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Article ; Online: Mapping of glacial lakes using Sentinel-1 and Sentinel-2 data and a random forest classifier

Sonam Wangchuk / Tobias Bolch

Science of Remote Sensing, Vol 2, Iss , Pp 100008- (2020)

Strengths and challenges

2020

Abstract: Glacial lakes pose a serious threat to downstream areas and significantly impact glacier melt. The number and area of lakes has grown in most regions during the last decades due to the ongoing atmospheric warming and retreating glaciers. It is therefore ... ...

Abstract	Glacial lakes pose a serious threat to downstream areas and significantly impact glacier melt. The number and area of lakes has grown in most regions during the last decades due to the ongoing atmospheric warming and retreating glaciers. It is therefore important to identify and monitor these lakes. However, mapping of glacial lakes in alpine regions is challenged by many factors. These factors include the small size of glacial lakes, cloud cover in optical satellite images, cast shadows from mountains and clouds, seasonal snow in satellite images, varying degrees of turbidity amongst glacial lakes, and frozen glacial lake surfaces. In our study, we have developed a fully automated method for mapping glacial lakes across alpine regions including the Python package called “GLakeMap”. The method uses multi-source data such as Sentinel-1 Synthetic Aperture Radar and Sentinel-2 Multi-spectral Instrument data, a digital elevation model, and a random forest classifier model. We use multi-source datasets as inputs for rule-based segmentation of images, mainly aiming at extracting glacial lake objects from satellite images using a set of rules. Segmented objects are then classified either as glacial lake or non-glacial lake objects by the random forest classifier model. The method was tested in eight sites across alpine regions mainly located in High Mountain Asia but also in the Alps and the Andes. We show that the proposed method overcomes a majority of the aforementioned challenges to detect and delineate glacial lakes. The method performs efficiently irrespective of geographic, geologic, and climatic conditions of glacial lakes.
Keywords	Sentinel-1 ; Synthetic Aperture Radar ; Radar backscatter ; Sentinel-2 ; Normalised difference water index ; Image segmentation ; Physical geography ; GB3-5030 ; Science ; Q
Subject code	550
Language	English
Publishing date	2020-12-01T00:00:00Z
Publisher	Elsevier
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Glacial Lake Area Change and Potential Outburst Flood Hazard Assessment in the Bhutan Himalaya

Sonam Rinzin / Guoqing Zhang / Sonam Wangchuk

Frontiers in Earth Science, Vol

2021 Volume 9

Abstract: Against the background of climate change-induced glacier melting, numerous glacial lakes are formed across high mountain areas worldwide. Existing glacial lake inventories, chiefly created using Landsat satellite imagery, mainly relate to 1990 onwards ... ...

Abstract	Against the background of climate change-induced glacier melting, numerous glacial lakes are formed across high mountain areas worldwide. Existing glacial lake inventories, chiefly created using Landsat satellite imagery, mainly relate to 1990 onwards and relatively long (decadal) temporal scales. Moreover, there is a lack of robust information on the expansion and the GLOF hazard status of glacial lakes in the Bhutan Himalaya. We mapped Bhutanese glacial lakes from the 1960s to 2020, and used these data to determine their distribution patterns, expansion behavior, and GLOF hazard status. 2,187 glacial lakes (corresponding to 130.19 ± 2.09 km2) were mapped from high spatial resolution (1.82–7.62 m), Corona KH-4 images from the 1960s. Using the Sentinel-2 (10 m) and Sentinel-1 (20 m × 22 m), we mapped 2,553 (151.81 ± 7.76 km2), 2,566 (152.64 ± 7.83 km2), 2,572 (153.94 ± 7.83 km2), 2,569 (153.97 ± 7.79 km2) and 2,574 (156.63 ± 7.95 km2) glacial lakes in 2016, 2017, 2018, 2019 and 2020, respectively. The glacier-fed lakes were mainly present in the Phochu (22.63%) and the Kurichu (20.66%) basins. A total of 157 glacier-fed lakes have changed into non-glacier-fed lakes over the 60 years of lake evolution. Glacier-connected lakes (which constitutes 42.25% of the total glacier-fed lake) area growth accounted for 75.4% of the total expansion, reaffirming the dominant role of glacier-melt water in expanding glacial lakes. Between 2016 and 2020, 19 (4.82 km2) new glacial lakes were formed with an average annual expansion rate of 0.96 km2 per year. We identified 31 lakes with a very-high and 34 with high GLOF hazard levels. These very-high to high GLOF hazard lakes were primarily located in the Phochu, Kurichu, Drangmechu, and Mochu basins. We concluded that the increasing glacier melt is the main driver of glacial lake expansion. Our results imply that extending glacial lakes studies back to the 1960s provides new insights on glacial lake evolution from glacier-fed lakes to non-glacier-fed lakes. Additionally, we ...
Keywords	glacial lake mapping ; GLOF hazard potential ; Corona KH-4 ; Sentinel-2 ; Analytical Hierarchy Process (AHP) ; Bhutan Himalaya ; Science ; Q
Subject code	550
Language	English
Publishing date	2021-11-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Testing Positive for SARS-CoV-2 in Two Countries 105 Days Apart

