High Mountain Slopes Research Articles

Full four-dimensional change analysis of topographic point cloud time series using Kalman filtering

Abstract. Four-dimensional (4D) topographic point clouds contain information on surface change processes and their spatial and temporal characteristics, such as the duration, location, and extent of mass movements. To automatically extract and analyze changes and patterns in surface activity from this data, methods considering the spatial and temporal properties are required. The commonly used model-to-model cloud comparison (M3C2) point cloud distance reduces uncertainty through spatial averaging for bitemporal analysis. To extend this concept into the full spatiotemporal domain, we use a Kalman filter for change analysis in point cloud time series. The filter incorporates M3C2 distances together with uncertainties obtained through error propagation as Bayesian priors in a dynamic model. The Kalman filter yields a smoothed estimate of the change time series for each spatial location in the scene, again associated with an uncertainty. Through the temporal smoothing, the Kalman filter uncertainty is generally lower than the individual bitemporal uncertainties, which therefore allows the detection of more changes as significant. We apply our method to a dataset of tri-hourly terrestrial laser scanning point clouds of around 90 d (674 epochs) showcasing a debris-covered high-mountain slope affected by gravitational mass movements and snow cover dynamics in Tyrol, Austria. The method enables us to almost double the number of points where change is detected as significant (from 24 % to 47 % of the area of interest) compared to bitemporal M3C2 with error propagation. Since the Kalman filter interpolates the time series, the estimated change values can be temporally resampled. This provides a solution for subsequent analysis methods that are unable to deal with missing data, as may be caused by, e.g., foggy or rainy weather conditions or temporary occlusion. Furthermore, noise in the time series is reduced by the spatiotemporal filter. By comparison to the raw time series and temporal median smoothing, we highlight the main advantage of our method, which is the extraction of a smoothed best estimate time series for change and associated uncertainty at each location. A drawback of the Kalman filter is that it is ill-suited to accurately model discrete events of large magnitude. It excels, however, at detecting gradual or continuous changes at small magnitudes. In conclusion, the combined consideration of temporal and spatial information in the data enables a notable reduction in the associated uncertainty in quantified change values for each point in space and time, in turn allowing the extraction of more information from the 4D point cloud dataset.

Characterizing large rockfalls using their seismic signature: A case study of Hongya rockfall

A preliminary, yet timely characterization of rockfall hazards is essential for effective emergency response and mitigation measures. Such characterization is, however, particularly challenging for events occurring on high-mountain slopes in remote locations, for which precursory information remains often undetected. Large rockfalls are known to produce seismic signatures that, if properly interpreted, provide key information on the magnitude and destructiveness of the event. To achieve this, we establish a seismic signal-based assessment scheme and demonstrate its capability by taking a large event – the 5 April 2021 Hongya rockfall (Sichuan, China) – as a case study. First, we show how a rockfall can be distinguished from an earthquake and a rockslide by analyzing its seismic signatures. Then, we demonstrate how the kurtosis-based method can be used to rapidly detect the initiation of a rockfall and determine the seismic wave velocity accordingly, as well as how the arrival-time-based location method can be used to locate the event. The rockfall volume can be estimated from the magnitude of radiated seismic energy. Furthermore, we characterize the different phases in seismograms and link them to the typical stages of rockfall, i.e., precursory small rockfalls, impact and fragmentation, sliding and entrainment, and gravity deposition stages. Finally, a discussion and suggestions are provided for further improving the robustness of the assessment scheme. Our results show that the seismic signal-based scheme presented in this study is suitable for characterizing large rockfalls and has the potential for rapid and effective emergency management.

