GEOLOGY AND HIDROGEOLOGY OF NAINGGOLAN REGION AND SURROUNDING AREAS, SAMOSIR DISCTRICT, NORTH SUMATERA

• Main Author: Kristian Sinaga, Yosua
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/38270
• Institution: Institut Teknologi Bandung

The research area encompasses some parts of Nainggolan District, Onanrunggu District, and Sitio-tio District, Samosir Regency, North Sumatera. Geographically, the research area is located at UTM coordinates 477533 mE, 263250 mN; 477533 mE, 264213 mN; 482786 mE, 267460 mN; 487720 mE, 280424 mN; 490856 mE, 280424 mN; 489285 mE, 267460 mN; 482473 mE, 263250 mN (Zone 47 N). The research area is 55.19 km2. According to the BMB classification, the research area can be divided into three geomorphological units, namely Homoclinal Hills Unit, Toba Caldera Ridge Unit, and Alluvial Plain Unit. The research area is in young and mature geomorphic stage. Stratigraphically, the research area can be divided into seven non-formal rock units which were formed during Early Miocene – Recent, deposited in shallow marine and lacustrine environment. The rock units from older to younger strata are Sandstone unit, Microdiorite unit, Tuff 1 Unit, Tuff 2 Unit, Silt-Sandstone Unit, Diatomite Unit, and Alluvial Deposit Unit. Geological structure found in the research area is normal fault. This structure was formed in Late Pleistocene, after the uplift of the six oldest units in the research area. Aquifer in the research area is in the Sandstone Unit, Silt-Sandstone Unit, Diatomite Unit, Alluvial Deposit Unit, and potential aquifer is in the Microdiorite Unit, Tuff 1 Unit, and Tuff 2 Unit. The type of aquifer in the research area is unconfined aquifer and all springs and dug wells in the research area are drinkable according to PERMEN No.492/MENKES/PER/IV/2010 based on pH and TDS value criteria. The chemical parameter of groundwater in the form of pH have a value of 6.6-8.5 and physical parameter in the form of TDS have a value of 5.3-328 mg / L.