Remote Detection of Surge-Related Glacier Terminus Change across High Mountain Asia

High Mountain Asia (HMA) hosts the largest glacier concentration outside of polar regions. It is also distinct glaciologically as it forms one of two major surge clusters globally, and many glaciers there contradict the globally observed glacier recession trend. Surging glaciers are critical to our understanding of HMA glacier dynamics, threshold behaviour and flow instability, and hence have been the subject of extensive research, yet many dynamical uncertainties remain. Using the cloud-based geospatial data platform, Google Earth Engine (GEE) and GEE-developed tool, GEEDiT, to identify and quantify trends in the distribution and phenomenological characteristics of surging glaciers synoptically across HMA, we identified 137 glaciers as surging between 1987–2019. Of these, 55 were newly identified, 15 glaciers underwent repeat surges, and 18 were identified with enhanced glaciological hazard potential, most notably from Glacier Lake Outburst Floods (GLOFs). Terminus position time series analysis from 1987–2019 facilitated the development of a six-part phenomenological classification of glacier behaviour, as well as quantification of surge variables including active phase duration, terminus advance distance and rate, and surge periodicity. This research demonstrates the application of remote sensing techniques and the GEE platform to develop our understanding of surging glacier distribution and terminus phenomenology across large areas, as well as their ability to highlight potential geohazard locations, which can subsequently be used to focus monitoring efforts.

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Mapping glacier lakes in Peru

10.5194/egusphere-egu2020-9741 ◽

2020 ◽

Author(s):

Joanne Wood ◽

Stephan Harrison ◽

Ryan Wilson ◽

Christian Yarleque ◽

Georgie Bennett ◽

...

Keyword(s):

Google Earth ◽

High Mountain ◽

Peruvian Andes ◽

Water Index ◽

Mountain Glaciers ◽

Outburst Floods ◽

Glacial Lake Outburst Floods ◽

Glacier Front ◽

Google Earth Engine ◽

Over Time

One consequence of current and likely future melting of high mountain glaciers is the development of glacial lakes. Their evolution over time has implications for future water supplies in arid mountains and for the timing and magnitude of glacier hazards, such as Glacial Lake Outburst Floods (GLOFs).GLOF initiation depends on how lakes are connected to the glacial system, resulting from myriad processes such as the destabilisation of moraine dams and glacier front calving. To better understand these processes, we have undertaken an inventory of all glacier lakes in the Cordillera Blanca of Peru for 2019. We used manual digitisation from Landsat RGB at 30m resolution and have recorded the type of lake dam and its connection with surrounding glaciers and mountain slopes. We have also obtained lake inventories from INIAGEM (Instituto Nacional de Investigaci&#243;n en Glaciares y Ecosistemas de Monta&#241;a; 2016) and ANA (Autoridad Nacional del Agua; 2018), and have created an automatic inventory using the Normalised Difference Water Index and Normalised Difference Snow Index in Google Earth Engine. In this presentation we compare these different inventories and discuss both the methods and effectiveness of each for understanding GLOF hazards in the Peruvian Andes.&#160;

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Simulation and Assessment of Future Glacial Lake Outburst Floods in the Poiqu River Basin, Central Himalayas

Water ◽

10.3390/w13101376 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1376

Author(s):

Taigang Zhang ◽

Weicai Wang ◽

Tanguang Gao ◽

Baosheng An

Keyword(s):

River Basin ◽

Hazard Assessment ◽

Glacial Lake ◽

High Mountain ◽

Glacial Lakes ◽

Central Himalayas ◽

Outburst Floods ◽

Glacial Lake Outburst Floods ◽

Social And Economic Development ◽

Glacial Lake Outburst Flood

A glacial lake outburst flood (GLOF) is a typical glacier-related hazard in high mountain regions. In recent decades, glacial lakes in the Himalayas have expanded rapidly due to climate warming and glacial retreat. Some of these lakes are unstable, and may suddenly burst under different triggering factors, thus draining large amounts of water and impacting downstream social and economic development. Glacial lakes in the Poiqu River basin, Central Himalayas, have attracted great attention since GLOFs originating there could have a transboundary impact on both China and Nepal, as occurred during the Cirenmaco GLOF in 1981 and the Gongbatongshaco GLOF in 2016. Based on previous studies of this basin, we selected seven very high-risk moraine-dammed lakes (Gangxico, Galongco, Jialongco, Cirenmaco, Taraco, Beihu, and Cawuqudenco) to simulate GLOF propagation at different drainage percentage scenarios (i.e., 25%, 50%, 75%, and 100%), and to conduct hazard assessment. The results show that, when any glacial lake is drained completely or partly, most of the floods will enter Nepal after raging in China, and will continue to cause damage. In summary, 57.5 km of roads, 754 buildings, 3.3 km2 of farmland, and 25 bridges are at risk of damage due to GLOFs. The potentially inundated area within the Chinese part of the Poiqu River basin exceeds 45 km2. Due to the destructive impacts of GLOFs on downstream areas, appropriate and effective measures should be implemented to adapt to GLOF risk. We finally present a paradigm for conducting hazard assessment and risk management. It uses only freely available data and thus is easy to apply.

