Environmental risk assessment of the Nile Delta, Egypt, based on radar interferometry, altimetry, and geodetic measurements.

Egypt is confronted with a number of hazardous environmental incidents, mainly sea level rise (SLR) and land subsidence. The Nile Delta is a low-relief surface that is particularly vulnerable to flooding and SLR, making it important to study inundation scenarios for the region. Potential social and economic consequences of this anticipated sea encroachment were projected utilizing (1) crustal deformation calculations derived from the time series analysis using the Persistent Scatterer Interferometry (PSI) technique based on Least Squares Estimation. (a stack of 191 Sentinel-1 ascending scenes), and eight permanent stations of Global Navigation Satellite System (GNSS); both spanning the period 2014-2019, (2) SLR values using Satellite Altimetry, and (3) a high-resolution digital elevation model (TerraSAR-X/TanDEM-X). The The key findings of this study are summarized as follows; (1) large cities and urban regions adjacent to the two main active branches of the Nile Delta (Rosetta and Damietta) experienced the majority of subsidence rates, (2) the cities of Damietta, Mansoura and Port said (eastern side of the Nile Delta) experienced the maximum rates of subsidence (- 11 ± 0.6, - 8.9 ± 0.7, and - 6.3 ± 0.7 mm/year, respectively), (3) the cities of Shebin El Kom, Damanhour, Tanta, New-Damietta, Kafr El-Sheikh had moderate subsidence rates (- 3.2 ± 0.6, - 2.4 ± 0.7, - 4.2 ± 0.6, - 3.8 ± 0.7, - 3.2 ± 0.7 mm/year, respectively), (4) the Nile Delta subsidence seems to be dominated by anthropogenic reasons such as urbanization, ground water and hydrocarbon extraction, (5) the linear trend of sea level anomaly (SLA) from satellite altimetry data over the period from 1993 to 2019 along the Delta shoreline, the SLR is ~ 3.42 ± 0.5 mm/year, and (6) based on GIS tools and IDW interpolation, wide swaths of the northern Nile Delta would be flooded in the worst-case scenario, which would result in approximately 482 km² being flooded in fifty years, 2433 km² in one hundred years, and 3320 km² in one hundred and fifty years due to the ongoing land subsidence and SLR of 3.4 mm/year.