Characteristics and dynamic analysis of the February 2021 long-runout disaster chain triggered by massive rock and ice avalanche at Chamoli, Indian Himalaya

A massive rock and ice avalanche occurred on the western slope of the Ronti Gad valley in the northern part of Chamoli, Indian Himalaya, on 7 February 7, 2021. The avalanche on the high mountain slope at an elevation of 5600 m above sea level triggered a long runout disaster chain, including rock mass avalanche, debris avalanche, and flood. The disaster chain had a horizontal travel distance of larger than 17,600 m and an elevation difference of 4300 m. In this study, the disaster characteristics and dynamic process were analyzed by multitemporal satellite imagery. The results show that the massive rock and ice avalanche was caused by four large expanding discontinuity planes. The disaster chain was divided into five zones by satellite images and field observation, including source zone, transition zone, dynamic entrainment zone, flow deposition zone, and flood zone. The entrainment effect and melting water were recognized as the main causes of the long-runout distance. Based on the seismic wave records and field videos, the time progress of the disaster was analyzed and the velocity of frontal debris at different stages was calculated. The total analyzed disaster duration was 1247 s, and the frontal debris velocity colliding with the second hydropower station was approximately 23 m/s. This study also carried out the numerical simulation of the disaster by rapid mass movement simulation (RAMMS). The numerical results reproduced the dynamic process of the debris avalanche, and the mechanism of long-runout avalanche was further verified by parametric study. Furthermore, this study discussed the potential causes of disaster and flood and the roles of satellite images and seismic networks in the monitoring and early-warning.

Alpine rock glacier activity over Holocene to modern timescales (western French Alps)

Abstract. Active rock glaciers are some of the most frequent cryospheric landforms in midlatitude high-elevation mountain ranges. Their activity strongly influences the hydrology and geomorphology of alpine environments over short (years to decades) and long (centuries to millennia) timescales. Being conspicuous expressions of mountain permafrost and important water reserves in the form of ground ice, rock glaciers are seen as increasingly important actors in the geomorphological and hydrological evolution of mountain systems, especially in the context of current climate change. Over geological timescales, rock glaciers both reflect paleoclimate conditions and transport rock boulders produced by headwall erosion, and they therefore participate in shaping high mountain slopes. However, the dynamics of rock glaciers and their evolution over different timescales remain under-constrained. In this study, we adopt a multi-method approach, including field observations, remote sensing, and geochronology, to investigate the rock glacier system of the Vallon de la Route (Combeynot Massif, western French Alps). Remotely sensed images and correlation techniques are used to document the displacement field of the rock glacier over timescales ranging from days to decades. Additionally, to estimate displacement over periods from centuries to millennia, we employ terrestrial cosmogenic nuclide (quartz 10Be) surface-exposure dating on rock boulder surfaces located along the central flow line of the rock glacier, targeting different longitudinal positions from the headwall to the rock glacier terminus. The remote sensing analysis demonstrates that between 1960 and 2018 the two lower units of the rock glacier were motionless, the transitional unit presented an integrated surface velocity of 0.03±0.02 m a−1, and the two upper active units above 2600 m a.s.l. showed a velocity between 0.14±0.08 and 0.15±0.05 m a−1. Our results show 10Be surface-exposure ages ranging from 13.10±0.51 to 1.88±0.14 ka. The spatial distribution of dated rock glacier boulders reveals a first-order inverse correlation between 10Be surface-exposure age and elevation and a positive correlation with horizontal distance to the headwall. These observations support the hypothesis of rock boulders falling from the headwall and remaining on the glacier surface as they are transported down valley, and they may therefore be used to estimate rock glacier surface velocity over geological timescales. Our results also suggest that the rock glacier is characterized by two major phases of activity. The first phase, starting around 12 ka, displays a 10Be age gradient with a rock glacier surface velocity of about 0.45 m a−1, following a quiescent period between ca. 6.2 and 3.4 ka before the emplacement of the present-day upper two active units. Climatic conditions have favored an integrated rock glacier motion of around 0.18 m a−1 between 3.4 ka and present day. These results allow us to quantify back-wearing rates of the headwall of between 1.0 and 2.5 mm a−1, higher than catchment-integrated denudation rates estimated over millennial timescales. This suggests that the rock glacier system promotes the maintenance of high rock wall erosion by acting as debris conveyor and allowing freshly exposed bedrock surfaces to be affected by erosion processes.

