Radar Interferometry Technique Research Articles

Uncertainty analysis for forest height inversion using L / P band PolInSAR datasets and RVoG model over kryclan forest site

Forest height, as a measure of the quantity and quality of forest resources, plays a significant role in the study of the ecological functions performed by forests. Although the polarimetric synthetic aperture radar interferometry (PolInSAR) technique has evolved as a potent method for forest height inversion, uncertainties still exist in the process of estimating forest height, and the uncertainties in predicted forest height directly lead into the uncertainty of terrestrial carbon stock calculation results. In this study, we took the Random Volume over Ground (RVoG) model as likelihood function and constructed a hierarchical Bayesian framework to calculate and reduce the uncertainty of forest height inversion using L / P band PolInSAR airborne data via RVoG model. Uncertainties resulted from five canopy types and three forest densities were analyzed, respectively. The results showed that among the five different canopy types, L band has the highest prediction accuracy in pure coniferous canopy with Acc. = 0.90. The uncertainty is extremely low for pure forest, with the ratio of uncertainty values of 0.09 for L band and 0.15 for the P band in pure coniferous canopy, and uncertainty values of 0.16 for L band and 0.11 for P band in pure broadleaf canopy, respectively. Furthermore, when the forest density is between 300 and 600 stems/ha, the ratio of uncertainties for the L band is 0.27, whereas the P band is 0.24. As forest density increases, the uncertainty in forest height estimates decreases for both bands. The changes in canopy types and forest density affect forest height estimation uncertainties obviously, the effects are different at each frequency. The forest height inversion accuracy of the L band in pure coniferous canopy surpasses that in other canopy types, with the lowest uncertainty. P band performed well in broadleaf canopy forest height inversion. The inversion uncertainties at both frequencies decrease with increase of forest densities.

A national-scale assessment of land subsidence in China's major cities.

China's massive wave of urbanization may be threatened by land subsidence. Using a spaceborne synthetic aperture radar interferometry technique, we provided a systematic assessment of land subsidence in all of China's major cities from 2015 to 2022. Of the examined urban lands, 45% are subsiding faster than 3 millimeters per year, and 16% are subsiding faster than 10 millimeters per year, affecting 29 and 7% of the urban population, respectively. The subsidence appears to be associated with a range of factors such as groundwater withdrawal and the weight of buildings. By 2120, 22 to 26% of China's coastal lands will have a relative elevation lower than sea level, hosting 9 to 11% of the coastal population, because of the combined effect of city subsidence and sea-level rise. Our results underscore the necessity of enhancing protective measures to mitigate potential damages from subsidence.

InSAR supported by geophysical and geotechnical information constrains two-dimensional motion of a railway embankment constructed on peat

Rail and road embankments constructed on peatlands are subjected to significant challenges due to the high compressibility of peat. They are, therefore, susceptible to considerable settlement following construction. Accurate and timely monitoring of such embankments is important in order to enable proactive intervention strategies and to avoid failures. Multi-temporal Synthetic Aperture RADAR Interferometry (MT-InSAR) techniques applied to satellite-derived SAR data have been shown to be effective for remotely measuring and monitoring the deformation of civil engineering infrastructure. This paper presents a comprehensive approach, involving MT-InSAR supported by local geophysical and geotechnical information, for the detection and investigation of the movement of a railway embankment constructed on peatland. The Small Baselines approach, implemented in StaMPS (referred to as StaMPS-SB), was performed to measure long-term deformation of the embankment in vertical, horizontal east-west and satellite line-of-sight (LOS) directions. In this regard, a Sentinel-1 A/1B dataset composed of 362 descending images, acquired from 2015 to 2022, was analysed to measure LOS displacement. Also, 282 Sentinel-1 A/1B images of both ascending and descending tracks, collected from 2017 to 2022, were analysed to obtain vertical, horizontal and LOS displacements. According to the results, the maximum ground motion rate along the LOS direction was −29 mm/year for the period from 2015 to 2022. However, from 2017 to 2022, this value was about −25 mm/year and − 22 mm/year for descending and ascending tracks, respectively. During this period, the maximum motion rate obtained was −23.1 mm/year in the vertical direction. Moreover, horizontal movement up to −10 mm/year was observed in the westward direction and + 7 mm/year in the eastern direction. We used in-situ data to support corroborate and improve our interpretation of the InSAR results. In this context, peat thickness profiles, records of tamping activities and interpretations of the railway ballast base from ground penetrating radar data, were employed. The in-situ data revealed that the embankment section exhibiting the greatest vertical motion detected by InSAR corresponds closely to the thickest section of railway ballast, the zone of greatest number of tamping activities and the deepest section of peat. As such, this case study highlights how remote detection of embankment motion, coupled with targeted in-situ investigation, can underpin proactive intervention to improve safety.

