Land Subsidence, Groundwater Extraction, and Flooding in Bandung Basin (Indonesia)

Increase in urban development activities and urbanization rate in the Bandung Basin have increased groundwater extraction from the aquifers, which has then led to land subsidence in several locations in the basin. Based on GPS (Global Positioning System) and InSAR (Interferometry Syntetic Aperture Radar) data, the estimated subsidence rates vary spatially from 2 to 20 cm/year. Maximum subsidence during the period of 1999-2010 is about 3 m and largest in industrial areas. Site visit surveys were also conducted to map and evaluate the impacts of the land subsidence. Based on the site visit surveys, the impacts of land subsidence can be seen in several forms such as cracks in buildings, damage of infrastructure (road and bridges), tilting and damaged houses, and change in the flooding inundation area. Flooding frequently occurs in the area where the subsidence rate is high. For example, the 2010 heavy flooding covered the areas where the subsidence is about 7-10 cm/year. This suggests that land subsidence aggravates the flooding hazard in the Bandung Basin.