Key Physiographic Features and River Systems of India

Formation and Characteristics of the Himalayas

The Himalayas, one of the most prominent mountain ranges in the world, were formed as a result of the collision between the Indian Plate and the Eurasian Plate. This collision led to the upliftment of the Himalayas, creating a series of parallel mountain ranges with varying orientations in different regions of India.

The Great Himalayas, also known as the central axial range, span approximately 2,500 km from east to west and have a width ranging from 160-400 km from north to south. The Himalayas act as a natural barrier between the Indian subcontinent and Central and East Asian countries, influencing the climate and biodiversity of the region. The range is characterized by diverse ecosystems, including alpine meadows, temperate forests, and snow-capped peaks, making it a hotspot for biodiversity and a crucial source of freshwater for the Indian subcontinent.

Physiographic Features of the Peninsular Plateau

The Peninsular Plateau in India is a vast elevated region characterized by its irregular triangular shape and relatively stable landmass. Rising from approximately 150 m above the river plains to elevations of 600-900 m, the plateau is bordered by prominent features such as the Delhi Ridge, Rajmahal Hills, Gir Range, and Cardamom Hills.

This plateau is home to a series of plateaus, including the Hazaribagh, Palamu, Ranchi, Malwa, Coimbatore, and Karnataka plateaus. As one of the oldest landmasses in India, it plays a crucial role in influencing the drainage patterns of the region. The general eastward slope of the plateau is reflected in the flow of rivers, which support fertile alluvial soils and sustain agricultural activities, contributing significantly to the economy and livelihoods of the local population.

Characteristics of the Northern Plains

The Northern Plains extend approximately 3,200 km from east to west, with an average width varying between 150-300 km. The maximum depth of alluvium deposits varies between 1,000-2,000 m. Covering an area of 7 lakh square km, it is the most densely populated region of the country.

From north to south, these plains are divided into three sub-divisions: Bhabar, Tarai, and Alluvial Plains (further divided into Khadar and Bhangar).

1. Bhabar

A narrow belt ranging between 8-16 km parallel to the Shiwalik foothills. Streams and rivers coming from the mountains deposit heavy rocks and boulders here, often disappearing into this zone.

2. Tarai

A zone approximately 20-30 km wide where streams and rivers re-emerge without a properly demarcated channel, creating marshy and swampy conditions. It features luxurious natural vegetation and varied wildlife.

3. Alluvial Plains

These plains feature mature fluvial landforms such as sand bars, meanders, ox-bow lakes, and braided channels. The Brahmaputra plains are known for riverine islands. The mouths of these rivers form some of the world's largest deltas, such as the Sunderbans. The fertile soil supports crops like wheat, rice, sugarcane, and jute.

The Indus River System

• It is one of the largest river basins in the world, covering 11,65,000 sq. km (321,289 sq. km in India) with a total length of 2,880 km. The Indus, also known as the Sindhu, is the westernmost Himalayan river in India.
• It originates from a glacier near Bokhar Chu in the Tibetan region at an altitude of 4,164 m in the Kailash range.
• Tributaries include the Shyok, Gilgit, Zaskar, Hunza, Nubra, Shigar, Gasting, and Dras. It emerges near Attock, receiving the Kabul river on its right bank.
• Other right-bank tributaries originating in the Sulaiman ranges include the Khurram, Tochi, Gomal, Viboa, and Sangar.
• The river receives the 'Panjnad' (Satluj, Beas, Ravi, Chenab, and Jhelum) above Mithankot.
• It discharges into the Arabian Sea, east of Karachi, and flows in India through the Leh district of Ladakh.

The Ganga River System

1. The Ganga is India's most important river regarding its basin and cultural significance. It rises in the Gangotri glacier (Gaumukh) in Uttarakhand as the Bhagirathi, cutting through the Central and Lesser Himalayas.
2. At Devaprayag, the Bhagirathi meets the Alaknanda to form the Ganga. The Alaknanda originates in the Satopanth glacier and consists of the Dhauli and Vishnu Ganga.
3. The river spans 2,525 km across Uttarakhand, Uttar Pradesh, Bihar, and West Bengal, covering a basin of 8.6 lakh sq. km.
4. It is the largest river system in India, fed by perennial Himalayan rivers and non-perennial peninsular rivers. The Son is its major right-bank tributary.
5. Left-bank tributaries include the Ramganga, Gomati, Ghaghara, Gandak, Kosi, and Mahananda. The Yamuna is the longest and westernmost tributary.
6. The river discharges into the Bay of Bengal near Sagar Island.