GROUNDWATER STUDY USING RESISTIVITY GEOELECTRIC METHOD MISE-A-LA-MASSE (MALM) AND VERTICAL ELECTRICAL SOUNDING (VES) IN ADHIDARMA VILLAGE, CIREBON DISTRICT, WEST JAVA

• Main Author: Chaesario, Joshua
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/86569
• Institution: Institut Teknologi Bandung

Water is vital to human life. Groundwater is the largest source of freshwater accessible to humans. Freshwater can be identified using the resistivity geoelectric method. The research was conducted in Adhidarma Village, Cirebon Regency, West Java. The research location is 1.6 km from the shoreline and there is a 2.81 m deep borehole. The geological map shows an area of alluvium like sand, clay, silt, gravel, and river deposits. The study was conducted using the Mise-à-la-Masse (MALM) resistivity method, Vertical Electrical Sounding (VES), water quality tests, and Electrical Resistivity Tomography (ERT). MALM measurements to draw a map of the distribution of conductive bodies (water in the well), VES to determine vertical variations in resistivity, and ERT for subsurface 2D resistivity modeling to validate other measurements. In MALM measured 108 points and the data was processed using surfer to produce a pseudo resistivity map. VES measurements at 2 points with a range of 30 m Schlumberger configuration, and data processed using IPI2WIN. Water tests conducted in three days, by measuring of pH, temperature, TDS, conductivity, and salinity. ERT was conducted with 3 lines, 20 electrodes spaced 1.5 m apart and Dipole-dipole, Schlumberger, and Wenner Alpha configurations. Results were modeled with RES2DINV software. It was found that MALM was effective in describing the distribution of conductive bodies. ERT measurements confirm the results of MALM measurements of the distribution of conductive bodies, and the three measurements confirm each other and corroborate the truth of the measurement results. The layers in the study area are clay, sandy clay, and sandy clay. Water quality tests show that the water is categorized as alkaline, with moderately saline water conditions. However, the conductivity value was categorized as seawater-infiltrated. The resistivity model of line 1 shows that there is a high conductivity area which is interpreted as seawater intrusion but this area is at the bottom of the conductive body. It is analyzed that seepage occurs at the bottom of the conductive body which makes the water categorized as saline.