Des cartes mentales pour analyser la vulnérabilité au risque d’une ville de l’Arctique russe : Khamagatta

L’article présente les résultats principaux d’un atelier cartographique conduit à Khamagatta (Sibérie orientale). L’objectif en était double : observer la vulnérabilité aux inondations de débâcle de la ville par les connaissances d’enfants et d’adolescents y vivant ; utiliser la carte comme instrument de dialogue, d’intégration des connaissances et de recueil de données. Récits et cartographies ne s’opposent pas, mais se renforcent. L’atelier cartographique a permis que se côtoient différents registres de connaissances et produit au final des informations précieuses pour l’analyse scientifique.The paper presents the main results of a cartographic workshop in Khamagatta (Eastern Siberia). The objective was twofold: observing the town vulnerability to ice break-up floods through a group of children and teenagers knowledge living there; use the map as an instrument for dialogue, knowledge integration and data collection. Narratives and cartographies are not opposed but rather mutually reinforcing. This cartographic worskhop allowed different registers of knowledge to be brought together and ultimately produced valuable information for scientific analysis.Este artículo presenta los principales resultados de un taller de cartografía realizado en Khamagatta (Sibería Oriental). El objectivo era doble: observar la vulnerabilidad de esa ciudad a inundaciones devastadoras mediante las percepciones de los niños y adolescentes que viven en ella; y utilizar el mapa temático como herramienta para el diálogo, la integración de conocimientos y la recopilación de información. Narración y cartografía no se oponen sino que se refuerzan. El taller cartographico facilitó aunar distintos registros de conocimiento y, en última instancia, produjo valiosa información de gran interés para el análisis científico

Structure et organisation spatiale du paysage de pergélisol montagneux et boréal en Yakoutie

Pour les régions de pergélisol, et pour la Yakoutie en particulier, le rythme du changement climatique est deux fois plus rapide que la moyenne mondiale. Par conséquent, les changements de paysage et les problèmes d'utilisation des terres associés aux processus du pergélisol devraient s'intensifier dans un avenir proche. Dans cette recherche, nous avons exploré l'organisation spatio-temporelle des paysages de pergélisol en Yakoutie à travers l'exemple de deux cas d’étude: la Ridge Orulgan et l'interfluve Lena-Amga. Comme les zones étudiées couvrent de vastes régions sporadiquement étudiées, nous avons effectué une modélisation multi-échelle et multi-temporelle des variables biogéographiques, géomorphologiques et lithologiques pour l'analyse des paysages en utilisant des séries temporelles d'images Landsat et Sentinel 2. Les résultats obtenus nous ont permis d'avoir un aperçu inédit de la distribution spatiale des paysages. Deuxièmement, grâce à l'utilisation de l'analyse typologique comparative, nous avons identifié de grands groupes de paysages au sein des bassins fluviaux. Troisièmement, l'analyse multitemporelle de toutes les données disponibles de la série Landsat a révélé la dynamique du paysage sur la période 1999-2020, où des changements cohérents sont associés au "greening" de la toundra et à l'expansion des forêts, et a identifié les perspectives d'application de l'imagerie thermique pour identifier les processus cryogéniques. Enfin, l'intégration des connaissances sur les paramètres du pergélisol et le potentiel écologique nous a permis d'évaluer la durabilité et les risques environnementaux, ce qui est nécessaire pour la planification territoriale.For the permafrost regions, and for Yakutia in particular, the rate of climate change is twice as fast as the global average. Therefore, landscape changes and land use problems associated with permafrost processes are expected to intensify in the near future. In this doctoral research, we explored the spatio-temporal organization of boreal and mountain permafrost landscapes in Yakutia by the example of the two study cases: the Orulgan Ridge and the Lena-Amga interfluve. As the study areas cover extensive sporadically studied areas, we carried out multiscale and multi-temporal modelling of biogeographic, geomorphological and lithological variables for analysis of permafrost landscapes using time series of Landsat and Sentinel 2 satellite images. The results obtained allowed us to take a novel insight into the spatial distribution of permafrost landscape. Second, through the use of landscape metrics and comparative typology analysis, we identified large landscape clusters within river basins. Third, the multi-temporal analysis of all available Landsat series data revealed landscape dynamics over the period 1999-2020, where consistent changes are associated with "greening" of tundra and expansion of forests, and identified prospects for applying thermal imagery to identify cryogenic processes. Finally, the integration of knowledge on landscape changes, permafrost parameters and ecological potential allowed us to assess sustainability and environmental risks in permafrost landscape types, which is necessary for territorial planning

