The increasing importance of water supply systems, particularly in drought-prone regions, and the construction of linear structures, like reservoir dams, have led to the need for adapting these structures to changing conditions. Proper management of dam risks is crucial, as their failure can have severe economic and social consequences. Aging dams, such as those in Spain, require effective monitoring strategies to identify structural issues before they become critical threats. In-person inspections are conducted for maintenance, but modern dams integrate monitoring devices. Satellite radar interferometry (InSAR) technology, specifically the European Ground Motion Service (EGMS), enables precise and non-invasive monitoring of surface deformations using Sentinel-1 satellite data. EGMS provides millimeter-scale precision data, offering insights into subsidence, landslides, and stability issues impacting infrastructure. It is a valuable tool for civilian users and dam managers, providing monitoring data without requiring technical expertise. The SIAGUA project in Spain utilizes EGMS to monitor dams and surrounding areas, providing surveillance information to dam managers.

This article contains description of an improved tool for phase unwrapping, as developed and to be applied routinely within COMET LiCSAR system producing Sentinel-1 interferograms in 0.001° resolution (WGS-84). We apply existing standard methods on routinely available data in a way to improve reliability of the standard phase unwrapping procedure and increase coverage of unwrapped pixels. The primary idea is to reduce high phase gradients, causing both decorrelation and zonal unwrapping errors, by extracting and unwrapping long-wave spatial signal (extracted by a combination of multilooking and Gaussian filtering) and signal related to atmosphere that can be modeled (e.g. using COMET GACOS data or by correlation of phase with a DEM). We show the effect of the improved approach is significant in standard time series processing (here using LiCSBAS).

This article contains brief overview on current key improvements in the interferograms generator part of LiCSAR, a system to generate open access moderate resolution Sentinel-1 interferograms aiming towards monitoring tectonic and volcanic deformation. We were focusing on improvements in performance and quality of unwrapping, and quality control of LiCSAR data.

Interferometric Synthetic Aperture Radar (InSAR) is a powerful tool for monitoring ground deformation associated with earthquakes, volcanoes, landslides, and different anthropogenic activities. The accuracy of the estimated deformation depends on a number of parameters including tropospheric and ionospheric delays, unwrapping errors, phase decorrelation due to changes in scattering behavior and system noise. However, recently an additional source of phase noise has been identified [1], which is strongest in short-interval multi-looked interferograms and, unlike other sources of noise, leads to biased, non-zero loop closure phases. This is problematic for time-series analysis because short-interval interferograms may be the only ones that maintain coherence for some areas. In this study, we explore the characteristics of this phenomenon and propose a mitigation strategy.

After the great activity of infrastructure development experienced in the 20thcentury, there are thousands of engineering infrastructures that require safety monitoring worldwide. Rigorous inspection programs and the monitoring of these infrastructures, such as reservoir dams, are essential for the safety of citizens and properties. These interventions are usually costly and time-consuming, making in many cases, virtually impossible to monitor individually each dam which may represent a potential security risk. Multi-temporal InSAR has been successfully applied in the monitoring of infrastructures affected by tunneling works, aquifer extraction, and natural phenomena (tectonics, volcanism, seism, …), among others. The great advantage of MT-InSAR is that it provides measurement uncertainties of the order of 1 mm/year, interpreting time series of interferometric phases of coherent reflectors present in the area, called Persistent Scatterers, without the need for field work or any special equipment. To demonstrate the potential and reliability of this technique, in this paper, we present the adaptation and application of MT-InSAR technique to monitor embankment dams, obtaining vertical displacements, characterizing their consolidation rates, and allowing the identification of potential problems that require further field investigation. This study is part of the ReMoDams project, a Spanish research initiative developed for monitoring dam structural stability from space using satellite radar interferometry.

Geodetic measurements of crustal deformation rates provide important information on earthquake hazard, indicating that strain is accumulating either faster or slower than the rate suggested by known earthquakes. With the COMET-LiCSAR InSAR processing system, which performs large-scale automated processing and timeseries analysis of Sentinel-1 data, we aim to generate strain rate maps for the entire Alpine-Himalayan Belt, and use these to investigate seismic hazard. In this paper we will present results for Anatolia. Deformation is also a key indicator of volcanic unrest, and is often associated with the flow of magma to shallower depths. The operational nature of Sentinel-1, with frequent revisits and rapid data delivery, makes it suitable for monitoring subaerial volcanoes globally. In order to deal with the large quantity of new data that is continuously being generated, we have developed machine learning approaches to flag when either a new deformation pattern emerges, or an existing deformation pattern changes rate.

