Land Deformation Research Articles

Geoinformatics-based assessment of land deformation and damage zonation for Gorkha earthquake, 2015, using SAR interferometry and ANN approach

The Gorkha earthquake 2015 was one of the largest disastrous events that occurred in the main Himalayan thrust (MHT) region with epicenter at Gorkha region and magnitude of 7.8 which caused severe causality to life as well as property. The spatial statistics on vertical displacement and extent of damage zone is still too scarce to provide strong evidences of its hazard potential. In the present study, quantitative assessment on surface deformation has been carried out to compare land displacement of two different regions of Nepal (the Central Nepal and the Eastern Nepal), which are located at different distances from the epicenter, using InSAR technique on post- and pre-earthquake images from Sentinel 1A SLC product. The Central Nepal experiences an upliftment of 1.1 m and land subsidence of − 0.61 m, whereas for the Eastern Nepal the estimated upliftment and subsidence were 1.0 m and − 0.33 m, respectively. Further a regional earthquake-prone zone map was generated using the historical earthquake epicenter data and geographic information system (GIS) to understand the major vulnerability zones in the area. A total of 564 earthquake events were reported by USGS in Nepal region during 2000–2019, of which 476 (84.39%) were of magnitude greater than 4 on Richter scale and 376 events (66%) occurred at depth greater than 15 km. The damage assessment was done using machine learning (artificial neural network) back-propagation model in which the satellite imagery retrieved from the optical satellite Landsat 8 OLI sensor and digital elevation model was used to map slope, aspect, relief, drainage and lineament to be used as input layers to generate damage proxy map. The result obtained from ANN illustrated that despite being located comparatively at more distance from epicenter, the Eastern Nepal exhibited more damage-prone area (587 sq. km) in comparison with Central Nepal with 457sq. km damage prone in similar zone. Central Nepal evidences more damage-prone areas over compact build-up in contrast to Eastern Nepal, making greater risk potential in urban areas of Central Nepal during earthquake activity.

Measuring land deformation in a mega city Karachi-Pakistan with sentinel SAR interferometry

This study incorporates European Space Agency (ESA) C-band Sentinel-1a data to evaluate and identify land deformation in natural and reclaimed land of coastal city Karachi, Pakistan on a multi-temporal scale (2014‒2018) using Differential Interferometric Synthetic Aperture Radar (DInSAR) analysis. Average displacement in LOS was between −78.81‒42.97 mm, whereas, the average vertical displacement was 179.74 to −85.05 mm. Few areas have shown an alarming annual subsidence of −21.26 mm/year. Korangi industrial area (−34.34 mm), Liaquatabad (−1.88 mm) and SITE (−2.93 mm) area has shown significant land subsidence that resulted in collapse of few buildings. Maximum subsidence was observed in industrial cum residential areas (−85.05 mm) compared to reclaimed areas (−33.69 mm). Major uplifting was observed along the Kirthar range due to various tectonic activities Rapid urbanization and excessive groundwater abstraction are identified as main reasons for land deformation leading which requires in-depth attention of policy makers to insure sustainable urban development.

Risk Assessment of Coastal Flooding under Different Inundation Situations in Southwest of Taiwan (Tainan City)

The Pacific island countries are particularly vulnerable to the effects of global warming including more frequent and intense natural disasters. Seawater inundation, one of the most serious disasters, could damage human property and life. Regional sea level rise, highest astronomic tide, vertical land motions, and extreme sea level could result in episodic, recurrent, or permanent coastal inundation. Therefore, assessing potential flooding areas is a critical task for coastal management plans. In this study, a simulation of the static flooding situation in the southwest coast of Taiwan (Tainan city) at the end of this century was conducted by using a combination of the Taiwan Digital Elevation Model (DEM), regional sea level changes reconstructed by tide gauge and altimetry data, vertical land deformation derived from leveling and GPS data, and ocean tide models. In addition, the extreme sea level situation, which typically results from high water on a spring tide and a storm surge, was also evaluated by the joint probability method using tide gauge records. To analyze the possible static flood risk and avoid overestimation of inundation areas, a region-based image segmentation method was employed in the estimated future topographic data to generate the flood risk map. In addition, an extreme sea level situation, which typically results from high water on a spring tide and a storm surge, was also evaluated by the joint probability method using tide gauge records. Results showed that the range of inundation depth around the Tainan area is 0–8 m with a mean value of 4 m. In addition, most of the inundation areas are agricultural land use (60% of total inundation area of Tainan), and two important international wetlands, 88.5% of Zengwun Estuary Wetlands and 99.5% of Sihcao Wetlands (the important Black-faced Spoonbills Refuge) will disappear under the combined situation. The risk assessment of flooding areas is potentially useful for coastal ocean and land management to develop appropriate adaptation policies for preventing disasters resulting from global climate change.

