daene mckinney: mitigation at imja lake 6(150ppi)
DESCRIPTION
Slides to Daene McKinney's presentation to HiMAP in Huaraz, Peru on 14 July 2013.TRANSCRIPT
Mitigation Strategies for Risk Reduction at Imja lake, Nepal
Daene C. McKinneyUniversity of Texas at Austin
Khumbu RegionNepal Himalaya
Nepal
1956
2012
Imja Lake
Imja Glacier
Photos Courtesy of Alton Byers
Sept2011
Sept2012
Imja LakeTerminal Moraine Lake Glacier
Imja Glacier GPR Transect
North
SouthImja Glacier
Imja Lake
Imja Glacier GPR Transect
Ice
Bedrock
SouthNorth
~220 m
Bottom of Ice in Outlet Area
Background image Source: Google Earth 19 February 2010Interpreted from GPR results assuming velocity = 124x106 m/s
Imja Lake Bathymetric Survey
Bathymetric Survey - Results
105
110100
80
60
40
20
10
5
Outlet
Lake
Interpolated values
IcebergCover
Bathymetric Survey - ResultsArea(km2)
Average Depth
(m)
Maximum Depth
(m)
Volume(106 m3)
Potential GLOF Water
(106 m3)
1992 0.60 47.0 98.5 28.0 152002 0.86 41.6 90.5 35.8 212012 1.21 52.6 116 63.8 34
19922002
2012
Potential GLOF Water
Ice
Glacier
LakeOutlet
Rock/Ice?
Rock
Rock
Rock
Zone A Zone B
Conceptual Model of Imja Lake
Potential GLOF Water
Imja Lake GLOF ModelingTerminal Moraine Lake Glacier
HEC-RAS Unsteady ModelPiping/Seepage triggerPeak outflow = 10,000 m3/sImpact at:Dingboche = 8.4 kmPhakding = 33.6 km
What Is Risk?
Dingboche
Imja Lake
Risk Reduction Alternatives: a. Lower lake (3 m, 10 m, 20 m, …)
b. Add downstream dam
Risk: Communities want to be safe, i.e., not flooded
GLOF Stage and Discharge at Dingboche
Time breach peak and Dingboche peak = 20 minutes
15.2 m
Ice
Glacier
Lake
Rock
Rock
Rock
Zone A Zone B
Siphons to Drain Then Excavate
Point 1 (surface level)
Point 2 (top)
Point 3 (outlet)
Siphon
Downstream Dam
60 m
Trail to Dingboche
Imja Khola
Possible Dam
Scenarios
•Lake lowering: 0, 3, 10 and 20 m•Dams: 20, 40, or 60 m
60 m Dam
FeasibleFeasible
Feasible
40 m Dam
20 m Dam
No Dam
GLOF Risk Reduction Scenarios
Community Consultation at Imja
Thank You!