INTEGRATION OF KALMAN FILTERING OF NEAR-CONTINUOUS SURFACE CHANGE TIME SERIES INTO THE EXTRACTION OF 4D OBJECTS-BY-CHANGE

Abstract. Automatic extraction of surface activity from near-continuous 3D time series is essential for geographic monitoring of natural scenes. Recent change analysis methods leverage the temporal domain to improve the detection in time and the spatial delineation of surface changes, which occur with highly variable spatial and temporal properties. 4D objects-by-change (4D-OBCs) are specifically designed to extract individual surface activities which may occur in the same area, both consecutively or simultaneously. In this paper, we investigate how the extraction of 4D-OBCs can improve by considering uncertainties associated to change magnitudes using Kalman filtering of surface change time series. Based on the change rate contained in the Kalman state vector, the method automatically detects timespans of accumulation and erosion processes. This renders change detection independent from a globally fixed minimum detectable change value. Considering uncertainties associated to change allows detecting and classifying more occurrences of relevant surface activity, depending on the change rate and magnitude. We compare the Kalman-based seed detection to a regression-based method using a three-month tri-hourly terrestrial laser scanning time series (763 epochs) acquired of mass movements at a high-mountain slope in Austria. The Kalman-based method successfully identifies all relevant changes at the example location for the extraction of 4D-OBCs, without requiring the definition of a global minimum change magnitude. In the future, we will further investigate which kind of change detection method is best suited for which types of surface activity.

VIRTUAL LASER SCANNING OF DYNAMIC SCENES CREATED FROM REAL 4D TOPOGRAPHIC POINT CLOUD DATA

Abstract. Virtual laser scanning (VLS) allows the generation of realistic point cloud data at a fraction of the costs required for real acquisitions. It also allows carrying out experiments that would not be feasible or even impossible in the real world, e.g., due to time constraints or when hardware does not exist. A critical part of a simulation is an adequate substitution of reality. In the case of VLS, this concerns the scanner, the laser-object interaction, and the scene. In this contribution, we present a method to recreate a realistic dynamic scene, where the surface changes over time. We first apply change detection and quantification on a real dataset of an erosion-affected high-mountain slope in Tyrol, Austria, acquired with permanent terrestrial laser scanning (TLS). Then, we model and extract the time series of a single change form, and transfer it to a virtual model scene. The benefit of such a transfer is that no physical modelling of the change processes is required. In our example, we use a Kalman filter with subsequent clustering to extract a set of erosion rills from a time series of high-resolution TLS data. The change magnitudes quantified at the locations of these rills are then transferred to a triangular mesh, representing the virtual scene. Subsequently, we apply VLS to investigate the detectability of such erosion rills from airborne laser scanning at multiple subsequent points in time. This enables us to test if, e.g., a certain flying altitude is appropriate in a disaster response setting for the detection of areas exposed to immediate danger. To ensure a successful transfer, the spatial resolution and the accuracy of the input dataset are much higher than the accuracy and resolution that are being simulated. Furthermore, the investigated change form is detected as significant in the input data. We, therefore, conclude the model of the dynamic scene derived from real TLS data to be an appropriate substitution for reality.

Side threats: further possible effects of warming on the high alpine narrow endemic Carabus cychroides (Coleoptera: Carabidae)

Carabus cychroides is an endemic ground beetle of a few high mountain slopes in the Cottian Alps. We have modelled the presence-absence data collected in a sample area, related to this species, the congener C. depressus with which it can hybridise and the small snail Chilostoma glaciale, specific prey of Carabus cychroides. The models were projected to three future periods according to four greenhouse gas emission scenarios. The results indicated the future increase in niche and spatial overlap of the two beetles, which could lead to more hybridisation and competition between them. If these threats occur over the entire geographic range of the already endangered C. cychroides, they could accelerate its predicted decline in the coming decades due to climate warming.

