Unit 6 Glaciated Landscapes

KEY TEME ONE:

• impacts of glacial processes and landforms on human activity- GLOFs, Impacts and Management

what is a GLOF?

• a glof can occur where a terminal/recessional moraine acts as a dam for glacial meltwater

• behind the moraine a pro-glacial lake will develop

• if the lake overtops the dam or the dam fails, a torrent of floodwater and rock debris will cascade down the valley

examples of areas that are at risk to GLOFS?

Iceland

Himalayas

European Alps

What are the two causes of GLOFs?

1. potential triggers to wave generation

2. damn failure

what are triggers to wave generation?

• rapid input of meltwater (more volume of water will lead to a greater wave generation)

• contact glacier calving (large block of ice falling into lake, displaces a large volume of water and generates waves which will over top the dam)

triggers to dam failure?

• large lake volume and low point in dam wall

• seismic activity (subglacial volcanoes can create an influx of meltwater which can over top the dam)

• melting of buried ice within the moraine (this will destabilise the dam and make it more likely to fail)

what are the common stages of a GLOF?

1. formation of displacement waves in the lake

2. breach of dam/dam failure

3. resultant flood wave down valley

why is climate change leading to an increased frequency of GLOFs?

• this is because as the ice mass or zone of ablation increases, there will be an increased volume of meltwater which means larger volumes of meltwater= larger wave generation and overflowing

CASE STUDY: GLOFs IN BHUTAN, LAKE THORTHORMI

• What is the location of Lake Thorthormi and why is this important?

Lake thorthormi is a particular threat as it is made up of numerous supraglacial lakes that have enlarged and become connected

small, mountainous underdeveloped kingdom in the eastern HImalayas

what are the potential impacts if it were to burst?

• three major hydro power projects could be destroyed

• 117 buildings affected

• 362 people affected

• 15 historia monuments affected

• 53 million cubic metres of water would be released

• 5.22km of road destroyed

IMPACTS AND MANAGEMENT OF GLOFs IN BHUTAN:

How have glacial meltwaters in the area benefitted the people who live in the local area?

• irrigation

• hydroelectricity

• what were the socio economic impacts from the 1994 lugge tsho GLOF which devastated the village of Punakha?

killed 24 people

killed livestock

high increase in homelessness

destruction of homes

MANAGEMENT STRATEGY: LKE LOWERING OF LAKE THORTHORMI

what is the aim of the strategy?

to stop the lake from overflowing and flooding the kingdom of Bhutan

what were th socioeconomic benefits of the strategy?

• >150,000 dollars distributed to people

• creates jobs

• uses expertise of the locals

• ‘high’ paying jobs compared to national average

EVAL: to what extent has the strategy worked? what factors have hindered the progress?

• getting to the site was challenging

• machinery isn’t able to be used

• time restrictions- site could only be reached a few times a year

• people suffered from altitude sickness

HOWEVER,

• in 2011, 3.63m of water was decreased

ESSAY PLAN: Examine the strengths and weaknesses of one strategy used to manage glacial environments

INTRODUCTION:

• introduce strategy= lake lowering

• identify the aim of lake lowering

• introduce case study, lake thorthormi in Bhutan

MAIN BODY:

structure it as strengths v weaknesses

STRENGTHS:

• Created employment opportunities for people (economic)

• >150,000 dollars distributed, which is 3x the national avg wage (economic)

• 3.63m of water lowered

• uses expertise of the locals

however,

WEAKNESSES

• Energy and time consuming (social)

• no machinery can be used due to its location

• time restrictions (lake can only be accessed a couple times a year (social)

• people suffered from altitude sickness

CONCLUSION,

the weaknesses of the strategy are more social, as it affects the people more. the strengths outweighs the weakness due to the aim of the projected being achieved and the economic benefits of the scheme. therefore it can be said that the strengths are greater

KEY THEME 2: impacts of human activity on glacial processes and landforms/landscapes

construction of reservoirs: what is a reservoir?

a large natural or artificial lake used as a source of water supply

why are glacial troughs ideal sites for constructing dams and reservoirs?

because they can collect water and have steep sides which can help create reservoirs by damning.

also they normally have impermeable underlying geology so the water cant infiltrate and percolate downwards

socio-economic arguments for reservoir construction in upland glaciated areas

• provide water and power

• ensure water is available during drought periods

• provide water for HEP generation

• used for recreation and conservation

envrironemntal arguments for reservoir construction

• provision of clean water

• enhances quality of local environment e.g. fishing, sailing

socio economic arguments against reservoir construction

• relocation of people living in the area

• require significant funding

environmental arguments against reservoir construction

• require large amounts of land

• micro climatic changes my occur through varying humidity= affect crops and biodiversity

• inhibit migratory fish movements

• inhibit navigation

CASE STUDY: THE ELAN VALLEY RESERVOIRS, WALES

background information?