Land Subsidence Induced by Rapid Urbanization in Arid Environments: A Remote Sensing-Based Investigation

The rapid increase in the population of many of the older major cities within the countries of the Saharan-Arabian Desert is steering vast and disorganized urban expansion and in many cases introducing adverse environmental impacts such as soil erosion, rise in groundwater levels, and contamination of shallow aquifers, as well as development of deformational features including land subsidence. Using the rapidly growing city of Riyadh (1992: 467 km2; 2018: 980 km2), the capital of the Kingdom of Saudi Arabia as a test site, we utilized Small Baseline Subset (SBAS) interferometric analyses of 2016 to 2018 Sentinel-1 images together with multi-temporal high-resolution images viewable on Google Earth, GPS, field, land use land cover (LULC), and geological data to assess the distribution and rates of land subsidence and their causal effects. Three main causes of subsidence were identified and assessed: (1) discharge of wastewater effluents from septic systems in newly urbanized areas that lead to an increase in soil moisture, rise in groundwater levels, waterlogging, and wetting and hydrocompaction of dry alluvium loose sediments causing land subsidence (up to −20 mm/y) in wadis and lowlands; (2) the subsurface dissolution of karst formation by wastewater effluents and the collapse of voids and cavities at depth under stresses introduced by heavy construction machinery, causing sagging and land subsidence (up to −5 mm/y); and (3) leveling, compaction, and degradation of municipal and building waste materials in organized landfills and disorganized dump sites that resulted in significant land subsidence (up to −21 mm/y) and differential settling that could jeopardize the stability of structures erected over these sites. Our findings highlight the potential use of the advocated integrated approach to assess the nature and extent of land deformation associated with rapid urban growth in arid lands, and to identify areas most impacted for the purpose of directing and prioritizing remediation efforts.

Reservoir-Induced Land Deformation: Case Study from the Grand Ethiopian Renaissance Dam

The Nile River stretches from south to north throughout the Nile River Basin (NRB) in Northeast Africa. Ethiopia, where the Blue Nile originates, has begun the construction of the Grand Ethiopian Renaissance Dam (GERD), which will be used to generate electricity. However, the impact of the GERD on land deformation caused by significant water relocation has not been rigorously considered in the scientific research. In this study, we develop a novel approach for predicting large-scale land deformation induced by the construction of the GERD reservoir. We also investigate the limitations of using the Gravity Recovery and Climate Experiment Follow On (GRACE-FO) mission to detect GERD-induced land deformation. We simulated three land deformation scenarios related to filling the expected reservoir volume, 70 km3, using 5-, 10-, and 15-year filling scenarios. The results indicated: (i) trends in downward vertical displacement estimated at −17.79 ± 0.02, −8.90 ± 0.09, and −5.94 ± 0.05 mm/year, for the 5-, 10-, and 15-year filling scenarios, respectively; (ii) the western (eastern) parts of the GERD reservoir are estimated to move toward the reservoir’s center by +0.98 ± 0.01 (−0.98 ± 0.01), +0.48 ± 0.00 (−0.48 ± 0.00), and +0.33 ± 0.00 (−0.33 ± 0.00) mm/year, under the 5-, 10- and 15-year filling strategies, respectively; (iii) the northern part of the GERD reservoir is moving southward by +1.28 ± 0.02, +0.64 ± 0.01, and +0.43 ± 0.00 mm/year, while the southern part is moving northward by −3.75 ± 0.04, −1.87 ± 0.02, and −1.25 ± 0.01 mm/year, during the three examined scenarios, respectively; and (iv) the GRACE-FO mission can only detect 15% of the large-scale land deformation produced by the GERD reservoir. Methods and results demonstrated in this study provide insights into possible impacts of reservoir impoundment on land surface deformation, which can be adopted into the GERD project or similar future dam construction plans.

