-District Belinteng Village, Sei Bingei 6 MA-6 318 -8.08 ± 0.09 -48.78 ± 1.41 Sub-District Pekan Sawah Village, Sei Bingei 7 SG-5 282 -8.22 ± 0.32 -49.12 ± 1.24 Sub-District Belinteng Village, Sei Bingei 8 MA-10 220 -8.11 ± 0.31 -50.41 ± 1.43 Sub-District Pasar X Village, Kutalimbaru 9 SG-7 211 -7.64 ± 0.84 -45.61 ± 1.28 Sub-District Pekan Sawah Village, Sei Bingei 10 MA-9 189 -7.67 ± 0.62 -45.21 ± 1.38 Sub-District Pasar X Village, Kutalimbaru 11 SB-7 187 -7.64 ± 0.98 -45.95 ± 1.72 Sub-District Gergit, Gunung Ambat Village, Sei 12 SG-1 183 -7.95 ± 0.41 -48.55 ± 2.41 Bingei Sub-District Simpang Buruh, Belinteng, Sei Bingei 13 SG-3 180 -8.02 ± 0.07 -48.67 ± 1.51 Sub-District Belinteng Village, Sei Bingei 14 MA-5 179 -7.92 ± 0.51 -48.87 ± 1.24 Sub-District South Namu Ukur Village, Sei Bingei 15 SG-2 170 -8.21 ± 0.08 -50.98 ± 1.31 Sub-District Pasar X Village, Kutalimbaru 16 SB-8 168 -7.71 ± 0.87 -45.72 ± 1.09 Sub-District North Namu Ukur Village, Sei Bingei 17 MA-7 119 -8.17 ± 0.61 -50.24 ± 1.12 Sub-District Namu Terasi Village, Sei Bingei 18 SB-2 118 -6.21 ± 0.43 -36.18 ± 1.31 Sub-District South Namu Ukur Village, Sei Bingei 19 MA-11 107 -8.25 ± 1.01 -49.85 ± 1.71 Sub-District Sawit Rejo Village, Kutalimbaru 20 MA-8 105 -8.02 ± 0.16 -50.01 ± 1.93 Sub-District Raja Tengah Village, Kuala 21 SG-4 95 -8.23 ± 0.32 -50.23 ± 0.86 Sub-District North Namu Ukur Village, Sei Bingei SB Sei 22 94 -8.16 ± 0.21 -49.01 ± 1.48 Sub-District Bingei North Namu Ukur Village, Sei Bingei 23 Sub-District MA-4 85 -8.01 ± 0.08 -50.15 ± 1.22

Explanation: = Group A–; = Group B–; = Group C–

Journal of Applied Geology 21 NUHA et al.

Genesis-B Groundwater Group is the main -35 deep groundwater system in the research

18 O + 14.162 with the lowest value of the isotopic ratio × δ -40 of δ18O and δD, and (c) Genesis-C Ground- δD = 8.052 Genesis-A water Group is groundwater which it may

D (‰) -45 Genesis-C δ come from the intermediate system be- LMWL-Langkat tween shallow and deeper groundwater Local rainwater Garunggang -50 Groundwater non Sei Bingei group Groundwater Sei Bingei group system. Genesis-B Sei Bingei borehole Local rainwater Namu Terasi -55 ACKNOWLEDGEMENTS -8 -7.5 -7 -6.5 -6 δ18O (‰) The authors would like to thank all the parties that support the research project and the prepa- FIGURE 5. Isotope data of groundwater samples rel- ration of this article, especially for the Aqua- ative to LMWL-Langkat. Danone-Indonesia (PT. Tirta Investama) and Department of Geological Engineering, Faculty c. Genesis-C group is groundwater source of Engineering, University of Gadjah Mada. with isotope ratios of δ18O and δD are Any opinions, ﬁndings, conclusions expressed in between the Genesis-A and Genesis-B in this paper are those of authors and do not groundwater isotopes, so it can be in- necessarily reﬂect the views of the employers or terpreted that this may come from lower granting organizations. recharge area of 883 masl nor these ground- REFERENCES water source has no hydraulic intercon- nection with Genesis-A and Genesis-B Clark, I.D. and Fritz, P. (1997) Environmental Iso- topes in Hydrology. Lewis Publishers. Boca Ra- groundwater. Members of this group are ton, New York. SG-7, SB-7, SB-8, and MA-9. Clark, I. (2015) Groundwater Geochemistry and Iso- topes, Taylor & Francis Group, CRC Press, 421p. 6C ONCLUSION Craig, H. (1961) Standard for reporting concentra- tions of deuterium and oxygen-18 in natural wa- According to the result and discussion, there ters. Science, 133(3467), pp.1833-1834. are several conclusion which can be drawn re- Crawford, J., Hughes, C.E., and Lykoudis, S. (2014) lated to the objectives of the research as written Alternative least squares methods for determin- below: ing the meteoric water line, demonstrated using GNIP data. Journal of Hydrology, 519, pp. 2331– a. The Local Meteoric Water Line of Langkat 2340. area follows the equation; δD = 8.052 × Hendrayana, H., Nuha, A., Wijatna, A.B., Muham- δ18O + 14.162, this equation is based on the mad, A.S. (2019) Hydrogen Isotope Study to De- termine Groundwater Genesis in Mambal Spring, average data of rainwater taken between Bali, Indonesia, Proceeding of 11th Regional December 2018 to February 2019. Conference on Geological and Geo-Resources b. The main groundwater recharge in the re- Engineering-Innovations and Emerging Tech- search area is located above 883 masl, how- nologies for Responsible Mineral Resource De- ever, the value must be carefully used as velopment, Eastwood Richmonde Hotel, Quezon there is a lack of rainwater sample coming City, Philippines. IAEA, W. (2014) Global network of isotopes in pre- from the top elevation of the near moun- cipitation. GNIP database. tain and the different times of sampling Kresic, N. and Stevanovic, Z. (eds) 2010. Groundwa- between groundwater and rainwater sam- ter Hydrology of Springs: Engineering, Theory, ples. Management, and Sustainability. Amsterdam, c. Groundwater in the study area can be Butterworth-Heinemann (Elsevier); 573 pages. differentiated into 3 genesis group: (a) Mazor, E. (2004) Chemical and isotopic groundwa- Genesis-A Groundwater Group represent- ter hydrology (p. 453). New York: Marcel Dekker. Mook, W. and Rozanski, K. (2000) Environmental ing shallow-local groundwater system originated from local direct rainfall, (b)

