Lur labainketen analisirako hurbilketa metodologikoa eskala erregionalean: Datuen bilketa, suszeptibilitate modeloak eta euri prezipitazioen atalaseak. Gipuzkoako Lurralde Historikoan aplikatua (Euskal Herria).

227 p.Lurraldearen zonazioa lur labainketak jasotzeko aukeren arabera, suszeptibilitate mapen bitartez hain zuzen ere, hauek eragindako kalteak arindu eta mehatxua eta arrisku maila ebaluatu ahal izateko oinarrizko pausoa da. Tesi honek bide-orri baten definizioa aurkezten du, hutsetik abiatuta, lurraldearen suszeptibilitate mapen garapenerako eskala erregionalean. Helburua ikuspegi metodologiko eguneratu bat zehaztea da, prozeduraren pauso bakoitzean hartutako erabakia zientifikoki justifikatuak eta onartua izan daitezen. Hainbat esperimentu eta aplikazio gauzatzeko Gipuzkoako Probintzia hautatu da (1980 km2) . Ezaugarri eta izaera desberdineko hainbat aldagai independente, mota eta iturri desberdineko lur labainketa inbentarioak eta metodo ezagun nahiz metodo berritzaileekin batera ikuspegi desberdinak jorratu dira, azkenean lan honek aurkezten dituen ondorioak lortzeko.Emaitzen arabera, inferentzia geomorfologikoaren beharra azpimarratu daiteke estatistikoki gidatutako arauen arabera aldagai independenteen hautaketa egiterako orduan, hala nola, aldagai kategorikoen transformatzea aldagai jarraietan suszeptibilitate-modeloak garatzerako orduan onuragarria dela ere ondorioztatu da. Gainera, lur labainketen suszeptibilitate modeloak kalibratzeko ikuskatutako eremu efektiboaren erabilera positiboa dela frogatu da, lur labainketen inbentarioa landa lanaren bitartez eskuratu den kasuetan. Bestalde, malda unitateen erabilerak lurralde unitate bezala, ohikoak diren pixel unitateak izan beharrean, landa laneko inbentario batek ezarri dezakeen ziurgabetasuna arintzeko ahalmena erakutsi du.Horretaz gain, lur labainketak gertatzeko beharrezko prezipitazio atalasa definitzeko algoritmo baten aplikazioak ikerketa eremu berberean, aurreikuspenak egiteko beharrezkoa den informazioa erakutsi du, alerta goiztiar sistema baterantz aurreratzen joateko dauden aukerak goraipatuz

r.survey: a tool for calculating visibility of variable-size objects based on orientation

Identification of terrain surface features can be done using approaches such as visual observation or remote sensing image processing. Accurate detection of survey targets at the ground level primarily depends on human visual acuity or sensor resolution, and then on acquisition geometry (i.e. the relative position and orientation between the surveyor and the terrain). Further, the delimitation of the observer's viewshed boundary or of the sensor's ground footprint is sometimes insufficient to ensure that all enclosed targets can be correctly detected. Size and orientation can hamper ground target visibility. In this paper we describe a new release of r.survey, an open-source spatial analysis tool for terrain survey assessment. This tool offers the necessary information to assess how terrain morphology is perceived by observers and/or sensors by means of three basic visibility metrics: 3D distance, view angle, and solid angle. It is also fully customizable, allowing single or multiple observation points, ground or aerial point of view, and size setting of the observed target, making it useful for many different purposes. This work was supported by the postdoctoral fellowship program of the Basque Government obtained by one of the authors [grant numbers POS_2019_1_0020] in collaboration with the Geological Survey of Canada; the research group IT1029-16 of the University of the Basque Country (UPV/EHU); and the geomorphology group of CNR IRPI

Exploring available landslide inventories for susceptibility analysis in Gipuzkoa province (Spain)

Similar to many mountainous regions of the world, landslides are a recurrent geological hazard in the Gipuzkoa province (northern Spain) that commonly cause damage to communication infrastructure, such as roads and railways. This geomorphological process also threatens buildings and human beings, albeit to a lesser degree. Over time, different institutions and academic research groups have individually collected crucial information on historic and ancient landslides in this region, resulting in various landslide inventories. However, these inventories have not been collectively assessed, and their suitability for landslide susceptibility modelling projects has often been assumed without comprehensive evaluation. In this study, we propose a simplified method to explore, describe, and compare the various landslide inventories in a specific study area to assess their suitability for landslide susceptibility modelling. Additionally, we present the results of an illustrative experiment that demonstrates the direct effect of using different inventories in landslide susceptibility modelling through a data-driven approach. We found that out of the five digitally available inventories in the study area, only three provide sufficient guarantees to be used as input data for susceptibility modelling. Furthermore, we observed that each individual inventory exhibited inherent biases, which directly influenced the resulting susceptibility map. We believe that our proposed methods can be easily replicated in other study areas where multiple landslide inventory sources exist, and that our work will induce other researchers to conduct preliminary assessments of their inventories as a critical step prior to any landslide susceptibility modelling project.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. Txomin Bornaetxea is financially supported by the postdoctoral fellowship program of the Basque Govern- ment (Grant Numbers POS_2020_2_0010) and hosted by the University of the Basque Country (UPV/EHU, Group IT1678) in the framework of a scientific collaboration with the Geological Survey of Canada as well as his association with the Geomorphology Group of the Research Institute for the Geo-Hydrological Pro- tection in Perugia, Italian National Research Council (CNR-IRPI)

Lur labainketen analisirako hurbilketa metodologikoa eskala erregionalean: Datuen bilketa, suszeptibilitate modeloak eta euri prezipitazioen atalaseak. Gipuzkoako Lurralde Historikoan aplikatua (Euskal Herria).