Surface response and subsurface features during the restriction of groundwater exploitation in Suzhou (China) inferred from decadal SAR interferometry

Groundwater overexploitation has caused dramatic land subsidence over the metropolitan areas in the Yangtze River Delta (YRD) and many other economic centers worldwide. Suzhou (China) is such a sinking city and faces enhanced flood risks. Restrictions on groundwater exploitation (RGE) have been imposed by the government since 1997 to prevent further elevation loss. However, knowledge on the spatiotemporal evolution of the urban land deformation during the RGE is limited by sparse and infrequent field measurements, which may bias the evaluation of the RGE policy and the strategy formulation of water management. Interferometric synthetic aperture radar (InSAR) provides regional surface deformation at a regular temporal interval of dozens of days. Here we present the decadal evolution of ground deformation in Suzhou using multiple InSAR datasets from ERS1/2, ENVISAT-ASAR, and ALOS-1 PALSAR-1 during 1993–2010, spanning the entire RGE period. An elongated zone from southern to northwestern Suzhou is highlighted by a drastic cumulative land subsidence exceeding 0.9 m due to inelastic aquifer compaction. We characterize the spatiotemporal ground deformation response to the RGE policy using an exponential decay function, from which we also infer the subsurface boundaries with sharp bedrock gradients. We identify a corridor connecting the Yangcheng and Taihu lakes, which is highly sensitive to RGE during the decelerated subsidence. Our analysis also suggests that urban subsidence in Suzhou was under control by 2006−0.4+1.4.

Recent land deformation detected by Sentinel-1A InSAR data (2016–2020) over Hanoi, Vietnam, and the relationship with groundwater level change

ABSTRACT Interferometric synthetic aperture radar (InSAR), one of the most commonly used remote sensing methods for observing and monitoring land subsidence, has been applied in Hanoi, Vietnam in several studies with results showing deformation up to 2014. However, freely accessible Sentinel-1 InSAR data have not been investigated thoroughly to date. Here, we investigate the most recent land surface deformation in Hanoi for the period 20162020 using Sentinel-1A SAR data. The analysis is conducted on 114 SAR scenes with both the Persistent Scatterer InSAR (PSInSAR) and Small BAseline Subset (SBAS) methods. The GPS-based deformation time series are used to verify InSAR results and borehole groundwater level measurements are employed to evaluate the relationship between groundwater depletion and surface subsidence. The results show that observed deformation from SBAS and PSInSAR is consistent in both spatial patterns and statistics, in which two high-rate subsiding bowls were detected in Dan Phuong/Hoai Duc and Ha Dong/Thanh Tri districts with the mean subsiding rates of ∼5 mm per year. GPS and InSAR deformation generally agree well except for the comparison at the JNAV station after 2017, which can be attributable to the local deformation detected by GPS and the average movement of a 100-m radius area captured by InSAR. An agreement in the drawdown trend between borehole groundwater and InSAR-derived deformation was found at four wells located within or in proximity to the two bowls. The declining rates of groundwater level at about 0.31 m per year were found at the two wells Q57a and Q58a located within the Dan Phuong/Hoai Duc bowl, corresponding to the surface subsidence rates found at 6–8 mm per year. The Q68a well was found to experience groundwater level declining at the highest rate of ∼0.9 m per year corresponding to the subsidence rate of ∼7 mm per year found by InSAR.