Assessment of the change of trend in precipitation over Afghanistan in 1979–2019

The civil war, harsh climate, tough topography, and lack of accurate meteorological stations have limited the number of consecutive synoptic data across Afghanistan. The global data (gridded precipitation datasets) pave the way to assess the precipitation indicators of climate, where stations are sparsely located. This study assessed the mean annual precipitation trend in 33 stations over Afghanistan. Non-parametric linear regression technique was employed to find upward and downward trends and magnitudes. The daily of precipitation was obtained from the database of the CPC-NOAA (Climate Prediction Center - National Oceanic Atmospheric Administration) for the period of 1979–2019. The CPC spatial resolution of daily precipitation is 0.5×0.5 degree. Analysis of mean annual precipitation showed a significant decreasing trend at six provinces in the north, while an increasing trend of 9.2 mm per decade has been observed at three provinces. In the south, a notable reduction of the precipitation trend has been experienced in Helmand, Kandahar, and Nimruz provinces, but Ghazni and Uruzgan show a positive trend. Data revealed that mean annual precipitation has remarkably decreased in the western part of Afghanistan. According to the study period, the mean annual rainfall in the central regions indicates a raise of 37.5 mm per decade in Kabul, while in Vardak, the precipitation increases up to 9.21 mm per year. Eastern regions include 8 provinces, and the eastern highland covers the smallest area that is mainly covered by rangeland and the largest existing forests. These regions are directly influenced by the moist air masses of Indian monsoon getting trapped at the high mountain slopes, and it can lead to an increase of rain. Data reveals an upward trend of precipitation in the eastern part of Afghanistan.

Numerical Experiments on Effect of Topographical Slope Changes in the Dynamics of Landslide Generated Water Waves and Submarine Mass Flows

When gravitational mass flows hit water bodies, they create water waves, called tsunami. The slopes of the mountain flanks surrounding a glacial lake or the slopes of the side walls of artificially constructed reservoirs play important roles in the intensity of splash on landslide impact, amplitudes and propagation speeds of the resulting water waves and possible dam breaching or overspilling of water. The proper analyses of such dynamics are useful for the possible mitigation measures. Here, we apply a general two-phase mass flow model to perform several numerical experiments and present geometrically three-dimensional, high-resolution simulation results for rapidly moving two-phase landslide/debris flow down a plane with varying slopes at its different parts, impacting a fluid reservoir. First, the upstream slope is kept constant; later to make it closer to reality, sudden changes in slopes are imposed one after another at different parts of the topography. The results focus on the effects of the sudden slope changes in the formation and propagation of dynamically different solid- and fluid wave-structures in the reservoir. Results show that steeper upper part of the topography produces more highly intensified tsunami that propagates more longitudinally than the steeper lower part. Thus, steeper upper parts need stronger right coast and steeper lower parts demand stronger side walls in mountain reservoirs to withstand the wave impacts. The results may help for the proper modeling of landslide and debris induced mountain tsunamis in rapidly changing slopes, the dynamics of turbidity currents and sediment transports in fluid reservoirs in high mountain slopes.

Habitat and Landform Types Drive the Distribution of Carabid Beetles at High Altitudes

The high altitude mountain slopes of the Dolomites (Italian Alps) are characterized by great habitat and landform heterogeneities. In this paper, we investigated the effect of Nature 2000 habitat and landform types in driving the high altitude ground beetle (Carabidae) distribution in the Western Dolomites (Brenta group, Italy). We studied the carabid assemblages collected in 55 sampling points distributed in four Nature 2000 habitat types and four landform types located between 1860 and 2890 m above sea level (a.s.l.). Twenty-two species, half of them Alpine endemics, were sampled. Species richness and taxonomic distinctness did not show any significant difference among habitat types; conversely, these differences became significant when the landform type was considered. Total activity density and the frequency of brachypterous, endemic and predatory species showed significant differences between both habitat and landform types. Indicator species analysis identified twelve species linked to a specific habitat type and thirteen species linked to a specific landform type. Canonical correspondence analysis showed that altitude and vegetation cover drove the species distribution in each habitat and landform type while the aspect had a weak effect. Our results highlight the need for a geomorphological characterization of the sampling points when high altitude ground-dwelling arthropods are investigated.