This work focuses on a reservoir with water leaks since its construction, the Benínar reservoir. The purpose of this reservoir was to regulate the Adra River basin, lying between the provinces of Almería and Granada, and located south of Sierra Nevada Mountains (in the Inner Zones of the Betic Cordilleras, SE Spain). This basin extends over 746 km2, at an altitude of 2780 m, with a very rough terrain and frequent torrential water flow. Due to the continuous extension of greenhouses in the east and west parts of Almería, the water demand for agriculture and urban consumption increases day by day. As a consequence, aquifers are being overexploited, causing the current system to not be sustainable for a long time, that is, the storage capacity of the underground media and their possible contributions to an efficient management of resources have not been adequately taken into account. The Benínar dam has always had problems with water leaks. The dam was built even knowing that the land was not the most suitable, due to the frequent earth movements that took place in the town of Benínar, which was submerged beneath the waters of the reservoir. In this work, we process multi-temporal SAR datasets coming from the C-band satellites ERS-1/2, Envisat, and Sentinel-1A/B using MT-InSAR techniques, being able to monitor the deformation behavior of this dam for a long time period of more than 25 years, from 1992 to 2018.

The Aswan High Dam, Egypt, was built in the 1960s and is one of the biggest dams in the world. It stopped the seasonal flood of Nile river allowing the urban expansion of cities/villages and the full year cultivation, producing 10×109kWh of power annually. The dam is located in an area where several earthquakes (ML<;6) occurred from 1981 to 2007. In this paper, we want to identify any potential damage that could be caused to the dam, and assess its overall structural stability using Multi-Temporal InSAR (MT-InSAR). To reach this goal, we process Envisat data from descending orbits acquired between 2003 and 2010. Our initial estimates show relatively small rates (maximum around -3 mm/yr in the satellite Line-Of-Sight) of subsidence, whose implications must be further investigated. In addition, we perform a preliminary stress-strain analysis of the dam using FEL and FEM methods to assess if the detected movements correspond to the expected vertical behavior for such mega-structure.

Synthetic Aperture Radar Interferometry (InSAR) is a remote sensing technique very effective for the measurement of small displacements of the Earth's surface over large areas at a very low cost in comparison with conventional geodetic techniques. Advanced InSAR time series (Multi-Temporal InSAR or MT - InSAR) algorithms for monitoring and investigating surface displacement on Earth are based on conventional radar interferometry. These techniques allow us to measure deformation with uncertainties of one millimeter per year, interpreting time series of interferometric phases at coherent point scatterers (PS) without the need for human or special equipment presence. By applying InSAR processing techniques to a series of radar images over the same region, it is possible to monitor large areas and detect vertical displacements of ground, and infrastructures on the ground, and therefore identify abnormal or excessive movements indicating potential problems requiring detailed ground investigation. In this paper, we apply the PS- InSAR technique to a dataset of ERS-1/2 and Envisat radar images covering the period 1993-2010, to monitor the northern sector of the Valencia basin (Valencia city and its surroundings). Some subsiding areas were detected, with rates up to -5 mm/yr, whose causes are being investigated.

In the undermined Northern Moravia region, the land is subsiding even more than a metre per year causing damages to many human-made objects. Such a fast subsidence is almost not possible to estimate using multitemporal radar interferometry techniques that were applied to ERS-2 data of 1996–2001. Classic differential radar interferometry approaches were successfully applied allowing to visually interprete the evolution of subsidence in the area using Envisat and ERS-1/2 images from years 1996–2009. Results of the radar interferometry usage have been compared with the levelling data. Because of several factors, most of the interferograms are decorrelated. These factors are depicted and several solution scenarios are pointed out. To overcome such limitations as a relatively strong vegetation cover in the area and to detect such a fast subsidence in small areas, the ALOS PALSAR images in fine resolution mode has been successfully used.