• aim was to provide a source of clean, safe water for growing population and manufacturing industries

• The Elan and Claerwan rivers were damed to create the resevoirs

• location was chosen due to high levels of orographic rainfall (1800mm annually)

• 80% of the valley is a designated environmentally protected area

Why was the Elan Valley a good location?

• narrow valleys were easy to dam, and the impermeable bedrock in the area impedes infiltration, allowing large amounts of water to collect

• higher altitude which means water travels by gravity alone.

What were the impacts of creating the reservoir?

• dams provide HEP to the surrounding areas through the use of 5 water turbines

• 100 people were displaced due to the construction of the dam and flooding of the land, with many recieiving no compensation

• wildlife conservation

• two churches and a school were flooded along with 18 farms

THE EXTRACTION OF SANDS AND GRAVELS:

Wat do outwash plains often contain?

thick deposits of fluvio-glacial sands and gravels

what are sand and gravel used for?

• road construction

• production of construction materials

• icy roads for winter

• glass making

CASE STUDY: GLACIAL SAND AND GRAVEL EXTRACTION, WOOD LANE, ELLESMERE, SHROPSHIRE

background info:

glacial sand and gravel occurs extensively in the northern half of the country and is quarried at Wood Lane, Ellesmere located 15km north of Shrewsbury

what are the negative impacts of sand and gravel extraction in Ellesmere

• environmental degradation

• habitat destruction

• destruction of the natural outlook of the land

What are the positive impacts of sand and gravel extraction in Ellesmere?

• supplies over 2 million tonnes of vital aggregates, providing over a third of Warwickshire’s needs

• Prevention of dust generation

• Wasperton is surrounded by a 4- metre high green embankment to protect the view and noise and dust escaping

• creation of space for nature (10% minimum is reserved for nature)

THEME 3: PERMAFROST DEGRADATION THROUGH HUMAN ACTIVITY

what are human activities doing to the active layer?

increasing the rates of thawing which creates various issues

what human activities cause melting of permafrost and how can these be managed?

DIRECT CAUSES:

1. Buildings and infrastructure

• in cold climates, humans need to heat their homes/ buildings. however, the heat from the buildings can transfer from the buildings into the ground, melting the permafrost. This will cause buildings to sink

MANAGEMENT:

• Building houses on foundations to stop heat from transferring to the ground

• costs of thaw-related damage to structures and infrastructure have been estimated at about £35 million per year

2. The Trans-Alaskan Pipeline- how has this caused melting of permafrost?

• warm oil in the pipe may cause melting of permafrost around it

how was the Trans-Alaskan Pipeline managed?

• 400 miles of pipeline were elevated on piles to keep the ground frozen.

• additional cost of $800 million

• however, breaks in the pipeline and other repair costs due to melting permafrost could become even more significant in the future. ($2 million per mile)

IDNDIRECT CAUSES: CLIMATE CHANGE

impacts and management of melting permafrost in Siberia

key information?

• vast areas are now thawing

• rising temps= melting of permafrost

• mounds, hollows and depressions left in the lands

• Entire town built on permafrost

what are the impacts of melting permafrost in Siberia?

less pasture land

accessibility troubles

ground fallen away leaves abandoned aiport runaway

climate is affected

what is the management of permafrost degradation in Siberia?

• scraps of wood used to plug permafrost ponds = scrap wood insulates permafrost

• the houses are built on stilts to avoid the sinking feeling of the ground subsiding

INDIRECT: Anthropogenic climate change and permafrost degradation

how has anthropogenic climate chnage led to permafrost degradation?

• due to cold temps, organic matter in permafrost regions dont decay

• as global warming increases global temperatures (1.2 degrees) has led to tundra regions hving a more intense temp rise of 4 degrees which results in permafrost melting

• remains of dead organic matter are exposed to higher air temps and start to decay which releases methane and CO2

• permafrost could shift 500km north in regions such as Alaska

What is the positive feedback loop of permafrost melting?

1. temps in tundra regions increased by 4 degrees since 1880

2. remains of plants start to decompose due to melting of permafrost and exposure to heat

3. releases methane and CO2

4. methane is 23x more potent than CO2 and leads to global warming