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The duration of the active phase on surge-type glaciers: contrasts between Svalbard and other regions

Journal of Glaciology ◽

10.1017/s0022143000005827 ◽

1991 ◽

Vol 37 (127) ◽

pp. 388-400 ◽

Cited By ~ 144

Author(s):

Julian A. Dowdeswell ◽

Gordon S. Hamilton ◽

Jon Ove Hagen

Keyword(s):

Time Series ◽

North America ◽

Active Phase ◽

Aerial Photographs ◽

Polar Ice ◽

Phase Duration ◽

Field Surveys ◽

The World ◽

Glacier Surges ◽

Fast Motion

AbstractMany glaciers in Svalbard and in other glacierized areas of the world are known to surge. However, the time series of observations required to assess the duration of fast motion is very restricted. Data on active-phase duration in Svalbard come from aerial photographs, satellite imagery, field surveys and airborne reconnaissance. Evidence on surge duration is available for eight Svalbard ice masses varying from 3 to 1250 km2. Worldwide, active-phase duration is recorded for less than 50 glaciers. Few observations are available on high polar ice masses. The duration of the active phase is significantly longer for Svalbard glaciers than for surge-type glaciers in other areas from which data are available. In Svalbard, the active phase may last from 3 to 10 years. By contrast, a surge duration of 1–2 years is more typical of ice masses in northwest North America, Iceland and the Pamirs. Ice velocities during the protracted active phase on Svalbard glaciers are considerably lower than those for many surge-type glaciers in these other regions. Mass is transferred down-glacier more slowly but over a considerably longer period. Svalbard surge-type glaciers do not exhibit the very abrupt termination of the active phase, over periods of a few days, observed for several Alaskan glaciers. The duration of the active phase in Svalbard is not dependent on parameters related to glacier size. The quiescent phase is also relatively long (50–500 years) for Svalbard ice masses. Detailed field monitoring of changing basal conditions through the surge cycle is required from surge-type glaciers in Svalbard in order to explain the significantly longer length of the active phase for glaciers in the archipelago, which may also typify other high polar ice masses. The finding that surge behaviour, in the form of active-phase duration, shows systematic differences between different regions and their environments has important implications for understanding the processes responsible for glacier surges.

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How can drone imagery and dendrogeomorphology contribute to GLOF hazard assessment in remote areas? A case study from Chilean Patagonia.

10.5194/egusphere-egu21-10821 ◽

2021 ◽

Author(s):

Sandra Gorsic ◽

Alberto Muñoz-Torrero Manchado ◽

Jérôme Lopez-Saez ◽

Simon K. Allen ◽

Juan A. Ballesteros-Canovas ◽

...

Keyword(s):

Tree Ring ◽

High Energy ◽

High Mountain ◽

Remote Areas ◽

Mountain Environments ◽

Outburst Floods ◽

Object Based ◽

Detection Approach ◽

Chilean Patagonia ◽

San Rafael

With the substantial glacier mass reduction projected by the end of the century, the formation and rise of periglacial lakes has to be expected. Even though these changes often occur in remote areas, they can nevertheless have catastrophic impacts on populations and infrastructure through processes such as glacial lake outburst floods (GLOF). GLOFs are the result of complex geomorphic changes and subject to various timescales, thus urging the need for a multidimensional approach. The present study combines two approaches to analyze natural hazards in the secluded San Rafael National Park in Chilean Patagonia (North Patagonian Icefield). The Grosse glacier outlet was chosen after interpreting satellite imagery and historical pictures showing a historical emptying of a lateral lake, which was also supported by local testimonies. Dendrogeomorphology was primarily used with an automatic detection approach to identify possible dates of occurrence of past GLOFs at the Grosse outlet. A total of 105 disturbed Nothofagus trees were sampled highlighting 6 event years between 1958 and 2011. The second method aimed at complementing the tree-ring-based findings with UAV imagery acquired during fieldwork and the mapping of geomorphic evidence of past GLOFs. Huge boulders and deposits are one of the signs recognized as remnants of past lake outbursts and were thus used to differentiate small, rainfall-induced floods from high magnitude events. More precisely, through an object-based strategy, we mapped deposits and extrapolated a theoretical flow orientation. Whereas the first method allowed to select dates of potential events, the second facilitated identification and mapping of the spatial extent of past high-energy events. Analysis of imagery also allowed detection of the occurrence of a 200-m wide breach in the frontal moraine as well as the vanishing of a lateral lake estimated to be 1.8 &#215; 106 m2 in the 1950s, which we date to 1958 using tree-ring records. When used together the two approaches can represent a valuable contribution to historical records and help future assessments of natural hazard at Grosse glacier, but also in other high-mountain environments.