Time-series InSAR reveals new insights into land subsidence in the Yellow River Delta, China

In the past decade, the synthetic aperture radar interferometry (InSAR) technique has been extensively employed in deltas, making it possible to obtain more subsidence signals. However, the spatiotemporal nonlinearity of land subsidence often results in inaccurate estimations. Based on 72 Sentinel-1A images captured from 2016 to 2021 and the time-series persistent scatterer-interferometric SAR (PS-InSAR) method, we comprehensively analyze the temporal and spatial dynamics of recent land subsidence in the Yellow River Delta (YRD). The findings suggest a notable spatial shift in the subsidence funnel area within this delta region over the past 6 years (2016–2021), with gradual westward movement from the salt fields in the northeast to those in the central north. Additionally, with 2020 as the demarcation point, there was a notable change in magnitude, initially exhibiting acceleration at −333 mm/yr, followed by deceleration at −231 mm/yr and culminating in renewed acceleration at −413 mm/yr. The subsidence characteristics may be attributed to changes in the underground brine reserves, leading to consolidation of the confined aquifer. Furthermore, the ground subsidence trend suddenly slowed at the end of 2019, which we speculate is related to the significant reduction in human activities caused by COVID-19 prevention and control measures.

Evolution of the magma system at Makushin volcano, Alaska, from 2004 to 2021

Located in the northeast of Unalaska Island in the central part of the Aleutian, Alaska, Makushin volcano is one of the more active volcanoes in the United States, with the most recent eruption occurred in 1995. Pre-eruptive inflation and post-eruptive deflation were identified from 1993 to 1995 and 1996 to 2000, respectively, and were interpreted as volume changes associated with magma movement within the plumbing system. In this study, we investigate the surface deformation of Makushin from 2004 to 2021 to evaluate its present-day activity, using Synthetic Aperture Radar (SAR) interferometry technique. SAR images acquired from C-band Envisat and Sentinel-1, X-band TerraSAR-X, and L-band ALOS-2 satellites are analyzed using an advanced multiple temporal Interferometric SAR (InSAR) algorithm. The produced deformation time series are then used to track the temporal evolution of the volcanic system with Ensemble Kalman Filter (EnKF) assuming Mogi sources. The results show that Makushin is characterized by time-varying deformation episodes including quiescence, and inflation/deflation cycles at varied rates since 2004. The derived deformation histories can be well reproduced by a spatially stationary pressure source located to the east-northeast of the summit, at a depth about 6 km beneath the sea level (BSL). The inflation/deflation cycles with distinct temporal patterns are interpreted as results from volatile-dominated volume accumulation/loss in the magmatic reservoir. A secondary reservoir connected to the main magma chamber is revealed from the deformation time series. No surface displacement associated with the large earthquake swarm in 2020 is identified from the InSAR-derived deformation. The cumulative volume change in the magma reservoir is about −6×106m3 from 2004 to 2021, indicating a volume/pressure deficit in the magma plumbing system.

