Model Answer

Glacial lakes are bodies of water formed by the melting of glaciers. They typically occur at the foot of a glacier but can also form within, on, or under it. These lakes are commonly found at the edges of glaciers and ice sheets, and they are categorized into two types: ice contact lakes, where glacier ice meets lake water, and distal lakes, located further from the glacier but still influenced by it.

Factors Contributing to Glacial Lake Outburst Floods (GLOFs)

Glacial Lake Outburst Floods (GLOFs) happen when a glacial lake’s dam, often made of moraine or ice, suddenly bursts, releasing large amounts of water downstream. Several factors contribute to the occurrence of GLOFs:

1. Heavy Rainfall: Excessive rainfall, particularly in mountainous regions, can lead to the overfilling of glacial lakes, causing the moraine dams to breach.
2. Snowmelt: Global warming accelerates glacier melting, increasing the volume of water in glacial lakes, raising the risk of a breach.
3. Rapid Slope Movement: Landslides, avalanches, or rockfalls into the lake can exert pressure on the dam, triggering a breach.
4. Earthquakes: Seismic activity can destabilize slopes, leading to the collapse of moraine dams.
5. Anthropogenic Activities: Human activities like dam construction or infrastructure development can destabilize slopes, contributing to the risk of GLOFs.

Conclusion

These floods can cause catastrophic downstream damage, as seen in the 2013 Kedarnath disaster and Chamoli flash floods in 2021 (Source: NDMA).

Model Answer

Tsunamis are large, destructive waves typically triggered by underwater disturbances. The key factors responsible for their formation are:

1. Earthquakes: Most tsunamis are caused by underwater earthquakes, particularly those near tectonic plate boundaries. To generate a tsunami, the earthquake must be strong (magnitude ≥6.5), occur beneath the ocean, and involve vertical movement of the seafloor. These conditions can displace large volumes of water, creating waves that travel across the ocean.
2. Landslides: Coastal or underwater landslides can also displace water and generate tsunamis. When the mass of land or sediment rapidly shifts into the ocean, it disturbs the water, sending out waves.
3. Volcanic Eruptions: Violent volcanic eruptions, although less frequent, can displace enough water to trigger tsunamis, particularly when parts of the volcano collapse into the sea.
4. Extra-terrestrial Collisions: Though extremely rare, collisions with asteroids or meteors that strike the ocean could displace vast amounts of water and produce a tsunami.

Measures Taken by India to Mitigate Tsunami Impact

India has implemented several strategies to minimize the damage caused by tsunamis, focusing on early warning systems and disaster management:

1. Early Warning System: Managed by the Indian National Centre for Ocean Information Services (INCOIS), the system uses real-time data from sensors to monitor seismic and sea-level activity. When tsunami thresholds are reached, alerts are generated and disseminated to relevant authorities for prompt action.
2. National Disaster Management Authority (NDMA): The NDMA has developed Tsunami Risk Management Guidelines, which outline roles and responsibilities, emergency response protocols, and preparedness measures. These guidelines emphasize awareness, capacity building, and the involvement of local and national agencies in emergency response.
3. Coastal Protection Infrastructure: Measures like bio-fencing, repairs to coastal defences, and the construction of new sea walls are being implemented to protect vulnerable coastal areas.

Conclusion

Together, these steps are designed to reduce the vulnerability of coastal populations and infrastructure to tsunami hazards.

Model Answer

Footloose Industries

Footloose industries are those that are not bound to any specific location and can be established anywhere, regardless of the availability of raw materials. Examples include information technology (IT), software development, and consulting services. These industries typically rely on a highly skilled workforce, are not heavy on raw materials, and have minimal environmental impact.

Factors Influencing the Location of Footloose Industries

1. Access to Skilled Labor: Footloose industries require a highly educated and skilled workforce. For example, the IT industry in India is concentrated in cities like Bangalore and Hyderabad, which have large pools of skilled professionals.
2. Infrastructure: Availability of communication networks, reliable power, water, and technology is crucial for these industries.
3. Cost of Living and Business: Locations with lower living and operating costs attract these industries, helping reduce overall expenses.
4. Government Incentives: Tax breaks, subsidies, and grants can encourage industries to set up operations.
5. Quality of Life: Good living standards and amenities help attract talent to such locations.
6. Transportation: Good transportation links facilitate global connectivity with clients and suppliers.

By focusing on these factors, footloose industries can thrive even in areas without traditional locational advantages.

Model Answer

Land Subsidence

Land subsidence refers to the gradual sinking or sudden collapse of the earth’s surface due to the removal or displacement of subsurface materials. It can occur naturally due to earthquakes, erosion, or sinkholes, or as a result of human activities like groundwater extraction, mining, and infrastructure development.

Factors Contributing to Subsidence in Joshimath, Uttarakhand

In Joshimath, land subsidence is attributed to both natural and anthropogenic factors:

• Built on Ancient Landslide Material: Joshimath is situated on loose sand and stone deposits from an ancient landslide, which lack high load-bearing capacity, making the region vulnerable to subsidence under increasing infrastructure and population pressure.
• Geographic Faults: The region is located along a tectonic fault line where the Indian Plate subducts under the Eurasian Plate, contributing to instability.
• Extreme Weather: Frequent heavy rainfall causes erosion and exacerbates landslides, as seen during the 2013 and 2021 floods.
• Hydroelectric Projects: Construction activities, including tunneling for hydropower projects, have disrupted aquifers, contributing to land subsidence.
• Unplanned Construction: Lack of proper drainage systems and unregulated construction has further aggravated the problem (Source: Indian Institute of Remote Sensing, M.C. Mishra Committee).

Model Answer

Heat Budget of the Earth

The heat budget of the Earth refers to the balance between the amount of solar energy the Earth receives and the amount it radiates back into space. This balance is crucial for maintaining the Earth’s average temperature. Of the 100 units of solar radiation received from the Sun, 35 units are reflected back into space by Earth’s albedo, and the remaining 65 units are absorbed—14 units by the atmosphere and 51 units by the Earth’s surface. The Earth then radiates 51 units of energy back into space in the form of terrestrial radiation. Of this, 17 units are directly radiated into space, while the remaining 34 units are absorbed by the atmosphere and later radiated back into space. This cycle ensures that the incoming and outgoing radiation balance at 65 units, maintaining a stable temperature.

Factors Influencing Temperature Distribution

1. Latitude: The closer a region is to the equator, the more direct sunlight it receives, leading to higher temperatures. Conversely, areas near the poles receive more diffuse sunlight and have lower temperatures.
2. Altitude: Higher altitudes are cooler because the atmosphere at higher elevations is thinner and less able to absorb and retain heat.
3. Continentality: Land heats up and cools down more quickly than water. Thus, coastal areas have milder temperatures, while inland areas experience greater temperature fluctuations.
4. Air-mass and Ocean Currents: Warm air masses and ocean currents raise temperatures, while cold currents and air masses lower them.
5. Other Factors: Winds, soil type, surface slope, and aspect also play significant roles. For example, dark soils absorb more heat, affecting local temperatures.

Conclusion

Understanding the heat budget is essential in grasping Earth’s climate system, although human-induced changes, like global warming, threaten to disrupt this balance.