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Title: Application of a physiotherapy protocol to women during the active phase of labour improves obstetric outcomes: a randomized clinical trial.

10.22541/au.161271575.57289965/v1 ◽

2021 ◽

Author(s):

LICIA SANTANA ◽

Rubneide Gallo ◽

Silvana Quintana ◽

Geraldo Duarte ◽

Cristine Homsi Ferreira ◽

...

Keyword(s):

Controlled Trial ◽

Perinatal Outcomes ◽

Active Phase ◽

Labour Pain ◽

Obstetric Outcomes ◽

Control Group ◽

Phase Duration ◽

Intention To Treat ◽

Reference Centre ◽

Care Protocol

Objective: To evaluate the effectiveness of a non-pharmacological childbirth care protocol in women in the active phase of labour in improving obstetric and perinatal outcomes. Design: Randomized trial with concealed allocation, assessor blinding, and intention-to-treat analysis. Setting: Reference Centre of Women’s Health of Ribeirão Preto–MATER, São Paulo, Brazil. Methods: Eighty low-risk primiparous women at the end of pregnancy and beginning of the active phase of labour were randomized to experimental group (EG) (n=40) or control group (CG) (n=40). Women in EG received four interventions: ambulation at 4 to 6 cm of cervical dilation; alternative maternal positions associated with TENS at 6 to 7 cm, and a warm shower bath at >7 cm. The CG received only routine obstetric. Main outcome measures: The length of the active phase of labour, the expulsive phase duration, and the prevalence of labour dystocia assessed by the partograph. Results: The parturients who received the sequential non-pharmacological protocol had a shorter length of the active phase of labour (CG=444 minutes; EG=373 minutes; p=0,02), presented rupture of membranes later in labour (CG=7cm; EG=8cm; p<0,01), requested pharmacological analgesia with more significant cervical dilatation (CG=5cm; EG=8cm; p<0,01) and had lower labour dystocia rates than the patients in the CG. Conclusion: The implementation of a sequential non-pharmacological protocol has the potential in decreased and delayed use of pharmacological analgesia, duration of the active phase of labour and dystocia rates. Keywords: length of labour, labour pain, dystocia, randomized controlled trial, non-pharmacological resources, pharmacological analgesia. Trial registration: NCT01601860 Link: https://clinicaltrials.gov/ct2/show/NCT01601860

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Status of Major Glaciers of Hunza River Basin, Under Changing Climatic Conditions of Pakistan Over the Period of (1990-2018)

10.21203/rs.3.rs-248279/v1 ◽

2021 ◽

Author(s):

Sajid Ali ◽

Garee Khan ◽

Wajid Hassan ◽

Javed Akhter Qureshi ◽

Iram Bano

Keyword(s):

