Drainage System: Types, Patterns & Key Concepts

The Drainage System of a region is a vital component of its geography, shaping both natural landscapes and human settlements. The drainage systems are essential for effective water resource management, flood control, and ecological preservation. This article aims to study in detail the drainage system, its key concepts, types, and patterns of drainage systems, highlighting their importance in managing water resources and maintaining ecological balance.

What is Drainage System?

• Drainage can be defined as the naturally occurring flow of water in well-defined channels formed by streams and rivers that carry the surface water to sea, lake or water body. 
• A network of such channels is known as a Drainage System.

Drainage System: Key Concepts

Drainage Basin

• When a river and its tributaries function as a drainage system for a specific area, this area is referred to as a Drainage Basin.

Drainage System

• A Drainage System is defined as the pattern created by rivers, streams, and lakes within a specific drainage basin.

Water Divide

• When we go through a map of India or the world, it will indicate many elevated areas such as a mountain, plateaus or other uplands. 
  • At various stages of time, these elevated areas act as a boundary, which separates the drainage basin of one river from the other, and it is called as the Water Divide. 

Watershed

• The boundary line separating one drainage basin from the other is known as the Watershed.

River Basins

• The catchments of large rivers are known as River Basins, whereas those of smaller rivulets and rills are often referred to as Watersheds.

Types of Drainage Systems

There are following two major types of Drainage Systems:

• Sequent Drainage Systems, and
• Insequent Drainage Systems.

Each of the types of drainage systems has been discussed in detail in the section that follows.

Sequent Drainage System

Sequent streams generally follow the regional or general slope. It has the following four categories of Drainage Systems:

• Consequent Streams (Dip Stream),
• Subsequent Streams,
• Obsequent Streams, and
• Resequent Streams.

All these streams have been discussed in detail in the section mentioned below. 

Consequent Streams (Dip Stream)

• When a river originates from a particular region and it follows the initial and developed course of the slope according to its general formation, then it is called a Consequent Stream.
• It generally follows the regional slope in its course of drainage. Prominent rivers of Peninsular India are Consequent Streams.
• E.g. Krishna, Godavari and Cauvery follow the path of Western Ghat to the Bay of Bengal.

Subsequent Streams

• The is a master stream that generates first, then other streams flow in the axis of the ridge and strike the beds of a river called as Subsequent Streams. 
• They almost join each other at a right angle.
• E.g. Tributary of Ganga at Dehradun Valley.

Obsequent Streams

• If streams flow in the opposite direction of the main consequent stream, they are called Obsequent Streams.
• They follow the regional slope.
• For example, the Mahabharata range of the Himalayas has several obsequent streams.

Resequent Streams

• If the streams of the drainage system follow the direction of the main consequents, then it is called as Resequent Streams.
• They originated after the origination of the mainstream.

Insequent Drainage Systems

Insequent streams do not follow the regional slope. It has the following four categories of Drainage Systems:

• Antecedent Drainage System, and
• Superimposed Drainage System.

All these drainage systems have been discussed in detail in the section mentioned below.

Antecedent Drainage System

• This drainage system originates before the upliftment of the formations, for example, mountain, land surface, plateau etc, they flow across the upliftment of the formation by down-cutting the valley in their course.
• They also form gorges in their path. 
• E.g. – Indus, Sutlej, Ganga, and Saryu across the Himalayas etc. are prominent Antecedent Rivers.

Superimposed Drainage System

• The rivers which do not follow their regional slope or courses.
• When the nature of the valleys and the flow course of resultant drainage on the upper geological formation and structure is superimposed on the lower geological formation of entirely different characteristics then it is called a Superimposed Drainage System. 
• E.g. Son River flowing across the Khainjua Ridge etc.

Drainage Pattern

• Drainage Patterns are defined as the generalized movement of active channels in accordance with prevailing relief and structure. 
• A prominent type of drainage pattern results as a consequence of different activities of the drainage system, due to various natural phenomena.
• E.g. shaping of rock systems, climatic conditions, slope etc.

Types of Drainage Patterns

The streams within a drainage basin form certain patterns, depending on the slope of the land, underlying formations as well as the climatic conditions of the area. There are mainly six different types of Drainage Patterns:

• Dendritic Drainage Pattern,
• Parallel Drainage Pattern,
• Trellis Drainage Pattern,
• Radial Drainage Pattern,
• Rectangular Drainage Pattern, and
• Deranged Drainage Pattern.

All these Drainage Patterns have been discussed in detail in the section mentioned below.

Dendritic Drainage Pattern

• The Drainage Pattern that represents the combination of broader valleys involving a dense network of tributaries which project to be the example of radiating branches of trees is called the Dendritic Pattern.
• This pattern develops where the river channel follows the slope of the terrain.
• E.g. The Ganga river system, The Godavari river system, the Krishna river system etc.

Parallel Drainage Pattern

• It comprises numerous rivers which are parallel to each other and follow the regional slope.
• It is due to the steeper slopes, the rivers become so swift that they travel in straight course and thus become parallel to each other.
• River Narmada and River Tapi are considered prominent examples.

Trellis Drainage Pattern

• Several streams developed on both the flanks of the ridges and joined the longitudinal synclinal streams at the right angle.
• This pattern also resembles the rectangular pattern, however, the streams are closely spaced in a trellised pattern as compared to the rectangular pattern.
• It involves alternating outcrops of soft and hard rocks. Soft rocks get eroded with time, eventually leading trellis pattern.
• The extra-peninsular river system exemplifies this pattern, with the Ganga river system being the most developed example.

Radial Drainage Pattern

• It forms a drainage pattern involving channels of different systems and represents centrifugal flow, where water flows radially outward and downward from a central topographic high.
• E.g. Amarkantak (Narmada, Son, and Hasdeo).

Rectangular Drainage Pattern

• This pattern is considered to be a specific type of Trellis pattern where tributaries merge with the main river almost at a right angle (90 degrees). 
• It is indicative of streams following prominent faults or joints that break the rock into rectangular blocks. 
• E.g. The Brahmani River System and the Mahanadi River System.

Deranged Drainage Pattern

• It is a drainage system where there is no coherent pattern to the rivers and lakes
• It occurs in areas where significant geological disruption has taken place.
• E.g. It is found in the glaciated valleys of Karakoram.

Conclusion

In conclusion, understanding drainage systems is essential for comprehending how water flows through different landscapes, influencing ecosystems and supporting human activities. The detailed examination of drainage basins, water divides, and different drainage patterns illustrate the complexity and significance of these systems. Whether through natural formations or engineered solutions, effective drainage systems are essential for flood control, agriculture, and urban planning. By recognizing the intricate connections and functions of these networks, we can better manage our water resources and promote sustainable environmental stewardship.

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