Моделирование разносезонных космических снимков и цифровой модели рельефа для распознавания растительности горных мерзлотных ландшафтов бассейна реки Адыча

International audienc

ПРОСТРАНСТВЕННАЯ СТРУКТУРА МЕРЗЛОТНЫХ ЛАНДШАФТОВ ЯКУТИИ: ГЕОИНФОРМАЦИОННОЕ МОДЕЛИРОВАНИЕ (НА ПРИМЕРЕ СРЕДНЕТАЕЖНЫХ И ГОРНЫХ МЕРЗЛОТНЫХ ЛАНДШАФТОВ)

The solution of many issues of rational land use management is based on information about the state of the landscape complexes. The possibilities of obtaining reliable information on the spatial structure of permafrost landscapes become especially relevant for state assessment and evolution trends. Increasing environmental changes in the cryolithozone zone are associated with trends in climate change and vulnerability to anthropogenic impacts. The aim of this dissertation is to study the spatial structure of the permafrost landscapes of Yakutia on the basis of geoinformation modeling, taking as the object of research the middle taiga permafrost landscapes of Central Yakutia and the mountain permafrost landscapes of the Verkhoyansk region. To achieve this aim, the methods of the analysis and the processing of the time series of multi-sensor remote sensing data and digital elevation model has been developed. The methods allow modeling to map the visible morphological features of permafrost landscapes (relief and vegetation) with the implementation of ontological properties with the permafrost and lithogenic base. Time series of Sentinel 2 and Landsat 8 OLI images for the period 2015-2020 are used to map vegetation classes and analyze the state of vegetation cover. The vegetation classes are recognized by the variation in the photosynthetic activity of plant associations on the spectral reflectance characteristics. This allows us to use differences in phenological phases to increase the recognizable classes of plant associations. The accuracy assessments of the classification results are calculated by the comparison with high resolution images and field data to ensure a high level of validation confidence. Based on the ASTER GDEM relief data, we determined the genetic type of Quaternary sediments according to the landform classification calculated by the Topographic Position Index (TPI) and GIS analysis. Thus, modeling these two morphological features allows the development of a geospatial database of test study area. The database includes information on the existence of intensity transformation factors for the identified landscape complexes. The GIS models of permafrost landscapes provide information on the type of soil cover, soil conditions (moisture, temperature) and cryogenic texture. Obtaining such data demonstrates the effectiveness of the modeling for assessing the spatial structure of permafrost landscape in local level.La solution de nombreux problèmes de gestion rationnelle de l'utilisation des terres repose sur des informations sur l'état des ensembles paysagers. Les possibilités d'obtenir des informations fiables sur la structure spatiale des paysages de pergélisol deviennent particulièrement pertinentes pour l'évaluation de l'état et les tendances d'évolution. Les changements environnementaux croissants dans la zone cryolithozone sont associés aux tendances du changement climatique et à la vulnérabilité aux impacts anthropiques. L'objectif de cette thèse est d'étudier la structure spatiale des paysages de pergélisol de Yakoutie sur la base de la modélisation de la géoinformation, en prenant comme objet de recherche les paysages de pergélisol de la taïga moyenne de la Yakoutie centrale et les paysages de pergélisol de montagne de la région de Verkhoyansk. Pour atteindre cet objectif, les méthodes d'analyse et de traitement des séries temporelles de données de télédétection multi-capteurs et de modèle numérique d'élévation ont été développées. Les méthodes de modélisation permettent de cartographier les caractéristiques morphologiques visibles des paysages de pergélisol (relief et végétation) avec la mise en œuvre de propriétés ontologiques avec le pergélisol et la base lithogène. Des séries temporelles d'images Sentinel 2 et Landsat 