Geography related articles in News

News- Recently, heavy rain and strong winds lashed Delhi and nearby areas, causing waterlogging and flight delays at the airport. The weather was triggered by a fresh Western Disturbance over northern India.

About Western Disturbances

• Definition– Western Disturbances are eastward-moving, extra-tropical weather systems that bring sudden winter rainfall to the northwestern parts of the Indian subcontinent.These disturbances originate beyond Iran and Afghanistan and travel across these countries, as well as Pakistan, before reaching India.
• Origin and Characteristics:
  • They are driven by low-pressure systems that form due to the interaction of polar and tropical air masses.
  • These systems pick up moisture from the Mediterranean Sea, Black Sea, Caspian Sea, and occasionally the Arabian Sea.
  • They are embedded in the Subtropical Westerly Jet Stream (STWJ), which flows from west to east at high altitudes over the Himalayas and Tibetan Plateau.
• Seasonal occurrence: Most active during the boreal winter months (December to March), but can also affect weather patterns during the pre-monsoon and post-monsoon periods.
• Geographical impact:
  • Affect weather in northwestern India, northern Pakistan, parts of Afghanistan, and Tajikistan.
  • In India, they bring winter rainfall to states like Punjab, Haryana, Rajasthan, Himachal Pradesh, Uttarakhand, and parts of Uttar Pradesh.
  • Often responsible for snowfall in the Himalayas and cold wave conditions in the plains.
• Importance for Agriculture:
  • Beneficial for Rabi crops, especially wheat, by providing much-needed winter rainfall.
  • However, excessive rainfall or untimely storms can damage standing crops and disrupt normal life

News: A growing number of sizable companies, from mining giants to energy majors, are embracing the hype for natural hydrogen.

About Natural Hydrogen

• It refers to hydrogen gas that is generated and found naturally in the earth’s crust or atmosphere, rather than being produced artificially through industrial processes.
• It is also called white/gold/geological hydrogen, to distinguish it from “green” (from renewables), “blue” (from natural gas with carbon capture), or “grey” (from fossil fuels) hydrogen.

• Production: It is produced by processes such as –
  • Serpentinisation – It is a geological process where ultramafic rocks are altered by water and heat, transforming them into serpentinite. This process also releases hydrogen gas.
  • Radiolysis of water by radioactive rocks
  • From organic matter at depth.
• Current reserves: The total size of worldwide natural hydrogen reserves is still poorly known because of a lack of concentrated exploration. But still some of the Hydrogen reserves catalogued globally include-
  • Australia (Eyre Peninsula and Kangaroo Island),
  • United States (Kansas, Nebraska)
  • France (Lorraine region)
  • Spain, Albania, Colombia, South Korea, and Canada
  • Mosselle region: A massive 46-million-ton natural hydrogen reserve discovered here. It is a river valley spanning north-eastern France, south-western Germany, and eastern Luxembourg.
• In India: The natural hydrogen potential is quite promising because of the existence of –
  • Favourable geological structures like hard rock formations of diverse ultramafic/mafic and basaltic assemblages
  • Andaman and Himalayan ophiolite complexes
  • Greenstone volcanic-sedimentary sequences in cratons (Dharwar, Singhbhum)
  • Sedimentary basis (for example, in Vindhyan, Cuddapah, Gondwana and Chhattisgarh)
  • Basement rocks with fractures
  • Areas with active hydrothermal systems e.g. hot springs.

News: India raises continental-shelf claim in Arabian Sea region by nearly 10,000 square km.

About Continental Shelf

The ocean floors can be divided into four major divisions: (i) Continental Shelf; (ii) Continental Slope; (iii) Deep Sea Plain; (iv) Oceanic Deeps. Besides, these divisions there are also major and minor relief features in the ocean floors like ridges, hills, sea mounts, guyots, trenches, canyons, etc.