22 Journal of Applied Geology DETERMINATION OF GROUNDWATER SYSTEMBY USING HYDROISOTOPE METHODOF SEI BINGEI

430000 435000 440000 445000 450000 GROUNDWATER GENESIS MAP MENCIRIM MEDAN KRIO 0 BINJAI ESTATE 0

0 SUKA PULUNG 0 PADANG BRAHRANG TUNGGURONO TELAGA SARI BASED ON 0 PUJI DADI 0 5 LAU MULGAP TANJUNG MERAHE 5 9 KUTA PARIT SUKA MAJU 9 HYDROISOTOPE STUDY 3 NAMO RUBE JULU 3 TANAH SERIBU SEI MENCIRIM TANAH MERAH LANGKAT, SUMATERA UTARA SELESAI EMPLASMEN KWALA MENCIRIM PADANG CERMIN BHAKTI KARYA MA 8 SUKA RAYA BINJAI SELATAN !( BEKIUN PERKEBUNAN BEKIUN SAWIT REJO 0 0

0 BELA RAKYAT NAMBIKI PASAR VI KWALA MENCIRIM 0 0 0 0 1.25 2.5 5 7.5 10 0 PURWO BINANGUN SILEBO LEBO 0 9 9 Kilometers

3 DALAN NAMAN BALAI KASIH 3 PEKAN KUALA GUNUNG TINGGI .! SISTEM PROYEKSI...... DECIMAL DEGREE PASAR IV NAMU TERASI TUNTUNGAN I DATUM...... WGS 84 SG 4 Sumber : - Peta Rupa Bumi Indonesi, BIG SEI PENJARA NAMU UKUR UTARA [ - Survai Lapangan, 2018 SIDO MAKMUR !( RAJA TENGAH LAU BAKERI 0 MA 11 SB 2 NAMORIH 0 0 MA 4 0 PASAR 8 NAMU TERASI LEGEND : 0 !( MA 7 !( 0

5 !( 5 BLANKAHAN SG 2 8 !( SUKA RENDE 8 District Boundary 3 NAMU UKUR SELATAN !( 3 SUKA DAMAI SG 1 Village Boundary SUKA DAMAI !( MEKAR JAYA SAMPE CITA BERUAM DURIAN LINGGA KUTALIMBARU National Road River GUNUNG AMBAT MA 9 SG 3 SUGAU Collector Road 0 !( SB 7 0 0 !( SB 8 0 0 !( 0 Elevation Countour 0 BESADI !( 0 Local Road

8 PARIT BINDU MA 10 8

3 SG 7 3 !( PEKAN SAWAH !( Hidrogeology Sei Bingei Borehole SIMPANG KUTA BULUH MA 5 PASAR X Boundary .! MA 3SB 1 !( PERPANDEN !(!( SG 5 !( !( Genesis A SUKA DAME 0 0

0 0 !( 0 MA 2 NAMO MIRIK 0 Genesis B 5 !( 5 7 7

3 KUALA 3 !( Genesis C PARANGGUAM BUAH NABAR MA 6 GARUNGGANG RUMAH GALUH !( TANJUNG GUNUNG SUKA MAKMUR 0 0

0 SG 6 TAMBUNEN 0 0 0

0 !( TANJUNG BERINGIN 0 7 7 3 3 BELINTENG PUANG AJA ADIN TENGAH DURIN SERUGUN MA 1 !( SEI BINGAI UJUNG DELENG

0 0 INDEX MAP

0 0 ACEH TENGAH ACEH TIMUR

0 SUKA MAKMUR 0 NAGANRAYA ACEH TENGAH LANGKAT ACEH TAMIANG

5 5 LANGKAT

6 UJUNG BANDAR 6

3 3 GAYOLUES

TELAGAH ACEH BARAT DAYA LANGKAT KUTALIMBARU KOTA MEDAN KOTA BINJAI

DELISERDANG

ACEH TENGGARA SERDANG BEDAGAI KOTA TEBINGTINGGI SIKEBEN KARO BANDAR BARU ACEH SELATAN KARO 0 0 0 0 SIMALUNGUNKOTA PEMATANGSIANTA 0 0 KOTA TANJUNGBALAI

0 SIBOLANGIT MARTELU 0 DAIRI

0 KUTA MBELIN 0

FIGURE 6. Group of groundwater genesis in the research area.

Journal of Applied Geology 23 NUHA et al.

isotopes in the hydrological cycle. IAEA Publish, Wijatna, A.B., Hendrayana, H., Aliyah, F., Muham- 39p. mad, A.S. and Pratikno, B. (2018) Determina- Salonga, N.D. (2015) Estimating the isotopic com- tion LMWL Wonosobo Area by Using Nuclear position of meteoric Water index in geothermal Technology, Case Study: Hydrogeology Study for ﬁelds in the Philippines. In Proceedings of the Aqua Danone CSR Program. In E3S Web of Con- World Geothermal Congress (p. 7). ferences (Vol. 43, p. 01013). EDP Science.

24 Journal of Applied Geology