8 OLI pour la période 2015-2020 sont utilisées pour cartographier les classes de végétation et analyser l'état du couvert végétal. Les classes de végétation sont reconnues par la variation de l'activité photosynthétique des associations végétales sur les caractéristiques de réflectance spectrale. Cela nous permet d'utiliser les différences dans les phases phénologiques pour augmenter les classes reconnaissables d'associations de plantes. Les évaluations de précision des résultats de classification sont calculées par comparaison avec des images haute résolution et des données de terrain pour assurer un niveau élevé de confiance de validation. Sur la base des données de relief ASTER GDEM, nous avons déterminé le type génétique des sédiments quaternaires selon la classification des reliefs calculée par l'indice de position topographique (TPI) et l'analyse SIG. Ainsi, la modélisation de ces deux caractéristiques morphologiques permet le développement d'une base de données géospatiale de la zone d'étude test. La base de données comprend des informations sur l'existence de facteurs de transformation d'intensité pour les complexes paysagers identifiés. Les modèles SIG des paysages de pergélisol fournissent des informations sur le type de couverture du sol, les conditions du sol (humidité, température) et la texture cryogénique. L'obtention de telles données démontre l'efficacité de la modélisation pour évaluer la structure spatiale du paysage de pergélisol au niveau local.Решение многих вопросов рационального землепользования основано на информации о состоянии ландшафтных комплексов. Возможности получения достоверной информации о пространственной структуре мерзлотных ландшафтов становятся особенно актуальными для оценки состояния и тенденций развития. Усиление экологических изменений в зоне криолитозоны связано с тенденциями изменения климата и уязвимостью к антропогенным воздействиям. Целью данной диссертации является изучение пространственной структуры криолитозоны Якутии на основе геоинформационного моделирования, взяв в качестве объекта исследования среднетаежные мерзлотные ландшафты Центральной Якутии и горные мерзлотные ландшафты Верхоянского района. Для достижения этой цели были разработаны методы анализа и обработки временных рядов данных многосенсорного дистанционного зондирования и цифровой модели рельефа. Методы моделирования позволяют отображать видимые морфологические особенности многолетнемерзлых ландшафтов (рельеф и растительность) с реализацией онтологических свойств с многолетнемерзлым и литогенным основанием. Временные ряды изображений Sentinel 2 и Landsat 8 OLI за период 2015-2020 гг. Используются для картирования классов растительности и анализа состояния растительного покрова. Классы растительности распознаются по вариации фотосинтетической активности растительных ассоциаций по спектральным характеристикам отражения. Это позволяет нам использовать различия в фенологических фазах для увеличения узнаваемых классов растительных ассоциаций. Оценка точности результатов классификации рассчитывается путем сравнения с изображениями с высоким разрешением и полевыми данными, чтобы обеспечить высокий уровень достоверности проверки. Основываясь на данных рельефа ASTER GDEM, мы определили генетический тип четвертичных отложений в соответствии с классификацией рельефа, рассчитанной с помощью индекса топографического положения (TPI) и анализа ГИС. Таким образом, моделирование этих двух морфологических особенностей позволяет разработать геопространственную базу данных тестовой области исследования. База данных включает информацию о наличии коэффициентов трансформации интенсивности для выделенных ландшафтных комплексов. ГИС-модели многолетнемерзлых ландшафтов предоставляют информацию о типе почвенного покрова, почвенных условиях (влажность, температура) и криогенной структуре. Получение таких данных демонстрирует эффективность моделирования для оценки пространственной структуры и ландшафтного разнообразия на локальном уровне

Cryogenic Land Surface Process Detection in Siberian High Latitude Mountain Permafrost Landscape by Time Series Landsat Thermal Imagery