Natural resources of the mountain valley of zarafshan and its economic development

The distinctive particularities of the geographical position of Zarafshan valley, variety of natural components and their importance in economic activity of the person were described in the article. Including, an analysis of physics-geographical indexes, referring to flat part of valley, foot-hills, mountain and alpine high-altitude belts was given. As well as, a modern condition of natural-economic development of Zarafshan valley was characterized. Each of these parts of the Zarafshan valley includes territories that differ sharply in natural conditions and especially in the direction of agriculture, from desert pastures to the oasis strip and irrigated lands occupied by cotton, rice crops on the plain part of the oasis strip, horticulture and viticulture, rainfed and tobacco growing, located on the high terraces of the plain and mid-mountain parts of the valley, rained wine growing, apricot gardening in the mountainous part and ending with summer pastures of high-mountain slopes.

NEW RESOURCE-SAVING TECHNOLOGY OF POTATO CULTIVATION ON SLOPE LANDS OF MOUNTAIN PROVINCE IN DAGESTAN

The potato is grown in all natural environment and climatic zones, along from high-mountain slope lands, situated up to 2500 meters above sea level to Pricaspian plains, situated under sea level. The total area of planted potato in the Republic is 22 thousand hectares, where potato producing takes more than half of mountain region. The mountain area occupies 2.04 million hectares, which is 38.3% of total area of Dagestan with highest peaks over 1000 meters above the sea. There are some methods of potato growing that are nearly effective in all climatic conditions, and improve yield and tuber quality. The proposed resource-saving technology enables to reduce expenses by 50 % for ploughing, soil preparation after ploughing, pre-planting soil preparation, preserving soil fertility and decreasing erosion processes. The results based on experimental data presented were to show the influence of resource-saving technology on growth, development and yield augmentation when growing on slope lands of mountain province of Dagestan. Advantages of this resource-saving technology and its economic efficiency were shown as well.

Long-term monitoring of a large deep-seated landslide (La Clapiere, South-East French Alps): initial study

The large-scale deformation of high mountain slopes finds its origin in many phenomena (inherent parameters, external stresses) with very different time constants (instantaneous to geological scale). Gravitational effect, tectonic forces and water infiltration are generally the principal causes of slope instability. However, it can be very difficult to distinguish which cause is dominant and which are their respective effects. To gain a better understanding of the complex processes taking place during the evolution of an unstable slope and separate the causes responsible of the landslide dynamic, an observational study based on geodetic, meteorological, seismological and electrical data has been performed on the La Clapiere rockslide (Southern French Alps). This deep-seated landslide (DSL) is known for many years as one of the largest and fastest rock slide in Europe (60 million m3 of highly weathered metamorphic material, moving at 1 to 3 m year−1). The set-up of the “Observatoire Multidisciplinaire des Instabilites de Versants” (OMIV, http://omiv.osug.fr) in 2011 has allowed the production and availability of an important and original data set over several years of accurate monitoring. Thus, for the first time, the long-term study of geodetic data permitted us to highlight acceleration phases in the general movement of the landslide that affect its dynamic. These modifications are associated with variations of the velocity by a factor 3 to 6. The characterization of the origin of these variations was possible due to the comparison with meteorological, electrical and seismological data. Based on these various signals, we were able to establish correlations and contributions of meteorological water infiltration in the dynamic evolution of the La Clapiere slope. We determine several response times to the meteorological stress for seismic endogenous events (mainly rockfalls), the resistivity of the ground (quasi-instantaneous) and the kinematics of the slope (from 2 weeks to 2.5 months). Moreover, our results strongly suggest the existence of rainfall threshold of 3.5 ± 1 mm day−1 from which the number of seismic endogenous events is highly increased.

Simulating glacial lake outburst floods with a two-phase mass flow model

AbstractTo simulate a glacial lake outburst flood, we employ a comprehensive physically based general two-phase mass flow model (Pudasaini, 2012). This model accounts for a strong interaction between the solid and fluid phases and incorporates buoyancy and other dominant physical aspects of the mass flows such as enhanced non-Newtonian viscous stress, virtual mass force and generalized drag. Our real two-phase mass flow simulation describes explicit evolution of the solid and fluid phases and the debris bulk as a whole, akin to torrential debris flows or debris floods during glacial lake outburst floods (GLOFs). The emptying of a lake following rapid collapse of a restraining dam, the consequent downslope motion of a mixed solid–fluid mass, and the tendency of the mass to form extruding plumes are analyzed in detail for different flow configurations, volumes, conduit geometries and boundary conditions. The solid and fluid phases evolve completely differently and reveal fundamentally different dynamical behaviours. During the flow, the relatively long fluid tail follows the solid-rich dense frontal surge head. The bulk debris develops into a frontal and side levee as derived from the initial frontal moraine dam. Results show that our high-resolution, unified simulation strategies and the advanced model equations can be applied to study the flow dynamics of a wide range of geophysical mass flows such as snow and rock–ice avalanches, debris flows and flash floods as well as GLOFs. This may help substantially in forming a basis for appropriate mitigation measures against potential natural hazards in high mountain slopes and valleys.