Tshokey Tshokey / Jamyang Choden / Lila Adhikari / Binay Thapa / Sonam Wangchuk

Prague Medical Report, Vol 122, Iss 3, Pp 228-

2021 Volume 232

Abstract: Recovered COVID-19 patients may test positive for SARS-CoV-2 for a long time from intermittent shedding of viral fragments. A 36-year-old man who tested positive for SARS-CoV-2 in the Czech Republic and recovered tested positive again in Bhutan, 105 days ...

Abstract	Recovered COVID-19 patients may test positive for SARS-CoV-2 for a long time from intermittent shedding of viral fragments. A 36-year-old man who tested positive for SARS-CoV-2 in the Czech Republic and recovered tested positive again in Bhutan, 105 days beyond his first positive test. He experienced minimal symptoms and recovered without complications. Although no virological test was conducted to rule out reinfection, the repeat positive test after initial recovery likely resulted from prolonged shedding of dead viral particles than a reinfection.
Keywords	Medicine ; R ; Medicine (General) ; R5-920
Language	English
Publishing date	2021-10-01T00:00:00Z
Publisher	Karolinum Press
Document type	Article ; Online
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Article ; Online: Influence of Meteorological Conditions on Artificial Ice Reservoir (Icestupa) Evolution

Suryanarayanan Balasubramanian / Martin Hoelzle / Michael Lehning / Jordi Bolibar / Sonam Wangchuk / Johannes Oerlemans / Felix Keller

Frontiers in Earth Science, Vol

2022 Volume 9

Abstract: Since 2014, mountain communities in Ladakh, India have been constructing dozens of Artificial Ice Reservoirs (AIRs) by spraying water through fountain systems every winter. The meltwater from these structures is crucial to meet irrigation water demands ... ...

Abstract	Since 2014, mountain communities in Ladakh, India have been constructing dozens of Artificial Ice Reservoirs (AIRs) by spraying water through fountain systems every winter. The meltwater from these structures is crucial to meet irrigation water demands during spring. However, there is a large variability associated with this water supply due to the local weather influences at the chosen location. This study compared the ice volume evolution of an AIR built in Ladakh, India with two others built in Guttannen, Switzerland using a surface energy balance model. Model input consisted of meteorological data in conjunction with fountain discharge rate (mass input of an AIR). Model calibration and validation were completed using ice volume and surface area measurements taken from several drone surveys. The model was successful in estimating the observed ice volume evolution with a root mean square error within 18% of the maximum ice volume for all the AIRs. The location in Ladakh had a maximum ice volume four times larger compared to the Guttannen site. However, the corresponding water losses for all the AIRs were more than three-quarters of the total fountain discharge due to high fountain wastewater. Drier and colder locations in relatively cloud-free regions are expected to produce long-lasting AIRs with higher maximum ice volumes. This is a promising result for dry mountain regions, where AIR technology could provide a relatively affordable and sustainable strategy to mitigate climate change induced water stress.
Keywords	icestupa ; water storage ; climate change adaptation ; geoengineering ; energy balance (EB) model ; water resource management ; Science ; Q
Subject code	550
Language	English
Publishing date	2022-02-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: An Exemplary National COVID-19 Vaccination

Sangay Phuntsho / Tshokey Tshokey / Mongal Singh Gurung / Sonam Wangdi / Sonam Wangchuk

Tropical Medicine and Infectious Disease, Vol 7, Iss 7, p

Lessons from Bhutan

2022 Volume 131

Abstract: Vaccination remains a key public health intervention against the COVID-19 pandemic. However, vaccine distribution and coverage are variable between countries due to access and implementation issues. Vaccine inequity was evident with some countries having ...

