scholarly journals Effects of ground freezing and snow avalanche deposits on debris flows in alpine environments

2004 ◽  
Vol 4 (4) ◽  
pp. 519-530 ◽  
Author(s):  
E. Bardou ◽  
R. Delaloye
Keyword(s):  
Debris Flows ◽  
Soil Aggregates ◽  
Base Flow ◽  
Slope Instability ◽  
Snow Avalanche ◽  
Extreme Weather Events ◽  
Precipitation Event ◽  
High Mountain ◽  
Ground Freezing ◽  
The Impact

Abstract. Debris flows consist of a mixture of water and sediments of various sizes. Apart from few exceptions, the water is usually contributed directly from precipitation. In a high mountain environment like the Alps, it appears necessary to consider infiltration of water into the ground during rainfall events, the runoff characteristics and the potential supply of sediment as a function of a multitude of climatic and hydrogeological factors. This paper outlines several new processes - either linked to ice formation in the ground before an event, or to the presence of snow avalanche deposits - that change the probability of observing an event. These processes were identified during field observations connected with extreme weather events that occurred recently in the Valais Alps (south-western Switzerland): they can be seen as factors either amplifying or reducing the potential of slope instability caused by the precipitation event. An intense freezing of the ground during the week preceding the exceptional rainfall event in mid-October 2000 amplified the probability of triggering debris flows between roughly 1800 and 2300m asl. Both growth of ice needles and superficial ground freezing destroyed soil aggregates (increasing the availability of sediments) and/or, a deeper ground freezing resulted in decreased infiltration rate (increased runoff) during the first hours of heavy rainfall. The presence of snow avalanche deposits in a gully could be simultaneously an amplifying factor (the snow deposits increase the base flow and create a sliding plane for the sediments, mainly at the time of summer storms) or a reducing factor (reduction in the impact energy of the raindrops, mainly at the time of winter storms) of the risk of triggering debris flows. If it is not currently possible to establish rainfall threshold values for debris flow triggering, the knowledge and the implementation of these processes in the analysis of the potential triggering (for example by comparing the catchment hypsometric curve with the meteo-climatic situation) would nevertheless make the analysis of debris flows and forecasting more efficient.

scholarly journals Roads at risk – traffic detours from debris flows in southern Norway

2014 ◽  
Vol 2 (10) ◽  
pp. 6623-6651 ◽  
Author(s):  
N. K. Meyer ◽  
W. Schwanghart ◽  
O. Korup ◽  
F. Nadim
Keyword(s):  
Debris Flows ◽  
Road Network ◽  
Traffic Load ◽  
Extreme Weather Events ◽  
Northwestern Part ◽  
Link Failure ◽  
The Road ◽  
On The Road ◽  
Southern Norway ◽  
The Impact

Abstract. Globalization and interregional exchange of people, goods, and services has boosted the importance of and reliance on all kinds of transport networks. The linear structure of road networks is especially sensitive to natural hazards. In southern Norway, steep topography and extreme weather events promote frequent traffic disruption caused by debris flows. Topographic susceptibility and trigger frequency maps serve as input into a hazard appraisal at the scale of first-order catchments to quantify the impact of debris flows on the road network in terms of a failure likelihood of each link connecting two network vertices, e.g., road junctions. We compute total additional traffic loads as a function of traffic volume and excess distance, i.e. the extra length of an alternative path connecting two previously disrupted network vertices using a shortest-path algorithm. Our risk metric of link failure is the total additional annual traffic load expressed as vehicle kilometers because of debris-flow related road closures. We present two scenarios demonstrating the impact of debris flows on the road network, and quantify the associated path failure likelihood between major cities in southern Norway. The scenarios indicate that major routes crossing the central and northwestern part of the study area are associated with high link failure risk. Yet options for detours on major routes are manifold, and incur only little additional costs provided that drivers are sufficiently well informed about road closures. Our risk estimates may be of importance to road network managers and transport companies relying of speedy delivery of services and goods.

Global warming, slope stability, and the dynamization of geological hazards in high mountain regions: a case study from the Eastern Alps.

