Measurements of land subsidence rates on the north-western portion of the Nile Delta using radar interferometry techniques

The Nile Delta is home to around 75 million people and most of Egypt's farmland and agricultural production.This area is currently threatened by Mediterranean Sea waters due to factors such as sediment starvation, climate change, and sea level fluctuations as well as subsidence.The low elevation and relief of the Nile Delta exposes many coastal communities, including the city of Alexandria, to potential inundation.This situation has become a concern for the area's residents but a better understanding of the processes occurring there can aid in deciding a suitable response.Recent studies have documented Holocene subsidence rates in the northeast part of the Nile Delta that average up to 8mm/year.In this study, PS-InSAR techniques are used to measure modern land subsidence rates on the north-central and north-western Nile Delta.Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) techniques were applied to 23 ESA radar scenes from 2 orbital tracks spanning from 1992 to 2000 in the north-central and north-west portions of the Nile Delta.The area includes the cities of Alexandria, Greater Mahala, and Mansoura as well as the Rosetta iv promontory and lake Burullus, Idku Lagoon, and Maryut Lagoon.Results indicate that modern average-vertical ground motion velocities for the north-western and north-central Nile Delta range from emergent to subsidence of 8.5 mm/yr.The range of velocities measured are spatially varied in a complex way across the study area.Patterns of subsidence correlate closely to areas of most recent sediment deposition such as along coastlines and rivers, as well as in lagoons and lakes.Average subsidence velocities are also lower across the western sections of the Nile Delta than in the northeastern delta.v