Abstract	Vaccination remains a key public health intervention against the COVID-19 pandemic. However, vaccine distribution and coverage are variable between countries due to access and implementation issues. Vaccine inequity was evident with some countries having no access to the vaccines while others have initiated multiple booster doses. We share Bhutan’s approach to COVID-19 vaccination and lessons learned during the successful conduct of a nationwide vaccination program. As of 12 December 2021, 80.3% of the Bhutanese population have received at least one dose of COVID-19 vaccine and 77.0% have received at least two doses. Considering age groups, 97.2% of adults (18 years) have received at least one dose and 93.6% have received at least two doses. The first dose coverage for the adolescents 12–17 years was 99.7% and second dose coverage was 92.3% since some were not yet due for their second dose at the time of writing this report. The well-established existing national immunization program was especially useful in the implementation of the national COVID-19 vaccination program. The Bhutan Vaccine System, a digital platform for registration and monitoring of vaccination, was rapidly developed and extensively utilized during the campaign. The selfless leadership of the king, the government, and prior detailed planning with multi-sectoral collaboration and coordination, was the key in this exemplary vaccination program. Bhutan has successfully vaccinated children between 5–11 years with high coverage and no serious issues. Many adults have also received first and second booster doses, based on their risks and preferences.
Keywords	Bhutan ; COVID-19 ; vaccination program ; national campaign ; Medicine ; R
Subject code	070
Language	English
Publishing date	2022-07-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: A new species of Zographetus Watson, 1893 (Lepidoptera: Hesperiidae) from Sikkim, eastern Himalaya, India.

Karmakar, Tarun / Lepcha, Sonam Wangchuk / Basu, Dipendra Nath / Kunte, Krushnamegh

Zootaxa

2021 Volume 5072, Issue 4, Page(s) 373–379

Abstract: A new species, Zographetus dzonguensis sp. nov., is described based on three male specimens from Upper Dzongu, North Sikkim District, Sikkim, India. The new species is closely similar to Z. pangi from Guangdong and Z. hainanensis from Hainan, China, from ...

Abstract	A new species, Zographetus dzonguensis sp. nov., is described based on three male specimens from Upper Dzongu, North Sikkim District, Sikkim, India. The new species is closely similar to Z. pangi from Guangdong and Z. hainanensis from Hainan, China, from which it is distinguished based on the following combination of external characters: (a) forewing with the white spot at the base of space M3 being sharply pointed at the inner edge and conspicuously more elongated, and (b) on underside of hindwing, all chocolate-brown spots being smaller, in Z. dzonguensis sp. nov. compared with both Z. pangi and Z. hainanensis. In Z. dzonguensis sp. nov., the male genitalia may be distinguished as follows: (c) tegumen and uncus are almost equal in length, (d) the dorsal outline of tegumen is relatively flat, and (e) saccus is distinctly bent upward as angle between vinculum and saccus is more acute than in Z. pangi and Z. hainanensis.
MeSH term(s)	Animals ; Genitalia, Male ; India ; Lepidoptera ; Male ; Moths ; Sikkim
Language	English
Publishing date	2021-12-01
Publishing country	New Zealand
Document type	Journal Article
ISSN	1175-5334
ISSN (online)	1175-5334
DOI	10.11646/zootaxa.5072.4.4
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Surveillance of norovirus among children with diarrhea in four major hospitals in Bhutan

Sonam Wangchuk / Takashi Matsumoto / Hidekatsu Iha / Kamruddin Ahmed

PLoS ONE, Vol 12, Iss 9, p e

Replacement of GII.21 by GII.3 as a dominant genotype.

