Subsidence is generated by numerous natural and anthropogenic processes. Land subsidence is a widespread phenomenon, particularly relevant to transitional environments, such as wetlands, deltas, and lagoons, characterized by low elevation with respect to the mean sea level. The influence of land subsidence on hydrogeological hazard and sustainable development of coastlands is often under-estimated with respect to sea level rise. However, in many places human-induced subsidence (often superimposed on subsidence due to natural processes) is orders of magnitude higher than sea-level rise, increasing vulnerability for flooding and salt-intrusion, threatening agriculture and ecological functions. Quite often, especially at the onset of the occurrence, land subsidence goes unnoticed as it affects a large portion of the territory (up to thousands of square kilometres) and usually occurs at slow velocity, only discovered when severe damages are observed. At this stage, undertaking effective remedial measures to mitigate the associated environmental and socio-economic impacts may prove tremendously expensive.
The goal of this workshop series is to assemble a team of international experts to re-examine our understanding of coastal subsidence drivers, to explore new paths forward in subsidence prediction, and to define best practices for integration of subsidence science into coastal risk assessments. With the new millennium, improved methods for measuring changes of land surface elevation, the application of geophysical modeling, the development of advance mathematical models have greatly advanced our understanding of potential rates and mechanisms of subsidence and provide valuable tools for planners and resources managers in coastal areas throughout the world. However, many uncertainties remain about the rates and spatial distributions of present and future subsidence at a time when low elevation coastal areas are under increasing threat from rising sea levels and severe storms. Also today, large coastal cities and deltaic regions, mainly in the developing or newly-development countries, are strongly threatened by large subsidence rates.
During the workshop, Yilin Liu made an oral presentation entitled:“Land Subsidence Monitoring and Mechanism Research over the Yellow River Delta, China”. The presentation demonstrates the relative contribution of groundwater and precipitation to subsidence in the Yellow River Delta and provides critical insight into the primary drivers of subsidence in the delta. The members of the workshop were very interested in the study and communicated widely with the scientists.