scholarly journals Sentinel-1 for Monitoring Land Subsidence of Coastal Cities in Africa Using PSInSAR: A Methodology Based on the Integration of SNAP and StaMPS

Geosciences ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 124 ◽  
Author(s):  
Fabio Cian ◽  
José Blasco ◽  
Lorenzo Carrera

The sub-Saharan African coast is experiencing fast-growing urbanization, particularly around major cities. This threatens the equilibrium of the socio-ecosystems where they are located and on which they depend: underground water resources are exploited with a disregard for sustainability; land is reclaimed from wetlands or lagoons; built-up areas, both formal and informal, grow without adequate urban planning. Together, all these forces can result in land surface deformation, subsidence or even uplift, which can increase risk within these already fragile socio-ecosystems. In particular, in the case of land subsidence, the risk of urban flooding can increase significantly, also considering the contribution of sea level rise driven by climate change. Monitoring such fast-changing environments is crucial to be able to identify key risks and plan adaptation responses to mitigate current and future flood risks. Persistent scatterer interferometry (PSI) with synthetic aperture radar (SAR) is a powerful tool to monitor land deformation with high precision using relatively low-cost technology, also thanks to the open access data of Sentinel-1, which provides global observations every 6 days at 20-m ground resolution. In this paper, we demonstrate how it is possible to monitor land subsidence in urban coastal areas by means of permanent scatterer interferometry and Sentinel-1, exploiting an automatic procedure based on an integration of the Sentinel Application Platform (SNAP) and the Stanford Method for Persistent Scatterers (StaMPS). We present the results of PSI analysis over the cities of Banjul (the Gambia) and Lagos (Nigeria) showing a comparison of results obtained with TerraSAR-X, Constellation of Small Satellites for the Mediterranean Basin Observation (COSMO-SkyMed) and Environmental Satellite advanced synthetic aperture radar (Envisat-ASAR) data. The methodology allows us to highlight areas of high land deformation, information that is useful for urban development, disaster risk management and climate adaptation planning.

Author(s):  
A. M. H. Ansar ◽  
A. H. M. Din ◽  
A. S. A. Latip ◽  
M. N. M. Reba

Abstract. Technology advancement has urged the development of Interferometric Synthetic Aperture Radar (InSAR) to be upgraded and transformed. The main contribution of the InSAR technique is that the surface deformation changes measurements can achieve up to millimetre level precision. Environmental problems such as landslides, volcanoes, earthquakes, excessive underground water production, and other phenomena can cause the earth's surface deformation. Deformation monitoring of a surface is vital as unexpected movement, and future behaviour can be detected and predicted. InSAR time series analysis, known as Persistent Scatterer Interferometry (PSI), has become an essential tool for measuring surface deformation. Therefore, this study provides a review of the PSI techniques used to measure surface deformation changes. An overview of surface deformation and the basic principles of the four techniques that have been developed from the improvement of Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR), which is Small Baseline Subset (SBAS), Stanford Method for Persistent Scatterers (StaMPS), SqueeSAR and Quasi Persistent Scatterer (QPS) were summarised to perceive the ability of these techniques in monitoring surface deformation. This study also emphasises the effectiveness and restrictions of each developed technique and how they suit Malaysia conditions and environment. The future outlook for Malaysia in realising the PSI techniques for structural monitoring also discussed in this review. Finally, this review will lead to the implementation of appropriate techniques and better preparation for the country's structural development.


2018 ◽  
Vol 10 (11) ◽  
pp. 1781 ◽  
Author(s):  
Mehdi Darvishi ◽  
Romy Schlögel ◽  
Christian Kofler ◽  
Giovanni Cuozzo ◽  
Martin Rutzinger ◽  
...  

