Vulnerability of coastal lowlands. A case study of land subsidence in Shanghai, PR China

Abstract

Groundwater withdrawal caused drastic land subsidence in Shanghai, located in the Changjiang (Yangtze) coastal plain. Geological investigations, focusing on the need of a 3-dimensional approach, were carried out in the framework of the design of a mathematical model aiming at the management of land subsidence. The compaction of the sediments, due to groundwater withdrawal, is occurring mainly in the upper 70 m deposits, belonging to the Late Pleistocene and Holocene. In the Holocene, although characterized by the post-glacial sea level rise, the coastal processes were dominated by a huge sediment supply from the Changjiang and Huanghe rivers. This resulted initially in a considerable salt marsh deposit followed by tidal flat deposits characterized by coastal progradation. -from Author