Land deformation monitoring by GNSS in the Nile Delta and the measurements analysis

Nile Delta, one of the most populated deltas around the world, is suffering from subsidence due to the natural compaction of its sediment. Land subsidence has a great impact on the infrastructure, economic, and social. This study investigatesthe evaluation of the land subsidence in Nile Delta using GNSS measurements. Eight stations of GNSS points through period 2013–2015 distributed around Nile Delta and the Northern part of Egypt are utilized using differential GPS with nine IGS stations by GAMIT/GLOBK V. 10.61. The main objective is to monitor the spatiotemporal variations of land surface within the Nile Delta by time series analysis of the ellipsoidal height. The northern part of Egypt can be divided into three major parts; the western part shows subsidence rate of 2 mm/year downward; Nile Deltaof 2.5 to 10 mm/year downward from west to east and the eastern part shows an uplift.

An Assessment of Monitoring Technologies Deployed in Multiple Carbonate Reef Reservoirs at the MRCSP Large-Scale CO2-EOR Site Michigan

The Midwest Regional Carbon Sequestration Partnership (MRCSP) is one of seven regional partnerships established in October 2003 as part of the U.S. Department of Energy’s (DOE’s) Regional Carbon Sequestration Partnership (RCSP) program to assess the technical and economic viability and public acceptability of carbon sequestration in the U.S. The MRCSP Phase III project injected over 1 million metric tons (MT) of CO2 into a group of Silurian (Niagaran)-age pinnacle reef reservoirs in Otsego County, Michigan (USA) that are operated by Core Energy, LLC [1]. There are over 800 pinnacle reefs in northern Michigan, and collectively, these geologic features have enough capacity to store several hundred million MT of CO2. Moreover, most of the reefs are depleted oil- or gas-reservoirs having previously undergone primary production in the 1970s and 1980s; therefore, they offer the opportunity to achieve CO2 storage through enhanced oil recovery (CO2-EOR) (associated storage) and via geologic sequestration (injection alone without production). A key objective of the MRCSP Phase III project was to evaluate the effectiveness of various monitoring technologies for use in associated storage or sequestration projects in the Niagaran pinnacle reefs. Over the period 2013 to 2020, the MRCSP Phase III project conducted monitoring using eleven different technologies for their effectiveness for CO2 plume delineation, assessing geochemical interactions, well integrity, leak detection, induced seismicity, land deformation, and mass balance accounting in the group of study reefs operated by Core Energy. This paper discusses the effectiveness of selected monitoring technologies that had the goal of detecting/delineating the extent of CO2 in the subsurface. The results are relevant to others planning or currently conducting CO2 sequestration or associated storage projects in similar carbonate reef reservoirs.

The Assessment of Hydrologic- and Flood-Induced Land Deformation in Data-Sparse Regions Using GRACE/GRACE-FO Data Assimilation

The vertical motion of the Earth’s surface is dominated by the hydrologic cycle on a seasonal scale. Accurate land deformation measurements can provide constructive insight into the regional geophysical process. Although the Global Positioning System (GPS) delivers relatively accurate measurements, GPS networks are not uniformly distributed across the globe, posing a challenge to obtaining accurate deformation information in data-sparse regions, e.g., Central South-East Asia (CSEA). Model simulations and gravity data (from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO)) have been successfully used to improve the spatial coverage. While combining model estimates and GRACE/GRACE-FO data via the GRACE/GRACE-FO data assimilation (DA) framework can potentially improve the accuracy and resolution of deformation estimates, the approach has rarely been considered or investigated thus far. This study assesses the performance of vertical displacement estimates from GRACE/GRACE-FO, the PCRaster Global Water Balance (PCR-GLOBWB) hydrology model, and the GRACE/GRACE-FO DA approach (assimilating GRACE/GRACE-FO into PCR-GLOBWB) in CSEA, where measurements from six GPS sites are available for validation. The results show that GRACE/GRACE-FO, PCR-GLOBWB, and GRACE/GRACE-FO DA accurately capture regional-scale hydrologic- and flood-induced vertical displacements, with the correlation value and RMS reduction relative to GPS measurements up to 0.89 and 53%, respectively. The analyses also confirm the GRACE/GRACE-FO DA’s effectiveness in providing vertical displacement estimates consistent with GRACE/GRACE-FO data while maintaining high-spatial details of the PCR-GLOBWB model, highlighting the benefits of GRACE/GRACE-FO DA in data-sparse regions.

