STUDY ON TIME-LAPSE MICROGRAVITY MODELLING USING GROUNDWATER MOVEMENT DATA IN BANDUNG

• Main Author: Amin Tahta, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/46726
• Institution: Institut Teknologi Bandung

Bandung-Soreang Basin is a basin with a high level of industrial growth and population in Indonesia. However, the growth in the economic and social sectors had caused harm to the environment, especially the decline in ground water level. To avoid potential water crisis, monitoring of groundwater level is a matter that needs to be done. Time-lapse microgravity is a method that can be used for this purpose. In this study, a program was made using the forward modeling method to calculate time-lapse microgravity anomalies caused by changes in ground water level. Rectangular prism is being chosen as the method to approximate the density change zone. The calculation program is tested with synthetic data to determine its success in calculating the time-lapse microgravity anomaly. The program that has passed the testing process is applied to the research area data with several inputs, namely digital elevation model data, observation and digitation groundwater data, and calculation parameters in the form of grid spacing, water density, and porosity of rocks. The data used has several shortcomings thereby reducing its accuracy. The amount of time-lapse microgravity in 2015-2010 ranged from -210 to 182 ?Gal in observation groundwater data and -133 to 148 ?Gal in digitation groundwater data. A time-lapse microgravity map of gravity data has also been successfully made with 2015-2010 values ranging from -125 to 460 ?Gal with increasingly positive shifting patterns from north to south. The comparisons between three timelapse microgravity maps, which is gravity data, observation groundwater data, and digitation groundwater data show differences in values caused by the influence of other factors, namely changes in buildings and subsidence. The analysis shows that building changes do not have a significant impact, while subsidence has a significant effect.