INVESTIGATIONS ON INSAR DATA PROCESSING STANDARD FOR VOLCANO ISLAND MONITORING IN INDONESIA

Abstract. In critical situations such as disaster and humanitarian relief, the reliable geospatial data will present an appropriate decision on a timely manner. As fundamental datasets, large-scale topographic maps are are mandatory in order to perform geospatial analysis for many societal challenges. Indeed, Large Scale Topographic Mapping in Indonesia shall be accelerated in an innovative and productive way to consider the production efficiency, especially for the geospatial data acquisition as its primary source. Interferometric Synthetic Aperture Radar (InSAR) data acquisition presents some advantages, especially in conjunction with the security clearance and global weather as some main constraints for the geospatial data acquisition. In terms of disaster preparedness and emergency response, radar interferometry techniques can play an important role by generating a Digital Elevation Model (DEM) as an input to Decision Support Systems (DSS). In addition, the techniques of differential Interferometric Synthetic Aperture Radar (D-InSAR) can provide the earth surface deformation from time series Radar Datasets. A set of standards related to the InSAR data acquisition are essential, especially with regards to the improved sensors, and processing methods implemented by the worldwide space agencies nowadays. Hence, the precise definition of a standard is fundamental in order to prepare the InSAR data as one potential source of geospatial data and information, especially for LSTM data production. Generated time series of Digital Elevation Model (DEM) can identify the potential cause of 2018’s Sunda Strait tsunami (Tampubolon, 2019). It was related with the increasing eruption activity of Anak Krakatau (Child of Krakatoa). From DEM analysis, the Volcanic mudflow material avalanche has been detected before the tsunami hit the coastal surrounding area. In this paper, more advanced techniques was investigated by the combination between Time Series DEM Analysis and Ground Displacement detection. The focus on the integration between reliable TanDEM-X and up-to-date Sentinel 1A/B was proposed on another volcano island of Gamalama in Ternate. As TanDEM-X uses X-band as its medium wave, it can produce more reliable DEM as a reference data. On the other hand, Sentinel 1 uses C-band that can contribute to detect the ground deformation over the aforementioned volcano island. TanDEM-X uses a more robust and consistent approach to scan the earth surface by single data acquisition scheme, which is generally more accurate and reliable for the DEM generation. However, many factors influence the selection of a platform that can be best suited for radar interferometry. Initially, the German TanDEM-X Coregistered Singlelook Slant-range Complex (CoSSC) using bi-static InSAR approach has been implemented in order to generate DEMs comply with the LSTM specification in Indonesia. The basic principle is performing a simultaneous measurement of the same scene and identical doppler spectrum by using 2 sensors, thereby avoiding temporal decorrelation (DLR, 2012). Subsequently, the differential InSAR techniques by using Sentinel 1A/B has been performed in order to detect the ground deformation. Finally, tt can be shown that the reliable TanDEM-X data has increased the ground deformation resolution and accuracy in order to provide potential solution for disaster preparedness.

SURFACE DISPLACEMENT MONITORING OF SUBURBAN EXPRESSWAY UNDER CONSTRUCTION BASED ON SENTINEL-1 SBAS-INSAR ANALYSIS

Abstract. The Synthetic Aperture Radar Interferometry (InSAR) technique can quickly obtain millimeter-level surface deformation in urban areas with high coherence. However, expanding the application of time series InSAR in non-urban areas is an important research focus. An improved SBAS-InSAR analysis approach is applied in this study to present the surface displacement along two expressways under construction. Taking the Kejiao and Yicheng Highway in the Shenzhen Shanwei Special Cooperation Zone as examples, the deformation along the highways under construction and the surrounding ground objects is revealed. Moreover, the time series displacements and construction conditions are combined to explain the possible mechanisms behind the different displacements of various ground objects along the expressways. The results show that the climate, environment, and construction conditions of the cooperation zone had an impact on the deformation of various ground objects along the route. Compared to traditional PS-InSAR methods, the density and accuracy of coherence points are improved, which better overcomes the spatiotemporal incoherence effects in non-urban areas.