Environmental impact assessment of cement industries using mathematical matrix method: case of Ghayen cement, South Khorasan, Iran.

Cement industries produce millions of tons of by-products each year, including dust, toxic gases, and heavy metals, which pose respiratory health hazards and environmental pollution. Although several literatures have investigated environmental impact in cement factories, the extent to which these assessments affect the population has received limited responsiveness. This study investigates this gap by examining the environmental impacts of the Ghayen Cement Industry on environmental components and public health. Using a mathematical matrix, it found that the effect of the cement factory on the environment produced four categories of significant effects: L, low; M, medium; H, high; and VH, very high. Results in terms of basic criteria revealed 0.70 of the most destructive effect was related to water pollution. Regarding the interaction effect of project activities (basic and complimentary basic criteria) on environmental components, the highest destructive effect was excavation and land deformation while the lowest effect was on public health. The study also found out that the use of compensation factors reduced the negative effect of the project on the environment. The use of common methods of environmental improvement such as erosion control, proper location of facilities, and the creation of green spaces is essential to mitigate the impact of projects on the environment.

Sentinel-1 InSAR captures 2019 catastrophic White Island eruption

The andesitic volcanic island Whakaari (White Island) explosively erupted on 9 December 2019. White Island is a popular tourist destination, and 47 people were on the island at the time. Twenty-one died, and a further twenty-six people suffered injuries. Persistent scatterer (PS) interferometry with synthetic aperture radar (SAR) is a powerful satellite-based remote sensing tool to monitor land deformation associated with volcanic unrest. This study examined deformation on White Island over the eruption period and identified a dome on the crater floor that inflated for 15 months preceding the eruption, consistent with a previous analysis of TerraSAR-X satellite data. Results here show the dome began to collapse after 25 November, about two weeks prior to the eruption. This finding has immediate relevance for ongoing hazard monitoring at White Island and other volcanoes worldwide where sudden dome contraction may presage an eruption.

Identifying Land Subsidence Using Global Digital Elevation Models

Recent developments in space-based surveying methods of the Earth's topography, including the differential interferometric synthetic aperture radar (DInSAR), have increased the availability of options for monitoring land subsidence. However, DInSAR methods require expert knowledge and specialized software, and they are time-consuming. Here, we demonstrate that a land subsidence signal can be identified in the differences in the freely available global digital elevation models (e.g., SRTM and TanDEM-X) using a simple statistical method. This finding opens up a venue to develop a computer application to identify land subsidence or uplift of a few decimeters per at least a decade order. Such an application enables monitoring the effects of underground mining, seismic/tectonic movements, landslides, volcanic activities, and similar effects on the Earth's topography. It can also provide a valuable and cost-effective tool for studying land deformation.

Landslide susceptibility mapping using MT-InSAR and AHP enabled GIS-based multi-criteria decision analysis

Landslide susceptibility maps (LSMs) are generally prepared by integrating multiple prominent thematic layers, including DEM derived products (elevation, slope, and aspect), and other parameters such as lithology, geomorphology, LULC, etc. These parameters can be assigned optimum weights using the analytic hierarchy process (AHP) method, followed by a GIS-based weighted overlay analysis. In recent years, multi-temporal interferometric synthetic aperture radar (MT-InSAR) techniques have been rigorously explored, for land deformation detection and monitoring, by extracting highly stable measurement pixels using tens of SAR acquisitions simultaneously. In this research work, a GIS-based multi-criteria decision analysis to prepare LSMs is proposed, with MT-InSAR derived displacement estimates used as a critical input parameter. An LSM is generated by processing 20 ERS-1/2 and Envisat ASAR images, acquired over ∼120 sq. km wide river basin, located in Uttarakhand, India. The generated LSM is found to be congruent with the susceptible maps made available by the Geological Survey of India (GSI) under the National Landslide Susceptibility Mapping (NLSM) program. Preliminary results indicate that the majority of the unstable zones along the Alaknanda River are correctly identified. The approach is further implemented to generate an updated susceptibility map using 60 scenes of freely available Sentinel-1A dataset, followed by validation through actual field survey. This resulted in the generation of an updated susceptibility map, which helped in the identification of 44.5% new landslide susceptible zones (LSZs). Furthermore, the status of previously identified zones is also quantified. The performance of the proposed approach suggests its usability in generating and updating near-real-time LSMs.