A 5000-year pollen and plant macrofossil record from the Osogovo Mountain, Southwestern Bulgaria: Vegetation history and human impact

Pollen and plant macrofossil analyses were performed on a sequence 105cm deep obtained from a peat bog (1750m) that is located above the present timber-line in the Osogovo Mountain, Southwestern Bulgaria. The palaeovegetation reconstruction, supported by a radiocarbon chronology, revealed the vegetation dynamics and human impact during the last 5000years. The peat bog formed when a coniferous belt of Abies alba and Pinus (Pinus sylvestris, Pinus nigra) covered the high mountain slopes. Charcoal fragments indicate the presence of a broad-leaved tree community composed of Quercus, Corylus, Carpinus, Tilia, Acer and Ulmus at lower altitudes. Stands of Fagus sylvatica in places with higher air and soil humidity, like river valleys and deep ravines, became established. The pollen assemblages after c. 3200cal. BP record an important change in the forest composition that led to the replacement of the conifers, mostly A. alba, by the invading communities of F. sylvatica. The reasons for this replacement included factors related to both climate change and anthropogenic disturbance. During the last centuries a large-scale degradation of the woodlands in the mountain has occurred. On a regional scale the palaeoecological evidence is compared with information from palynological, archaeological and historical sources in Southwestern Bulgaria.

Treeline dynamics with climate change at the central Nepal Himalaya

Abstract. Treeline shifting in tandem with climate change has widely been reported from various parts of the world. In Nepal, several impacts of climate change on the physical environment have been observed, but study on the biological impacts is lacking. This dendrochronological study was carried out at the treeline in the high mountain slope of Kalchuman Lake (3750–4003 m a.s.l.) area of Manaslu Conservation Area in the central Nepal Himalaya to explore the impact of climate change on the treeline dynamic. Two belt transect plots (size: 20 m wide, > 250 m long) were laid which included treeline as well as tree species limit. Ecological mapping of all individuals of dominant trees Abies spectabilis and Betula utilis was done and their tree cores were collected. Stand character and age distribution revealed an occurrence of more matured B. utilis (max. age 198 years) compared to A. spectabilis (max. age 160 years). A. spectabilis contained an overwhelmingly high population (89%) of younger plants (< 50 years) indicating its high recruitment rate. Population age structure along the elevation gradient revealed an upward shifting of A. spectabilis at the rate of 2.61 m year-1 since AD 1850. The upper distribution limit of B. utilis was found to be stagnant in the past few decades. An increment in plant density as well as upward shifting in the studied treeline ecotones was observed. The temporal growth of A. spectabilis was correlated negatively with the monthly mean and minimum temperature of June to September of the current and previous year. The regeneration of A. spectabilis, on the other hand, was positively correlated with August precipitation and monthly maximum temperature of the month of the current year. The growth and regeneration of A. spectabilis was more sensitive to maximum and minimum temperature rather than average temperature. The growth of the B. utilis was mainly limited by moisture stress during the pre-monsoon season. As these two species presented species-specific responses to climate change with differential pattern in regeneration condition, much wider differences are anticipated in their population status as climate continues to change throughout the century.

