TY - JOUR AU - Nugroho, Arif AU - Sijabat, Roynardus AU - Chasanudin, Achmad Muzni AU - subagjo, Isa Adi PY - 2022 TI - Multibeam Bathymetric Measurements for Shallow Seabed Features Mapping using Unmanned Surface Vehicle JF - Jurnal Geofisika; Vol 20 No 2 (2022): Jurnal Geofisika DO - 10.36435/jgf.v20i2.546 KW - N2 - Subsea pipelines are constructions of pipelines laid onto or embedded into the seabed used for the distribution of fluid s such as gas or oil . Over time , changes in the morphological seabed around the pipeline area possibl y caused by natural process es such as erosion, scouring, or other geological anomalies may potentially lead to pipeline failure due to the presence of pipe anomalies in the form of free-span ning pipes. In general, this phenomenon occurs in pipeline s with a dynamic sedimentation environment caused by tidal changes or underwater current s . Pertamina Hulu Mahakam (PHM) p erforms regular pipeline inspection as part of the pipeline maintenance program. Visual methods via underwater camera and acoustic methodology such as bathymetry were used to obtain the seabed pattern as well as underwater object s . The Mahakam pipeline networks extend from very shallow waters within the river delta area offshore at a depth more than 100m. For very shallow environment s where manned vessels have a limited access, bathymetr ic measurements were done using Multibeam Echosounder (MBES) installed on an Unmanned Surf ace Vehicle (USV), controlled and monitored via radio communication over a certain distance. I n 2021, PHM, in collaboration with Elnusa, conducted a pipeline inspection survey on one of the pipes, with a diameter of 24 inch es and a length of 109 meters. . The results of the bathymetric measurements using the USV demonstrated that no indication of the presence of free-spanning pipeline s could be found in the underwater vicinity . The depth of the river varie d from -1.2 meters to 2.7 meters (Chart Datum). The topographical condition s show ed a sloping riverbed with a maximum slope of 12°-13° from the direction fo the floodplain area towards the center of the river/main channel. Seven (7) pockmarks were identified around the pipeline having a diameter of about 29 to 52 cm and a depth of about 6 to 20 cm. In addition, a ttention should be paid to the possible presence of gas seepage in the pockmarks area, interpreted from the image of reflected acoustic waves in the water column captured by the MBES e quipment . Keywords: Pipelines, bathymetry, seabed, MBES, USV UR - https://jurnal-geofisika.or.id/index.php/jurnal-geofisika/article/view?path=