3. Physiography and Drainage

(a) Differentiate between the physiography of Brazil and India.

(b) What measures are being taken to control pollution in the rivers of India?

(c) Explain the characteristics of the North Indian Plains.

• Location and Extent: This division lies between the Himalayan Mountains in the north and the Peninsula in the south. It extends from Rajasthan and Punjab in the west to Assam in the east.
• Topography: It is mostly a flat, low-lying area and is divided into two main parts.
• Eastern Part (Ganga Plains): The part lying to the east of the Aravalis is the basin of the river Ganga, which slopes eastward. It includes the Sunderbans delta in West Bengal and Bangladesh, considered the world's largest delta.
• Western Part: The western part is largely occupied by the Thar Desert (Marusthali) in Rajasthan. To the north of this desert lie the fertile plains of Punjab, formed by the depositional work of the river Sutlej and its tributaries, which slope towards the west.

(d) What could be the reasons behind the formation of swamps in the extensive continental location of Pantanal?

• The Pantanal is located towards the southwestern part of the Brazilian highland areas, acting as a transition zone.
• It forms the source region for the Paraguay and Parana rivers, receiving significant water flow.
• The region experiences a gentle slope and lies in a basin-like depression, which restricts rapid drainage of water.
• Due to seasonal heavy rainfall and the inability of the flat terrain to drain water quickly, the area becomes waterlogged, resulting in one of the largest wetlands and swamps in the world.

(e) Which are the major water divides of India? Explain by giving examples.

A water divide is an elevated area, such as a mountain or plateau, that separates two distinct drainage basins. The major water divides in India are:

• The Western Ghats: They form a major water divide in the Indian Peninsula, separating the west-flowing rivers (like Narmada, Tapi, and short coastal rivers) that meet the Arabian Sea from the east-flowing rivers (like Godavari, Krishna, and Kaveri) that meet the Bay of Bengal.
• The Aravali Ranges: They act as a water divide between the river systems flowing into the Gulf of Khambhat/Arabian Sea (like Luni and Sabarmati) and the Ganga river system flowing eastward.
• The Vindhyas and Satpudas: These central ranges divide the Ganga river basin in the north from the Narmada and Tapi river basins flowing westwards through rift valleys in the central peninsula.

(a) Amazon River basin

• The Amazon River basin is the largest plain land in Brazil, lying between the Guyana Highlands in the north and the Brazilian Highlands in the south.
• It is quite wide in the west (about 1300 km) and narrows eastward to about 240 km where the two highlands come closer, before widening again as it approaches the Atlantic Ocean.
• The basin generally slopes eastwards and is mostly covered by dense tropical rainforests.
• Due to frequent flooding and dense undergrowth, these areas are largely inaccessible.

(b) Himalayas

• The Himalayas are one of the young fold mountains in the world, extending from the Pamir Knot in Tajikistan to the east.
• In India, they extend from Jammu and Kashmir to Arunachal Pradesh.
• It is not a single range but a system of parallel ranges. From south to north, they are: the Siwaliks (youngest), Lesser Himalayas, Greater Himalayas (Himadri), and Trans-Himalayan ranges.
• They are also divided longitudinally into Western Himalayas (Kashmir), Central Himalayas (Kumaun), and Eastern Himalayas (Assam).

(c) The coasts of Brazil

• Brazil has a coastline of about 7400 km, divided into the northern coast and the eastern coast.
• The northern coast extends from Amapa to Rio Grande do Norte. It is low-lying, characterized by the mouths of many rivers including the Amazon, and features large coastal islands like Marajo.
• The eastern coast extends southwards from Rio Grande do Norte. It receives many smaller rivers, with the Sao Francisco being the only major river meeting the Atlantic here.
• The eastern coast is characterized by large beaches, sand dune complexes, and is protected in some areas by coral reefs and atolls.

(d) The Indian peninsula

• The Indian Peninsula lies to the south of the North Indian Plains and tapers towards the Indian Ocean.
• It consists of numerous plateaus and hill ranges, with the Aravalis in the north being the oldest fold mountains.
• The central part includes a series of plateaus bordering the plains, along with the Vindhyas and Satpuda ranges.
• The region is flanked by the hilly regions of the Western Ghats on the west and the Eastern Ghats on the east.

(e) The Great Escarpment

• Though it occupies a small area, the Great Escarpment is considered a separate physiographic region due to its steep slope and significant effect on Brazil's climate.
• It demarcates the eastern side of the Brazilian Highlands, reaching an altitude of 790m.
• The escarpment is particularly steep between Sao Paulo and Porto Alegre.
• It acts as a barrier to the Southeast Trade winds, which causes heavy rain on the coast but creates a rain-shadow area called the 'Drought Quadrilateral' to its north in the northeastern part of the highlands.

(a) There are no west-flowing rivers in Brazil.

• The major physical divisions of Brazil, namely the Brazilian Highlands and the Guyana Highlands, gently slope towards the north and steeply towards the east.
• Due to this underlying topography, the major river systems originate in these highlands and are naturally directed to flow either northwards or eastwards/southwards.
• Additionally, the massive Andes mountain range lies to the west of the Amazon basin, acting as a massive barrier and water divide that prevents any rivers from flowing westwards into the Pacific Ocean.

(b) There are dissimilarities between the eastern and western coasts of India.

• The western coast borders the Arabian Sea and is a rocky coast where spurs from the Western Ghats extend right up to the sea, making it narrow. Rivers here are short and swift, forming estuaries rather than deltas.
• The eastern coast borders the Bay of Bengal and was formed by the depositional work of rivers.
• Due to a gentle slope, the east-flowing rivers run at lower velocities and deposit heavy sediments at the coast, leading to the formation of wide deltas.

(c) There are fewer natural ports on the eastern coast of India.

• The eastern coast has a very gentle slope and the coastal waters are relatively shallow.
• Major east-flowing rivers deposit large amounts of sediment brought from the Western and Eastern Ghats, forming extensive deltas along the coast.
• This heavy sediment deposition and shallow depth make it difficult for large ships to navigate close to the shore, naturally restricting the development of deep, natural ports.

(d) As compared to Amazon, pollution in river Ganga will affect human life greatly.

• The Ganga river basin covers the North Indian Plains, which is one of the most fertile and densely populated regions in the world. Millions of people depend directly on the Ganga for drinking water, agriculture, and industrial use.
• In contrast, the Amazon basin is covered by dense tropical rainforests, making it largely inaccessible and very sparsely populated by humans.
• Because human settlements and activities are intensely concentrated along the Ganga, any pollution directly threatens public health, agriculture, and the economy, whereas pollution in the Amazon would have a relatively lower direct impact on human populations.