Electronic Theses and Dissertation

Lokasi penelitian berada di Kecamatan Babahrot dan sekitarnya, Kabupaten Aceh Barat Daya, Provinsi Aceh. Secara geografis terletak pada koordinat 3o48’49,22” - 3o51’31,38” BT dan 96o43’7,90” - 96o45’ 50,060’’ LU dengan luas 5x5 km2. Berdasarkan peta Geologi Regional daerah penelitian tersusun atas 4 Formasi dan 1 Endapan yaitu, Formasi Babahrot (Muba), Formasi Meurah Buya (Tmm), Formasi Meulaboh (Qpm) serta Endapan Alluvium Fluviatil dan Pantai (Qh). Lokasi penelitian memiliki kondisi topografi dataran yang relatif berbukit. Daerah dengan topografi landai berpotensi menjadi tempat untuk genangan air. Selain itu, sebagian besar daerah penelitian merupakan tempat yang digunakan untuk lahan pertanian sawit yang berpotensi mencemari air karena limbah dan bahan kimia yang digunakan. Oleh sebab itu, perlu dilakukan penelitian untuk mengetahui kondisi geologi dan kerentanan airtanah terhadap pencemaran menggunakan metode GOD serta melakukan pengujian kualitas airtanah secara fisik dan kimia untuk mengatahui seberapa besar airtanah di lokasi penelitian layak untuk digunakan. Tujuan penelitian ini adalah untuk mengetahui kondisi geologi dan tingkat kerentanan airtanah terhadap pencemaran menggunakan metode GOD serta untuk mengetahui kualitas airtanah melalui paramerer fisik dan kimia di lokasi penelitian. Metode yang digunakan dalam penelitian ini yaitu pemetaan geologi, analisis petrografi, analisis resistivitas batuan, analisis kerentanan airtanah terhadap pencemaran dengan metode GOD serta analisis kualitas airtanah melalui parameter fisik dan kimia. Hasil yang diperoleh dari penelitian ini adalah 2 satuan batuan yaitu satuan batuan andesit Babahrot (Muba) dan satuan batuan lanau karbonatan Meurah Buya (Tmmsi) serta 3 satuan endapan yaitu satuan endapan lanau Meulaboh (Qpms), satuan endapan pasir Alluvium (Qhs) dan satuan endapan kerikil kerakal Alluvium (Qhg). Geomorfologi di lokasi penelitian tersusun atas bentuklahan struktural (S1), bentuklahan struktural (S3), bentuklahan denudasional (D1), bentuklahan denudasional (D5), bentuklahan fluvial (F1) dan bentuklahan fluvial (F5). Kondisi hidrogeologi yang terdiri dari 3 parameter yaitu kedalaman muka airtanah memiliki kedalaman 0,425 – 1,58 meter, litologi penyusun akuitar yaitu lempung, lempung pasiran dan kerikil kering serta memiliki tipe akuifer bebas dan tertekan. Kerentanan airtanah di lokasi penelitian masuk kedalam 3 kelas kerentanan yaitu rendah (0,1 – 0,3), tinggi (0,5 – 0,7) dan sangat tinggi (0,7 – 1). Berdasarkan pengujian kualitas airtanah secara fisik seperti suhu, TDS, DHL, rasa dan kekeruhan pada sumur (S-01, S-02, S-03, S-04, S-05 S-06, S-07 dan S-08) masih berada di bawah batas aman. Berdasarkan sifat fisik warna, sumur (S-01, S-02, S-03, dan S-04) berwarna kuning, sedangkan pada sumur (S-05, S-06, S-07 dan S-08) memiliki warna yang jernih. Berdasarkan pengujian secara kimia dengan hasil analisis anion dan kation pada sumur (S-02, S0-3, S-06 dan S-07) masih berada dibawah batas aman dan pengujian kimia COD pada sumur (S-01, S-02, S-03, S-04, S-05, S-06, S-07 S-08) juga masih berada dibawah batas aman, sedangkan pada pengujian BOD sumur (S-01, S-02 dan S-05) sudah melewati batas aman. Berdasarkan hasil plot dengan menggunakan diagram stiff unsur kation yang dominan yaitu Ca dan unsur anion yang dominan yaitu SO4 serta berdasarkan hasil plot pada diagram piper airtanah di lokasi penelitian masuk kedalam tipe airtanah calcium chloride.