The Comparison of Land Subsidence between East and West Side of Bangkok, Thailand

The land deformation in line of sight (LOS) direction can be measured using time series InSAR. InSAR can successfully measure land subsidence based on LOS in many big cities, including the eastern and western regions of Bangkok which is separated by Chao Phraya River. There are differences in prosperity between both sides due to human activities, land use, and land cover. This study focuses on the land subsidence difference between the western and eastern regions of Bangkok and the most possible cause affecting the land subsidence rates. The Radarsat-2 single look complex (SLC) was used to set up the time series data for long term monitoring. To generate interferograms, StaMPS for Time Series InSAR processing was applied by using the PSI algorithm in DORIS software. It was found that the subsidence was more to the eastern regions of Bangkok where the vertical displacements were +0.461 millimetres and -0.919 millimetres on the western and the eastern side respectively. The districts of Nong Chok, Lat Krabang, and Khlong Samwa have the most extensive farming area in eastern Bangkok. Besides, there were also three major industrial estates located in eastern Bangkok like Lat Krabang, Anya Thani and Bang Chan Industrial Estate. By the assumption of water demand, there were forty-eight wells and three wells found in the eastern and western part respectively. The number of groundwater wells shows that eastern Bangkok has the demand for water over the west, and the pumping of groundwater is a significant factor that causes land subsidence in the area.Keywords: Subsidence, InSAR, Radarsat-2, Bangkok

Investigating land surface deformation using InSAR and GIS techniques in Cluj–Napoca city’s most affected sector by urban sprawl (Romania)

The last three decades have marked an unprecedented urban expansion of the city of Cluj-Napoca, leading to strong anthropogenic influences on the natural environment and important changes in the land-use. Due to the specific morphology of Cluj area, characterized by limited available plane surfaces which are insufficient to support the urban expansion, more and more territories with slopes between 5°-26° are used for constructions. These areas are marked by high risks of mass movements due to their specific geological and geomorphological characteristics, therefore the present study proposes a more detailed and complex GIS and remote sensing analysis of the western urban part of Cluj-Napoca, in order to highlight the main changes of the city and the consequences of the human actions. One of the most used radar interferometry (InSAR) technique was applied in order to detect land deformations that can threaten the infrastructure and the population. Sentinel-1B SAR imagery were processed by the DInSAR methodology, resulting in a land deformation map, which represents an important support in generating the vulnerability assessment. Based upon this evaluation, we concluded that the most vulnerable neighbourhoods to land deformations from the western part of the city are the peripheral ones, as following: Dâmbul Rotund, Bună Ziua, Europa, Mănăștur, West Iris and Făget, proving that human activity and the geological setting are the main triggering factors of the discussed phenomenon.

Land Deformation Monitoring in Lanzhou City Based on SBAS-InSAR Technology

With the continuous advancement of urban construction, the original natural landscapes such as wetlands, vegetation, and soil are converted into artificial landscapes such as buildings and roads, resulting in a wide range of changes in urban surface. Monitoring urban surface changes is of great significance to the healthy development of cities and the prevention of geological disasters. The traditional land deformation monitoring technology has the disadvantages of small monitoring range, large workload and low efficiency. Interferometric Synthetic Aperture Radar technology can effectively solve the defects in the traditional deformation monitoring technology. This paper takes Lanzhou as the research area, selects the Sentinel-1A data of 25 scenes from 2014 to 2016, and uses the Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) for land deformation monitoring. The sedimentation observation results obtained by the SBAS-InSAR technique was analyzed with the methods of statistical analysis and time series analysis. The results show that: (1) The overall urban area of Lanzhou City has been slightly sunk, and the funnel in the deformation area is mainly concentrated in the mountainous areas, new residential buildings and subway stations. (2) From the perspective of each region, Shajingyiin Anning District, near XuanshengRundi in Jiuzhou, near Xiaodaping Driving Test Center, and near Xuanmagou-Badaoping Village in Chengguan, near Donggang Cargo Center, near Fulongping, near Hendafeicuihuating in Qilihe District, near Lanzhou West Railway Station and other places all showed strong subsidence trends, and the area with the highest deformation rate is Xiaodaping, which maximum average annual deformation velocity can reach 30.8mm/a, and the cumulative deformation is as high as 65.9mm.(3) The land deformation of Lanzhou City shows a non-linear downward trend, and the deformation gradually spreads in the east-west direction. Eventually, deformation also occurred in some foothills in the north and south, and in some urban areas. (4) The main driving factors for settlement in the urban area of Lanzhou are loess soil, rail transportation and urbanization.