Slope-Scale Evolution Categorization of Deep-Seated Slope Deformation Phenomena with Sentinel-1 Data

Deep-seated gravitational slope deformations (DsGSDs) are slope-scale phenomena which are widespread in mountainous regions. Despite interacting with human infrastructures and settlements, only a few cases are monitored with ground-based systems. Remote sensing technologies have recently become a consolidated instrument for monitoring and studying such widespread and slow processes. This paper proposes a three-step novel methodology to analyze the morpho-structural domain of DsGSDs by exploiting the advanced Differential Synthetic Aperture Radar Interferometry (A-DInSAR) technique through (i) the analysis of A-DInSAR measurement point density and distribution defining a coverage threshold; (ii) the assessment of the actual ground deformation with respect to the orientation of phenomena based on slope, aspect, and C-index; and (iii) ground deformation mapping with previously ranked velocity interpolation. The methodology was tested on two differently oriented phenomena: the mainly north–south-oriented Croix de Fana and the mainly east–west-oriented Valtournenche DsGSD, located in the Aosta Valley Region, northern Italy. The results show a variation in the kinematic behavior between the morpho-structural domains, while also considering any other superimposed surficial deformations. This work provides the lines for the implementation of a rapid and low-cost tool based on the use of A-DInSAR measurements which are suitable for assessing the impact of any type of DsGSD on the anthropic facilities and infrastructures in mountainous areas.

What Have We Learned from the Past? An Analysis of Ground Deformations in Urban Areas of Palermo (Sicily, Italy) by Means of Multi-Temporal Synthetic Aperture Radar Interferometry Techniques

This study focuses on analyzing and monitoring urban subsidence, particularly in the city of Palermo, Italy. Land subsidence, induced by natural and human factors, poses threats to infrastructure and urban safety. Remote sensing (RS), specifically synthetic-aperture radar interferometry (In-SAR), is employed due to its ability to detect ground displacements over large areas with great precision. The persistent scatterer InSAR (PS-InSAR) technique is utilized to identify stable targets and track millimeter-level surface deformations. This research spans from October 2014 to October 2021, using Sentinel-1 satellite data to capture ground deformation from various angles. The findings are integrated into an accessible web app (ArcGIS) for local authorities that could be used aiding in urban planning and enhancing safety measures. This study’s results offer updated deformation maps, serving as an operational tool to support decision-making and community resilience, emphasizing risk awareness and responsible practices. This study highlights that the exponential expansion of urban areas, which does not take into account historical information, can gravely jeopardize both the integrity of urban infrastructure and the well-being of its inhabitants. In this context, remote sensing technologies emerge as an invaluable ally, used in monitoring and safeguarding the urban landscape.

Multi-temporal insar analysis of ground displacement in solotvyno

AbstractRecent studies showed a significant peak of the salt contamination in the Tisza River that exceeded ten times over the average level. The document summarizes the works performed on the investigation of ground displacement using multi-temporal satellite radar interferometry technique in Solotvyno mine located in Tiachiv region. Multi-temporal InSAR aims to identify coherent radar targets exhibiting high phase stability over the entire observation period and derives point data with locations corresponding mainly to the point-wise, man-made features. The middle area with no persecuted targets may correspond to the substantial physical changes of the surface caused by activities like mining or tunneling, adding, or removing structures or their components, and motion perceptible in one pixel.

Dynamic damage characterization of slender masonry structures by radar interferometry: a case study

The work shows an experimental and numerical investigation on the dynamic identification of damage in slender masonry structures using the innovative remote sensing technique of ground-based radar interferometry. The case study concerns San Cataldo’s masonry lighthouse, which is located in Puglia (Italy). Here, we experimentally determine the natural frequencies of the lighthouse by carrying out Ambient Vibration Tests (AVT) using an interferometric radar system. Starting from the experimental results, we calibrate a numerical model of the structure and study the sensitivity of the first natural frequencies of the model to five possible damage scenarios involving different parts of the structure and different degrees of damage. Comparing numerical and experimental results, we show that the interferometric radar can be effectively applied to detect damage involving the lower part of the structure.

