Persistent Scatterer Interferometry (PS-InSAR) represents a technique that has the advantage of detecting, measuring and monitoring millimetre terrain and buildings displacements with a high degree of accuracy and rapidity, over wide areas. PS-InSAR involves the identification of persistent scatterers (PS) within the interferograms generated based on large time-series of synthetic aperture radar (SAR) images. In PS-InSAR processing, the temporal and geometrical decorrelation are reduced as well as the atmospheric artefacts. Presently, PS-InSAR represents an excellent tool for cultural heritage sites monitoring considering that no other investigation technique can produce such accurate and detailed measurements over large areas in a rather short period of time. The paper focuses on the application of PS-InSAR for monitoring two representative Romanian cultural heritage sites, namely Magna Curia Palace and the Medieval Fortress of Deva.
The Magna Curia Palace (Bethlen Palace) is the oldest functional building in the municipality of Deva. The first structure was raised in the 16th century, yet the plan of the respective medieval edifice is unknown. The current aspect of the palace is the result of the constructing endeavors carried out in the 17th and 18th centuries. Some of the owners of the building left their mark on its history, such as Prince Gabriel Bethlen (at the beginning of the 17th century) and Ioan Haller, governor of Transylvania (at the middle of the 18th century). On the course of the last major intervention, the palace received an upper floor and four corner bastions, while the facade displayed an evident Baroque aspect. We should also mention the monumental stairway from the northern side of the palace. Some of the inner chambers of Magna Curia are also spectacular, like the central hall which features a beautiful fireplace or the rooms with the roof decorated with stucco works.
The Medieval Fortress of Deva was built in the 13th century on a volcanic neck which dominates the Mureș Valley through its excellent strategic placement. The stronghold was attested for the first time in the documents in 1267, while the earliest architectonic elements belong to the Gothic style. Transformations of the initial plan were undertaken in the 15th-19th centuries, in accordance with the interests of the authorities of the time and the evolution of the art of war. The main edifice from the top of the hill is surrounded by three enclosures, following the conformation of the terrain. Their gates are defended by towers, while the walls are enforced by strong buttresses and bastions. The first precinct comprises the main structures: the princely palace, the kitchen, the water tank, possibly a chapel, etc. The access was made on a mobile bridge. The fortress was destroyed during the 1848-1849 Revolution due to an explosion of the ammunition chamber.
The research concentrates on the use of a multi-temporal series of Sentinel-1 data acquired over the region of interest that encompasses both Magna Curia Palace and the Medieval Fortress of Deva. The study aims at investigating the structure stability of the two cultural heritage sites aforementioned. The results will help the local authorities to better understand the characteristics of the sites in order to formulate and implement appropriate protection and preservation measures.

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Earth Observation satellite imagery ensures a comprehensive analysis of the built-up areas, including urban 2D and 3D mapping, detailed urban land cover and land use mapping, spatio-temporal evolution of the land use/land cover classes within the urban ecosystems, modelling of urban development and growth patterns, characterisation of urban areas based on radiometric indices derived from optical satellite imagery or information extracted from synthetic aperture radar (SAR) data, disaster risk assessment and reduction, identification and monitoring of the urban heat island effect and urban pollution, and urban subsidence. The test area of the present research study is represented by the city of Alba Iulia, including also the medieval Alba Carolina fortress, a place of monumental importance in the Romanian history. Considering the long-lasting efforts carried out by the local community to protect and preserve the cultural heritage of Alba Iulia, a special emphasis is put on heritage management and sustainability and also on the implementation of the digital heritage concept. In this context, the knowledge of the current conservation state of the Alba Iulia Citadel is essential.
The Alba Iulia bastion fortification is the largest fortress in Romania, which has been standing for more than 300 years. The Alba Carolina Citadel was erected in Alba Iulia at the beginning of the eighteenth century. The fortified assembly was configured as a premises defended by three rows of walls on a 110 hectare area. It is a star form fortification which was provided with seven bastions and six ravelins, crossed by vaulted galleries and all delimited by deep moats. The seven-star shape is given by the seven bastions, which form the "safety enclosure" of the most important and best-protected fortification. The bastions are generally counted from the 3rd gate, towards south, in a clockwise direction. Their walls are 2.5 meters thick with a height of over 10 meters. Built right in the heart of Transylvania, the fortified city proved to be the most imposing Baroque monument of the province. A peculiarity of the Citadel is given by the succession of the six gates, located on an east-west axis – the Tourist Route of the Citadel Gates, linking the civic center with the Roman Plateau. The Alba Carolina Citadel has seen spectacular transformations in recent years, today representing an exceptional Romanian cultural heritage site.
The paper focuses on a multisensor, multiscale and multitemporal approach to urban mapping and monitoring. The wide range of products that are derived from satellite data enables the comprehensive characterisation of an urban area based on the huge and manifold amount of information available. For example, the evolution of the urban landscapes in terms of land use / land cover change and extent, strongly correlated with the population and economic growth, enables analysis studies resulting in an accurate modelling of the evolution trends. The historical analysis of urban growth, the assessment of the current urban parameters, and the analysis of ground and infrastructures stability for future urban planning are equality important. Considering that the continuous knowledge of changes is critical in an urban context, these value-added satellite-based products represent the cornerstone for future urban development strategies, including measures for safeguarding the cultural heritage site of Alba Carolina. In this way, the Alba Iulia community will benefit from more appropriate and harmonised local policies.