2017 Volume 0184826

Abstract: Diarrhea is a major cause of morbidity and mortality among Bhutanese children. The etiology of diarrhea is not well known due to the challenges of conducting routine surveillance with Bhutan's modest research facilities. Establishing an etiology is ... ...

Abstract	Diarrhea is a major cause of morbidity and mortality among Bhutanese children. The etiology of diarrhea is not well known due to the challenges of conducting routine surveillance with Bhutan's modest research facilities. Establishing an etiology is crucial toward generating evidence that will contribute to policy discussions on a diarrheal disease control program. Our previous study, during 2010-2012, revealed that norovirus (NoV) is an important cause of diarrhea among Bhutanese children, and that GII.21 was the major genotype circulating at that time. In other countries, GII.4 is the major genotype responsible for NoV infections. In this update report, we provide new prevalence data to describe the progression of the transformation and distribution of the NoV genotype among Bhutanese children.From June 2013 through May 2014, diarrheal stool samples were collected at one national referral hospital in Thimphu, two regional referral hospitals in the eastern and central regions, and one general hospital in the western region of Bhutan. NoV was detected by reverse transcription-polymerase chain reaction (RT-PCR), by amplifying the capsid gene. The RT-PCR results were confirmed by nucleotide sequencing of the amplicons.The proportion of NoV-positive stool samples was 23.6% (147/623), of which 76.9% were NoV GII and the remainders were NoV GI. The median age of infected children was 15.5 months, with a fairly balanced female: male ratio. NoV GII was most prevalent in the colder months (late November-mid April) and NoV GI had the highest prevalence in the summer (mid April-late September). Nucleotide sequencing was successful in 99 samples of GII strains. The most common genotypes were GII.3 (42.6%), GII.4 Sydney 2012 (15.8%), and GII.4 unassigned (11.9%). No GII.21 was found in any child in the present study. Phylogenetic analysis showed that GII.3 strains in the present study belonged to an independent cluster in lineage B. These strains shared an ancestor with those from different countries and Bhutanese strains ...
Keywords	Medicine ; R ; Science ; Q
Subject code	590
Language	English
Publishing date	2017-01-01T00:00:00Z
Publisher	Public Library of Science (PLoS)
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Epidemiological Analysis of the 2019 Dengue Epidemic in Bhutan

Tsheten Tsheten / Angus Mclure / Archie C. A. Clements / Darren J. Gray / Tenzin Wangdi / Sonam Wangchuk / Kinley Wangdi

International Journal of Environmental Research and Public Health, Vol 18, Iss 354, p

2021 Volume 354

Abstract: Bhutan experienced its largest and first nation-wide dengue epidemic in 2019. The cases in 2019 were greater than the total number of cases in all the previous years. This study aimed to characterize the spatiotemporal patterns and effective reproduction ...

Abstract	Bhutan experienced its largest and first nation-wide dengue epidemic in 2019. The cases in 2019 were greater than the total number of cases in all the previous years. This study aimed to characterize the spatiotemporal patterns and effective reproduction number of this explosive epidemic. Weekly notified dengue cases were extracted from the National Early Warning, Alert, Response and Surveillance (NEWARS) database to describe the spatial and temporal patterns of the epidemic. The time-varying, temperature-adjusted cohort effective reproduction number was estimated over the course of the epidemic. The dengue epidemic occurred between 29 April and 8 December 2019 over 32 weeks, and included 5935 cases. During the epidemic, dengue expanded from six to 44 subdistricts. The effective reproduction number was <3 for most of the epidemic period, except for a ≈1 month period of explosive growth, coinciding with the monsoon season and school vacations, when the effective reproduction number peaked >30 and after which the effective reproduction number declined steadily. Interventions were only initiated 6 weeks after the end of the period of explosive growth. This finding highlights the need to reinforce the national preparedness plan for outbreak response, and to enable the early detection of cases and timely response.
Keywords	dengue ; epidemic ; Bhutan ; dispersion ; transmissibility ; Medicine ; R
Subject code	612
Language	English
Publishing date	2021-01-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Policy or poverty trap? Attitude of goat farmers towards the conservation rule on goat rearing in Bhutan

Wangchuk, Kesang / Mindu á / Thukten á / Sonam Wangchuk

Pastoralism. 2016 Dec., v. 6, no. 1

2016

Abstract: The study objectives were to gather feedback and opinions of goat farmers on the Forest and Nature Conservation Rule on goat rearing in Bhutan and identify field constraints arising from the conservation rule. Focus group and individual farmer survey ... ...

