TRANSIENT ELECTROMAGNETIC DATA PROCESSING IN HIGH CULTURAL NOISE AREA: CASE STUDY OF CISARUA HIDROGEOLOGY

• Main Author: MARTHEN MANURUNG (NIM: 22316017), RIO
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/30516
• Institution: Institut Teknologi Bandung

<p align="justify">A geophysical investigation was conducted to study the hydrogeological conditions in the catchment area for the Bandung basin hydrological system. The research location were in Cisarua, West Bandung Regency which geologically consisted of old and young volcanic products. Resistivity-based geophysical methods are used because they are sensitive to the presence of water in rock formations, namely the Transient Electromagnetic and 2D Geoelectric (Electrical Resistivity Tomography) methods. TEM measurement is carried using a grounded wire transmitter configuration with a transmitter length of 500m, current of 13 A and a period of 40 seconds. ERT measurement uses Wenner-Schlumberger configuration with a space between electrodes of 10 meters and the maximum space between electrode is 560 m. The measurement area is located in a residential area and is very close to the man-made electromagnetic noise source including PLN cables, radio transmitter and cellular transmitters. Therefore, the periodic noise recorded were very high, where the main noise amplitude with 50 Hz frequency is higher than the transient signal in early time. This poses a challenge where a technique that can reduce noise and reconstruct transient data is needed so the data can be inverted and subsurface models can be generated. Based on the results of smoothness constrained TEM inversion, subsurface model which shows 2 low resistivity zones are obtained. The first zone is at depth of about 10-70 meters which is also confirmed by the ERT results and interpreted as unconfined shallow aquifer. The second low resistivity zone depth is around 300-450 and is thought to be old undifferentiated volcanic product filled with water related to the presence of faults in the east of the study area.<p align="justify">