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Earth Observation imagery allows the generation of complete, consistent, accurate and timely information for an effective cultural heritage site management, as an increasing number of satellites are launched every year. Satellite imagery enables a detailed analysis of the cultural heritage sites, including the constant monitoring and assessment of their conservation status. Moreover, Earth Observation data provides important information on the risks that might endanger the integrity of a cultural heritage site and its protection area. The continuous monitoring of the risks induced by geohazards and human-related processes offers critical information in support of the protection and preservation measures that should be taken by the responsible authorities. Scientific research in archeological remote sensing had led to significant results and continues to evolve by progressively embracing a multi-disciplinary approach.
The Roman city of Ulpia Traiana Sarmizegetusa lies in Țara Hațegului (Land of Hațeg), a picturesque depression at the Iron Gates of Transylvania. A modern village is built on the ruins of the ancient capital of Dacia, therefore the foundations of many local houses or other structures were erected with materials from the Roman edifices. Ulpia Traiana Sarmizegetusa was the first city founded in the province of Dacia after Emperor Trajan conquered the Dacian Kingdom, spreading on a surface of 30 ha, while the settlement outside the walls covered other 60 ha. Important monuments have been unearthed during the archaeological excavations and are still visible for the tourists: the old and new forum of the city, the amphitheater, the palace of the financial procurator of the province, granaries, the wall of the city, and numerous temples dedicated to various divinities (Aesculapius and Hygia, Liber Pater, Nemesis, the Nymphae, Malagbel, Mithras, the Palmyran Gods, Serapis, etc.). Many of them comprise architectonic elements carved in marble, taken from the nearby quarry of Bucova. Segments of the imperial road have been identified as well, together with the necropolises of the city. During the reign of Emperor Severus Alexander, Ulpia Traiana Sarmizegetusa gained the prestigious title of metropolis.
The paper focuses on the use of very high resolution synthetic aperture radar (SAR) and optical satellite data for deriving complementary information to characterize the Ulpia Traiana archeological site. The complete integration and fusion of these two types of satellite data enabled the generation of advanced and reliable products for the investigated cultural heritage site.

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Multitemporal analysis of satellite data acquired on the same geographical area enables the identification of changes that occurred within the monitoring interval. In the recent years, the increased number of satellite missions that have an open-access data policy both for the archive and the newly-acquired data led to the development of advanced automatic image classification and change detection techniques. Hence, the exceptional potential provided by the massive archives of satellite imagery allows the detection of long term changes. As the undeniable process of climate change increases the vulnerability of the cultural heritage sites, the permanent knowledge of the current state of conservation is essential. Satellite imagery provides essential information regarding the vulnerabilities of the cultural heritage sites and their surroundings, thus enabling the responsible authorities to carry out prevention and mitigation actions. Therefore, remote sensing is a powerful tool for monitoring of the cultural heritage sites and even for the discovery of new ones. In this paper, multitemporal time series analysis of satellite images was performed for two archaeological heritage sites located in Romania, namely Micia and Germisara.
The Roman fort from Cigmău was built on the first terrace of the Mureș River, on its right bank. The plateau is called by the locals “Turiac” and the exact place of the fortification bears the toponym “Cetatea Urieșului” (Fortress of the Giant). Archaeological researches were undertaken in the last two decades, with notable results. The wall of the fortification was unearthed, together with several inner stone buildings. The remains of the vicus may be spotted to the North of the camp. The fort was connected with the thermal complex from Geoagiu, ancient Germisara, by a road, still visible today on a few hundred meters. The function of the Roman camp from Cigmău was to control the territory and the communication routes, but also to secure the western border. The site was severely affected by landslides and the modern road.
Located on the left bank of the Mureș River, the archaeological site from Vețel comprises the ruins of the Roman fort and of the vicus: the ancient settlement of Micia, spread on more than 25 ha. Archaeological investigations began in 1880 and are still ongoing to this day. The military enclosure measures 360 × 189 meters, being one of the largest auxiliary forts in the province of Dacia. The emblematic structures of the site are the Roman baths and the amphitheater, but other several public and private structures are still visible for the tourists. The camp from Micia is placed right on the border, thus it was assigned with the protection of the limes and of the direct communication route with the Pannonian Plain. Major infrastructure projects caused immense damage to the fort and the settlement in the last two centuries, while nowadays private and public constructions are still and will be affecting the site.
The research integrates multitemporal optical and synthetic aperture radar data with various spatial resolution. The value-added satellite-derived products enhance the identification and understanding of the anthropogenic impacts on safeguarding Micia and Germisara.