DInSAR Data Reveal an Intriguing Contemporaneous Onset of Deep Deflation below Vesuvio and the Ongoing Campi Flegrei Uplift

Campi Flegrei and Vesuvio volcanoes are only about 25 km apart, located on opposite sides of the densely inhabited area of Naples (Italy). Since neighbouring volcanoes may influence each other’s activity, it is of great interest to identify signs of any mutual interaction between Campi Flegrei and Vesuvio, or at least note coincidences in their recent deformation dynamics. After a large uplift, Campi Flegrei was generally subsiding from 1985 to 2001, while it has been uplifting—probably driven by deep magma inflation—at an accelerating rate since then. Here, we analysed the ground displacement in the whole Vesuvian area and its surroundings around the early 2000s using 1993–2010 ERS/ENVISAT ascending- and descending-orbit line-of-sight displacements obtained through the Small BAseline Subset Differential Synthetic Aperture Radar Interferometry technique. Although ground deformation is slow—a few millimetres per year—Empirical Orthogonal Function analysis shows a sudden trend change around 2001. Pre-2001 velocity maps confirm previously published results: subsidence mainly occurred inside the caldera rim—probably because of the sliding and compaction of young incoherent materials—and in a few spots around 10 km from the summital crater; eastward displacement occurred in a lobe east of Vesuvio, and westward displacement occurred in a lobe west of Vesuvio, as in the case of the spreading of the volcanic edifice and/or extensional tectonics. We attribute the subsidence spots to the previous high local number of new buildings per year. Post-2002 velocity maps provide evidence of a very different scenario: general subsidence in the whole Vesuvian area, westward displacement in a lobe east of Vesuvio, and eastward displacement in a lobe west of Vesuvio. This last arrangement of the ground displacement field is made even clearer by subtracting the post-2002 velocity from the pre-2001 value. The results of our analyses are consistent with the deflation of a deep pressurised source. Additionally, Vesuvio’s deep seismicity decreased at the beginning of 2002. The coincidence between the transition from deflation to inflation at Campi Flegrei and the onset of deflation below Vesuvio may suggest the possible transfer of magma and/or magmatic fluids between the two plumbing systems.

Landslide Measurement in Glendroud Region (From the Central Part of Noor City) in Mazandaran Province Iran by Using Remote Sensing and Radar Interferometry Techniques

Studying and monitoring the amount of displacement caused by changes in the shape of the earth's surface is one of the important and practical studies in various topics of geology and geophysics, which plays a significant role in the prevention and behavior of natural disasters such as earthquakes, subsidence, and landslides. Among them, there are various methods for geodetic measurements and monitoring of these deformations, among them the radar interferometric technique with the capabilities of producing wide, frequent and continuous ground covers, as well as high temporal and spatial resolution, is one of the techniques has become importantand significant. Landslides in the Yilagh area of GlenrodRoyan, Noor city, caused a lot of damage to some residential areas, gardens and roads of several villages in the region. Due to the movement of the earth, water and electricity have been cut off in some areas. About one kilometer of the north-south road has been destroyed and the most damage has been done to the houses of Foulad welfare complex. After passing through a long period (more than 60 years) of drought, the country of Iran has faced various risks in recent years, especially in 2018 and 2019, including floods and landslides. The aim of this thesis is to obtain the amount of displacements caused by the landslide in Glenrod region in 2019 using sentinel-1 satellite images by using the differential radar interferometry method using snap software. In this regard, from 4 satellite images It has been used during the years 2019-2020, and according to the results obtained, the largest landslide during the second period was 15 cm, which is based on the information obtained from the mapping organization and the opinion of geologists and experts in the region who stated that the largest displacement in area under report was March 2019 and it matches with the findings carried out by the present authors.

Review on the Use of Satellite-Based Radar Interferometry for Monitoring Mining Subsidence in Urban Areas and Demographic Indicators Assessment

Abstract Mining activities represent one of the main causes leading to subsidence in the natural and urban environment. Sustainable urban planning and detection of potential hazards in mining areas involve the use of adequate instruments such as the continuous monitoring of land subsidence. The complexity of urban environment demands the utilization of new methods for monitoring and quantifying the effects of the mining processes. In the last decades, considering the technological developments from the remote sensing domain, the Synthetic Aperture Radar Interferometry (InSAR) techniques offer the opportunity for early detection and continuous monitoring of subsidence in mining areas, including urban centers. Considering various parameters of mining subsidence monitoring, a review of several tens of studies realized in different mining sites, based on InSAR techniques, is presented. As mining subsidence in urban areas has a direct impact on the quality of life, the review is completed with demographic indicators assessment, followed by a study case on the dynamics of the population in an urban mining area from Romania, Ocnele Mari.

