Coastal area cities Jakarta and Semarang in Indonesia portray higher hazard that links to an annual sinking rate of up to 20cm. Four main factors have been determined to contribute: groundwater extraction, sea-level rise (SLR), land subsidence, and coastal floods. It accounts for people living in those high-risk regions to prevent the exacerbating situation.

This study’s main objective is to generate risk mapping in Jakarta and Semarang using Geographic Information System (GIS) from three open-source websites: Surging Seas, OpenStreetMap (OSM), and Healthsites.io. Through GIS analysis, prediction can be analyzed more accurately with precision when the sinking hits slowly to identify the risks involved.

Satellite data geographical analysis risk mapping done via Surging Seas, OpenStreetMap (OSM), and Healthsites.io showed that by 2050, North, West, part of Central Jakarta and Semarang will sink 5.6 meters below sea level with an annual sinking rate up to 20cm. Critical infrastructure will be affected in Jakarta, including Soekarno-Hatta International Airport and Tanjung Priok Port. Similarly, in Semarang, the Jenderal Ahmad Yani International Airport, Tanjung Mas Port, and Terboyo Bus Station are affected as well. Consequently, it will situate 13 million at both coastal cities as the worst impacted, categorized by the World Bank data, updated Sept 2022 as Urban Poverty, the population living at 2.15 US Dollar a day poverty line. Those living below the poverty line are also deprived of education and access to infrastructure, mainly electricity, water and sanitation hygiene indicators measured by the World Bank 2021 and 2022, Multidimensional Poverty Measure.

As a conclusion, GIS mapping of Jakarta and Semarang by 2050 using Surging Seas, OpenStreetMap, and Healthsites.io showed a high risk of sinking, especially in the northern areas of both cities, with the mapping done as of April 2022.