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Nowadays, the protection of cultural heritage through a sustainable development is a great concern for all the scientific communities, with transdisciplinary studies, from nanotechnologies to satellites. New technologies play an important role in cultural heritage management, in order to offer tremendous information to conservators and restorers. Physical, mechanical or chemical alterations, but also the aesthetic ones, are the first symptoms of cultural heritage deteriorations and are caused by the synergistic action of environmental factors or microbial activity on civil structures or monuments. These changes can be monitored using both physico-chemical methods and remote-sensing methods, having as advantage their rapid and large-scale application. Establishment of a research methodology that integrates inter/multidisciplinary scientific proficiency can greatly contribute to the conservation, protection and scientific and cultural enhancement of a significant part of the immobile historical heritage in Romania. In the analytical sciences, many non/micro-destructive techniques are available and can offer information on identification of the materials and their production techniques, origins, characterization and location of natural sources of the raw materials or preservation and conservation methods. The benefits of using remote sensing technologies in this domain are: accurate and effective measurements (i.e. detection of sub-millimeter displacements), providing a “big picture” analysis of the entire studied object (monument/historic area), including its vast surroundings that might indirectly affect the cultural heritage site, the ability to “look back” using archived imagery to compare the state of the monument at different moments, the capacity to identify trends that derive from the analysis of huge datasets, providing support data and information to improve the documentation, visualization and modelling of cultural heritage.
These domains are intertwined within the on-going complex project “Multidisciplinary complex project for monitoring, conservation, protection and promotion of the Romanian cultural heritage”, formed of 4 component projects: 1). Monitoring of cultural heritage objectives using space technologies; 2). Nanotechnology - Innovative approach with the development of materials and techniques for safeguarding cultural heritage; 3). Integrated management (conservation, restoration, protection) of cultural heritage objectives; 4). Promoting cultural heritage using current digital reconstruction technologies.
The main objective of the research project 2 is to provide practical solutions based on new antifungal prescriptions, to reduce the impact of biodegradation of cultural heritage artifacts. The specific objectives of the project are: optimizing nanomaterial synthesis by controlling properties and dimensions for better antifungal effect and material characterization; Establishing an optimal ratio of materials in the proposed innovative recipe and exploiting synergistic action; Determining the method of application depending on the support material of the artifact; Study of the interaction between proposed prescriptions and support materials (archaeometry studies before and after treatment); Determining the effectiveness of the proposed recipes, depending on the morphology and properties of the organisms identified in the biodegradation process and the applied procedures.
As mentioned before, remote sensing represents a powerful tool for the documentation, mapping, evaluation of the conservation state, monitoring, preservation and the efficient management of the cultural heritage sites. A wide range of products may be generated based on Earth Observation data, including historical maps (showing the evolution of the cultural heritage site and its surroundings from the '80s to present), reference maps (containing administrative boundaries, land use and land cover classes, etc.), situation maps (highlighting areas affected by floods, deforestation, landslides, pollution, extreme weather events, uncontrolled urban growth) and advanced maps (presenting buildings and ground displacements, terrain heights, etc.).
The key element of this project is the development of a genuine linkage between the results obtained through different technologies and their rigorous integration in order to provide meaningful results in support of the cultural heritage site managers.
Acknowledgements
This work was supported by a grant of the Romanian National Authority for Scientific Research and Innovation, CNCS/CCCDI – UEFISCDI, project number PN-III-P1-1.2-PCCDI-2017-0413, contract 50PCCDI/2018, within PNCDI III.

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Cities with an ancient history are characterized by a variegated typology of archaeological evidences, both on its surface and in the underground. In urban environments the archaeological vestiges are still partially visible in the non-fully built-up areas while the subterranean ancient levels can be in some case still standing in their integrity. In the case of Rome, the dense networks of subterranean levels, that can be dated back to the Pre-Roman or Roman period, belong to different categories such as catacombs, subterranean traits of aqueducts, thermal conduits, sewers drainage tunnels, pipelines of tanks and finally, in the majority of the cases, they can be classified as ancient quarries for the exploitation of building materials. This last class has so far been little studied from an archaeological point of view, so its extent is only partly known, to the detriment of their conservation. The area of Centocelle in Rome, with the concomitant presence of the roman Villa Ad Duas Lauros, Villa della Piscina(and several other pre-roman and mediaeval remnants) and the roman quarries of tuff and pozzolana, is a perfect test zone for the setting of a multipurpose method based on satellite data analysis, applied both on the study of superficial archaeological entities and the monitoring of the state of preservation of hypogeal cavities. The test area allowed the use of a wide range of remote prospection methods, spanning from aerial optical imageries to optical and IR remote sensing, involving as well the SAR sensors data. This intervention is proposed as a pilot setting of a methodology applied on landscape archaeology, that favors the allocation of this very traditional discipline in the newborn and innovative research branch of the space archaeology. Landscape archaeology is herein intended as the discipline that is devoted to the description and interpretation of anthropogenic modifications to the territory cause by human activities and their impact on large scale: this discipline shall be beneficiated largely by a systematic application of aerial and Earth Observation methods. This variegated field of application has both small and large scale aspects such as the identification of macro and micro-topography, and the definition of environmental impact and the monitoring of structural changes. The recognition of this big variety of structure dimensions requires a very keen interpretation skills in the photodetection.
For each type of feature, a dedicated protocol based on a selection of satellite data type has been executed.
The approach favored the use of open and available data coming from European Space Agency and international programs such as Heritage missions data and Copernicus programme (the Sentinels) and Third Party Missions (TPS), by using catalogues and portals for their free access, visualization and download. The use of these free EO data for archaeology is aimed at addressing an additional valorization to them: this methodological approach is in fact still currently not enough developed.
Starting from the aspect of identification of archaeological structures, aerial photography can be used at hand, allowing to carry on a change-detection study that allows to analyze the landscape of Centocelle before the intensive urbanization of the 70’s and 80’s. The images have been processed with computer analysis approaches such as the radiometric and spatial adjustments, statistical and convolution filters that increase the edge thresholding and edge enhancement, edge detection and lineament extractions and automatic vectorialization. This methodology allowed to identify traces of the roman villas and the delimitation of residual dump heaps, artificial terraces and infrastructures related to the quarrying activities.
Similar processing was then applied to the optical satellite images coming from the Copernicus Open HUB tool that allowed the download of Sentinel 2 data.
Sentinel 2 with a wide swath high-resolution imagery in 13 bands, permitted the study of archaeological evidences and land use and vegetation state that are strictly related to the presence of buried structures. With the same aim also Third Party Missions products such as Landsat –STM and Landsat 7 ETM have been exploited. The use of optical-to-IR data from satellites for feature recognitions allowed to apply several additional techniques starting from simple operations such as the use of IR bands to extract information related to vegetation status that can be used as indicator for buried features and for environmental aspects. Negative and positive vegetation marks were visible in several different types of satellite images, making use of relative vegetation indices such as the NDVI.
High resolution DEM were created from the processing of stereo-couples of VHR satellite images such as Pleiades (0,5 meters for the panchromatic). This detailed DEM allowed the study of topography and micro-topography, much related with they ancient quarrying landscape and the presence of semi-buried perimetral walls of ancient housing structures. A high resolution DTM has been as well produced, to evaluate also the entity of heaps that partially cover the archaeological sites.
Sentinel 1 SAR data, band C, 5 meter resolution in the Spot Light and Strip Map modes, was used for archaeological prospection, especially considering the availability of single polarization for the Wave mode and the dual polarization for Strip Map, Interferometric Wide Swath and Extra Wide Swath modes. Radar images are free from the issues related to cloud and vegetation coverage so they are surely a valid tool for this type of study. SAR is also used in archaeological studies because of its penetration capabilities and because of thedistinction of features with different orientation, roughness and dielectric properties, permitting the identification ofelements that are not visible in optical images. All the low and high backscattering anomalies, due to different depth of penetration of the radar signal in relation of differences of topography, moisture and vegetation cover, can be used to detect archaeological features. Polarimetric SAR, was tried as well to detect the presence of buried structures, by extracting the polarimetric signature to enhance their visibility.
Finally the SAR long time-series was used with the DInSAR and PSInSAR processing, as a trial of monitoring stabilities of the cavities considering that several phenomena of degradation, such as the gradual compression failure of the pillars, the sub-horizontal cracks between pillar and vault and the gradual bowing of vaults, could at times develop gradually in time, causing a subsidence of the entire asset of underground and surface entities that it can be monitored. The Radar images come from the COSMO-SkyMed satellite observation programs (X-band SAR data) and Copernicus (Sentinel 1, C-band) and are processed for extrapolation of the PSs. The extraction of permanent scatterers was aimed at the evaluation of the possibility to evaluate entities of displacement through a large time span.
The use of satellite data for the study and monitoring of ancient subterranean archaeological structures is proposed as an experimental approach that could represent a way of identification special types of hidden hypogeal cultural heritage, such as ancient quarries, whose role in the documentation of ancient human activities is of great value and must therefore be protected.