Kata Kunci: Pemetaan Geologi, Kerentanan Airtanah, Metode GOD, Kualitas Airtanah

The research location is in Babahrot Sub-district and surrounding areas, Southwest Aceh Regency, Aceh Province. Geographically, it is located at coordinates 3o48’49,22” - 3o51’31,38” BT dan 96o43’7,90” - 96o45’ 50,060’’ LU, covering an area of 5 x 5 km2. Based on the Regional Geological map, the research area is composed of a Formations and 1 Deposit namely, the Babahrot Formation (Muba), the Meurah Buya Formation (Tmm), the Meulaboh Formation (Qpm), and Fluviatile and Beach Alluvium Deposits 9Qh). The research location has a topography that is relatively hily. Areas with gentle topography that is relatively hily. Areas with gentle topography have the potential to become watrerlogged. Furthermore, a large part of the research area is used for oil palm plantations, wich potentially pollute the watrer due to the waste and chemicals used. Therefore, research is needed using to GOD method, as well as to conduct physical and chemical groundwater quality testing to determine the suitability of the groundwater in the study area for use. The objectives of this research are to determine the groundwater in the study area for use. The objectives of this research are to determine the geological conditions and the level of groundwater vulnerability to pollution using the GOD method, and to determine the groundwater quality through physical and chemical parameters in the research location. The methods used in this study are geological mapping, petrographic analysis, rock resistivity analysis, groundwater pollution vulnerability analysis using the GOD method, and groundwater quality amalysis through physical and chemical parameters. The results obtained from this research are 2 rock units namely, the Babahrot andesite rock unit (Muba) and the Meurah Buya carbonaceous silt rock unit (Tmmsi), and 3 deposits unit namely, the Meulaboh silt deposit unit (Qpms) the Alluvium sand deposit unit (Qhs), and the Alluvium pebble cobble deposit unit (Qhg). The geomorphology of the research location consists of structural landforms (S1), structural landforms (S3), denudational landforms (D1), denudational landforms (D5), fluvial landforms (F1), and fluvial landforms (F5). The hydrogeological conditions, wich consist of 3 parameters, show that the groundwater table depth ranges from 0,425 to 1,58 meters, the aquifer forming lithology is clay, sandy clay and dry gravel, and the aquifer type is unconfined and confined. The groundwater vulnerability in the research location falls into 3 vulnerability classes, low (0,1 – 0,3), high (0,5 – 0,7) and very high (0,7 – 1). Based on physical groundwater quality testing parameters such as temperature, TDS, EC, taste, and turbidity in the wells (S-01, S-02, S-03, S-04, S-05, S-06, S-07 and S-08) are still below the safe limit. Based on the physically property pf color, wells 9S-01, S-02, S-03 and S-04) are yellow, while wells (S-05, S06, S-07, and S-08) have a color. Based on chemical testing, the results of anion and cation analysys in wells (S-02, S-03, S-06, and S-07) are still below the safe limit, and the chemical cod test in all wells 9s-01 to s-08) is also still below the safe limit, whereas the BOD test in wells (S-01, S-02, and S-05) has already exceeded the safe limit. Based on the plot results using the stiff diagram, the dominant cation element is Ca and the dominant anion element is SO4, and based on the plot results on the piper diagram, the groundwater in the research location falls into the calcium chloride groundwater type. Keywords: Geological Mapping, Groundwater Vulnerability, GOD Method, Groundwater Quality