Hydrocarbon extraction lead to compaction of the gas reservoir which is visible as subsidence on the surface. We have used surface height difference measurements to quantify compaction of the Groningen gas reservoir in the Netherlands. This procedure yielded areas of increased and decreased levels of compaction compared to the existing compaction model in agreement with observed discrepancies in porosity and aquifer activity.

In many coastal and delta cities land subsidence now exceeds absolute sea level rise up to a factor of ten. The total worldwide damage of resulting increased floodrisk and structural damage to structures is estimated at billions of dollars annually. In this study a quick-assessment of subsidence is performed on mega-cities. Results of these case studies are presented and compared, and a (generic) approach how to deal with subsidence in current and future subsidence-prone areas is provided.

In many delta cities land subsidence exceeds absolute sea level rise up to a factor of ten by excessive groundwater extraction related to rapid urbanization and population growth. An Integrated Assessment Framework (IAF) for subsidence is introduced, illustrated by several (delta) case studies. Based on that a list of 10 generic key issues and possible solutions is presented in order to further develop and support a (generic) approach how to deal with subsidence in subsidence-prone areas.