Terrain visibility impact on the preparation of landslide inventories: some practical cases

Landslide inventories are used for multiple purposes including landscape characterisation and monitoring, and landslide susceptibility, hazard and risk evaluation. Their quality can depend on the data and the methods with which they were produced. In this work we evaluate the effects of a variable visibility of the territory to map on the spatial distribution of the information collected by four landslide inventories prepared using different approaches in two study areas. The method first classifies the territory in areas with different visibility levels from the paths (roads) used to map landslides, and then estimates the landslide density reported in the inventories into the different visibility classes. Our results show that 1) the density of the information is strongly related to the visibility in inventories obtained through fieldwork, technical reports and/or newspapers, where landslides are under-sampled in low visibility classes; and 2) the inventories obtained by photo-interpretation of images suffer from a marked under representation of small landslides close to roads or infrastructures. We maintain that the proposed procedure can be useful to evaluate the quality of landslide inventories and then properly orient their use.

A review of methods in the field of detecting illegal open-pit mining activities

Illegal open pit mining might be a very dangerous activity both for the environment and also for the people living in its neighbourhood. This kind of activity is connected with environmental degradation, disruption of sustainable development and lack of the most critical last stage of the mine’s “life”, i.e. land reclamation. An additional element connected with illegal exploitation is the fact of breaking the law and stealing mineral resources. Monitoring of illegal exploitation is therefore an important aspect. The presented here review was intended to investigate which methods can be used directly to detect open pit mining sites and to evaluate their effectiveness. In the reviewed works a wide variety of methods have been used, ranging from manual methods, such as photo-interpretation, to a combination of automatic methods and photo-interpretation, to fully automatic methods. Based on the analysis, it was indicated that different types of classification (supervised, unsupervised, hybrid) are the most commonly u sed. Besides, radar interferometry, image fusion techniques, or images spectral similarity are also used.

Peligro geológico, susceptibilidad y riesgo de desastre en la cuenca inambari

Se trata la susceptibilidad al peligro por movimientos de masas de tierra en zonas de geomorfología compleja como la cuenca Inambari y el problema se dirige a conocer cuáles son las característica que inducen a la ocurrencia de deslizamientos en la cuenca Inambari, el objetivo es obtener un documento que explique, que provocan estos movimientos y para esto se adecuó una metodología donde se emplean principalmente métodos de estudio que determinan la peligrosidad, vulnerabilidad y el nivel de riesgo de los deslizamientos, la metodología de investigación es científica cualitativa y de carácter básico aplicado con técnicas computarizadas y procedimientos matemáticos-estadísticos que en la práctica se materializan con el monitoreo y la comprobación de fotointerpretación lo que determinó la valoración de las zonas susceptibles del medio físico al peligro. Se obtienen resultados científicos con relación a la tolerancia de los procesos y a la susceptibilidad. Otros de carácter socioeconómico y cultural se basan en el establecimiento de un Sistema de Alerta Temprana. It is about the susceptibility to danger by movements of earth masses in areas of complex geomorphology as the Inambari basin and the problem is directed to know what are the characteristics that induce the occurrence of landslides in the Inambari basin, the objective is to obtain a document that explains, which cause these movements and for this a methodology was adapted where study methods are mainly used to determine the danger, vulnerability and risk level of landslides, the research methodology is qualitative scientific and basic applied with computerized techniques and mathematical-statistical procedures that in practice are materialized with monitoring and photo-interpretation verification, which determined the assessment of susceptible areas of the physical environment to the danger. Scientific results are obtained in relation to the tolerance of the processes and susceptibility. Other socioeconomic and cultural results are based on the establishment of an Early Warning System.

Comparison of different methods to assess the distribution of alien plants along the road network and use of Google Street View panoramas interpretation in Sicily (Italy) as a case study

The survey by foot in the field is compared to the survey from a car, the photo-interpretation of Google Street View (GSV) panoramas continuously and at intervals of 1.5 km and the photo-interpretation of Google Earth aerial images on a 10 km stretch of road in Sicily. The survey by foot was used as reference for the other methods. The interpretation of continuous GSV panoramas gave similar results as the assessment by car in terms of the number of species identified and their location, but with lower cost. The interpretation online of aerial photos allowed the identification of a limited number of taxa, but gave a good localisation for them. Interpretation of GSV panoramas, each of 1.5 km, allowed the recognition of twice as many taxa as the interpretation of aerial photos and taking half the time, but did not allow a complete localisation. None of these methods alone seems sufficient to carry out a complete survey. A mixture of different techniques, which may vary according to the available resources and the goal to be achieved, seems to be the best compromise. To further test the capabilities of the survey using the interpretation of GSV panoramas every 1.5 km along the roads, we proceeded to study the alien plants along 3500 km of the road network on the island of Sicily. This survey identified only 10% of the known species for the region, but allowed us to trace the distribution of invasive species whose distribution is currently poorly recorded.

