A methodology for the remotely sensed monitoring, measurement and quantification of littoral zone platform downwearing has been developed and is demonstrated, using Persistent Scatterer Interferometric Synthetic Aperture Radar data and analysis. The research area is a 30 km section of coast in East Sussex, UK. This area combines a range of coastal environments and is characterised by the exposure of chalk along the cliffs and coastal platform. Persistent Scatterer Interferometry (PSI) has been employed, using 3.5 years of Sentinel-1 SAR data. The results demonstrate an average ground level change of −0.36 mm a⁻¹ across the research area, caused by platform downwearing. Protected sections of coast are downwearing at an average of −0.33 mm a⁻¹ compared to unprotected sections, which are downwearing more rapidly at an average rate of −1.10 mm a⁻¹. The material properties of the chalk formations in the platform were considered, and in unprotected areas the weakest chalk types eroded at higher rates (−0.66 mm a⁻¹) than the more resistant formations (−0.53 mm a⁻¹). At a local scale, results were achieved in three studies to demonstrate variations between urban and rural environments. Individual persistent scatterer point values provided a near-continuous sequence of measurements, which allowed the effects of processes to be evaluated. The results of this investigation show an effective way of retrospective and ongoing monitoring of platform downwearing, erosion and other littoral zone processes, at regional, local and point-specific scales.

Analysis of ground movement rates along the coastline and upper sections of the Ventnor landslide complex was carried out utilizing Persistent Scatterer Interferometric Synthetic Aperture Radar methods using Sentinel-1 SAR data from 2015 to 2019 (four years). Results were compared with rainfall data, historical ground investigation records and monitoring surveys carried out at Ventnor to relate observations to geology, geomorphology and rainfall. Decomposition of InSAR viewing geometries to vertical and horizontal aligned well with previous ground-based studies. Subsidence of −9.8 mm a⁻¹ at the Lowtherville Graben and heave of +8.5 mm a⁻¹ along the coastline south of Ventnor Park were observed. Decomposition to east-west geometry results showed an eastward displacement of approximately 12.4 mm a⁻¹ along the coastline south of Ventnor Park, and a westward displacement of −3.7 mm a⁻¹ throughout built up sections of Ventnor town, indicating the landslide was displacing more in an eastern direction than vertically. The cause of this movement was investigated by using publicly available intrusive boreholes paired with Persistent Scatterer Interferometry, and a new ground model spanning east-west parallel to the coastline was presented. No evidence of significant ground movement was observed along heavily protected sections of the coastline, suggesting coastal defences comprised of concrete aprons and rip rap appear to be an effective coastal management/landslide stabilisation tool when compared to rip rap alone. The mechanism of this increased stability is likely due to the combination of toe weighting and reduced toe erosion. A lag of approximately 13–20 days was observed between high rainfall events and subsequent peaks in ground displacement, which was shorter than a 29 day lag observed in a previous study. Similar observations of prolonged rainfall resulting in prolonged displacements were also observed. The study demonstrates the capabilities of the PSI methodology in identifying the same ground movements that conventional methods provide. By providing detailed analysis of ground deformation of the Ventnor landslide, we demonstrate small ground movements, validated with existing ground movement surveys. Similar methodology can be applied to coastal landslides in urban environments worldwide, providing a relatively cheap and rapid resource for coastal landslide monitoring.

The consolidation history of chalk denotes that it has been subjected to different horizontal and vertical stresses throughout its geological history. A testing programme was developed to investigate whether this would mean that chalk exhibits anisotropic permeability. Three Southern Province Chalk formations in south east England were tested; West Melbury Marly Chalk, Seaford Chalk and Newhaven Chalk formations. All the specimens were collected in the field, orientations were recorded before the samples were cut and prepared for laboratory testing. The laboratory testing programme identified small anisotropies in permeability measurements in Seaford and Newhaven Chalk formations, and anisotropy in unconfined compressive strength measurements. Anisotropic permeability in the West Melbury Marly Chalk Formation is unresolved due to heterogeneity of the samples collected from the formation. All tested samples also had index properties measured, and they have also been presented in the paper. It can be concluded that vertical samples in the Seaford and Newhaven Chalk formations are more permeable and weaker than horizontally drilled samples.