Measuring Urban Subsidence in the Rome Metropolitan Area (Italy) with Sentinel-1 SNAP-StaMPS Persistent Scatterer Interferometry

Land subsidence in urban environments is an increasingly prominent aspect in the monitoring and maintenance of urban infrastructures. In this study we update the subsidence information over Rome and its surroundings (already the subject of past research with other sensors) for the first time using Copernicus Sentinel-1 data and open source tools. With this aim, we have developed a fully automatic processing chain for land deformation monitoring using the European Space Agency (ESA) SentiNel Application Platform (SNAP) and Stanford Method for Persistent Scatterers (StaMPS). We have applied this automatic processing chain to more than 160 Sentinel-1A images over ascending and descending orbits to depict primarily the Line-Of-Sight ground deformation rates. Results of both geometries were then combined to compute the actual vertical motion component, which resulted in more than 2 million point targets, over their common area. Deformation measurements are in agreement with past studies over the city of Rome, identifying main subsidence areas in: (i) Fiumicino; (ii) along the Tiber River; (iii) Ostia and coastal area; (iv) Ostiense quarter; and (v) Tivoli area. Finally, post-processing of Persistent Scatterer Inteferometry (PSI) results, in a Geographical Information System (GIS) environment, for the extraction of ground displacements on urban infrastructures (including road networks, buildings and bridges) is considered

Contribution of anthropogenic consolidation processes to subsidence phenomena from multi-temporal DInSAR: a GIS-based approach

The paper introduces an approach based on the combination of multi-temporal Differential Interferometric Synthetic Aperture Radar and geographical information systems analysis to investigate and separate several contributions to subsidence phenomena over the municipality of Ravenna (Emilia Romagna, Italy). In particular, the relationship between displacements detected over built environment and consolidation processes after construction was assessed and filtered out from the subsidence map to quantify the local overestimation of subsidence phenomena due to the mentioned processes. It requires descriptive attributes related to the age of construction and intended uses. The outcomes of the present study highlight ground consolidation processes that seem to be active over areas settled in the last 30 years with a component contributing to vertical rates up to 3 mm/yr. Such contribution represents the 20% of the cumulative displacements reported for coastal villages where different sources of subsidence increase the vulnerability to coastal erosion. We discuss the contribution of consolidation processes over a couple of recently settled areas to separate among contributions and avoid the misinterpretation of effects due to other anthropogenic sources of subsidence

Urban Deformation Monitoring using Persistent Scatterer Interferometry and SAR tomography

This book focuses on remote sensing for urban deformation monitoring. In particular, it highlights how deformation monitoring in urban areas can be carried out using Persistent Scatterer Interferometry (PSI) and Synthetic Aperture Radar (SAR) Tomography (TomoSAR). Several contributions show the capabilities of Interferometric SAR (InSAR) and PSI techniques for urban deformation monitoring. Some of them show the advantages of TomoSAR in un-mixing multiple scatterers for urban mapping and monitoring. This book is dedicated to the technical and scientific community interested in urban applications. It is useful for choosing the appropriate technique and gaining an assessment of the expected performance. The book will also be useful to researchers, as it provides information on the state-of-the-art and new trends in this fiel

Elevation change of Bhasan Char measured by persistent scatterer interferometry using Sentinel-1 data in a humanitarian context

This study investigates the elevation changes for the island of Bhasan Char, located in the Bay of Bengal, which was selected for the relocation of around 100,000 refugees of the Rohingya minority which were forced to leave their homes in Myanmar. Eighty-nine Sentinel-1 products were analysed using persistent scatterer interferometry (PSI) beginning August 2016 through September 2019, divided into three periods of one year to reduce the impact of temporal decorrelation. The findings indicate that the island is a recent landform which underlies naturally induced surface changes with velocities of up to ±20 mm per year. Additional displacement is probably caused by heavy construction loads since early 2018, although we found no statistical evidence for this. The main built-up area shows stable behaviour during the analysed period, but there are significant changes along the coasts and artificial embankments of the island, and within one separate settlement in the north. The moist surface conditions and strong monsoonal rains complicated the proper retrieval of stable trends, but the sum of findings supports the assumption that the island underlies strong morphologic dynamics which put the people to be relocated at additional risk. Its suitability for construction has to be investigated in further studies

