TY - JOUR
T1 - Reconstructing historic Glacial Lake Outburst Floods through numerical modelling and geomorphological assessment
T2 - Extreme events in the Himalaya
AU - Westoby, Matthew John
AU - Glasser, Neil Franklin
AU - Hambrey, Michael John
AU - Brasington, James
AU - Reynolds, John M.
AU - Hassan, Mohamed A. A. M.
N1 - Westoby, M. J., Glasser, N. F., Hambrey, M. J., Brasington, J., Reynolds, J. M., Hassan, M. A. A. M. (2014). Reconstructing historic Glacial Lake Outburst Floods through numerical modelling and geomorphological assessment: Extreme events in the Himalaya. Earth Surface Processes and Landforms, 39 (12), 1675-1692.
PY - 2014/9/30
Y1 - 2014/9/30
N2 - Recession of high-mountain glaciers in response to climatic change frequently results in the development of moraine-dammed glacial lakes. Moraine dam failure is often accompanied by the release of large volumes of water and sediment, termed a Glacial Lake Outburst Flood (GLOF). Chukhung Glacier is a small (~3 km2) receding valley glacier in Mt. Everest (Sagarmatha) National Park, Nepal. Unlike many Himalayan glaciers, which possess a thick mantle of supraglacial debris, its surface is relatively clean. The glacier terminus has receded 1.3 km from its maximum Holocene position, and in doing so provided the space for an ice-contact moraine-dammed lake to develop. The lake had a maximum volume of 5.5 × 10−5 m3 and drained as a result of breaching of the terminal moraine. An estimated 1.3 × 105 m3 of material was removed from the terminal moraine during breach development. Numerical dam-breach modelling, implemented within a Generalised Likelihood Uncertainty Estimation (GLUE) framework, was used to investigate a range of moraine-dam failure scenarios. Reconstructed outflow peak discharges, including failure via overtopping and piping mechanisms, are in the range 146–2200 m3 s−1. Results from two-dimensional hydrodynamic GLOF modelling indicate that maximum local flow depths may have exceeded 9 m, with maximum flow velocities exceeding 20 m s−1 within 700 m of the breach. The floodwaters mobilised a significant amount of material, sourced mostly from the expanding breach, forming a 300 m long and 100 m wide debris fan originating at the breach exit. moraine-dam. These results also suggest that inundation of the entire floodplain may have been achieved within ten minutes of initial breach development, suggesting that debris fan development was rapid. We discuss the key glaciological and geomorphological factors that have determined the evolution of a hazardous moraine-dammed lake complex and the subsequent generation of a GLOF and its geomorphological impact. This article is protected by copyright. All rights reserved.
AB - Recession of high-mountain glaciers in response to climatic change frequently results in the development of moraine-dammed glacial lakes. Moraine dam failure is often accompanied by the release of large volumes of water and sediment, termed a Glacial Lake Outburst Flood (GLOF). Chukhung Glacier is a small (~3 km2) receding valley glacier in Mt. Everest (Sagarmatha) National Park, Nepal. Unlike many Himalayan glaciers, which possess a thick mantle of supraglacial debris, its surface is relatively clean. The glacier terminus has receded 1.3 km from its maximum Holocene position, and in doing so provided the space for an ice-contact moraine-dammed lake to develop. The lake had a maximum volume of 5.5 × 10−5 m3 and drained as a result of breaching of the terminal moraine. An estimated 1.3 × 105 m3 of material was removed from the terminal moraine during breach development. Numerical dam-breach modelling, implemented within a Generalised Likelihood Uncertainty Estimation (GLUE) framework, was used to investigate a range of moraine-dam failure scenarios. Reconstructed outflow peak discharges, including failure via overtopping and piping mechanisms, are in the range 146–2200 m3 s−1. Results from two-dimensional hydrodynamic GLOF modelling indicate that maximum local flow depths may have exceeded 9 m, with maximum flow velocities exceeding 20 m s−1 within 700 m of the breach. The floodwaters mobilised a significant amount of material, sourced mostly from the expanding breach, forming a 300 m long and 100 m wide debris fan originating at the breach exit. moraine-dam. These results also suggest that inundation of the entire floodplain may have been achieved within ten minutes of initial breach development, suggesting that debris fan development was rapid. We discuss the key glaciological and geomorphological factors that have determined the evolution of a hazardous moraine-dammed lake complex and the subsequent generation of a GLOF and its geomorphological impact. This article is protected by copyright. All rights reserved.
KW - Moraine-dam
KW - Glacial Lake Outburst Flood (GLOF)
KW - Structure-from-Motion
KW - dam-breach modelling
KW - hydrodynamic modelling
KW - DEBRIS-COVERED GLACIERS
KW - MOUNT EVEREST REGION
KW - STRUCTURE-FROM-MOTION
KW - MORAINE-DAMMED LAKES
KW - BRITISH-COLUMBIA
KW - CATASTROPHIC DRAINAGE
KW - NEPAL HIMALAYA
KW - IMJA GLACIER
KW - NEW-ZEALAND
KW - SEDIMENT TRANSPORT
UR - http://hdl.handle.net/2160/14077
U2 - 10.1002/esp.3617
DO - 10.1002/esp.3617
M3 - Article
SN - 0197-9337
VL - 39
SP - 1675
EP - 1692
JO - Earth Surface Processes and Landforms
JF - Earth Surface Processes and Landforms
IS - 12
ER -