Drainage System

1. Understand the basic concept of drainage and drainage patterns.
2. Identify various river systems in India and their characteristics.
3. Differentiate between major and minor river basins and their significance.
4. Examine the differences between Himalayan and Peninsular river systems.
5. Discuss river pollution and management issues, including inter-basin water transfer schemes.

Drainage System Overview

A drainage system consists of water flowing through well-defined channels, crucial for managing excess water and preventing flooding. Without such systems, ill-defined or choked channels can cause flooding. The pattern of drainage in an area is influenced by geological time periods, rock structure, topography, slope, and water flow. A river collects water from its catchment area, and the combined area drained by the river and its tributaries is called a drainage basin. This leads to the classification of watersheds and river basins, which differ primarily in size, with watersheds being smaller.

Important Drainage Patterns

1. Dendritic Pattern: Resembling tree branches, it is commonly seen in rivers of the northern plain.
2. Radial Pattern: When rivers originate from a hill and flow outward in all directions, examples being rivers from the Amarkantak range.
3. Trellis Pattern: Formed when primary tributaries run parallel, and secondary tributaries join at right angles.
4. Centripetal Pattern: Occurs when rivers flow inward toward a depression or lake.

Note: A watershed forms the boundary separating two drainage basins, influencing how water affects different areas within a basin.

Indian Drainage System Classification

Indian rivers are grouped based on their flow orientation:

1. Arabian Sea Drainage: Including rivers like the Indus, Narmada, and Tapi.
2. Bay of Bengal Drainage: Consisting of the Ganga, Brahmaputra, Mahanadi, and Krishna. This group drains approximately 77% of India’s water, with the remainder going to the Arabian Sea.

On the basis of the size of watersheds:

1. Major River Basins: Over 20,000 sq. km of catchment area. Examples include the Ganga, Brahmaputra, and Krishna.
2. Medium River Basins: Between 2,000 and 20,000 sq. km, like the Kalindi and Periyar.
3. Minor River Basins: Less than 2,000 sq. km, usually found in low-rainfall areas.

Himalayan and Peninsular Drainage Systems

India’s drainage system can be divided into two distinct regions:

1. Himalayan Drainage System: Perennial rivers like the Ganga, Indus, and Brahmaputra flow due to snowmelt and rainfall. These rivers feature gorges, V-shaped valleys, and form deltas near their mouths. In the plains, rivers show meandering tendencies and frequent course changes, such as the Kosi River, notorious for shifting and causing floods.
2. Peninsular Drainage System: Older than its Himalayan counterpart, it has shallow valleys and lacks the perennial flow of water, except for rivers like the Narmada and Tapi, which flow westward through rift valleys.

Important Note: The Peninsular rivers, especially the Narmada and Tapi, show less meandering due to the stable topography, unlike the rivers from the northern Himalayan region.

Evolution of the Himalayan Drainage

Geologists suggest that the mighty Indo-Brahma river, flowing along the length of the Himalayas, evolved during the Miocene period. Eventually, the river dismembered into the Indus, Ganga, and Brahmaputra systems due to the tectonic activity that shaped the western Himalayas.

Major River Systems of India

1. The Indus River System: Originates in Tibet, traverses India through Jammu and Kashmir, and flows into Pakistan. Its major tributaries include the Jhelum, Chenab, Ravi, Beas, and Satluj. These tributaries form a significant part of the river system, contributing to both agriculture and water management in northwestern India.
2. The Ganga River System: The Ganga originates from the Gangotri Glacier in Uttarakhand and flows southeast, covering the vast plains of northern India. Its major tributaries include the Yamuna, Gandak, Ghaghara, and Kosi. The river is highly significant culturally and economically, supporting agriculture, transportation, and large populations along its banks.

Important Note: The Namami Gange Programme, launched in 2014, is an ambitious effort to clean and rejuvenate the river.

3. The Brahmaputra River System: Originating from the Chemayungdung Glacier in Tibet, the Brahmaputra flows through Arunachal Pradesh and Assam. It is known for its frequent floods due to heavy sediment load and rainfall in its catchment areas.

Peninsular River Systems

1. The Godavari: Also called the Dakshin Ganga, it is the largest river system in the Peninsular region. Originating in Maharashtra, it flows eastward, receiving numerous tributaries such as the Penganga, Indravati, and Manjra.
2. The Krishna: The second-largest Peninsular river, flowing east from Maharashtra, through Karnataka and Andhra Pradesh. The Tungabhadra, Bhima, and Koyna are its major tributaries.
3. The Mahanadi: Originating in Chhattisgarh, the Mahanadi flows east into Odisha. It is essential for irrigation and navigation, though prone to flooding.
4. The Kaveri: Known for its continuous flow throughout the year due to rainfall during both southwest and northeast monsoon seasons. The river supports agriculture in Tamil Nadu and Karnataka.
5. The Narmada and Tapi: Flowing through rift valleys, these rivers discharge their water into the Arabian Sea. They are exceptions to the eastward flow of most Peninsular rivers.

Note: The Sardar Sarovar Dam on the Narmada is a significant project for water management, irrigation, and power generation.

Challenges and Management of River Water

India faces challenges in the distribution of water, both spatially and temporally. Some regions experience floods, while others suffer from drought. Effective water management strategies are needed to address this imbalance, including inter-basin water transfer schemes like the Indira Gandhi Canal and Beas-Satluj Link Canal.

Important Concept: River interlinking can address water scarcity in dry regions by transferring surplus water from one basin to another.

River Pollution and Conservation Efforts

Rivers in India, particularly the Ganga and Yamuna, face significant pollution from industrial effluents, domestic sewage, and religious activities. Various programs, including the Ganga Action Plan and Yamuna Action Plan, aim to clean and conserve these rivers.

Important Note: The involvement of local communities and public awareness are crucial for the success of these river-cleaning programs.

Comparative Table: Major River Systems

MCQ:
Which river is known as the “Sorrow of Bihar” due to its frequent flooding?
Answer: Kosi

This content integrates the detailed study of India’s drainage systems, classifies them, and discusses the associated challenges and conservation efforts.