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Glacial lake flood hazard assessment and modelling : a GIS perspective

Jawaid, Maimoona Zehra LU (2017) In Lund University GEM thesis series NGEM01 20171
Dept of Physical Geography and Ecosystem Science
Abstract
High mountain regions have experienced decreased glacier stability due to varying climate conditions. As glaciers melt, they are being replaced by glacial lakes of different sizes, some of which are prone to outburst flooding, and have caused catastrophic damage to downstream settlements and infrastructure. The study proposes a framework for a first stage hazard assessment of glacial lakes using GIS techniques and a digital elevation model. It introduces a new dynamic flow runoff model in a glacial lake hazard context. Based on a triangular form based multiple flow algorithm, the model is used to estimate flood magnitude and hazard degree.

The assessment is applied to the Pho Chu sub-basin in the Himalayan region, Bhutan. The results... (More)
High mountain regions have experienced decreased glacier stability due to varying climate conditions. As glaciers melt, they are being replaced by glacial lakes of different sizes, some of which are prone to outburst flooding, and have caused catastrophic damage to downstream settlements and infrastructure. The study proposes a framework for a first stage hazard assessment of glacial lakes using GIS techniques and a digital elevation model. It introduces a new dynamic flow runoff model in a glacial lake hazard context. Based on a triangular form based multiple flow algorithm, the model is used to estimate flood magnitude and hazard degree.

The assessment is applied to the Pho Chu sub-basin in the Himalayan region, Bhutan. The results show 6 lakes in the basin of area greater than 0.2 km2 and 6 of them classified as potentially hazardous by at least one hazard indicator. It is found that there could be different ways to determine moraine dam steepness and several spatial methods are attempted. The possibility of measuring moraine dimensions is limited by the digital elevation model’s resolution. The assessment method can be further improved by including a hazard indicator for rock avalanches. Flood routing from Raphstreng lake is modelled over a pilot area in the sub-basin to demonstrate the application, assuming partial lake drainage. The maximum flood depth reached during model run time of 300 minutes, mostly falls between 1 to 15 m. Spatially concentrated in the main river channel, the flood extent enters the first settlement area at about 140 minutes from the start time. Rating hazard degree, the results show that most of the inundated extent fell under the extremely hazardous category. Where flood data are available from post-flood field surveys, it is recommended that the model be validated. A useful aspect of implementing the dynamic model in the future is that analysis of flood arrival time with respect to different settlements and infrastructure can be carried out, as water depths in the study area are saved for each time step. (Less)
Popular Abstract
High mountain regions have experienced decreased glacier stability due to varying climate conditions. As glaciers melt, they are being replaced by glacial lakes of different sizes, some of which are prone to flooding, and have caused catastrophic damage to downstream settlements and infrastructure. As glacial lakes need to be monitored, a first stage assessment method applying GIS techniques is proposed. In case of remote mountain regions where field work is quite labor intensive, the study proposes a framework which uses spatial techniques and a digital elevation model, derived from satellite imagery. A new dynamic flood model in a glacial lake hazard context is introduced, which is used to estimate flood magnitude and hazard degree. Such... (More)
High mountain regions have experienced decreased glacier stability due to varying climate conditions. As glaciers melt, they are being replaced by glacial lakes of different sizes, some of which are prone to flooding, and have caused catastrophic damage to downstream settlements and infrastructure. As glacial lakes need to be monitored, a first stage assessment method applying GIS techniques is proposed. In case of remote mountain regions where field work is quite labor intensive, the study proposes a framework which uses spatial techniques and a digital elevation model, derived from satellite imagery. A new dynamic flood model in a glacial lake hazard context is introduced, which is used to estimate flood magnitude and hazard degree. Such a hydrological model has not been used before in a glacial lake hazard context, is more comprehensive than the single flow or multiple flow GIS based models and can be applied in any region. The hazard assessment is applied to the Pho Chu sub-basin in the Himalayan region, Bhutan. The results show 6 lakes in the basin of area greater than 0.2 km2 and 6 of them classified as potentially hazardous by at least one hazard indicator. Flood propagation from Raphstreng lake is modelled over a pilot area in the sub-basin to demonstrate the application. The maximum flood depths reached during model run time of 300 minutes, mostly fall between 1 to 15 m. Rating hazard degree, the results show that most of the inundated extent falls under the extremely hazardous category. Where flood data are available from post-flood field surveys, it is recommended that the model be validated. A useful aspect of implementing the dynamic model in the future is that analysis of flood arrival time with respect to different settlements and infrastructure can be carried out, as water depths in the study area are saved for each time step. The hazard assessment framework could be useful to policy makers and disaster risk reduction professionals who are working in managing natural hazards in mountain regions. (Less)
Please use this url to cite or link to this publication:
author
Jawaid, Maimoona Zehra LU
supervisor
organization
course
NGEM01 20171
year
type
H2 - Master's Degree (Two Years)
subject
keywords
moraine dammed lake, Himalayas, Bhutan, GIS, hazard assessment, dynamic flood model, glacial lake, Physical Geography, ecosystem analysis, digital elevation model, GEM
publication/series
Lund University GEM thesis series
report number
20
funder
Erasmus Mundus Programme
language
English
id
8914523
date added to LUP
2017-06-13 12:26:27
date last changed
2017-06-13 12:26:27
@misc{8914523,
  abstract     = {High mountain regions have experienced decreased glacier stability due to varying climate conditions. As glaciers melt, they are being replaced by glacial lakes of different sizes, some of which are prone to outburst flooding, and have caused catastrophic damage to downstream settlements and infrastructure. The study proposes a framework for a first stage hazard assessment of glacial lakes using GIS techniques and a digital elevation model. It introduces a new dynamic flow runoff model in a glacial lake hazard context. Based on a triangular form based multiple flow algorithm, the model is used to estimate flood magnitude and hazard degree. 

The assessment is applied to the Pho Chu sub-basin in the Himalayan region, Bhutan. The results show 6 lakes in the basin of area greater than 0.2 km2 and 6 of them classified as potentially hazardous by at least one hazard indicator. It is found that there could be different ways to determine moraine dam steepness and several spatial methods are attempted. The possibility of measuring moraine dimensions is limited by the digital elevation model’s resolution. The assessment method can be further improved by including a hazard indicator for rock avalanches. Flood routing from Raphstreng lake is modelled over a pilot area in the sub-basin to demonstrate the application, assuming partial lake drainage. The maximum flood depth reached during model run time of 300 minutes, mostly falls between 1 to 15 m. Spatially concentrated in the main river channel, the flood extent enters the first settlement area at about 140 minutes from the start time. Rating hazard degree, the results show that most of the inundated extent fell under the extremely hazardous category. Where flood data are available from post-flood field surveys, it is recommended that the model be validated. A useful aspect of implementing the dynamic model in the future is that analysis of flood arrival time with respect to different settlements and infrastructure can be carried out, as water depths in the study area are saved for each time step.},
  author       = {Jawaid, Maimoona Zehra},
  keyword      = {moraine dammed lake,Himalayas,Bhutan,GIS,hazard assessment,dynamic flood model,glacial lake,Physical Geography,ecosystem analysis,digital elevation model,GEM},
  language     = {eng},
  note         = {Student Paper},
  series       = {Lund University GEM thesis series},
  title        = {Glacial lake flood hazard assessment and modelling : a GIS perspective},
  year         = {2017},
}