Identification of eroded sediment layer thickness and depth of Mahakam River at Tenggarong Bridge Area, Kutai Kartanegara East Kalimantan using Ground Penetrating Radar Method

Abstract

GPR measurements of lines are two lines intersect under the bridge of Tenggarong (southwest to northeast) along the 377 meters (segment-1 Line04) and 457 meters (Line03) and the other is Southeast to Northwest along the 533 meters (segment-2 Line04) with a starting point It is located on the side of the Mahakam River (Southern) to the West of Kumala island. and there is one track in this area, which is to the northeast to the southwest along the south side of the Mahakam River (Line02) with the length of line is 780 meters. This research used the AKULA-9000C, 100 MHz antenna frequencies, and in time mode. The purpose of this research is to know the depth of the bottom of the Mahakam River, and the thickness of sediments eroded around the bridge of Tenggarong. GPR data processing using the ReflexW software ver. 8.5 through static correction, subtract-mean (dewow) filter, gain, background removal, band-pass filters, and fk-filter. To convert two-way time of electromagnetic wave propagation data to depth units, we use velocity adaptation methods by selecting velocity value each layer anomaly. Cross sections of the line from line02 and Line03 showed that the average thickness of the layer of sediment erosion over 15 meters and depth variation ofthe river was 10 to 40 meters. The shallow depth is under the Tenggarong Bridge (10m). In addition, on Line04 shows the deepest depth of the Mahakam River is 35 meters, located in the middle of Line04 or the center of Mahakam river flow.