| Land subsidence in coastal areas increases the vulnerability to flooding, salinization of water resources and permanent inundation. For the Mekong Delta, whose mean elevation is less than 2 m above sea level, subsidence rates of up to several centimeters per year have been reported recently. This leads, in combination with the progressive sea level rise, to a growing risk for the resident population, infrastructure and economy. Precise monitoring of the subsidence rate is necessary for hazard analyses as well as planning and assessment of countermeasures. Here, we present an updated estimation of the recent subsidence rates in the Mekong Delta based on Sentinel-1 SAR-Interferometry.<br>
We use Sentinel-1 scenes acquired between 2015 and 2019 in a descending orbit and between 2017 and 2019 in an ascending orbit. The Persistent Scatterer Interferometry technique (PS-InSAR) is applied which allows for the estimation of displacement rates of coherent backscatter targets with mm-accuracy based on relative phase shifts in time series of the SAR acquisitions. We compare the results of the data from the descending and ascending orbits and combine them for the period 2017 to 2019, after interpolating to a common grid, in order to derive vertical displacement rates. The spatial distribution of the derived subsidence rates will be discussed, taking also their uncertainties into account.<br>
Land subsidence in Mekong Delta has different causes, most prominently natural compaction of young deltaic sediments and overexploitation of groundwater reservoirs with accompanying head decline. To better discriminate the driving forces of land subsidence, we investigate the correlation of observed subsidence rates and spatial distribution of lithostratigraphical units from quaternary sedimentary depositions. |