Detection of Ground Subsidence in the City of Durrës, Albania, by Persistent Scatterer Interferometry of Sentinel-1 Radar Imagery: Detection of Ground Subsidence in the City of Durrës, Albania, by Persistent Scatterer Interferometry of Sentinel-1 Radar Imagery

Persistent Scatterer Interferometry (PSI) analysis of multi-temporal Sentinel-1 synthetic aperture radar (SAR) imagery was carried out to detect ground displacement in the city of Durrës, Albania. The analyzed interferometric stack consisted of fifty-eight Sentinel-1 images in ascending orbit covering the time period January 2017-December 2018. The results show a zone of ground subsidence with values of up to -30 mm/year that occur within and very close to the boundaries of the reclaimed lands of the Durrës marsh. Rapid urbanization, generally in the form of informal settlements, has taken place in this area in the last twenty years. In the Port of Durrës, a recently constructed breakwater shows high rates of ground settlement up to -30 mm/year, as well. The study is the first application of satellite radar imagery for the detection of ground displacement in the city of Durrës, Albania. Further monitoring is needed to better understand the ground subsidence and ground settlement processes that occur in the city of Durrës

Groundwater Assessment and Monitoring in the Northeastern Part of Nigeria Using Microwave Remote Sensing

Dissertation submitted in partial fulfilment of the requirements for the Degree of Master of Science in Geospatial TechnologiesAs the human population continues to grow, the availability of surface water for convenient use is becoming increasingly scarce (Yu Fang et al., 2019). The negative effects of climate change such as drought has also been a major contributor to unavailability of surface water resources in certain regions (Brandon et al., 2017). Due to these reasons and more, natural reserves such as groundwater has become a primary and the most extensively used source of water (Brandon et al., 2017). The primary source of groundwater is gotten from precipitation, with a significant amount of precipitation in the presence of porous soils and with the help of gravity it infiltrates itself into the earth to form Groundwater, this in turn forms aquifers which can and has been harnessed over and over again through the construction of wells and boreholes and has been used for various purposes, including drinking, agriculture, and other human activities for centuries. Groundwater is also a key component of the water cycle; despite its invisibility it plays a crucial role in the ecosystem and the flow of various water bodies. Monitoring and investigating its variations and availability is therefore crucial for sustainability. Traditional methods such as geophysical and geo-electrical techniques have been utilized to detect, monitor and investigate groundwater resource for decades and have no doubt shown remarkable results, but these methods are not without limitations, they are expensive, timeconsuming, and in some cases limited in spatial coverage, therefore optimization is necessary for progressiveness. New and more effective microwave-based techniques have been developed and realized in recent times, they have shown to be promising in handling complex hydrological investigations and observations, one of such technique is the Interferometric Synthetic Aperture Radar (InSAR), which utilizes Sentinel-1 satellite images to assess land surface deformation. This technique allows for mappings and investigations of groundwater variability over time in a particular region by studying the subsidence or uplift pattern which could be associated with groundwater recharge or depletion (Teije et al., 2018). Another important instrument for water management is the Gravity Recovery and Climate Experiment (GRACE) mission. GRACE measures global spatial mass changes caused by gravitational anomalies by using microwave k-band ranging sensor, accelerometers, and global positioning system receivers. GRACE is particularly important for water management as water has mass and its volume varies over time, because of this GRACE can identify and measure its variations. It is also the only satellite that can analyse Terrestrial Water Storage (TWS), which comprises of all the water storages on earth. Another technique worthy of mention is the Standardised Precipitation Evapotranspiration Index (SPEI), this index makes use of hydroclimatological parameters to estimate and investigate drought conditions in regions where it is integrated. Drought could occur due to seasonal and annual variabilities of precipitation and or temperatures which in turn can be as a result of climate change. Sentinel-1 and GRACE complement each other and have varying sensitivity to aquifer system change. This project employed data from both satellites to monitor and evaluate groundwater variability in the north eastern region of Nigeria. Also, due to unavailability of in-situ data for validations and results comparisons, I considered the hydro-climatology of this region and investigated the drought situation over the specified years to strengthen my findings