An Unconventional Field Mapping Application: A Complete Opensource Workflow Solution Applied to Lithological Mapping of the Coatings of Cultural Heritage

The conservation of a primary importance historical building requires organization, management, continuous updating, comparison, and visualization of a large amount of data of different nature and origin. In relation to these aspects the use of a GIS brings various advantages including single and univocal management of the entire amount of existing data in a relational, dynamic, updatable and queryable way. The integration of a mobile solution permits the updating of the dataset and checking on site all information. The workflow presented uses opensource solutions, desktop and mobile, which allows the creation of an unconventional lithological Field Mapping activity: starting from photo interpretation and in situ survey, all the coating materials (stone, etc.) of some monuments of primary historical and cultural interest have been mapped (i.e., Duomo di Firenze, Duomo di Prato). The product can be considered as a lithological cartography, vertically oriented, processed by field surveys, geognostic surveys and photo interpretation. All combined to create a “lithological” mapping of the coatings of the various monuments; the advantage is a new approach for conservation and restoration of Cultural Heritage. The proposed workflow involves a mobile solution, opensource, that allows the verification and management of the database in the field.

Using UAV Imagery to Detect and Map Woody Species Encroachment in a Subalpine Grassland: Advantages and Limits

Woody species encroachment on grassland ecosystems is occurring worldwide with both negative and positive consequences for biodiversity conservation and ecosystem services. Remote sensing and image analysis represent useful tools for the monitoring of this process. In this paper, we aimed at evaluating quantitatively the potential of using high-resolution UAV imagery to monitor the encroachment process during its early development and at comparing the performance of manual and semi-automatic classification methods. The RGB images of an abandoned subalpine grassland on the Western Italian Alps were acquired by drone and then classified through manual photo-interpretation, with both pixel- and object-based semi-automatic models, using machine-learning algorithms. The classification techniques were applied at different resolution levels and tested for their accuracy against reference data including measurements of tree dimensions collected in the field. Results showed that the most accurate method was the photo-interpretation (≈99%), followed by the pixel-based approach (≈86%) that was faster than the manual technique and more accurate than the object-based one (≈78%). The dimensional threshold for juvenile tree detection was lower for the photo-interpretation but comparable to the pixel-based one. Therefore, for the encroachment mapping at its early stages, the pixel-based approach proved to be a promising and pragmatic choice.

Vertigo moulinsiana (Dupuy, 1849) et Vertigo angustior Jeffreys, 1830 en Sarthe : bilan de deux années d’étude

Une étude de trois ans, de 2017 à 2019, a été menée en Sarthe par le Centre permanent d’Initiatives pour l’Environnement (CPIE) Vallées de la Sarthe et du Loir sur la famille des Vertiginidae (Gastropoda: Pulmonata) et plus spécifiquement sur Vertigo moulinsiana (Dupuy, 1849) et Vertigo angustior Jeffreys, 1830. Cette étude a pour objectifs d’améliorer la connaissance de leur répartition et de leur écologie et de sensibiliser les acteurs locaux : naturalistes et gestionnaires. Nous présentons ici les principaux résultats des deux premières années d’études consacrées à l’inventaire de Vertigo moulinsiana et Vertigo angustior. La sélection des sites à inventorier est réalisée en deux étapes. D’abord le choix d’une zone d’étude, bassin versant ou site Natura 2000, puis celui des stations à prospecter à partir des cartographies existantes ou par photo-interprétation. Ce sont finalement 524 stations qui ont été prospectées sur deux ans. Quarante-neuf stations abritent V. moulinsiana, sept Vertigo angustior et neuf contiennent les deux espèces. Leur répartition dans le département de la Sarthe est très hétérogène. La vallée des Cartes abrite la grande majorité des stations à Vertigo angustior et de nombreuses localités de Vertigo moulinsiana, les deux espèces pouvant être répertoriées au sein du même site. Vertigo moulinsiana est retrouvé ponctuellement sur d’autres bassins versants comme ceux de la Fare et du Tripoulin.