Abstract	The study objectives were to gather feedback and opinions of goat farmers on the Forest and Nature Conservation Rule on goat rearing in Bhutan and identify field constraints arising from the conservation rule. Focus group and individual farmer survey methods were employed, and a semi-structured questionnaire was used to interview 180 goat farmers of six districts. All respondents were aware of the conservation rule. Majority of respondents knew goats as a threat to forest and crops. The vast majority of respondents felt that the conservation rule is not relevant in modern times, and all respondents felt the need to revise the rule. The main problem faced by farmers was difficulty in maintaining their goat numbers to four. The other problems faced were frequent conflicts with Forest personnel and restricted opportunities to earn more income. While the expected changes in the conservation rule included provisions to allow a farmer to rear more number of goats under stall-fed conditions, the additional rule suggested by farmers was allowing goats to browse freely in the forest. Majority of farmers reared goats under stall-fed conditions. The most common practice of managing goat populations was selling goats to fellow farmers. Despite the constraints, a majority of farmers expressed their willingness to continue goat rearing in the future, mainly to generate more income. The study findings suggest revision of the rule on goat rearing, with strong consideration of the needs of the modern farming system and growing economic demands. In revising the rule, the study recommends balanced representation from stakeholders and technical experts from both forest and livestock disciplines.
Keywords	attitudes and opinions ; browsing ; crops ; experts ; farmers ; forests ; goats ; human resources ; income ; issues and policy ; natural resources conservation ; poverty ; questionnaires ; rearing ; stakeholders ; surveys ; Bhutan
Language	English
Dates of publication	2016-12
Size	p. 19.
Publishing place	Springer Berlin Heidelberg
Document type	Article
ZDB-ID	2769408-2
ISSN	2041-7136
ISSN	2041-7136
DOI	10.1186/s13570-016-0066-9
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: A NOVEL STRAIN OF SHIGELLA SPECIES OUTBREAK IN A RESIDENTIAL SCHOOL IN PEMAGATSHEL, BHUTAN, 2012

Tsheten / Dorji Tshering / Kinley Gyem / Sangay Dorji / Sonam Wangchuk / Tri Hari Irfani / Letho

Public Health of Indonesia, Vol 2, Iss 4, Pp 165-

2016 Volume 171

Abstract: Background: A cluster of suspected shigellosis was reported from health center in Pemagatshel district to Royal Center for Disease Control on 14th May 2012. The investigation was done to determine the cause and risk factor for the outbreak so that ... ...

Abstract	Background: A cluster of suspected shigellosis was reported from health center in Pemagatshel district to Royal Center for Disease Control on 14th May 2012. The investigation was done to determine the cause and risk factor for the outbreak so that appropriate control and prevention measures can be implemented. Methods: A descriptive study was used for the outbreak investigation. The food items and drinks served to boarding students were collected from the mess in-charge in order to assess their risk for the outbreak. The kitchen and its premises were inspected to study the likely contamination by rodents and other animals. The water and stool specimens were tested in the laboratory to identify all possible enteric pathogens. Results: 82 boarding students were affected with an overall attack rate of 28% (82/294). Diarrhea was the predominant symptom followed by abdominal pain and headache. The onset date of the cases varied between 11th and 18th May, 2012. Shigella species was isolated from stool specimens that showed resistant to amoxicillin, nalidixic acid, chloramphenicol and sulfamethoxazole. Water specimen collected from source, distribution reservoir and tap water at school were found grossly contaminated. Conclusion: The outbreak was caused by novel strain of Shigella species which was not detected earlier in Bhutan. The promotion and provision of boiled water will greatly reduce the incidence of shigellosis especially in boarding facility.
Keywords	Shigellosis ; MDR-Shigella ; Boarding school ; Bhutan ; Medicine ; R ; Public aspects of medicine ; RA1-1270
Subject code	590
Language	English
Publishing date	2016-12-01T00:00:00Z
Publisher	YCAB Publisher
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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