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The first European Earth Observation Copernicus satellites are active since 2014 and are providing full, open and free (FOF) information, extremely useful for research purposes. Such a big amount of data, requires processing and, more importantly, alignment with local needs and with specific contexts, in all branches of environmental monitoring and emergency response management.
The use of Earth Observation datasets is especially important for monitoring Cultural Heritage sites and monuments that are under threat, providing quantitative and qualitative assessment. Currently, 54 sites are included in the list of World Heritage in Danger by UNESCO and the World Heritage Committee. Approximately the 40% of these are located in the Middle East area. In addition, only during this decade (2010 -today), 30 new sites have been reported as heritage at risk in a global scale.
Sentinel and Copernicus contributing missions, as well as other open and freely distributed data, such as the Landsat series, can be exploited in order to identify and map these sites, providing insights and valuable information, for a long period of time, even in areas where in situ observation is not an easy task (e.g. arm conflicted zones).
This paper aims to provide examples and case studies of heritage sites at risk, threaten by various anthropogenic hazards -such as terrorism, looting, urbanization etc.- based on image processing and multi-temporal analysis of satellite data, fused with other available information for each site.

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Nowadays, Cultural Heritage is more and more endangered due to a wide list of factors. Climate change consequences as sudden and heavy rains, floods, earthquakes, are increasingly frequent worldwide, and they constitute a new increasing threat especially in areas not used to those destructive phenomena. The present work exploits a multi-frequency and multi – incidence angle SAR analysis for the detection of archaeological features and it provides information related to the surface topography of the area in which the cultural heritage sites are located.

Thanks to the Copernicus missions and the exploitation of dual and fully polarised SAR data, combined with optical EO imagery, a multi temporal monitoring of cultural heritage sites is possible. Sentinel-1 (C-band), ALOS PALSAR (L-band), RADARSAT-2 (C-band) sensors are used specially for the monitoring detection of surface and subsurface archaeological structures. While ALOS PALSAR offers a good historical reference, Sentinel-1 time series provide recent and systematic monitoring opportunities. Sentinel-2 and additional high-resolution optical EO data are used for detecting land change use over time, visual inspection analysis and generating value added products (e.g. risk maps) for safeguard and preservation purposes. Ancillary data as historical aerial photographs, cartographic documentation and archaeological maps contribute to a complete analysis over the analysed areas of interest.

Several cultural heritage sites have been selected: the Nabataean caravan-city of Petra (Jordan), the Gebel Barkal and the sites of the Napatan region (Sudan), respectively inscribed in the UNESCO World Heritage List from 1985 and 2003, and the ancient city of Ashur (Iraq) inscribed in the UNESCO World Heritage List in Danger since 2003. Thanks to the multidisciplinary approach, several EO data exploitation techniques are able to retrieve important information in a so diverse morphological environment characterizing the selected areas: desert, rain-fed and irrigation agriculture fields, mountains and proximity to water bodies.

Remote sensing for Cultural Heritage is not a novel research field, but an unequivocal method capable of an automatic detection of archaeological features is still not existing: objective of the work is to exploit the potential of such complex and multidisciplinary study for detection, monitoring and safeguarding purposes.
Hence, the analysis of possible threatening factors that can affect the integrity of a cultural site becomes more and more important, especially in relation to the rate of extreme weather events and their impacts on our only Planet, the Earth.