Study of land subsidence by radar interferometry and hot spot analysis techniques in the Peshawar Basin, Pakistan

Land subsidence caused by anthropogenic activities is frequently reported in many megacities worldwide, affecting over 500 million residents. For the first time, this work is reporting substantial ground subsidence in the fifth largest city of Pakistan. Observation of surface deformation using the Small Baseline Subset (SBAS), Interferometric Synthetic Aperture Radar (InSAR) technique on Sentinel-1A datasets from 2015 to 2019 show subsidence up to 3.23 cm. Geologically, this region is going through active deformation associated with Himalayan orogeny. From August 1973 till December 2018, around ten thousand low- to moderate-magnitude earthquakes are reported.We used the emerging hot spot analysis on InSAR and earthquake data to assess the role of seismicity on subsidence. Four variables were analyzed; ground displacement measured by InSAR, earthquake count, earthquake depth, and earthquake magnitude. Analysis of InSAR data indicates that the vast majority of the area is subsiding. This investigation also reveals that earthquake activity near Peshawar is decreasing. In contrast, the earthquake activity is unstable but high in the direction of Tarbela Dam, which is the world's largest earth-filled dam.No systematic groundwater monitoring program has been implemented, and limited published data suggest that the water demand quadrupled in the last decade. A decline in the water table is also reported. Optimized hot spot analysis of water pumping data for 2017 shows a few isolated mild hot spots in the urban center. Excessive groundwater demand and Land-use change from agriculture to urban may have played a significant role in land subsidence in this region.

Three-stage inversion improvement for forest height estimation using dual-PolInSAR data

This paper addresses an algorithm for forest height estimation using single frequency and single baseline dual polarization radar interferometry data. The proposed method is based on a physical two layer volume over ground model and is represented by using polarimetric synthetic aperture radar interferometry (PolInSAR) technique. The presented algorithm provides the opportunity to take advantages of the dual polarimetric data, i.e, better spatial resolution and wider swath width, in comparison with the full polarimetric data, in forest height estimation application. In this research, a polarimetric optimization method is utilized to choose the optimum volume polarization basis in order to improve the results of the three-stage inversion algorithm. For the performance analysis of the proposed approach, the L-band ESAR data of the European Space Agency from BioSAR 2007 campaign (ESA) which is acquired over the Remningstorp test site in southern Sweden, is employed. The experimental result shows the dual PolInSAR HH/HV data capability in the forest height estimation without decreasing the accuracy of the result compared with the full polarimetric data. The suggested method leads to the average root mean square error (RMSE) of 4.39 m and the determination of coefficient of 0.66 in the forest height estimation in 15 predetermined stands in comparison with the LiDAR reference heights.

ВЛИЯНИЕ АТМОСФЕРЫ НА ИССЛЕДОВАНИЯ ПЕРЕСЕЧЕННОГО РЕЛЬЕФА МЕТОДАМИ РАДАРНОЙ ИНТЕРФЕРОМЕТРИИ

An influence of the atmosphere on the interferometric studies of the rugged terrain in the area of Tolbachik volcanic complex, Kamchatka, is discussed. Brief description of the radar interferometry technique and the components of the interferometric phase differences are presented. The two-component model of the troposphere is described, which assumes the decomposition of the refractive index into dry and wet components. An influence of the variations of the troposphere refractive index between radar observations on the phase measurements is simulated. The weather data of Klyuchi meteorological station were interpolated to the moments of the Canadian synthetic aperture radar «Radarsat-2» observations in summer-autumn 2013 and used as input data in the modeling. In the number of cases the calculated differential radar interferograms contain non-zero values of the phase difference that grow with the height of the relief. The non-zero phase differences observed on the interferograms are typically in the good agreement with simulation results. A noticeable discrepancy between interferometric measurements and simulation data occurs in the case of unstable weather with sharp alteration of relative humidity in the survey area, especially in the case the troposphere meteorological parameters vary in different directions during the radar observations. An assumption is made that the reason of the observed modeling errors is that the weather data of distant meteorological station do not match sometimes the actual weather conditions in the study area. The impact of variations of the refractive index between radar observations is less, the less the variations of the relief heights in the survey area.