The Copernicus Sentinel-1 mission provides synthetic aperture radar (SAR) acquisitions over large areas with high temporal and spatial resolution. This new generation of satellites providing open-data products has enhanced the capabilities for continuously studying Earth surface changes. Over the past two decades, several studies have demonstrated the potential of differential synthetic aperture radar interferometry (DInSAR) for detecting and quantifying land surface deformation. DInSAR limitations and challenges are linked to the SAR properties and the field conditions (especially in mountainous environments) leading to spatial and temporal decorrelation of the SAR signal. High temporal decorrelation can be caused by changes in vegetation (particularly in nonurban areas), atmospheric conditions, or high ground surface velocity. In this study, the kinematics of the complex and vegetated Corvara landslide, situated in Val Badia (South Tyrol, Italy), are monitored by a network of three permanent and 13 monthly measured benchmark points measured with the differential global navigation satellite system (DGNSS) technique. The slope displacement rates are found to be highly unsteady and reach several meters a year. This paper focuses firstly on evaluating the performance of DInSAR changing unwrapping and coherence parameters with Sentinel-1 imagery, and secondly, on applying DInSAR with DGNSS measurements to monitor an active and complex landslide. To this end, 41 particular SAR images, coherence thresholds, and 2D and 3D unwrapping processes give various results in terms of reliability and accuracy, supporting the understanding of the landslide velocity field. Evolutions of phase changes are analysed according to the coherence, the changing field conditions, and the monitored ground-based displacements.


2013 ◽  
Vol 184 (4-5) ◽  
pp. 441-450 ◽  
Author(s):  
Yu-Yia Wu ◽  
Jyr-Ching Hu ◽  
Geng-Pei Lin ◽  
Chung-Pai Chang ◽  
Hsin Tung ◽  
...  

Abstract Persistent scatterers SAR interferometry (PS-InSAR) was employed to monitor surface deformation in and around the Tainan tableland using 20 advanced synthetic aperture radar (ASAR) images from the ENVISAT satellite taken during the period from 2005 May 19 to 2008 September 25. In our study, we have found that the uplift rate of the northern Tainan tableland is faster than the southern tableland. The slant range displacement (SRD) rate for the area north along the precise leveling array is about 5 to 10 mm/yr with respect to the western edge of the Tainan tableland, whereas the SRD rate for the area south of the leveling array is about 1 to 5 mm/yr. In addition, the uplifted area extends eastward to the Tawan lowland with a maximum SRD rate of nearly 10 mm/yr, which is almost the same as the rate of the Tainan tableland. Results of this study differ from those suggested in previous researches that employed ERS-1/2 radar images taken from 1996 to 1999 and the differential interferometry synthetic aperture radar (D-InSAR) technique. Our findings indicated that the Tawan lowland no longer subsides with respect to the western edge of the Tainan tableland, and that both northern and southern areas are experiencing uplift.


Author(s):  
Justin T. Brandt ◽  
Michelle Sneed ◽  
Wesley R. Danskin

Abstract. Land subsidence associated with groundwater-level declines is stipulated as an “undesirable effect” in California's Sustainable Groundwater Management Act (SGMA), and has been identified as a potential issue in San Diego, California, USA. The United States Geological Survey (USGS), the Sweetwater Authority, and the City of San Diego, undertook a cooperative study to better understand the hydromechanical response of the coastal aquifer system using Interferometric Synthetic Aperture Radar (InSAR) techniques. Three periods of interest were analyzed for this study that correspond to the periods before and after two substantial changes were made to the location and volume of pumpage: (1) April–August 2016 when groundwater levels and land surface elevation were relatively stable during normal pumping, (2) September 2016–May 2017 when groundwater levels recovered and the land surface uplifted during a period of substantially reduced pumping, (3) June 2017–October 2018 when groundwater levels declined and land subsidence occurred when pumpage resumed and expanded to new wells. Spatial and temporal characterization of the hydromechanical response to changes in pumpage is important for managing land subsidence. Further study using InSAR techniques, especially when combined with ground-based geodetic and monitoring-well networks, will provide water managers information to help effectively manage groundwater resources as stipulated in the SGMA.