Anticipating the collapse of urban infrastructure: a methodology based on Earth Observation and MT-InSAR

Large-scale infrastructure monitoring and vulnerability assessment are crucial for the preservation and maintenance of built environments. To ensure the safety of urban infrastructure against natural and man-made disasters, constant monitoring is crucial. To do so, satellite Earth observation (EO) is being proposed, particularly radar-based imaging, because it allows large-scale constant monitoring since radar signals are not blocked by clouds and can be collected during both day and night. The proposed methodology for large-scale infrastructure monitoring and vulnerability assessment is based on MT-InSAR time series analysis. The homogeneity of the year-to-year displacement trend between each point and its surrounding points is evaluated to determine whether the area is a stable or vulnerable zone. To validate the methodology, four case studies of recently collapsed infrastructures are analyzed. The results indicate the potential of the proposed methodology for predicting and preventing structural collapses.Ministerio de Ciencia e Innovación | Ref. PID2021-124236OB-C3

Tracking hidden crisis in India's capital from space: implications of unsustainable groundwater use.

Funder: Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum - GFZNational Capital Region (NCR, Delhi) in India is one of the fastest-growing metropolitan cities which is facing a severe water crisis due to increasing water demand. The over-extraction of groundwater, particularly from its unconsolidated alluvial deposits makes the region prone to subsidence. In this study, we investigated the effects of plummeting groundwater levels on land surface elevations in Delhi NCR using Sentinel-1 datasets acquired during the years 2014-2020. Our analysis reveals two distinct subsidence features in the study area with rates exceeding 11 cm/year in Kapashera-an urban village near IGI airport Delhi, and 3 cm/year in Faridabad throughout the study period. The subsidence in these two areas are accelerating and follows the depleting groundwater trend. The third region, Dwarka shows a shift from subsidence to uplift during the years which can be attributed to the strict government policies to regulate groundwater use and incentivizing rainwater harvesting. Further analysis using a classified risk map based on hazard risk and vulnerability approach highlights an approximate area of 100 square kilometers to be subjected to the highest risk level of ground movement, demanding urgent attention. The findings of this study are highly relevant for government agencies to formulate new policies against the over-exploitation of groundwater and to facilitate a sustainable and resilient groundwater management system in Delhi NCR

MONITORING THE SLOWLY DEVELOPING LANDSLIDE WITH THE INSAR TECHNIQUE IN SAMSUN PROVINCE, NORTHERN TURKEY

Landslides are prominent natural events with high destructive power. Since they affect large areas, it is important to monitor the areas they cover and analyse their movement. Remote sensing data and image processing techniques have been used to monitor landslides in different areas. Synthetic aperture radar (SAR) data, particularly with the Interferometric SAR (InSAR) method, is used to determine the velocity vector of the surface motion. This study aims to detect the landslide movements in Samsun, located in the north of Turkey, using persistent scattering InSAR method. Archived Copernicus Sentinel-1 satellite images taken between 2017 and 2022 were used in both descending and ascending directions. The results revealed surface movements in the direction of the line of sight, ranging between −6 and 6 mm/year in the study area. Persistent Scatterer (PS) points were identified mainly in human structures such as roads, coasts, ports, and golf courses, especially in settlements. While some regions exhibited similar movements in both descending and ascending results, opposite movements were observed in some regions. The results produced in both descending and ascending directions were used together and decomposed into horizontal and vertical deformation components. It was observed that the western coastal part experienced approximately 4.5 cm/year vertical deformation, while the central part there is more significant horizontal deformation, reaching up to approximately 6 cm/year