River Basin ◽

Primary Source ◽

Climatic Conditions ◽

Climate Data ◽

Outburst Floods ◽

Glacial Lake Outburst Floods ◽

Digital Elevation ◽

Remote Sensing Techniques ◽

Elevation Model ◽

Hunza River

Abstract Ice masses and snow of Hunza River Basin (HRB) are an important primary source of fresh water and lifeline for downstream inhabitants. Changing climatic conditions seriously put an impact on these available ice and snow masses. These glaciers may affect downstream population by glacial lake outburst floods (GLOF) and surge events due to climatic variation. So, monitoring of these glaciers and available ice masses are important. This research delivers an approach for selected glaciers of the Hunza river basin. An attempt is made in this study using Landsat (OLI, ETM, ETM+, TM), digital elevation model (DEM), Geographic Information System and Remote Sensing techniques (RS&GIS) techniques. We delineated 27 glaciers within HRB from the period of 1990-2018. These glaciers' total area is about 2589.75 ±86km 2 in 1990 and about 2565.12 ±68km 2 in 2018. Our results revealed that from 2009 to 2015, glacier coverage of HRB advanced with a mean annual advance rate of 2.22±0.1 km 2 a -1 . Conversely, from 1994 to 1999, the strongest reduction in glacier area with a mean rate of - 3.126±0.3km 2 a -1 is recorded. The glaciers of HRB are relatively stable compared to Hindukush, Himalayan and Tibetan Plateau (TP) region of the world. The steep slope glacier's retreat rate is more than that of gentle slope glaciers, and the glaciers below elevation of 5000 m above sea level change significantly. Based on climate data from 1995-2018, HRB shows a decreasing trend in temperature and increasing precipitation. The glacier area's overall retreat is due to an increase in summer temperature while the glacier advancement is induced possibly by winter and autumn precipitation.

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TermPicks: A century of Greenland glacier terminus data for use in machine learning applications

10.5194/tc-2021-311 ◽

2021 ◽

Author(s):

Sophie Goliber ◽

Taryn Black ◽

Ginny Catania ◽

James M. Lea ◽

Helene Olsen ◽

...

Keyword(s):

Machine Learning ◽

Greenland Ice Sheet ◽

Median Number ◽

Google Earth ◽

Training Data ◽

Machine Learning Techniques ◽

Data Set ◽

Outlet Glacier ◽

Glacier Terminus ◽

Median Error

Abstract. Marine-terminating outlet glacier terminus traces, mapped from satellite and aerial imagery, have been used extensively in understanding how outlet glaciers adjust to climate change variability over a range of time scales. Numerous studies have digitized termini manually, but this process is labor-intensive, and no consistent approach exists. A lack of coordination leads to duplication of efforts, particularly for Greenland, which is a major scientific research focus. At the same time, machine learning techniques are rapidly making progress in their ability to automate accurate extraction of glacier termini, with promising developments across a number of optical and SAR satellite sensors. These techniques rely on high quality, manually digitized terminus traces to be used as training data for robust automatic traces. Here we present a database of manually digitized terminus traces for machine learning and scientific applications. These data have been collected, cleaned, assigned with appropriate metadata including image scenes, and compiled so they can be easily accessed by scientists. The TermPicks data set includes 39,060 individual terminus traces for 278 glaciers with a mean and median number of traces per glacier of 136 ± 190 and 93, respectively. Across all glaciers, 32,567 dates have been picked, of which 4,467 have traces from more than one author (duplication of 14 %). We find a median error of ∼100 m among manually-traced termini. Most traces are obtained after 1999, when Landsat 7 was launched. We also provide an overview of an updated version of The Google Earth Engine Digitization Tool (GEEDiT), which has been developed specifically for future manual picking of the Greenland Ice Sheet.

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Effect of Intramuscular Administration of Dexamethasone on Shortening of the Duration of Induction of Labor

QJM ◽

10.1093/qjmed/hcab115.034 ◽

2021 ◽

Vol 114 (Supplement_1) ◽

Author(s):

Hazem M Sammour ◽

Sherif A Ashoush ◽

Gihan E Elhawwary ◽

Sara H Rekaby

Keyword(s):

Active Phase ◽

Labor Induction ◽

Induction Of Labor ◽

Intramuscular Administration ◽

Controlled Study ◽

Phase Duration ◽

Second Stage Of Labor ◽

Uterine Contractions ◽

Third Stage Of Labor ◽

Double Blinded

Abstract Background Induction of labor refers to iatrogenic stimulation of uterine contractions to accomplish delivery prior to the onset of spontaneous labor. Induction of labor is undertaken when both of the following criteria are met: Continuing the pregnancy is believed to be associated with greater maternal or fetal risk than intervention to deliver the pregnancy, and there is no contraindication to vaginal birth. Aim of the Work to evaluate the effect of intramuscular administration of dexamethasone on the duration of vaginal delivery in women undergoing induction of labor. Patients and Methods This double-blinded randomized controlled study was conducted on 60 termed pregnant women who were divided into two groups, Dexamethasone group: injected with 2 ml of the product (dexamethasone®) 12 hours before initiation of labor induction and placebo group: injected with 2 ml distilled water 12 hours before initiation of labor induction. The two groups were induced by the same standard protocol. Determination of interval between initiation of induction and beginning of active phase, duration of active phase, duration of 2nd stage and duration 3rd stage have been detected for both groups and statistically analyzed. Results There were significant statistical differences between the two studied groups as regard rate of cervical dilatation. There were high significant statistical differences between the two studied groups as regard duration between initiation of labor induction and beginning of active phase of labor, duration of active phase of labor and duration of second and third stage of labor. Conclusion an intramuscular injection of dexamethasone before labor induction is found to shorten the duration of labor induction by decreasing the interval between the initiation of induction and the beginning of the active phase, duration of active phase and duration of second stage of labor with no observed maternal or neonatal complications.