Continental Shelf

• It is the extended margin of each continent occupied by relatively shallow seas and gulfs.
• It is the shallowest part of the ocean showing an average gradient of 1° or even less.
• Shelf break: The shelf typically ends at a very steep slope, called the shelf break.
• Continental slope: From the break, the shelf descends toward the deep ocean floor in what is called the continental slope.
• Width: The width of the continental shelves varies from one ocean to another. The average width of continental shelves is about 80 km.
  • Narrow shelves: The shelves are almost absent or very narrow along some of the margins like the coasts of Chile, the west coast of Sumatra, etc.
  • Wide shelves: On the contrary, the Siberian shelf in the Arctic Ocean, the largest in the world, stretches to 1,500 km in width.
• Depth: The depth of the shelves also varies. It may be as shallow as 30 m in some areas while in some areas it is as deep as 600 m.
• Sediment deposition: They are covered with variable thicknesses of sediments brought down by rivers, glaciers, wind, from the land and distributed by waves and currents, becoming the source of fossil fuels.

Legal aspects

• UNCLOS definition: Under the United Nations Convention on the Law of the Sea (UNCLOS), the continental shelf is the seabed and subsoil extending up to 200 nautical miles from a coastal state’s baseline or further if the natural margin extends beyond this limit.
• Sovereign rights: Coastal nations have exclusive rights to explore and exploit resources on their continental shelf.
• Extended Continental Shelf (ECS): Countries can claim beyond 200 nautical miles if they can prove the natural prolongation of their landmass, as India has done in the Arabian Sea and Bay of Bengal.

News: The Cosmology Education and Research Training Center (COSMOS), Mysuru, of the Indian Institute of Astrophysics observed ‘Zero Shadow Day’ recently. Zero Shadow Day (ZSD).

About Zero Shadow Day (ZSD)

• ZSD is a fascinating astronomical phenomenon that occurs twice a year in locations situated between the Tropic of Cancer and the Tropic of Capricorn.
• All places whose latitude equals the angle between the Sun’s location and the equator on that day experience ZSD.
• This event is a direct result of the Earth’s axial tilt (23.5 degrees) and revolution around the Sun.
• Frequency of phenomenon:
  • First time when the Sun is directly overhead the Tropic of Cancer on 21 June (summer solstice in the northern hemisphere) and then journeys southwards as seen from the Earth, called Dakshinayana.
  • Second time when the Sun is overhead the Tropic of Capricorn on 22 December. It is then seen to journey northwards, called Uttarayana.
  • Hence, the Sun is directly overhead locations between the two tropics twice a year, and this day varies with latitude.
  • When the Sun is directly overhead, the shadow of a vertical object falls under it, and hence no shadow will be seen at local noon.
• Although the exact moment of Zero Shadow occurs instantaneously, the effect can be observed for a short duration, typically lasting for about a minute to a minute-and-a-half.

News- Due to extreme heat, the Krishna River has dried up earlier than expected, significantly disrupting irrigation in Karnataka’s Bagalkot, Vijayapura, and Yadgir districts.

About Krishna river

• Origin: The Krishna River originates near Mahabaleshwar in the Western Ghats, located in Satara district, Maharashtra.
• It is India’s third-longest river, following the Ganges and Godavari.
• In terms of water inflows and basin area, it ranks as the fourth-largest river in India, after the Ganges, Indus, and Godavari.
• The Krishna River basin spans across the states of Maharashtra, Karnataka, Telangana, and Andhra Pradesh.
• Left Bank tributaries – Bhima, Dindi, Peddavagu, Musi, Paleru, Munneru.
• Right Bank tributaries – Kudali (Niranjna) Venna, Koyna, Panchganga, Dudhaganga, Ghataprabha, Malaprabha and Tungabhadra (largest tributary).
• Key projects– The key projects on the Krishna River include Tungabhadra, Srisailam, Nagarjuna Sagar, and Prakasam Barrage, all of which are crucial for irrigation and hydroelectric power generation.

News- China has accused the Philippines of an intrusion into the disputed waters of Scarborough Shoal in the South China Sea (SCS).

About Scarborough Shoal

• It is the largest atoll in the South China Sea, situated about 220 km west of the Philippines.
• While it lies within the Exclusive Economic Zone (EEZ) of the Philippines, it has been claimed by China as part of its ancestral territory, citing the nine-dash line since the 13th century.
• Marine Significance: The area is known for its rich marine life, including commercially valuable species like shellfish and sea cucumbers, making it a productive fishing ground.

Other Disputed Islands in the South China Sea: Paracel Islands and Spratly Islands are other key areas of dispute in the region.