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The study shows the analysis of natural hazards in the Derwent Valley, one of the World Heritage Site (WHS), obtained from in-situ observation, Interferometric Synthetic Aperture Radar (InSAR) results and flooding simulations based on different climate change scenarios.
Derwent Valley Mills WHS was inscribed by UNESCO in 2001 because it is regarded as the birthplace of the factory system, therefore having huge historical and technological interest. The site is complex containing a number of early industrial mills, each telling their own story, as well as the associated housing and buildings, and infrastructure networks such as canals and railways. Together, they illustrate the socio-economic development of the area during the 18th and 19th centuries.
Over the last two centuries most of the industrial landscape and complexes have been well-preserved and the upper reaches of the valley are still intact, however, present and future environmental and geological processes could expose these heritage assets to a series of threats, including surface water and fluvial flooding, contaminated sediment transport and remobilisation of deposits/minerals historic mining activities.
The analysis reveals that flooding, from both fluvial water flow (for over 50% of the site) and emergence of groundwater at the surface (for over 40% of the site), and landslides, with 44 events identified, represent the main geohazards that the WHS is susceptible to impact from, either directly affecting the historic mill complexes, or the surrounding infrastructure and landscape. Currently, three areas are considered as most critical: Starkholmes and Ambergate due to the active state of nearby landslides and Belper where damage connected to recent flooding events are still visible.
When modelled against UKCP09 (The UK Climate Projections 09) climate change scenarios, many areas show increased geohazard susceptibilities in the coming century.
The Derwent Valley is one of the demonstration sites, along with the Historic Centre of Rome (Italy), Alhambra (Spain) and Choirokoitia (Cyprus), selected within the PROTHEGO (PROTection of European Cultural Heritage for GeO-hazards) project.
The latter aims to make an innovative contribution towards the analysis of geohazards in areas of cultural heritage in Europe using novel space technologies.

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Tangible cultural heritage includes various categories of monuments and sites, from individual architecture to cultural landscapes, and from archaeological complexes to historic centers. Many of these sites are affected by a variety of processes, with rapid or slow onset. They include natural hazards, such as landslides, settlement, subsidence, earthquakes or extreme meteorological events, which could be worsened by climate change and/or human interaction. A comprehensive European database of cultural sites affected by geo-hazards is not yet available. The Protection of European cultural heritage from geo-hazards, (PROTHEGO) project provides an overview of remote sensing capabilities for monitoring geo-hazards affecting properties in Europe on the UNESCO World Heritage List (WHL). These properties will serve as a reference case for all the European cultural heritage (CH) properties where one of the most important problem to overcame is the lack of information on the number, typology, distribution and vulnerability of CHs in the entire Europe. The Principal Investigators of the Prothego project are the European National Geologic Surveys of Italy, United Kingdom and Spain along with the Department of Earth and Environmental Sciences of Milano-Bicocca and Cyprus University of Technology. Many other stakeholders have also been involved in the Project as Associated Partners at local levels (e.g. Archaeological Park Administrations of Roma, Alhambra and Petra, archaeologists local associations) and at international levels (e.g. UNESCO, European Space Agency, Geological Survey of Europe, International Consortium on Landslides). PROTHEGO project applies novel space technologies based on radar interferometry (InSAR) to monitor monuments and sites in Europe which are potentially unstable due to geo-hazards. These technologies provide crucial information in developing site management strategies sustainable for the preservation of cultural heritage and landscape. Remotely sensed information on ground stability conditions is combined with geohazard datasets in order to identify the most endangered sites across Europe. In order to assess observed motions and understand geological processes, an analysis of remotely sensed data in conjunction with local-scale geological analysis was implemented for each test site. Advanced modeling and field surveying were also carried out. At least one site for each partner country was chosen to validate and calibrate the methodology. PROTHEGO's goal is to enhance cultural heritage management practices at the national level, reinforcing institutional support and governance through knowledge and innovation, identifying, assessing and monitoring risks, and strengthening disaster preparedness for heritage properties in the future. The project promoted interdisciplinary and collaborative R&D activities, transferring the highest level of knowledge, quality and standards from space and earth sciences to Cultural Heritage conservation sciences. A general agreement around the use of satellite services for monitoring geo-hazards affecting cultural heritage needs to be implemented in order to define best practice guidelines and standard methodologies for adoption by practitioners in this field (e.g. the seventh Copernicus service). A multi-disciplinary approach among Earth Science disciplines, data providers, data processers and cultural heritage protection domain is required to make a positive difference. There is a need for developing simple and dedicated tools or downstream services that enable practitioners to make better use of available data by providing information on geohazards’s state of activity and potential impact to the cultural heritage. CH is an important pillar both for economic and social impact across Europe. Better understanding natural hazard processes affecting CH through low impact monitoring techniques like satellite methodologies improves the resilience and reduce the general vulnerability, saving money of post disaster recovery and obtaining long term cost benefit. Additional information on the activities that were developed during the project can be found on the dedicated website: www.prothego.eu.

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The UNESCO lists alone 54 endangered Cultural Heritage sites.  Quite a few of them around the world are subject to many threats by crisis, crime and natural hazards. In this work we show a mostly automatic approach for monitoring operationally many Cultural Heritage sites in parallel using Sentinel data and in case of a potentially detected problems to allow a deeper analysis using very high resolution (VHR) optical sensor data provided by Copernicus contributing missions like WorldView or Pléiades, which includes also automatic approaches in 2D and also 3D change detection.

The aim of the monitoring and change detection approach is investigation of the various processes potentially affecting the preservation and management of Cultural Heritage sites, including but not limited to anthropogenic and natural disasters such as extreme weather events, floods, earthquakes and fires. Further hazards to cultural heritage sites are inefficient protection policies and uncontrolled tourism. In our previous study, satellite stereo images have been successfully used in building and forest monitoring. The Digital Surface Models (DSMs) generated from stereo imagery can be fused with the spectral information to further improve accuracy of the results. In this article, the proposed 3D classification and change detection approaches for the monitoring of cultural heritage sites are further tested. 3D change detection can be applied to sites where very high resolution optical stereo data is available for at least two times. For this e.g. older archived imagery from Ikonos or even Keyhole as also combinations of imagery from different sensors and different orbits may be used.

