Electronic Theses and Dissertation

Kegiatan pemetaan geologi serta analisis kualitas air tanah dilaksanakan di wilayah Kecamatan
Birembayeun, Kabupaten Aceh Timur, Provinsi Aceh, yang secara geografis terletak pada koordinat
97°50’9,88” – 97°52’52,32” LU dan 4°27’52,78” – 4°30’35,56” BT, dengan luas wilayah pemetaan
sekitar ±25 km². Penelitian ini bertujuan utama untuk memetakan kondisi geologi permukaan serta
menganalisis kualitas air tanah berdasarkan sifat fisika dan sifat kimia. Berdasarkan geologi regional
pada Lembar Langsa, daerah penelitian tersusun atas tiga formasi yang diurutkan dari yang tertua
ke termuda, yaitu Formasi Baong (Tmb), terdiri atas satuan batulumpur gampingan, batupasir, dan
batupasir mengandung glaukonit; Formasi Keutapang (Tuk), terdiri atas satuan batupasir, batupasir
mengandung karbon, batulumpur, dan sedikit konglomerat; serta Formasi Seureula (Tps), terdiri atas
satuan selang-seling batupasir dan batulumpur. Mineral penyusun formasi tersebut memengaruhi
kandungan unsur kimia yang dapat berdampak pada kualitas air tanah. Metode pemetaan geologi
mencakup pengumpulan data primer melalui observasi langsung di lapangan, yang meliputi
deskripsi batuan, pengamatan geomorfologi, dan analisis petrogenesa menggunakan sayatan tipis
batuan. Sedangkan untuk penentuan kualitas air tanah, penelitian dilakukan melalui analisis
geokimia dengan menggunakan Diagram Stiff, kemudian dievaluasi berdasarkan standar kualitas air
menurut Permenkes No. 492/MENKES/PER/IV/2010 untuk menilai kelayakan air sebagai sumber
air minum dan air bersih. Hasil penelitian menghasilkan berbagai peta, antara lain peta
geomorfologi, peta pola aliran, peta lintasan, peta geologi, peta kedalaman muka air tanah, peta arah
aliran air tanah, peta sebaran kualitas air tanah yang dianalisis menggunakan Diagram Stiff, serta
kolom stratigrafi daerah penelitian. Pemetaan geologi mengidentifikasi 76 titik singkapan yang
dikelompokkan menjadi empat satuan batuan, yaitu: Satuan Batulumpur Gampingan (Tmb), Satuan
Batupasir Keutapang (Tuk), dan Satuan Batupasir Seureula (Tps). Analisis geomorfologi
menunjukkan tiga satuan bentuk bentang alam di wilayah penelitian, yaitu Satuan Dataran
Denudasional (D5), Satuan Perbukitan dan Lereng Denudasional dengan erosi kecil (D1), serta
Satuan Bentang Alam Struktural (S2). Pada pemetaan hidrogeologi, kedalaman muka air tanah di
tiga sumur yang tersebar di daerah penelitian berkisar antara 4–6 meter. Hasil pengujian
laboratorium menunjukkan nilai pH antara 6,9–7,2, yang mengindikasikan air memiliki tingkat
keasaman normal; nilai daya hantar listrik (DHL) berkisar 73–152 µS/cm, menunjukkan air masih
layak digunakan; serta nilai total zat terlarut (TDS) berkisar 38–60 ppm, yang memenuhi persyaratan
kualitas air minum dan air bersih. Berdasarkan analisis geokimia yang diplot pada Diagram Stiff,
disimpulkan bahwa Sumur 1 dan Sumur 3 termasuk tipe kalsium klorida, sedangkan Sumur 2
termasuk tipe sodium klorida.

Geological mapping and groundwater quality analysis were conducted in Birembayeun District, East Aceh Regency, Aceh Province, geographically located at coordinates 97°50’9.88” – 97°52’52.32” N and 4°27’52.78” – 4°30’35.56” E, with a mapping area of ​​approximately 25 km². This research primarily aimed to map surface geological conditions and analyze groundwater quality based on physical and chemical properties. Based on regional geology in the Langsa Plate, the study area consists of three formations, listed from oldest to youngest: the Baong Formation (Tmb), consisting of calcareous mudstone, sandstone, and glauconite-bearing sandstone; the Keutapang Formation (Tuk), consisting of sandstone, carbonaceous sandstone, mudstone, and a small amount of conglomerate; and the Seureula Formation (Tps), consisting of alternating sandstone and mudstone units. The minerals that make up these formations influence the chemical content, which can impact groundwater quality. The geological mapping method includes primary data collection through direct field observation, including rock descriptions, geomorphological observations, and petrogenesis analysis using thin sections of the rocks. To determine groundwater quality, the study conducted geochemical analysis using a Stiff Diagram, then evaluated based on water quality standards according to Minister of Health Regulation No. 492/MENKES/PER/IV/2010 to assess the water's suitability as a source of drinking and clean water. The research results produced various maps, including geomorphological maps, flow pattern maps, trajectory maps, geological maps, groundwater table depth maps, groundwater flow direction maps, groundwater quality distribution maps analyzed using a Stiff Diagram, and the stratigraphic column of the study area. Geological mapping identified 76 outcrop points grouped into four rock units: the Calcareous Mudstone Unit (Tmb), the Keutapang Sandstone Unit (Tuk), and the Seureula Sandstone Unit (Tps). Geomorphological analysis revealed three landform units in the study area: the Denudational Plain Unit (D5), the Denudational Hills and Slopes Unit with minor erosion (D1), and the Structural Landscape Unit (S2). Hydrogeological mapping revealed that the groundwater level in three wells spread across the study area ranged from 4 to 6 meters. Laboratory testing results showed a pH between 6.9 and 7.2, indicating normal water acidity. Electrical conductivity (DHL) values ​​ranged from 73 to 152 µS/cm, indicating the water is still suitable for use. and total dissolved solids (TDS) values ​​ranged from 38–60 ppm, which meets the requirements for drinking water and clean water quality. Based on geochemical analysis plotted on a Stiff Diagram, it was concluded that Wells 1 and 3 are calcium chloride, while Well 2 is sodium chloride.