2021 ◽  
Author(s):  
Sara Savi ◽  
Francesco Comiti ◽  
Manfred Strecker
Keyword(s):  
Slope Stability ◽  
Debris Flows ◽  
Slope Instability ◽  
Medium Size ◽  
Hazard Mapping ◽  
High Mountain ◽  
Permafrost Degradation ◽  
Mountain Regions ◽  
Extreme Precipitation Events ◽  
Altitudinal Shift

<p>In recent decades, slope instability in high-mountain regions has often been linked to the increase in temperature and the associated permafrost degradation and/or the increase in frequency/intensity of rainstorm events. In this context we analyzed the spatiotemporal evolution and potential controlling mechanisms of small to medium-size rockfalls and debris flows in a small catchment of the Italian Alps (Sulden/Solda basin). We found that rockfall events have been increasing since the 1990s, whereas debris flows have increased only since 2010. The current warming trend of mountain regions such as the Southern Alps is leading to an increased elevation of rockfall detachment areas (altitudinal shift of ca. 300-400 m in the study site), mostly controlled by frost-cracking and permafrost thawing. In contrast, the occurrence of debris flows does not exhibit such an altitudinal shift, as it is primarily driven by extreme precipitation events exceeding the 75th percentile of the intensity-duration rainfall distribution. The possible occurrence of a debris-flow event in this environment may be additionally influenced by the accumulation of unconsolidated debris over time, which is then released during extreme rainfall events. Overall, there is evidence that the upper Sulden basin (above ca. 2500 m asl), and especially the areas in the proximity of glaciers, have experienced a significant decrease in slope stability since the 1990s and that an increase in rockfalls and debris flows during spring and summer can be observed. Our study thus confirms that “forward-looking” hazard mapping should be undertaken in these increasingly frequented areas of the Alps, as these environmental changes have elevated the overall hazard level in these high-elevation regions.</p>

scholarly journals Roads at risk: traffic detours from debris flows in southern Norway

2015 ◽  
Vol 15 (5) ◽  
pp. 985-995 ◽  
Author(s):  
N. K. Meyer ◽  
W. Schwanghart ◽  
O. Korup ◽  
F. Nadim
Keyword(s):  
Debris Flows ◽  
Road Network ◽  
Linear Structure ◽  
Traffic Load ◽  
Extreme Weather Events ◽  
Link Failure ◽  
The Road ◽  
On The Road ◽  
Southern Norway ◽  
The Impact

Abstract. Globalisation and interregional exchange of people, goods, and services has boosted the importance of and reliance on all kinds of transport networks. The linear structure of road networks is especially sensitive to natural hazards. In southern Norway, steep topography and extreme weather events promote frequent traffic disruption caused by debris flows. Topographic susceptibility and trigger frequency maps serve as input into a hazard appraisal at the scale of first-order catchments to quantify the impact of debris flows on the road network in terms of a failure likelihood of each link connecting two network vertices, e.g. road junctions. We compute total additional traffic loads as a function of traffic volume and excess distance, i.e. the extra length of an alternative path connecting two previously disrupted network vertices using a shortest-path algorithm. Our risk metric of link failure is the total additional annual traffic load, expressed as vehicle kilometres, because of debris-flow-related road closures. We present two scenarios demonstrating the impact of debris flows on the road network and quantify the associated path-failure likelihood between major cities in southern Norway. The scenarios indicate that major routes crossing the central and north-western part of the study area are associated with high link-failure risk. Yet options for detours on major routes are manifold and incur only little additional costs provided that drivers are sufficiently well informed about road closures. Our risk estimates may be of importance to road network managers and transport companies relying on speedy delivery of services and goods.