As case studies the mapping and monitoring of damages caused by the Islamic
State to Cultural Heritage sites in Palmyra, Syria and in Nimrud, Iraq are presented. Furthermore, we applied the developed approach to detect damages at Cultural Heritage sites and their surroundings caused by the civil war in Yemen. The time series satellite data from Sentinels and Copernicus contributing missions (e.g. COSMO-SkyMed, TerraSAR-X, PAZ, ALOS, Proba-V, SPOT, Landsat, IKONOS, Pléiades, WorldView, GeoEye, SMOS) as well as thematic platforms will be exploited in the application.

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Cultural and natural heritage (CNH), the core carriers of the cultural diversity and biodiversity in our planet, are recognized as being of physical, biological, geological, historical, social, and anthropological outstanding-universal-values and are considered as enablers and catalysts of sustainable development. The World Heritage Convention has taken a step forward by adopting a policy on the integration of a sustainable development perspective into the processes of the World Heritage Convention in 2015, almost parallel to the adoption of the 2030 Sustainable Developments Goals (SGDs) by the UN. UN’s sub-SDGs 11.4 emphasizes to strengthen efforts on protection and safeguarding the world’s cultural and natural heritage and UN’s sub-SDGs 8.9 aims to promote sustainable tourism that creates jobs and promotes local culture and products. This paper briefly reviews the earth observation technologies and big data of multi-sensor satellite remote sensing and their applications to CNH. Detailed aspects of CNH-related SDGs, including monitoring and conservation, as well as the promotion of sustainable tourism are pointed out. Contributions of EO to each aspect are then identified and analyzed. Case studies of carried out by using multi-sensor and multi-temporal remote sensing data and geospatial analysis methods, are presented to demonstrate the potentials and limitations of EO to enhance CNH conservation and to promote sustainable tourism. The opportunities and challenges of EO for the assessment of UN’s SDGs indicators are discussed. Based on analysis of the literature review and the presented case studies, it is indicated that the contributions of EO to the achievement of CNH SDGs is essential, significant and self-evident. Moreover, following the UNESCO initiative to introduce CNH into the sustainable development agenda and related action plans from ICOMOS and IUCN, this paper tried to investigate and propose new CNH indices and indicators to enrich and feed into the UN’s 2030 SDGs from the perspective of earth observation.

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A globally well-known UNESCO World Heritage site since 1994, the ‘Lines and Geoglyphs of Nasca and Palpa’ in Peru have long been documented using surface and near-surface geophysical methods for identification of anthropogenic features and targets, and analysis of interactions between nature and human presence. In this work, we present experiments carried out with satellite Synthetic Aperture Radar (SAR) imagery acquired by the Copernicus Sentinel-1 constellation and its SAR Contributing Missions, to document the lines and geoglyphs of the Pampas de Jumana, and detect events of natural and human-induced landscape disturbance occurred over the last three decades. Regional to site scale assessments of landscape changes and condition of heritage assets are carried out using long series of medium and high spatial resolution ERS-1/2, ENVISAT and Sentinel-1 IW C-band SAR data acquired since the 1990s. Very high resolution scenes from the X-band COSMO-SkyMed and TerraSAR-X SAR constellations complement the assessment by going up to the single meter scale. We track two recent events of damage at the lines using StripMap and SpotLight mode COSMO-SkyMed scenes from a tailored satellite monitoring campaign being carried out at the site, in addition to the 12-day site revisit in both ascending and descending mode provided regularly by Sentinel-1 over this region. The first event occurred in December 2014, when environmental activists accessed the area near the Hummingbird geoglyph, marked the route followed to access the geoglyph and disturbed the surrounding terrain. The second occurred in January 2018, when a truck diverted off the Pan-American Highway, entered the protected area and crossed over 3 geoglyphs. Pre-, cross- and post-event Interferometric SAR (InSAR) pairs allow the detection of temporal decorrelation associated with the two events, the extent and time reference of which match with photographic and video evidence, literature, web news and press releases by the Peruvian Ministry of Culture. SAR data archives, such as those being built for Nasca by COSMO-SkyMed and Sentinel-1, prove valuable for digital recording and documentation of the lines and geoglyphs as well as of events of landscape disturbance from space, and therefore act as essential sources of geophysical and geospatial information on the condition and conservation history of the archaeological assets of this region. Our experiments with COSMO-SkyMed also demonstrate how a Copernicus Contributing Mission acquiring SAR imagery at very high resolution can be used to better substantiate events relevant to the conservation of cultural heritage, and provide spatially detailed and temporarily regular information to complement the 12-day revisit Sentinel-1 observation scenario at high resolution.

References:
- CIGNA F., TAPETE D. 2018. Tracking human-induced landscape disturbance at the Nasca Lines UNESCO World Heritage site in Peru with COSMO-SkyMed InSAR. Remote Sensing, 10 (4), 572, 13 pp. doi:10.3390/rs10040572
- TAPETE D., CIGNA F. 2017. Trends and perspectives of space-borne SAR remote sensing for archaeological landscape and cultural heritage applications. Journal of Archaeological Science: Reports, 14C, 716-726. doi:10.1016/j.jasrep.2016.07.017
- CIGNA F., TAPETE D., LASAPONARA R., MASINI N. 2013. Amplitude change detection with ENVISAT ASAR to image the cultural landscape of the Nasca region, Peru. Archaeological Prospection, 20 (2), 117–131. doi:10.1002/arp.1451
- TAPETE D., CIGNA F., MASINI N., LASAPONARA R. 2013. Prospection and monitoring of the archaeological heritage of Nasca, Peru, with ENVISAT ASAR. Archaeological Prospection, 20 (2), 133–147. doi:10.1002/arp.1449