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Reconstructing the History of Glacial Lake Outburst Floods (GLOF) in the Kanchenjunga Conservation Area, East Nepal: An Interdisciplinary Approach

Sustainability ◽

10.3390/su12135407 ◽

2020 ◽

Vol 12 (13) ◽

pp. 5407

Author(s):

Alton C. Byers ◽

Mohan Bahadur Chand ◽

Jonathan Lala ◽

Milan Shrestha ◽

Elizabeth A. Byers ◽

...

Keyword(s):

Interdisciplinary Approach ◽

Debris Avalanche ◽

Field Investigation ◽

Glacial Lake ◽

High Mountain ◽

Lateral Moraine ◽

Conservation Area ◽

Terminal Moraine ◽

Outburst Floods ◽

Glacial Lake Outburst Floods

An interdisciplinary field investigation of historic glacial lake outburst floods (GLOFs) in the Kanchenjunga region of Nepal was conducted between April and May, 2019. Oral history and field measurements suggested that at least six major GLOFs have occurred in the region since 1921. A remote sensing analysis confirmed the occurrence of the six GLOFs mentioned by informants, including two smaller flood events not mentioned that had occurred at some point before 1962. A numerical simulation of the Nangama GLOF suggested that it was triggered by an ice/debris avalanche of some 800,000 m3 of material, causing a surge wave that breached the terminal moraine and released an estimated 11.2 × 106 m3 ± 1.4 × 106 m3 of water. Debris from the flood dammed the Pabuk Khola river 2 km below the lake to form what is today known as Chheche Pokhari lake. Some concern has been expressed for the possibility of a second GLOF from Nangama as the result of continued and growing landslide activity from its right lateral moraine. Regular monitoring of all lakes and glaciers is recommended to avoid and/or mitigate the occurrence of future GLOF events in the region. Collectively, the paper demonstrates the benefits and utility of interdisciplinary research approaches to achieving a better understanding of past and poorly documented GLOF events in remote, data-scarce high mountain environments.

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Power-law correlations and coupling of active and quiet states underlie a class of complex systems with self-organization at criticality

EPJ Web of Conferences ◽

10.1051/epjconf/202023000005 ◽

2020 ◽

Vol 230 ◽

pp. 00005

Author(s):

Fabrizio Lombardi ◽

Jilin W.J.L. Wang ◽

Xiyun Zhang ◽

Plamen Ch Ivanov

Keyword(s):

Power Law ◽

Active Phase ◽

Continuous Phase ◽

Temporal Organization ◽

Fine Tuning ◽

Self Organization ◽

Specific Power ◽

Earthquake Dynamics ◽

Phase Duration ◽

Collective Behaviors

Physical and biological systems often exhibit intermittent dynamics with bursts or avalanches (active states) characterized by power-law size and duration distributions. These emergent features are typical of systems at the critical point of continuous phase transitions, and have led to the hypothesis that such systems may self-organize at criticality, i.e. without any fine tuning of parameters. Since the introduction of the Bak-Tang-Wiesenfeld (BTW) model, the paradigm of self-organized criticality (SOC) has been very fruitful for the analysis of emergent collective behaviors in a number of systems, including the brain. Although considerable effort has been devoted in identifying and modeling scaling features of burst and avalanche statistics, dynamical aspects related to the temporal organization of bursts remain often poorly understood or controversial. Of crucial importance to understand the mechanisms responsible for emergent behaviors is the relationship between active and quiet periods, and the nature of the correlations. Here we investigate the dynamics of active (θ-bursts) and quiet states (δ-bursts) in brain activity during the sleep-wake cycle. We show the duality of power-law (θ, active phase) and exponential-like (δ, quiescent phase) duration distributions, typical of SOC, jointly emerge with power-law temporal correlations and anti-correlated coupling between active and quiet states. Importantly, we demonstrate that such temporal organization shares important similarities with earthquake dynamics, and propose that specific power-law correlations and coupling between active and quiet states are distinctive characteristics of a class of systems with self-organization at criticality.

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