227 p.Lurraldearen zonazioa lur labainketak jasotzeko aukeren arabera, suszeptibilitate mapen bitartez hain zuzen ere, hauek eragindako kalteak arindu eta mehatxua eta arrisku maila ebaluatu ahal izateko oinarrizko pausoa da. Tesi honek bide-orri baten definizioa aurkezten du, hutsetik abiatuta, lurraldearen suszeptibilitate mapen garapenerako eskala erregionalean. Helburua ikuspegi metodologiko eguneratu bat zehaztea da, prozeduraren pauso bakoitzean hartutako erabakia zientifikoki justifikatuak eta onartua izan daitezen. Hainbat esperimentu eta aplikazio gauzatzeko Gipuzkoako Probintzia hautatu da (1980 km2) . Ezaugarri eta izaera desberdineko hainbat aldagai independente, mota eta iturri desberdineko lur labainketa inbentarioak eta metodo ezagun nahiz metodo berritzaileekin batera ikuspegi desberdinak jorratu dira, azkenean lan honek aurkezten dituen ondorioak lortzeko.Emaitzen arabera, inferentzia geomorfologikoaren beharra azpimarratu daiteke estatistikoki gidatutako arauen arabera aldagai independenteen hautaketa egiterako orduan, hala nola, aldagai kategorikoen transformatzea aldagai jarraietan suszeptibilitate-modeloak garatzerako orduan onuragarria dela ere ondorioztatu da. Gainera, lur labainketen suszeptibilitate modeloak kalibratzeko ikuskatutako eremu efektiboaren erabilera positiboa dela frogatu da, lur labainketen inbentarioa landa lanaren bitartez eskuratu den kasuetan. Bestalde, malda unitateen erabilerak lurralde unitate bezala, ohikoak diren pixel unitateak izan beharrean, landa laneko inbentario batek ezarri dezakeen ziurgabetasuna arintzeko ahalmena erakutsi du.Horretaz gain, lur labainketak gertatzeko beharrezko prezipitazio atalasa definitzeko algoritmo baten aplikazioak ikerketa eremu berberean, aurreikuspenak egiteko beharrezkoa den informazioa erakutsi du, alerta goiztiar sistema baterantz aurreratzen joateko dauden aukerak goraipatuz

LAND-SUITE V1.0: a suite of tools for statistically based landslide susceptibility zonation

In the past 50 years, a large variety of statisti- cally based models and methods for landslide susceptibility mapping and zonation have been proposed in the literature. The methods, which are applicable to a large range of spa- tial scales, use a large variety of input thematic data, differ- ent model combinations, and several approaches to evaluate the models’ performance. Despite the numerous applications available in the literature, a standard approach for suscepti- bility modeling and zonation is still missing. The literature search revealed that several software pro- gram and tools are available to evaluate regional slope stability using physically based analysis, but only a few use statistically based approaches. Among them, LAND-SE (LANDslide Susceptibility Evaluation) provides the possi- bility to perform and combine different statistical suscepti- bility models and to evaluate their performances and asso- ciated uncertainties. This paper describes the structure and the functionalities of LAND-SUITE, a suite of tools for sta- tistically based landslide susceptibility modeling which in- tegrates LAND-SE. LAND-SUITE completes and extends LAND-SE, adding functionalities to (i) facilitate input data preparation, (ii) perform preliminary and exploratory analy- sis of the available data, and (iii) test different combinations of variables and select the optimal thematic/explanatory set. LAND-SUITE provides a tool to assist the user during the data preparatory phase and to perform diversified statistically based landslide susceptibility applications.The implementation and improvement of LAND-SUITE with respect to the version published by Rossi and Reichenbach (2016) were funded mainly using internal funds. Txomin Bornaetxea was financially supported by the postdoctoral fellowship program of the Basque Government (grant numbers POS_2020_2_0010) and hosted by the University of the Basque Country (UPV/EHU, group IT1678) in the framework of a scien- tific collaboration with the Geological Survey of Canada as well as during scientific collaborations with the Geomorphological Group of the Research Institute for the Geo-Hydrological Protection in Perugia, Italian National Research Council (CNR-IRPI

Terrain visibility impact on the preparation of landslide inventories: a practical example in Darjeeling district (India)

Landslide inventories are used for multiple purposes including landscape characterisation and monitoring, and landslide susceptibility, hazard and risk evaluation. Their quality and completeness 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 in different landslide inventories prepared using different approaches in a study area. 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 areas; 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 and completeness of landslide inventories and then properly orient their use.This research has been supported by the Natural Environment Research Council (grant no. NERC/DFID NE/P000649/1) and the Eusko Jaurlaritza (grant no. POS_2020_2_0010)

Umbrales de lluvia para el desencadenamiento de inestabilidades de ladera en el norte de Portugal y de España: estado del arte

ES: Gran número de trabajos sobre umbrales de lluvia para el desencadenamiento de inestabilidades de ladera se ha desarrollado en áreas del norte de Portugal y España. Como resultado de una revisión, se han recopilado 103 umbrales. Más del 30% aún no han sido publicados. La comparación de cuatro umbrales regionales pone de manifiesto importantes diferencias ligadas al uso de múltiples metodologías para definir las condiciones críticas de lluvia.A great number of works focused on the calculation of empirical rainfall thresholds for the triggering of landslides have been developed in the northern areas of Portugal and Spain. Because of a review, 103 thresholds have been compiled. More than 30% of them have not yet been published. The comparison of four regional thresholds highlights relevant differences linked to the use of multiple methodologies to define the critical rainfall conditions