International audienceIn recent years, the accumulation of cloud-free remote sensing thermal infrared data for high-latitude permafrost regions makes it possible to use them to identify active cryogenic land surface processes (ACP) spurred by climate change and human activities. ACP is an extremely important indicator of excitations in the energy cycle of permafrost landscapes and changes in the carbon budget. In this paper, we test the time series of land surface temperature (LST) extracted from Landsat 8 OLI/TIRS datasets using a split window algorithm (SWA) to identify ACP for the study area in the mountains of Northeastern Siberia. We identified active cryogenic processes from thermal anomalies detected using standard deviation thresholds on 5 datasets for selected dates. Our results show that multi-year verified high resolution LST data for the second half of the summer period can be applicable for identifying an area with active cryogenic processes in the valley and disturbed permafrost landscapes, provided they can indicate the local effects of processes associated with drainage degradation and vegetation change

: 法俄两国对俄罗斯北极西伯利亚地区人类安全和适应全球变暖方式的联合研究—以研究雅库特永久冻土、风险承受和城市发展为例

International audienceThe importance, or rather the multiplicity of human security issues in the Russian Arctic is fundamental for the development of this region, whose growing economic significance with environmental problems linked to the adaptation of populations. Despite the distance, the direct impacts of global warming in the Russian Arctic are significant in France and in Western Europe. For example, the evolution of permafrost landscapes (methane, CO2 emissions, macro viruses, etc.) have directly affected human infrastructures in Yakutia Arctic and sub-Arctic zones, then at the regional level in Western Europe. Scientific cooperation makes sense because of the common issues. The built cooperation is based on the complementarity and cross-mobilization of methodologies and knowledge. This has resulted in significant advances in modeling risk exposure and the consequences for urban development in terms of understanding geophysical processes and for the development of the Russian Arctic territories in Yakutia. The research is carried out within the framework of the Franco-Russian project of FMSH-RFFI

Fundamental Issues in Geospatial Training for Arctic Environmental Management. An Example of Franco-Russian Cooperation: Фундаментальные вопросы обучения геопространственным методам управления окружающей средой Арктики. Пример франко-российского сотрудничества

International audienceThe importance, or rather the multiplicity of human security issues in the Russian Arctic is fundamental for the development of this region, whose growing economic significance with environmental problems linked to the adaptation of populations and mobilization of the humans' competencies. The Russian Federation has a significant lead in training and education in the Arctic, however, in some areas such as geomatics, there are significant gaps. This is mainly due to the positioning of geomatics and remote sensing in Russia and to a technical approach to the discipline. The International Franco-Russian Master's Degree in Geomatic and Environment (MIGE), the first Master's Degree in this field in Siberia, responds to this demand: to train specialists in geomatics applied to the management of the Arctic environment and the exploitation of natural resources. Academic cooperation makes sense because of the common issues. The built cooperation is based on the complementarity and cross-mobilization of competencies and knowledge

Landsat thermal images to estimate the dynamics of northeast Siberian mountain permafrost landscapes

International audienceShifting landscape boundaries is one of the long-term consequences of climate change. The transitional ecosystems between the arctic tundra and boreal forests in the mountains are open systems for the impact of climate change. The spread of continuous permafrost in these landscapes also accelerates the response of the ecosystem to climatic fluctuations. Thus, the bio productivity and boundaries of permafrost landscapes change in accordance with the dynamics of energy supply and humidity. This study presents the results of modelling the dynamics of the transitional permafrost landscapes between tundra and boreal forests of the Orulgan ridge in North-East Siberia. The modelling is based on the integration of Landsat 7 and 8 thermal infrared images. The methodology used is based on the analysis of mountain tundra areas with climatic characteristics close to boreal landscapes according to long-term data from WorldClim. These data show a positive trend in mean temperature and a negative trend in total precipitation. The distribution of landscape types on the territory of the ridge is associated with relief, which determines the contrast of climatic conditions on a local scale. The Land Surface Temperature (LST) extracted from thermal remote sensing data is a critical parameter in assessing the energy balance of mountain permafrost landscapes at the local level. Therefore, in the selected test area, we analysed the correlation between the land cover change from 1999 to 2020 with the extracted LST from Landsat 7 ETM+ and 8 TIRS thermal images. We found that the advance of forests on the tundra most often occurs on the slopes of the southern exposure with a significant increase in LST and a gentle slope of diluvial deposits and solifluction. Thus, we have determined the possibilities of using thermal images in assessing the impact of climate change in the Arctic mountainous territories of the permafrost zone with natural landscape dynamics, with a low intensity of anthropogenic impact and in conditions of remoteness from meteorological stations

