Unit 6

Question 1

What is a GLOF?

Answer 1

Glacial Lake Outburst Flood
• can occur when a terminal/recessional moraine acts as a dam for glacial melt-water
• behind the moraine a pro-glacial lake will develop
• if the lake overtops the dam or the dam gives way a torrent of floodwater and rock debris will cascade down valley

Question 2

What causes GLOFs?

Answer 2

Potential triggers wave generation:
• Contact glacier calving
• Icefall from hanging glaciers
• Rapid input of meltwater
• Seismic activity

Conditioning factors for dam failure:
• Large lake volume
• Melting of buried ice in moraine structure
• Seismic activity

Question 3

What happened at Lake Thorthormi, Bhutan?

Answer 3

Lake lowering strategy, increasing moraines and diverting lakes to stop chance of mega lake being created.

Question 4

Impacts of GLOFs?

Answer 4

• Job losses
• Infrastructure destroyed
• Loss of life
• Road systems destroyed

Question 5

What is a reservoir?

Answer 5

Large natural or artificial lake used as a source or water supply

Question 6

What are sands and gravels quarried for?

Answer 6

• Road construction
• Production of construction materials
• Grit salt for icy roads in winter
• Water filtration
• Glass making

Question 7

Negatives of sand and gravel extraction?

Answer 7

• Reduction in potential material
• Natural reservations and farmland destroyed
• Dust - may lead to health issues

• Locals upset
• More traffic (HGVs)
• Noise pollution