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Digital Elevation Model (DEM) products with global coverage, such as SRTM DEM and ASTER GDEM, have been increasingly used by archaeologists for morphological analysis of landforms, prospection of ancient settlements, discovery of palaeo-environmental features, and reconstruction of migration and trading routes. However, one of the major limitations might be the spatial resolution, alongside product coverage and data gaps. This constraint has been frequently overcome through the generation of DEMs from ad hoc very high resolution (VHR) optical stereo-pairs (e.g. Pléiades, GeoEye-1), while still limited is the literature on the use of high resolution (HR) DEMs from SAR missions (e.g. TanDEM-X) for archaeological surveys of anthropogenic deposits.
The collaborative project “LARICI: Landscape Archaeology Radar in Central Iraq” between the Italian Space Agency (ASI) and archaeologists of Ca’ Foscari University of Venice, aims to assess the value of HR to VHR SAR DEMs produced with COSMO-SkyMed data to facilitate the detection of low-relief features across wide (semi-)arid cultural landscapes. The geographic focus of this experimental research is the Wasit Governorate, Central Iraq, where a systematic archaeological survey has never been conducted before, and available DEMs from open sources provide 1 arcsecond (approx. 30 m mesh) resolution at best (e.g. ALOS World 3D; AW3D30). We present the results achieved by combining COSMO-SkyMed DEMs at 10-m posting and field surveys, the first of which was undertaken in April-May 2018.
A two-way approach has been used:
(1) GPS positions and archaeological properties (e.g. height, archaeological findings and ceramics at surface) collected during the site surveys were used to train the workflow of site detection, by matching the in situ evidence with the radar backscatter anomalies found in the SAR images and the topographic relieves highlighted in the DEMs;
(2) the radar backscatter anomalies and topographic relieves of hypothesized anthropogenic origin or modification were extracted semi-automatically from the COSMO-SkyMed DEMs, and used as a satellite-based evidence to inform the decision about the areas that the archaeologists could inspect during successive field surveys.
Through a selection of archaeological mounds formed from accumulation of anthropogenic stratifications over time (so-called ‘tells’) dating to different epochs, we will discuss the improvement in spatial resolution brought by COSMO-SkyMed, the benefit of digital field-working over wide areas and the complementarity with traditional surveying methods. We will also showcase how COSMO-SkyMed acquisitions and DEM generation have been tailored to meet specific user needs expressed by the archaeologists and local heritage stakeholders. From the lesson learnt during this collaborative project, we will finally outline some recommendations for the use, by a wider heritage community, of DEMs produced from HR SAR missions, such as those belonging to Copernicus Mission Group 1 - SAR VHR1-MR1.

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The current easy access to time-series remote sensing data for archaeological research provided by open databases and platforms, such as Sentinel and Copernicus, is putting the spotlight on the urgency of developing or advancing automated workflows able to streamline the examination of such data and unearth meaningful information from them. While in other disciplines availing remotely sensed data discussion and advancement are already well articulated, automated detection of ancient human footprint on aerial/satellite imagery has seen limited progress within the archaeological sphere. Advances in finetuning workflows for the automatic recognition of target landscape patterns are being trailed within the framework of VEiL, a landscape archaeology project based in NE Italy and focused on the engineered landscape of the Roman city of Aquileia (Udine). Here, the centurial grid deployed at the closing of the 2nd century BC still characterises the modern landscape and has affected space organisation development even in the centuries after the fall of the Roman domain. One of the major issues when tackling the detection of centurial systems is the identification of land division boundaries as they might have been formed by a variety of different natural or artificial elements (roads, fences/hedges, ditches, drainage channels, tree lines and other landmarks). Thus, the objects of interest in the detection are not archaeological features per se, but rather consist of a variety of similarly oriented scene elements that concur to structure the landscape organisation. This paper will expand on approaches in Feature extraction that can reveal anthropogenic landscape components and patterns based on recognition of recurring patterns and regularities in a variety of multitemporal imagery derived from local and freely accessible RS archives. The paper will cover the workflow’s utilisation of the textural and shape properties of real-world elements forming field patterns using multiscale analysis of dominant oriented response filters.

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The increase of looting of cultural property in the past decades (often related to the destabilization of the States, especially in the Near-Eastern regions) represent an increasing phenomenon with strong consequences in terms of security, economics, culture and society. It has reached an international scale, favored by the availability of technological resources and a growing level of scientific sophistication of looters. To coordinate existing but disconnected initiatives aiming to contrast looting phenomena the NETCHER project (NETwork and digital platform for Cultural Heritage Enhancing and Rebuilding) has been recently established thanks to a grant by the European Community (H2020 program). Among the initiatives included in the project, the potential of remote sensing in fighting pillaging of cultural sites will be explored. The Remote sensing community will be involved in defining future research and developments aimed at using satellite imagery and other forms of remote detection to contrast looting by monitoring endangered archaeological sites through time-series data and detecting sites under heavy looting, especially in conflict areas where direct inspection is too dangerous or in remote regions where inspection is not feasible. This paper will try to propose a roadmap for the exploitation of Sentinels and Copernicus contributing missions data in the fight to looting and to solutions for risk assessment and resilience strategies based on them. The availability of freely available data and of time-series that these platforms provide can be in fact game-changing in the fight providing a readymade tool for the use of satellite imagery in the monitoring of cultural sites. The discussion will concentrate on showcasing benefits of Sentinels and Copernicus data for documenting, monitoring, and safeguarding cultural heritage sites, and outline perspectives for different implementation scenarios in a variety of contexts, from rural areas of the most advanced European countries to the abandoned warzones of the Middle east.