Impact of Dead Sea Halo-Karst Development on an Earthen Dike Rehabilitation Project

From the 1970s, the Dead Sea experienced severe halo-karstification and anthropogenic modifications. Progressively, but at an accelerating rate, subsidence, landslides, and sinkholes have increased in number and magnitude. The hazards’ triggering factors are the terminal lake level lowering at more than one meter per year and the dynamic equilibrium of the hydrogeological system. Over the Lisan peninsula, archived satellite images revealed the extent of the damaged areas. On 22 March 2000, the destruction of dike 19 represented a loss of 38 M USD. This is the most important event recorded since the beginning of the Dead Sea recession some 50 years ago. In 2018, a rehabilitation project of that dike started. This research analyses the viability of the reinstatement works. The advanced space borne radar interferometry technique is applied to map ground deformations before and during the project. This article reveals that the ongoing rehabilitation and reinstatement works of dike 19 are threatened by ongoing halo-karstification processes. Field observations and subsidence/uplift dynamics support this statement. The past experiences are taken into consideration to adapt industrial expansion strategies. However, the permeability of the salt pan floor could trigger a fast development of a karst system able to destroy the rehabilitated dike 19.

Modal testing of masonry constructions by ground-based radar interferometry for structural health monitoring: A mini review

Modal testing is one of the most effective experimental techniques for the structural health monitoring of masonry constructions, as it provides useful information for the calibration of structural models and for the assessment of structural damage. However, the application of modal testing to masonry constructions is sometimes hindered by the complexity of the conventional experimental set-up, which is generally based on contact sensors. In order to overcome this issue, several researchers are exploring the application of the ground-based radar interferometry, which is an increasingly popular measurement technique for remotely monitoring displacement and vibration of structures. Given the recently increasing number of articles on this subject, here we propose a mini review on the most significant works dealing with the application of ground-based radar interferometry for modal testing of masonry constructions. In particular, we show the current state of the art and highlight the main research gaps with the purpose of assessing the effectiveness of ground-based radar interferometry for the structural health monitoring of these constructions. Our mini review is primarily aimed at engineers and scientists who already know about modal testing and radar interferometry technique and are interested in the specific application to masonry constructions.

МОНІТОРИНГ ВЕРТИКАЛЬНИХ ЗМІЩЕНЬ ЗЕМНОЇ ПОВЕРХНІ ПРАВОБЕРЕЖЖЯ КАНІВСЬКОГО ВОДОСХОВИЩА

Monitoring of vertical displacements of the earth's surface on the right bank of the Kaniv Reservoir in the Vytatchiv-Stajky region was carried out using the differential radar interferometry (DinSAR) technique. According to the results of observations during the spring period from 2015 to 2023, active landslide areas are displayed. The DinSAR method is briefly described, emphasising data filtering steps for landslide activation mapping. A high data correlation was recorded, and the presence of zones of active shifts on the shore of the reservoir was confirmed. The spread and intensity of landslide manifestations are determined by the peculiarities of the geological and geomorphological structure of the territory, its tectonic, neotectonic and seismic regimes, and hydrological and climatic conditions. Limitations of the method arising from the temporal decorrelation of the radar signal in regions with a large amount of vegetation are determined. Due to the significant decorrelation between the obtained results of forested and watered areas, the DinSAR technique, a digital elevation model (DEM), analysis of base surface maps and the results of spectral index calculations were combined to identify regions of active landslides caused by waterlogging of the Dnieper slopes. The study demonstrates the feasibility of using DinSAR to detect and monitor surface deformation.