Land management extends the duration of the impact of extreme on vegetation

2020 ◽  
Author(s):  
Tiexi Chen
Keyword(s):  
Land Management ◽  
Vegetation Index ◽  
Cropping System ◽  
Growth Period ◽  
Extreme Weather Events ◽  
Precipitation Event ◽  
Monthly Precipitation ◽  
Double Cropping ◽  
Winter Crops ◽  
The Impact

<p>Extreme weather events have a severe impact on vegetation and the carbon cycle. It is generally believed that the vegetation will begin to recover immediately after the extremes, slowly or rapidly. This study will initially report a new response mechanism. We investigated a case of an extreme precipitation event that occurred in a double-cropping (DC) systems dominated region located Yangtze-Huai plain in China, where winter crops and summer crops are planted rotationally within one year. Generally October and June are the transitional periods for harvesting and sowing. In October 2016, monthly precipitation showed strong positive anomalies. Strong negative anomalies of EVI (enhanced vegetation index) persisted during March to May 2017, in response to the farmland abundance due to the heavy rain, especially over the farmland with winter crops – summer rice paddy systems. Information on abandonment due to precipitation also has been confirmed in local agro-meteorological monthly reports and some local government announcements. Data from a flux observation station in the region showed that from January to May 2017, NEE dropped significantly compared to the same period in 2016. Our results demonstrate that, in such a double-cropping system, once extreme events occur during the key sowing period and the phenological conditions determine that it cannot be replanted after, the duration of the impact will last through the entire crop growth period until the next sowing. In other word, land management could extend the duration of the impact of extremes on vegetation.</p>

Focus on Thermokarst Lakes in Indian Himalaya: Inception and Implication under Warming Climate

2020 ◽  
Vol 6 (2) ◽  
pp. 59-69
Author(s):  
Pratima Pandey ◽  
S. Nawaz Ali ◽  
Vikram Sharma ◽  
Prashant K. Champati Ray
Keyword(s):  
Western Himalaya ◽  
High Mountain ◽  
Thermokarst Lakes ◽  
Glacial Environments ◽  
Global Warming Scenario ◽  
Scientific Attention ◽  
Topographic Depressions ◽  
Permafrost Thawing ◽  
The Impact ◽  
Thaw Lakes

Thermokarst (Thaw) lakes are landforms found in topographic depressions created by thawing ground ice in permafrost zones. They play an important role in the regulation of climatic functions. These lakes are a manifestation of warming surface temperatures that accelerates the ice-rich permafrost to degrade by creating marshy hollows/ponds. In the current global warming scenario, the thermokarst lakes in the high mountain regions (Himalaya) are expected to grow further. This accelerate permafrost thawing which will affect the carbon cycle, hydrology and local ecosystems. This phenomenon has attracted huge scientific attention because it has led to a rapid mass change of glaciers in the region, including extensive changes occurring on peri-glacial environments. The most striking fact is the release of an enormous amount of greenhouse gases, including methane, carbon dioxide and nitrous oxide that is locked in these lakes. The present study delves into the thermokarst lakes in the upper reaches of Chandra Valley and Western Himalaya. The study also aims at designating the impact of their changes on the ecosystem, particularly their influence on the atmospheric greenhouse gas concentrations.

scholarly journals Urban Heat Islands and Thermal Comfort: A Case Study of Zorrotzaurre Island in Bilbao

2021 ◽  
Vol 13 (11) ◽  
pp. 6106
Author(s):  
Irantzu Alvarez ◽  
Laura Quesada-Ganuza ◽  
Estibaliz Briz ◽  
Leire Garmendia
Keyword(s):  
Thermal Comfort ◽  
Heat Waves ◽  
Urban Environments ◽  
Urban Heat Islands ◽  
Extreme Weather Events ◽  
Climate Index ◽  
Physiological Equivalent Temperature ◽  
Heat Islands ◽  
The North ◽  
The Impact

This study assesses the impact of a heat wave on the thermal comfort of an unconstructed area: the North Zone of the Island of Zorrotzaurre (Bilbao, Spain). In this study, the impact of urban planning as proposed in the master plan on thermal comfort is modeled using the ENVI-met program. Likewise, the question of whether the urbanistic proposals are designed to create more resilient urban environments is analyzed in the face of increasingly frequent extreme weather events, especially heat waves. The study is centered on the analysis of temperature variables (air temperature and average radiant temperature) as well as wind speed and relative humidity. This was completed with the parameters of thermal comfort, the physiological equivalent temperature (PET) and the Universal Temperature Climate Index (UTCI) for the hours of the maximum and minimum daily temperatures. The results demonstrated the viability of analyzing thermal comfort through simulations with the ENVI-met program in order to analyze the behavior of urban spaces in various climate scenarios.