Mapping cryogenic processes and assessing the sustainability of permafrost landscapes in the North-East Arctic Siberian taiga and tundra from Landsat 8, Sentinel 2, and DEM data

International audiencePermafrost landscapes are one of the most sensitive ecosystems that humans inhabit. Geocryological conditions determined by the presence of ice content, the genetic type of sediments, and the active layer are one of the most important variables for classifying the vulnerability of an ecosystem to disturbances in vegetation and soil cover. These variables indicate cryogenic processes that can be activated during the degradation of permafrost. Cryogenic mapping is an important parameter for assessing the state of permafrost and infrastructure design in permafrost landscapes. However, the methods of remote sensing spatial modelling for understanding the distribution of cryogenic processes in the Arctic Siberian mountainous areas with continuous permafrost are still insufficient. The cartographies at the regional scales of 1:500 000 are inexistent. We need for permafrost landscape maps is increasing with the development of the North-East Siberian Arctic for the infrastructures and urban centres' risk assessments. Orulgan Ridge in North-East Siberia is one of these territories. This study examines the Orulgan Ridge region, as a case area, where we developed maps of the distribution of cryogenic processes based on the detailed landscape structure (including classification of environmental variables, vegetation covers and genetic type of sediments) with time-series Sentinel 2 MSI and Landsat 8 OLI, and stereogrammetric digital elevation model of the ArcticDEM data. The combination of Random Forest classifier and geomorphological GIS terrain analysis has successfully distinguished 6 classes of boreal mountain taiga and 3 classes of arctic tundra and mountain desert. Based on the indicator parameters of the interrelation of ecological variables (such as vegetation and topographic position) adopted in permafrost-landscape cartography, we carried out the regionalization of cryogenic processes. We made a classification of the genetic type of deposits, which determines the likelihood of the development of dangerous cryogenic processes. Only 5 zones of high risk have been identified according to the prevalence of thermokarsts, thermoerosion, frost cracking, soil suffusion, thermodenudation, and their combinations.The assessment of the sustainability of mountain permafrost landscapes integrates two scenarios using GRID modelling based on the annihilation of the vegetation by the mining industry and forest fires. To determine the sustainability of permafrost landscapes, median values were calculated, an indicator of variation (standard deviation) of environmental variables - elevation, vegetation association bio productivity, slope, aspect, average temperatures of July and January, and precipitation. We established the ranges of ecological potential values: optimal, suboptimal, and pessimal. The ecological potential models within which the landscape can maintain its characteristic structural and functional features. The low sustainability potential is characteristic of the zones with the development of thermokarst and soil suffusion. This state creates many environmental restrictions in the field of environmental management associated with the quality of human security. The analysis of cryogenic processes and the sustainability assessment give good potential modelling for the territorial planning, and the environmental restoration, and provide a quantitative method for achieving landscape sustainability in Arctic urban and industrial centres

Особенности дешифрирования урбанизированных территорий северных городов по спутниковым снимкам landsat на примере г. Якутск

International audienceCurrently, there are many approaches to the recognition of urbanized areas, mainly based on the methods supervised and unsupervised spectral image classifications. D. Statakis, K. Perakis, I. Yu. Savin proposed an index (VIBI - Vegetation Index - Built up Index), which is a combination of widely known NDVI and NDBI. In this article, we will conduct the experience of deciphering the urbanized territories of Yakutsk based on the VIBI index approach and define the features of the use for northern cities. The purpose of the study is to determine the most effective method for the urbanized territories of northern cities using the example of Yakutsk. We applied the VIBI index on Landsat 8 OLI multi-temporal for the recognition of the urban structures of Yakutsk. Images selected are from June 26, 2017, and November 4, 2017. Winter images are more efficient due to the absence of open water surfaces and various types of open soils. Results of the VIBI index are combined in GIS with other urban databases for the identification of the datchas and year-round houses