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Drainage System (India Advanced)

Drainage System

A drainage system refers to the pattern of streams and rivers in a basin. The way a river flows and the shape of the drainage basin it carves out is known as the drainage pattern. These patterns are influenced by the underlying geological structure, slope of the land, nature of the rock, and the stage of the river's evolution.

Important Drainage Patterns

Several drainage patterns are observed in India, each reflecting the underlying physiography and geological history:

1. Dendritic Pattern:

2. Trellis Pattern:

3. Rectangular Pattern:

4. Radial Pattern:

5. Annular Pattern:

6. Centripetal Pattern:

7. Superimposed Pattern (Epigenetic Pattern):


Drainage Systems Of India

India's drainage systems are broadly divided into two main categories based on their origin:

1. The Himalayan Drainage:

2. The Peninsular Drainage:

Other Drainage Systems:

The orientation of these river systems is largely controlled by the overall relief of the Indian subcontinent.


The Himalayan Drainage

The Himalayan drainage system is characterized by its youthful stage, large basins, long courses, and perennial flow. These rivers originate from the snow-covered mountain ranges, ensuring a continuous water supply throughout the year.

Evolution Of The Himalayan Drainage

The evolution of the Himalayan drainage system is a complex geological process, primarily attributed to the theory of Continental Drift and the subsequent collision of the Indian and Eurasian plates.

Key Stages and Theories:

1. Early Stages (Pre-collision): It is believed that before the collision of the Indian plate with the Eurasian plate, a large river, possibly called the Indus-Ganga-Brahmaputra river system (or a predecessor of it), flowed across the Tethys Sea, which existed between the two landmasses.

2. Formation of the Trough: As the Indian plate moved northwards, the Tethys Sea began to shrink, and a large depression or trough, known as the Indo-Ganga Trough, was formed between the northern edge of the Indian plate and the southern edge of the Eurasian plate.

3. Collision and Upliftment of Himalayas: The collision of the Indian and Eurasian plates led to the folding and upliftment of the Tethys sediments, forming the Himalayan mountains. This upliftment was not a single event but occurred in stages and continues to this day.

4. Reactivation of Drainage: The massive upliftment of the Himalayas created a vast, rugged terrain. The ancient river system, trapped in the trough, was forced to adjust its course. The upliftment caused the river to:

5. Theories of Evolution:

The ongoing upliftment of the Himalayas continues to influence the evolution of these river systems, leading to significant geological activity.

The River Systems Of The Himalayan Drainage

The Himalayan drainage is dominated by three major river systems, which arise from the northern mountain ranges.

The Indus System

Origin: Chemayungdung Glacier (Angsi Glacier) in Tibet, near Mansarovar Lake.

Course:

Tributaries:

Key Features:

The Ganga System

Origin: The river Ganga is formed by the confluence of the Bhagirathi and Alaknanda at Devprayag in Uttarakhand.

Course:

Major Tributaries:

Yamuna Tributary System: The Yamuna is the longest and most important tributary. It originates from the Yamunotri Glacier. Its tributaries include the Chambal, Sindh, Betwa, and Ken. The Chambal has a significant gorge.

Other Tributaries: Ghaghara, Gandak, and Kosi originate in the Nepal Himalayas and are known for their large sediment load and flood-prone nature (especially Kosi).

Confluence: At Prayagraj (Allahabad), the Ganga meets the Yamuna and the mythical Saraswati.

Key Features:

The Brahmaputra System

Origin: Chemayungdung Glacier in Tibet, near Mansarovar Lake (same source area as Indus). It originates as the Yarlung Tsangpo.

Course:

Tributaries:

Key Features:


The Peninsular Drainage System

The peninsular drainage system is much older than the Himalayan drainage. The drainage patterns of the peninsular rivers are largely determined by the underlying ancient crystalline and metamorphic rocks and the topography of the Peninsular Plateau.

The Evolution Of Peninsular Drainage System

The evolution of the peninsular drainage system is closely linked to the geological history of the Indian subcontinent, particularly the formation and subsequent erosion of the Peninsular Block.

Key Factors:

1. Gondwanaland Breakup: The ancient peninsular block was part of the Gondwanaland supercontinent. When it broke apart, the Indian peninsula drifted northwards.

2. Upliftment of Himalayas: The northward drift and subsequent collision with the Eurasian plate caused the upliftment of the Himalayas. This uplift also affected the northern margin of the Peninsular Block, leading to a subsidence in that area and the formation of the Indo-Ganga Trough.

3. Differential Uplift and Tilting: While the Himalayas were being uplifted, the northern part of the Peninsular Block tilted slightly eastwards, and the western part experienced some subsidence. This tilting is believed to be a primary reason why most of the major peninsular rivers (Godavari, Krishna, Kaveri, Mahanadi) flow from west to east into the Bay of Bengal.

4. Rift Valleys: The uplift and tilting also created fault lines or rift valleys. Two major rivers, the Narmada and the Tapi, are believed to have formed in these rift valleys, flowing westward into the Arabian Sea.

5. Erosion and Maturity: Being part of an old landmass, the peninsular rivers have eroded their beds over millions of years, carving out broad, shallow valleys and reaching a mature stage of geomorphic development.

6. Seasonal Flow: Most peninsular rivers are fed by monsoon rains, making them seasonal. They experience a sharp decline in water flow during the dry season, unlike the perennial Himalayan rivers.

River Systems Of The Peninsular Drainage

The peninsular rivers are classified based on the direction of flow, primarily towards the Bay of Bengal or the Arabian Sea.

Most peninsular rivers are eastward flowing, except for the Narmada and Tapi.

Smaller Rivers Flowing Towards The West

These rivers are shorter and faster than the east-flowing rivers due to their origin from the Western Ghats and their direct descent into the Arabian Sea.

1. Narmada River:

2. Tapi River:

3. Periyar, Bharatpuzha, Pamba: These are some of the important west-flowing rivers in Kerala, known for their scenic beauty and cultural significance.

4. Sabarmati and Mahi: Rivers originating in Rajasthan, flowing through Gujarat and emptying into the Arabian Sea.

Small Rivers Flowing Towards The East

These rivers originate in the Western Ghats and flow across the Deccan Plateau to the Bay of Bengal, forming large deltas.

1. Mahanadi River:

2. Godavari River:

3. Krishna River:

4. Kaveri River:

5. Other East-flowing Rivers: Vaigai, Pennar, Subarnarekha.


River Regimes

A river regime refers to the characteristic pattern of discharge (flow) of a river over a year. This pattern is primarily determined by the source of water (snowmelt, rainfall, or both) and the climate of the region.

Factors Influencing River Regimes:

Types of River Regimes in India:

1. Monsoon Regime:

2. Perennial Regime (Snowmelt and Monsoon Fed):

3. Seasonal Regime (Rainfall Dependent):

Impacts of River Regimes:


Extent Of Usability Of River Water

The usability of river water in India is a critical aspect of water resource management, encompassing availability, quality, and accessibility for various needs.

Factors Affecting Usability:

1. Availability (Flow):

2. Quality:

3. Accessibility:

Major Uses of River Water:

Challenges and Management:

The usability of India's river water is a complex issue requiring integrated management of water resources, pollution control, and equitable distribution.