2018 ◽  
Vol 2 (3) ◽  
pp. 118-127
Author(s):  
Cyntia Cyntia ◽  
I Putu Pudja

Land subsidence in DKI Jakarta influenced by several key factors, including the number of buildings that increase the load above the surface. There are still many people who explore groundwater sources as the principal source of clean water. Also,  the soil type is dominated by alluvial. This alluvial deposit can be one of the parameters for soil deformation in the form of land subsidence and uplift in land surface because basically, alluvial soil types have a susceptibility to the load support power above. So that the land subsidence in DKI Jakarta is relatively continuous. To find out the land subsidence is used a high-tech method,  Differential Interferometry Synthetic Aperture Radar (DInSAR) satellite image of radar data (SAR Sentinel-1A) in 2017. The result shows the land subsidence in the average value of DKI Jakarta which is about -3.685 cm/year and the highest subsidence happened in the West Jakarta district about -5.850 cm/year in average.


Sensors ◽  
2019 ◽  
Vol 19 (14) ◽  
pp. 3181 ◽  
Author(s):  
Bo Hu ◽  
Junyu Chen ◽  
Xingfu Zhang

In recent years, the enormous losses caused by urban surface deformation have received more and more attention. Traditional geodetic techniques are point-based measurements, which have limitations in using traditional geodetic techniques to detect and monitor in areas where geological disasters occur. Therefore, we chose Interferometric Synthetic Aperture Radar (InSAR) technology to study the surface deformation in urban areas. In this research, we discovered the land subsidence phenomenon using InSAR and Global Navigation Satellite System (GNSS) technology. Two different kinds of time-series InSAR (TS-InSAR) methods: Small BAseline Subset (SBAS) and the Permanent Scatterer InSAR (PSI) process were executed on a dataset with 31 Sentinel-1A Synthetic Aperture Radar (SAR) images. We generated the surface deformation field of Shenzhen, China and Hong Kong Special Administrative Region (HKSAR). The time series of the 3d variation of the reference station network located in the HKSAR was generated at the same time. We compare the characteristics and advantages of PSI, SBAS, and GNSS in the study area. We mainly focus on the variety along the coastline area. From the results generated by SBAS and PSI techniques, we discovered the occurrence of significant subsidence phenomenon in the land reclamation area, especially in the metro construction area and the buildings with a shallow foundation located in the land reclamation area.


Author(s):  
Fajrin Fajrin ◽  
Almegi Almegi ◽  
Aljunaid Bakari ◽  
Risky Ramadhan ◽  
Yudi Antomi

The land surface in the Padang City is thought to be experiencing a continuous relative subsidence due to natural processes and man-made activities. Factors that affect land subsidence include earthquakes, sea level rise, infrastructure development, sediment transport, and excessive use of groundwater sources. The purpose of this research is to map the rate of land subsidence which is processed from the Sentinel 1-A radar, satellite imagery using the Differential Synthetic Aperture Radar (DInSAR) method. The data used are two pairs of Sentinel-1A level 1 Single Looking Complex (SLC) imagery which were acquired in 2018 and 2019. Image processing is carried out by filtering and multilooking techniques on Synthetic Aperture Radar (SAR) images. The following process changes the phase unwrapping to the ground level phase using phase displacement. Land subsidence in 2018–2019 from DInSAR processing reached -10.5 cm / year. The largest land subsidence occurred in North Padang with an average of -7.64 cm/year. Land subsidence in the Padang City, which is located near the estuary, is due to the nature of the alluvial sediment material. The use of Sentinel 1 SAR remote sensing data can provide important information in the context of mitigating land subsidence in the Padang City. Therefore, we need the right policies to handle future land subsidence cases. Land subsidence mapping is one of the factors that determine the vulnerability of coastal areas to disasters


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