Types of Drainage Patterns| Class 11 Geography Notes

Class 11 Geography Types of Drainage Patterns Notes: The Class 11 Geography notes explain the different types of drainage patterns in easy-to-understand language. They have been created by experts to help students learn effectively.

Whether you’re new to the subject or want to improve your understanding, these notes provide clear explanations of each drainage pattern, how they form, and what makes them unique. By studying these notes, students can enhance their knowledge and perform better in their geography studies.

Types of Drainage Patterns| Class 11 Geography Notes

Drainage Patterns

A Drainage Pattern refers to the arrangement of streams, rivers, and lakes within a specific drainage basin. This pattern, shaped by the erosion of streams over time, reflects the geological features and rock types present in the area drained by the streams.

The formation of a drainage pattern is influenced by factors such as the landscape’s topography, the slope of the land, and the types of rocks present. These factors determine how water flows and collects, shaping the overall pattern of drainage in the region.

Types of Drainage Patterns

There are two main types of drainage patterns based on the shape and formation of river patterns:

1. Discordant Drainage Pattern
2. Concordant Drainage Pattern

Discordant Drainage Pattern

In a discordant drainage pattern, the river’s course does not align with the topography or geology of the area. It remains consistent despite changes in the landscape. This pattern is further divided into two types: antecedent and superimposed.

1. Antecedent Drainage:

Also known as inconsequent drainage, this occurs when a river maintains its original path even after the surrounding area is uplifted. It cuts through the uplifted portion, forming deep gorges through vertical erosion or down-cutting. Examples include the Indus, Sutlej, and Brahmaputra rivers.

2. Superimposed Drainage:

Also referred to as superinduced or epigenetic drainage, this occurs when a river flows over a softer rock layer but encounters harder basal rocks underneath. Despite the change in rock structure, the river maintains its original course due to its erosive power. This pattern reflects discordance with the underlying rock structure. Examples include the Damodar, Subarnarekha, and Chambal rivers.

Concordant Drainage Pattern

In a concordant drainage pattern, the river’s path aligns with the topology and geology of the area. The river’s course is largely determined by the terrain and the slope of the land. This type of drainage system is commonly categorized into two types: consequent drainage rivers and subsequent drainage rivers.

1. Consequent Drainage Rivers:

In a consequent drainage system, the river flows in the general direction of the slope of the land. Rivers like the Godavari, Krishna, and Cauvery in Peninsular India are examples of consequent rivers, descending from the Western Ghats and flowing into the Bay of Bengal.

2. Subsequent River System:

A subsequent river develops after the original consequent river has established its path. These tributary streams erode along non-resistant rock layers after the main drainage pattern has formed. Examples include the Chambal, Sind, Ken, Betwa, Tons, and Son rivers, which intersect the main drainage of the Yamuna and the Ganga at right angles.

Here are the types of drainage patterns under the consequent and subsequent drainage systems:

Dendritic Drainage Pattern:

• Resembles the branching of a tree.
• Found in regions with homogeneous material.
• Common in areas with uniform lithology and insignificant faulting or jointing.
• Examples include the Indus, Godavari, Mahanadi, Cauvery, and Krishna rivers.

Parallel Drainage Pattern:

• Rivers run parallel to each other in a uniformly sloping region.
• Found in regions with steep slopes and relief.
• Example: Rivers of the lesser Himalayas and swift rivers in the Western Ghats.

Trellis Drainage Pattern:

• Resembles a common garden trellis.
• Develops in folded or tilted sedimentary rocks eroded to varying degrees.
• Short subsequent streams meet the main stream at right angles.
• Example: Old folded mountains of the Singhbhum (Chotanagpur Plateau).

Rectangular Drainage Pattern:

• Main stream bends at right angles with tributaries joining at right angles.
• Found in regions with significant faulting and little topography.
• Example: Streams in the Vindhyan Mountains of India.

Radial Drainage Pattern:

• Streams radiate outwards from a central elevated point.
• Tributaries follow the slope downwards.
• Examples include rivers like Narmada, Son, and Mahanadi originating from Amarkantak Hills.

Centripetal Drainage Pattern:

• Streams converge from all sides into low-lying basins.
• Flow towards a central depression.
• Examples include streams of Ladakh, Tibet, and the Baghmati and its tributaries in Nepal.

Deranged Drainage Pattern:

• No coherent pattern to rivers and lakes.
• Develops from the disruption of a pre-existing drainage pattern.
• Example: Glaciated valleys of Karakoram.

Angular Drainage Pattern:

• Formed where bedrock joints and faults intersect at acute angles.
• Common in Himalayan Foothill region.

Annular Drainage Pattern:

• Subsequent tributaries follow a circular drainage around the summit of upland with an outer soft stratum.
• Examples include Pithoragarh (Uttarakhand) and Nilgiri Hills in Tamil Nadu and Kerala.

Barbed Drainage Pattern:

• A tributary with the main river characterized by a discordant junction.
• Result of capture of the main river, while tributaries continue pointing in the direction of former flow.
• Example: Arun River (Nepal), a tributary of the Kosi.

Conclusion

Studying drainage patterns helps us understand how water flows across different landscapes. By classifying these patterns into various types like dendritic, parallel, or radial, we can learn more about the land’s shape and composition. Each type tells us something different about how rivers and streams move through the land. This knowledge helps us manage water resources and protect the environment better.

Types of Drainage Patterns- FAQs

What are drainage patterns?

Drainage patterns refer to the arrangement and structure of rivers, streams, and lakes within a particular geographical area.

How are drainage patterns classified?

Drainage patterns are classified based on their shape, formation, and the underlying geology of the area. Common classifications include dendritic, parallel, trellis, rectangular, radial, and annular patterns.

What is a dendritic drainage pattern?

A dendritic drainage pattern resembles the branching pattern of tree roots. It forms in regions with uniform geological characteristics and minimal slope variations.

What causes a parallel drainage pattern?

A parallel drainage pattern occurs in regions with steep slopes and uniform terrain. Tributaries run parallel to each other due to consistent slope conditions.

How is a trellis drainage pattern formed?

A trellis drainage pattern develops in areas with folded or tilted sedimentary rock formations. Tributaries meet the main river at right angles, resembling a garden trellis.