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Advances in earth observation (EO) system have led to an increased application of EO data in studies of cultural and natural heritage (CNH), including but not limited to the investigation, documentation, monitoring, preservation and management of CNH sites. Despite the great potential of Sentinels and Copernicus contributing missions in archaeology by virtue of providing multi-mode, multi-band and multi-resolution space-borne images, the datasets in wooded areas cannot provide detailed terrain features under dense vegetation cover, especially for tropical regions. To get a complete understanding of archaeological landscape in forest area, we propose to combine space technologies of multiple load platforms and multiple remote sensing sensors. In this study, apart from EO data, we also use UAV (unmanned aircraft vehicle) LiDAR to investigate the ancient earthwork features under forest canopy in Pishan archaeological site in Zhejiang Province of China, and use airborne images obtain in 1970s to support our work for archaeological interpretation.

Recent studies have demonstrated that airborne LiDAR (light detection and ranging) is a potential tool for archaeological investigations in recognizing and mapping topographic earthwork features in wooded areas, but there is no published study about applying UAV LiDAR in archaeology. In this study, we first use UAV LiDAR to measuring the micro topographical features under vegetation cover. In order to get a reasonable balance between cost and data quality, we test two different types of UAV LiDAR system. One is Velydone 16E, representing the lower-cost UAV LiDAR system with single echo and measurement rate up to 300,000 meas./sec; the other is Rigel VUX-1, representing the higher-cost UAV LiDAR system with multiple echoes and measurement rate up to 500,000 meas./sec. The effects of the above two tests are compared and analyzed, including the density of LiDAR points reach to the underlying terrain and digital elevation model (DEM) generated by ground points. The study results point out that the multi-echo UAV LiDAR system enables the detection of micro-topographic relief of archaeological interest in densely vegetated areas.

In addition, the full-waveform (FW) data obtained by the Rigel VUX-1 LiDAR system is also processed by breaking-down the waveform into individual Gaussian Distribution Functions (GDF), based on which the ground points can be classified out more accurate. The study result shows that FW scanner, compared to conventional LiDAR scanner, can distinguish ground points from understory (brushwood and low-level vegetation) and contribute to identify detailed archaeological features in wooded areas.

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Neotropical forests are one of the most important global biomes which have for long provided resources for humans. Unravelling the influence of human presence on these forests is fundamental to our understanding of the biodiversity, ecosystem function, service-providing potential, and its cultural heritage. Human presence in Neotropical rainforests dates back 13,000 years, and the impacts of this presence are hotly debated. Evidence from remote sensing has become increasingly useful as a way to help settle these debates. Here we review past, current, and future uses of remote sensing technology to detect human infrastructure in the Amazon and other Neotropical forests over the several historical periods of human presence, from archaeological to post-modern societies. We define human presence in terms of activities that left behind a footprint that could be detectable with remote sensing, such as settlements, earth-mounds, roads, use of timber and fuelwood, agriculture, soil, etc. There have been many recent applications of remote sensing to the detection of Pre-Columbian human infrastructure, from visual inspection of aerial photographs over deforested sites to uses of LiDAR on airborne and UAV platforms to detect infrastructure and smaller settlements under the canopy. Similar efforts are yet to be conducted for the Post-Columbian period, especially during the colonization and imperialism periods. Finally, our knowledge of human impacts in the modern era (20th and 21st centuries) is not-surprisingly more extensive. Remote sensing is still under-used and extremely useful for this type of application, and new missions might provide solutions that were unavailable before. There are many opportunities and challenges for the use of remote sensing to provide data and information necessary to expand our understanding of cultural heritage in Neotropical forests. Yet systematic ground surveys are irreplaceable, and detection accuracies of human presence from the combination of remote sensing and ground surveys need to be improved. It is vital therefore to understand how Neotropical forest biodiversity has developed in the presence of people and its cultural heritage as this have major implications for predicting future directions of change in the Amazon and elsewhere.

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This study is part of the project “Environmental management with remote sensing for natural hazards and mapping as information for decision makers (FUNKIE)” funded by the German Federal Ministry of the Interior, Building and Community.

The 2018 European drought and heat wave with its unusually hot weather and low precipitation caused wildfires in many parts of Europe. Whereas about 3900 km² of the E.U. burn every year, the fires in 2018 burned nearly three times that much and affected areas where wildfires were not so common. For the monitoring of wildfires and the mapping of burned areas, optical satellite imagery and aerial photos have been successfully used in the past. However, smoke and clouds often impede the acquisition. Hence, to map these burned areas, a multi-sensor approach needs to be followed.

In this study, we compare the potential of optical and SAR sensors with different resolutions for the monitoring of wildfires in Europe and discuss their advantages and disadvantages for their use in disaster management. Our analysis focuses on a wildfire event in 2017 that occurred in Lieberoser Heide, near Cottbus, Germany. Our dataset include Sentinel-1, Sentinel-2, Sentinel-3 Landsat 8 imagery as well as high-resolution satellite imagery from satellites such as RapidEye, PlanetScope, and TerraSAR-X, and aerial photos.

The analysis of the optical imagery is based on false-colored composites and different measurement indices, such as Normalized Difference Vegetation Index (NDVI), Burned Area Index (BAI), and Normalized Burn Ratio (NBR). The analysis of the SAR imagery is based on change detection of intensity images before and after the fire event and a coherence analysis. The classified burned areas are compared to each other and validated with mapping results provided by the local forestry office.

The questions we aim to answer in this study are: how precisely can the burned area be detected in the high and medium resolution remote sensing imagery? What are the contributions of low resolution remote sensing data? What are the potential of SAR imagery? How does different vegetation cover influence the remotely-sensed monitoring?

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