Estimating Land Subsidence in Relation to Urban Expansion in Semarang City, Indonesia, Using InSAR and Optical Change Detection Methods

Land subsidence and flooding events in coastal Semarang City, Central Java, has had severe impacts on the region’s population and economy. This work presents a methodology based on a combination of InSAR subsidence mapping and optical classification and change detection techniques to estimate the spatial distribution of subsidence rate and assess its impact on urbanization growth, land conversion and coastal flooding. Significant spatial relationships were found between urban zones (building density), flood extent (shoreline retreat) and subsidence rates. The overexploitation of aquifers and city zoning development contribute to accelerate subsidence rates.