GROUNDWATER BASIN CHARACTERISTICS BASED ON SATELLITE GRAVITY DATA Ariq A. Naufal (a*), Gumilar Utamas Nugraha (b), Selly Feranie (a)
a) Department of Physics Education, Indonesia University of Education
Jalan Dr. Setiabudi 229, Bandung 40154, Indonesia
*ariqnaufal[at]upi.edu
b) Geotechnology research and development, Lembaga Ilmu Pengetahuan Indonesia (LIPI)
Jalan Sangkuriang, Kompleks LIPI, 40135, Dago, Kecamatan Coblong, Kota Bandung, Jawa Barat 40135
Abstract
Groundwater Basin on Lombok Island is 3,490 km2 or 36.83% of the total area of the groundwater basin in Nusa Tenggara Barat Province (9,475 km2). Information of Groundwater Basin characteristics is very important in planning and development of an area in order to avoid groundwater degradation and environmental damage. The objective of this study is to examine the basement characteristics of Lombok Groundwater Basin by satellite gravimetry data using gravity methode. Complete Bouguer Anomaly (CBA) map, regional and residual anomaly maps and 2D models were created using Oasis Montaj version 8.3 software. Complete Bouguer Anomaly (CBA) values in the study area were in the range of 45.0 to 208.5 mGal. The average regional gravity anomaly response is at a depth of 43856.83 m, while the average residual gravity anomaly response is at a depth of 301.73 m. In forward modeling, there are seven rock formations found in the study area, namely, the Alluvium (Qa) formation with a density value of 2.29 gr/cc, the inseparable volcanic rock formation (Qhv) has a density value in the range of 1.67 - 2 ,5 gr/cc, the Lekopiko formation (Qvl) has a density value in the range of 2.04 - 2.84 gr/cc, the breccia and lava groups consist of the Kalibabak formation (TQb) and the Kalipalung formation (TQp) with a density value are in the range of 2.06 - 2.84 gr/cc, the Ekas formation (Tme) with a density value of 2.56 gr/cc, and basement rocks formed in the tertiary period with a density value of 2.44 gr/cc.
