Impact of Sea-Level-Rise and Human Activities in Coastal Regions: An Overview

Coastal regions are becoming increasingly vulnerable to flooding because of accelerating sea-level-rise (SLR), local ground subsidence, and the changes in topography and morphology. Moreover, coastal areas are usually highly urbanized and increased human activities have an effect on the stability and preservation of the environment. For instance, the growing demand for new lands to accommodate the population and the industrial facilities in China has required the design and the deployment of land-reclamation projects from the ocean, with a marked impact on fragile coastal eco-systems. Specifically, the Yangtze River and Pearl River Estuary, two major estuaries of the world, have long been subject to intensive human activities over the past decades. Long-term ground subsidence evolution, topographic changes, and morphological variation of the coastal regions have drawn great attention. This paper provides an overview of well-established Earth Observation (EO) remote sensing (RS) technologies that are employed to continuously monitor the changes of urbanized regions. The combined use of EO-based DInSAR analyses along with the knowledge of the geomorphology of the coastal regions allows a more precise picture of the SLR risk in the investigated coastal regions. In this paper, we will concentrate on remote sensing technologies that allow the gathering of heterogeneous information, such as those based on the use of synthetic aperture radar (SAR), satellite altimeters and tide gauge data. We will underline how human activities trigger changes in the living environment of coastal zones and the associated risks for the population. Observed coastline changes, coastal regions terrain subsidence, and offshore bathymetry have a pronounced effect on the increasing risk of flooding. Accordingly, we also present insights into some inundation model projections employed for evaluating the potential flooding risk in coastal regions.