BRIN Reports Continuous Land Subsidence in Jakarta, Cirebon, Demak Coastal Areas

Several areas along North Java’s coast (Pantura) are experiencing varying rates of land subsidence and sea level rise of up to 4.3 millimetres (mm) per year, according to the National Research and Innovation Agency (BRIN). This condition affects coastal regions from Jakarta, Bekasi, Indramayu, Cirebon, Subang, Pemalang, Pekalongan to Demak, potentially increasing flood risks in the future. Senior Researcher at BRIN’s Geoinformatics Research Centre (PRGI), Agung Syetiawan, stated that land subsidence in Pantura can be monitored through geodetic and remote sensing approaches. The use of Interferometric Synthetic Aperture Radar (InSAR), Global Navigation Satellite System (GNSS), terrestrial observations, and multi-data geospatial modelling is crucial for mapping coastal deformation dynamics. ‘GNSS observations from Indonesia Continuously Operating Reference Station (InaCORS) also reveal non-linear vertical deformation patterns across most Pantura regions. These data are used to validate Synthetic Aperture Radar (SAR) satellite observations,’ Agung said during the BRIGHTS Series 2 event on Tuesday (26 May 2026). He explained that groundwater extraction is a primary cause of land subsidence in coastal areas. ‘The demand for clean water by communities and activities such as vannamei shrimp farming further strain groundwater reserves,’ Agung said. Additionally, land subsidence exacerbates the impact of sea level rise along North Java’s coast. Analysis of altimetry data shows sea levels are rising between 2.4 and 4.3 mm per year. Simple inundation modelling suggests several Pantura coastal areas could face permanent flooding without appropriate mitigation measures. Muara Gembong and parts of Jakarta, Tangerang, and Bekasi (Jatabek) have already experienced expanded flood areas due to the combined effects of land subsidence and sea level rise. He noted that mitigation infrastructure projects, such as giant sea walls, must consider comprehensive geospatial studies to accurately identify priority areas for intervention. He also stressed the importance of data-driven policies for sustainable coastal development, including borewell regulation, mangrove rehabilitation, and seawall evaluations. ‘Save water, save life; the clean water we conserve today is the lifeline for future generations,’ he stated. Agung highlighted limitations in subsidence monitoring systems, including observation stations not always being located in areas with high subsidence rates. To address this, BRIN, in collaboration with the Geodesy and Geomatics Engineering Department at Bandung Institute of Technology, conducts periodic observations by installing permanent benchmark pillars at key subsidence hotspots, monitored annually. PRGI BRIN Head Rokhis Khomarudin said land subsidence and coastal ecosystem degradation are multidisciplinary issues requiring sustained geospatial research and remote sensing support. ‘The use of GIS and remote sensing technologies is crucial for supporting monitoring, analysis, and the development of science-based mitigation strategies,’ he added.