Caracterización de unidades biofísicas a partir de indicadores ambientales en Milpa Alta, Centro de México

En este trabajo se delimitaron y caracterizaron a las unidades biofísicas a partir de indicadores ambientales en Milpa Alta, Centro de México. Se trazaron las unidades geomorfológicas morfogenéticas que sirvieron de base para la caracterización de las unidades ambientales biofísicas (UAB). Se llevaron a cabo recorridos de campo para la verificación de las UAB y para la toma de muestras de suelos y levantamientos botánicos. En laboratorio se determinaron las propiedades físicas y químicas de los suelos. Se determinaron los indicadores de los factores de relieve, suelo, cobertura vegetal y uso de suelo. Las UAB se caracterizaron considerando los indicadores de relieve, pendiente y altitud; clima, temperatura y precipitación; suelo, humedad, materia orgánica, densidad aparente, pH; vegetación, densidad de la cobertura vegetal y uso de suelo. Las unidades se caracterizan por ser de origen endógeno volcánico acumulativo de flujos lávicos. Los tipos de relieve que predominan en los sitios muestreados son laderas de montaña superiores, medias e inferiores, de flujos lávicos; laderas de montaña superiores, internas y externas, de cono cinerítico; laderas superiores e inferiores de lomeríos medios y bajos; piedemonte acumulativo local; piedemonte acumulativo de lomeríos medios y bajos y planicie aluvial. La caracterización de las UAB mediante los indicadores ambientales permite contar con información básica para la toma de decisiones en el manejo adecuado de los recursos naturales y en la planeación socioambiental.

Bornmuellerantha alshehbaziana (Orobanchaceae), a New Species from Turkey

Bornmuellerantha alshehbaziana Dönmez & Mutlu (Orobanchaceae), a hemiparasitic plant from Çiğdem Mountain, Antalya Province, Turkey, is described and illustrated. It is the second species in the previously monospecific Bornmuellerantha Rothm. Morphological comparison and distinguishing characters are given. The new species is a smaller plant, has smaller flowers, and is found on high mountain slopes, in comparison to the generitype, B. aucheri (Boiss.) Rothm. Bornmuellerantha alshehbaziana is also contrasted with species of the related genus Odontites Ludw. The IUCN Red List category of Critically Endangered (CR) is proposed for the new species.

Research advances on climate-induced slope instability in glacier and permafrost high-mountain environments

Abstract. High-mountain areas with glacier and permafrost occurrence are temperature sensitive environments. Climatic changes are, thus, likely to have an effect on slope stability. Several recent events have shown that rock and ice avalanches and related hazards can have severe consequences. For hazard analysis, the processes of slope failure and flow dynamics should therefore be better understood. In this article, recent advances in this field are presented, including high-resolution topographic monitoring of a large Alpine high-mountain flank (Monte Rosa) over the past 50 years and laboratory experiments with rotating drums and numerical modelling. This recent research has revealed important insight into the causes and dynamics of slope instabilities and contributes towards a better understanding of the influence of ice on avalanche dynamics and runout. It is emphasized that high-mountain slope failures need to be viewed from an interdisciplinary perspective, taking a number of process interactions into account.

Recent and future warm extreme events and high-mountain slope stability

The number of large slope failures in some high-mountain regions such as the European Alps has increased during the past two to three decades. There is concern that recent climate change is driving this increase in slope failures, thus possibly further exacerbating the hazard in the future. Although the effects of a gradual temperature rise on glaciers and permafrost have been extensively studied, the impacts of short-term, unusually warm temperature increases on slope stability in high mountains remain largely unexplored. We describe several large slope failures in rock and ice in recent years in Alaska, New Zealand and the European Alps, and analyse weather patterns in the days and weeks before the failures. Although we did not find one general temperature pattern, all the failures were preceded by unusually warm periods; some happened immediately after temperatures suddenly dropped to freezing. We assessed the frequency of warm extremes in the future by analysing eight regional climate models from the recently completed European Union programme ENSEMBLES for the central Swiss Alps. The models show an increase in the higher frequency of high-temperature events for the period 2001-2050 compared with a 1951-2000 reference period. Warm events lasting 5, 10 and 30 days are projected to increase by about 1.5-4 times by 2050 and in some models by up to 10 times. Warm extremes can trigger large landslides in temperature-sensitive high mountains by enhancing the production of water by melt of snow and ice, and by rapid thaw. Although these processes reduce slope strength, they must be considered within the local geological, glaciological and topographic context of a slope.