News- After two years of brutal civil war, Sudan’s Tuti Island has been retaken by the national army, but it remains ravaged and largely abandoned. Tuti Island

About Tuti Island

• Location– It is located at the confluence of the Blue and White Niles in Khartoum, Sudan.
• Bordering urban centres– It is surrounded by the “Three Towns”: Khartoum (Sudan’s capital), Omdurman (the country’s largest city), and Khartoum North (also called Bahri, a major industrial area).
• Significance:
  • The island covers 8 square kilometres and was traditionally known for farming and fishing, earning it the nickname “Khartoum’s garden.”
  • It is culturally important to the Mahas community, who settled there in the 15th century, making it a symbol of local identity and sustainable living.
• Flood management system– Due to its location, Tuti has always been susceptible to floods.  In response to increasing flood events, the community developed its own flood management system- The Taya system.
  • The HEART project (Heritage Empowered Action for Risk in Tuti) was launched to preserve the Taya system’s knowledge.

About Sudan

News: The Ramgarh Dam near Jaipur, which once served as a crucial source of water for the Rajasthan capital, is currently undergoing a survey to identify and remove encroachments and obstructions in its catchment area. Ramgarh Lake.

About Ramgarh Lake

• It is a man-made water body located near Jamwa Ramgarh, approximately 30 kilometers from Jaipur in Rajasthan, India.
• It hosted the rowing events during the 1982 Asian Games, underlining its prominence in Indian sports history.
• The lake last received water in 1999 and has remained dry since the year 2000.
• Due to the rich biodiversity in the area, the Government of India declared it a Wildlife Sanctuary in 1982.
• Historical Significance: Ramgarh was once a royal hunting ground for the Maharajas of Jaipur. The region has since evolved into a heritage site with significant cultural importance.
• Another major attraction near the lake is the shrine of Jamwa Mata, situated downhill from the lake. This temple was established by Rao Dulherao of the Kachhwaha clan of Jaipur.

News: Ministry of Shipping grants first digital NOC for jetty development on National Waterway-68 along River Mandovi in Goa.

About Mandovi River

• The Mandovi River (also known as Mahadayi or Mhadei) is one of the main West Flowing Rivers of Goa State. Alongside the Zuari River, it is one of the two principal rivers in the state, playing a crucial role in its ecology and economy.
• Origin: It rises at Bhimgad in the Western Ghats of Belgavi district in Karnataka state.
• River course: It travels 35 km in Karnataka; 82 km in Goa and 1 km in Maharashtra before joining the Arabian Sea at Panji (North-Goa).
• Tributaries: The important tributaries of Mandovi River are Kalasa Nala, Banduri Nala, Surla Nala, Haltar Nala, Singar Nala, Doli Nala, Kotni Nala, Irti Nala, Bail Nadi, Pansheer Nala, Madhuhalla Nala.
• Some Interesting Facts:
  • Dudhsagar Falls and Vajrapoha Falls: These prominent waterfalls are located on this river.
  • The Atal Setu (Third Mandovi Bridge), inaugurated in 2019, is the largest bridge in Goa.
  • The Salim Ali Bird Sanctuary is located on the island of Chorao in the Mandovi river.
  • National Waterway-68 is part of Mandovi River.

News: NGT orders the authorities to prevent illegal mining in Aravali land protected under Nicobar swap. Aravalli Range.

About Aravalli Range

• It is a mountain range in northern-western India, running approximately 670 km in a south-west direction.
• It is one of the oldest fold mountain in the world.
• It starts from near Delhi, passing through southern Haryana, Rajasthan and ending in Gujarat.
• It is divided into two sections: The Sambhar-Sirohi ranges, taller and including Guru Shikhar; and the Sambhar-Khetri ranges, consisting of three ridges that are discontinuous.
• Formation: The Aravalli Range is one of the oldest geological features on Earth having its origin in the Proterozoic era through tectonic plate collisions that led to the formation of the Aravalli-Delhi orogenic belt.
• Highest peak: The highest peak is Guru Shikhar on Mount Abu at 1,722 m (5,650 feet).
• Rivers: It gives rise to several rivers, including the Banas, Luni, Sakhi, Sahibi and Sabarmati.