Improved Monitoring of Land Subsidence towards Quantifying Relative Sea-Level Rise Hazards in the Low-Lying Deltas

Sea-level rise (SLR), widely recognized as one of consequences resulting from anthropogenic climate change, has induced substantial coastal vulnerability in many populated deltas worldwide, such as three densely populated regions in Asia: Bangladesh, Mekong, and Yangtze deltas. The relative SLR (RSLR), combining eustatic/regional SLR with severe land subsidence due to fluvial sediment loading and anthropogenic extraction of ground water, have significantly exacerbate the coastal vulnerability of these deltas. The topographic surfaces of land and ocean have been measured individually worldwide from space, while several global products are available from multiple agencies. However, the accurate link between both spatially varying quantities remains elusive. The uncertain estimates of land deformation and inundation areas, which base on the biased topography and ocean surface models, would eventually lead to an inadequate assessment of coastal vulnerability. Our objective is to improve the understanding of the relative position between ocean and low-lying lands and their interactions that govern coastal vulnerability. The linkage is essential to deciphering the factors to address long-term sustainability in these three populous deltas.