PSI Clustering for the Assessment of Underground Infrastructure Deterioration

Remote sensing images find application in several different domains, such as land cover or land usage observation, environmental monitoring, and urbanization. This latter field has recently witnessed an interesting development with the use of remote sensing for infrastructural monitoring. In this work, we present an analysis of Sentinel-1 images, which were used to monitor the Italian provinces of Bologna and Modena located at the Emilia Region Apennines foothill. The goal of this study was the development of a machine learning-based detection system to monitor the deterioration of public aqueduct infrastructures based on Persistent Scatterer Interferometry (PSI). We evaluated the land deformation over a temporal range of five years; these series feed a k-means clustering algorithm to separate the pixels of the region according to different deformation patterns. Furthermore, we defined the critical areas as those areas where different patterns collided or overlapped. The proposed approach provides an informative tool for the structural health monitoring of underground infrastructures.

An approach for multi-dimensional land subsidence velocity estimation using time-series Sentinel-1 SAR datasets by applying persistent scatterer interferometry technique

The time-series interferometric synthetic aperture radar (InSAR) techniques has the potential of estimating the land subsidence at a high accuracy of nearly in millimeter scale. The major limitation of the present InSAR methods like persistent scatterer interferometry (PSI) is that they measure land deformation velocities only in the direction of the radar line of sight (LOS). Hence, the real prospects of the deformation velocity, i.e. the horizontal and vertical components of velocity remain uncertain. This study is focusing on retrieving PSI based multi-dimensional land deformation velocity along horizontal and vertical directions in an urban region by using ascending and descending pass Sentinel-1 datasets. The area for this study is Lucknow city in Uttar Pradesh state of India. The estimated LOS velocity vectors from ascending and descending pass time-series datasets are utilized for retrieving multidimensional subsidence velocity. Further, the retrieved time-series land subsidence is correlated to the groundwater level variation during the considered time span.

Post-earthquake monitoring of landslides along the Southern Kaikōura Transport Corridor, New Zealand

The magnitude (Mw) 7.8 earthquake that struck North Canterbury on New Zealand’s South Island on the evening of 14 November 2016 caused widespread damage to infrastructure, in particular to road and rail within the South Kaikōura Transport Corridor (SKTC). This is the main transport corridor along the east coast of the South Island, and the coseismic landslides covered and destroyed parts of the State Highway 1 (SH1) road, as well as the railway lines. Post-earthquake aftershocks and significant rainfall events (e.g. Cyclones Debbie, Cook and Gita), further mobilised the de-stabilised greywacke rock mass and paleo-landslide debris that mantled the slopes. Indeed, the SKTC was affected by > 80 separate landslides that have impacted either the rail corridor, the road corridor, or both. A number of different landslide mechanisms occurred, including shallow translation slides of existing paleo-landslide debris and rotational slumping, as well as rock mass failure via wedge, planar or toppling. Here, we report on monitoring of three case study landslides, using multi-temporal analyses of digital elevation data (from LiDAR, TLS and UAV surveys), real-time extensometer and land deformation monitoring using GPS receivers, as well as survey prisms. These datasets provided important monitoring of near-surface movement, important for risk management along the transport corridor during the reinstatement works.