scholarly journals Potential Impact of the Current and Future Climate on the Yield, Quality, and Climate Suitability for Tea [Camellia sinensis (L.) O. Kuntze]: A Systematic Review

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 619
Author(s):  
Sadeeka Layomi Jayasinghe ◽  
Lalit Kumar
Keyword(s):  
Climate Change ◽  
Future Climate ◽  
Mitigation Strategies ◽  
Extreme Weather Events ◽  
Impact Of Climate Change ◽  
Advantages And Disadvantages ◽  
Tea Quality ◽  
Climate Suitability ◽  
Yield Quality ◽  
The Impact

Even though climate change is having an increasing impact on tea plants, systematic reviews on the impact of climate change on the tea system are scarce. This review was undertaken to assess and synthesize the knowledge around the impacts of current and future climate on yield, quality, and climate suitability for tea; the historical roots and the most influential papers on the aforementioned topics; and the key adaptation and mitigation strategies that are practiced in tea fields. Our findings show that a large number of studies have focused on the impact of climate change on tea quality, followed by tea yield, while a smaller number of studies have concentrated on climate suitability. Three pronounced reference peaks found in Reference Publication Year Spectroscopy (RYPS) represent the most significant papers associated with the yield, quality, and climate suitability for tea. Tea yield increases with elevated CO2 levels, but this increment could be substantially affected by an increasing temperature. Other climatic factors are uneven rainfall, extreme weather events, and climate-driven abiotic stressors. An altered climate presents both advantages and disadvantages for tea quality due to the uncertainty of the concentrations of biochemicals in tea leaves. Climate change creates losses, gains, and shifts of climate suitability for tea habitats. Further studies are required in order to fill the knowledge gaps identified through the present review, such as an investigation of the interaction between the tea plant and multiple environmental factors that mimic real-world conditions and then studies on its impact on the tea system, as well as the design of ensemble modeling approaches to predict climate suitability for tea. Finally, we outline multifaceted and evidence-based adaptive and mitigation strategies that can be implemented in tea fields to alleviate the undesirable impacts of climate change.

scholarly journals Public Perceptions of Climate Change in the Peruvian Andes

2021 ◽  
Vol 13 (5) ◽  
pp. 2677
Author(s):  
Adrian Brügger ◽  
Robert Tobias ◽  
Fredy S. Monge-Rodríguez
Keyword(s):  
Climate Change ◽  
Low Income ◽  
Public Perceptions ◽  
Climate Impacts ◽  
Vulnerable Groups ◽  
Extreme Weather Events ◽  
High Mountain ◽  
Peruvian Andes ◽  
Food Shortages ◽  
Education Levels

How people subjectively perceive climate change strongly influences how they respond to its challenges. To date, relatively little is known about such perceptions in the Global South. This research examines public perceptions of climate change in the Peruvian Andes, a semi-arid high-mountain region that is highly exposed and vulnerable to adverse effects of climate change. Based on questionnaire data collected through face-to-face interviews (N = 1316), we found that respondents identify various climate-related issues as the most important challenges for their country. Many of these issues are related to water. Respondents also noticed more subtle changes and expected them to continue (e.g., extreme temperatures, food shortages). Climate impacts were clearly seen as negative, which was also reflected in the presence of emotions. When compared to previous research, more respondents had personally experienced extreme weather events (80%) and they were more certain that the climate is already changing, is caused by human activity, and is affecting distant and close places similarly. A comparison of the perceptions along different socioeconomic characteristics suggests that more vulnerable groups (e.g., rural, low income and education levels) tended to perceive climate change as more consequential, closer, and as a more natural (vs. anthropogenic) phenomenon than those from less vulnerable groups. The salience of water-related problems and personal experiences of climate-related events, as well as differences between various subgroups, could be used to improve measures to adapt to the consequences of climate change by correcting misconceptions of the population and of decisionmakers.

scholarly journals Extreme Meteorological Events in a Coastal Lagoon Ecosystem: The Ria de Aveiro Lagoon (Portugal) Case Study

2021 ◽  
Vol 9 (7) ◽  
pp. 727
Author(s):  
José Fortes Lopes ◽  
Carina Lurdes Lopes ◽  
João Miguel Dias
Keyword(s):  
Water Temperature ◽  
Coastal Lagoon ◽  
Early Summer ◽  
Extreme Weather Events ◽  
Climate Change Scenarios ◽  
State Variables ◽  
Ria De Aveiro ◽  
Physical Conditions ◽  
Weather Events ◽  
The Impact

Extreme weather events (EWEs) represent meteorological hazards for coastal lagoon hydrodynamics, of which intensity and frequency are increasing over the last decades as a consequence of climate changes. The imbalances they generated should affect primarily vulnerable low-lying areas while potentially disturbing the physical balances (salt and water temperature) and, therefore, the ecosystem equilibrium. This study arises from the need to assess the impact of EWEs on the Ria de Aveiro, a lagoon situated in the Portuguese coastal area. Furthermore, it was considered that those events occur under the frame of a future sea-level rise, as predicted by several climate change scenarios. Two EWEs scenarios, a dry and an extremely wet early summer reflecting past situations and likely to occur in the future, were considered to assess the departure from the system baseline functioning. It was used as a biogeochemistry model that simulates the hydrodynamics, as well as the baseline physical and biogeochemistry state variables. The dry summer scenario, corresponding to a significant reduction in the river’s inflow, evidences a shift of the system to a situation under oceanic dominance characterized by colder and saltier water (~18 °C; 34 PSU) than the baseline while lowering the concentration of the nutrients and reducing the phytoplankton population to a low-level limit. Under a wet summer scenario, the lagoon shifted to a brackish and warmer situation (~21 °C, <15 PSU) in a time scale of some tidal periods, driven by the combining effect of the tidal transport and the river’s inflow. Phytoplankton patterns respond to variability on local and short-term scales that reflect physical conditions within the lagoon, inducing nutrient-supported growth. Overall, the results indicate that EWEs generate local and transient changes in physical conditions (namely salinity and water temperature) in response to the characteristic variability of the lagoon’s hydrodynamics associated with a tidal-dominated system. Therefore, in addition to the potential impact of changing physical conditions on the ecosystem, saline intrusion along the lagoon or the transfer of brackish water to the mouth of the system are the main consequences of EWEs, while the main biogeochemistry changes tend to remain moderate.

scholarly journals The Impact of Probability Density Functions Assessment on Model Performance for Slope Stability Analysis

Geosciences ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 322
Author(s):  
Evelina Volpe ◽  
Luca Ciabatta ◽  
Diana Salciarini ◽  
Stefania Camici ◽  
Elisabetta Cattoni ◽  
...  
Keyword(s):  
Probability Density ◽  
Central Italy ◽  
Model Performance ◽  
Probability Density Functions ◽  
Slope Instability ◽  
Complex Nature ◽  
Density Functions ◽  
Umbria Region ◽  
Input Variables ◽  
The Impact

The development of forecasting models for the evaluation of potential slope instability after rainfall events represents an important issue for the scientific community. This topic has received considerable impetus due to the climate change effect on territories, as several studies demonstrate that an increase in global warming can significantly influence the landslide activity and stability conditions of natural and artificial slopes. A consolidated approach in evaluating rainfall-induced landslide hazard is based on the integration of rainfall forecasts and physically based (PB) predictive models through deterministic laws. However, considering the complex nature of the processes and the high variability of the random quantities involved, probabilistic approaches are recommended in order to obtain reliable predictions. A crucial aspect of the stochastic approach is represented by the definition of appropriate probability density functions (pdfs) to model the uncertainty of the input variables as this may have an important effect on the evaluation of the probability of failure (PoF). The role of the pdf definition on reliability analysis is discussed through a comparison of PoF maps generated using Monte Carlo (MC) simulations performed over a study area located in the Umbria region of central Italy. The study revealed that the use of uniform pdfs for the random input variables, often considered when a detailed geotechnical characterization for the soil is not available, could be inappropriate.

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