The Drainage System of India

The Drainage System of India is controlled by the geographical features of the Indian subcontinent. The drainage system is an integrated system or geographical organization of rivers, tributaries, or any other water bodies that collect and funnel the surface water either to the sea or any other body of water. The area (total) that contributes to the single drainage system is called a drainage basin. 

By examining the situation of Indian Geography, rivers of India are divided into two categories; Himalayan Rivers (Drainage System) and Peninsular Rivers. This section of Rivers of India is the most important topic for UPSC prelims and other State PSCs prelims examinations.

Basic Terms related to Drainage System of India

Catchment Area (Or) Basin Area the area in which a river drains its water collected from a specific source Command Area is the area around the dam, where the benefits of the dam, such as irrigation water, electricity, etc., reach. Govt. runs various Command Area development programs nearby almost all big & small Dams.

Drainage pattern: The geographical arrangement of rivers, streams, or any other water body depending upon various physiological factors such as slope, structural control of the land, climate, hydrologic variability, rock resistance, weathering, erosion, etc. is called Drainage pattern.

Rivers of India

Types of Drainage Patterns in India

The geographical arrangement of rivers, streams, or any other water body depending upon various physiological factors such as slope, structural control of the land, climate, hydrologic variability, rock resistance, weathering, erosion, etc. is called Drainage pattern. In simple words, this is a design formed by the river and its tributaries from source to its mouth (the point where the river ends in the sea or other water body). There are many factors that control the drainage of a particular region. These factors are the nature of rocks, slope, tectonic plates, supply of water, structural control, and more importantly geographical history of that region. We will discuss only drainage patterns that are available in India.

Antecedent or Inconsequent Rivers

The rivers that cut their streams southward by making gorges (a much narrower V-shaped Valley) in the mountains are called antecedents rivers. These are rivers that are older than the physical barrier (Himalayas) it cuts through. For instance, all rivers originating from Tibet are older than the Himalayas. These rivers thus originate before the Himalayan shape is formed (Tibet is older than the Himalayas). Antecedent rivers are those rivers that originate before their slope or gradient. The Satluj, Indus, Ganga, Tista, Brahmaputra are some of the important antecedent rivers. originating from beyond the Greater Himalayas.

V-Shaped Valley: In conditions of high altitude, high slope and flow are over soft rocks, then steep, deep and narrow valley is formed due to Vertical Erosion. Such valleys are V-shaped valleys.

Climate of India
V-shaped Valley

Consequent Rivers

The rivers whose stream follows the direction of the slope are called Consequent Rivers.  Consequent Rivers are those rivers that originate only after the formation of their slope. All Peninsular rivers and their drainage system emerge only after the formation of landforms that created a slope towards the sea (Deccan Plateau is the geologically oldest landform in India). The rivers Godavari, Krishna, and Kaveri are the example of consequent rivers.

Subsequent Rivers

These rivers are tributaries river to consequent rivers. These streams flow across the underlying belt of non-resistant rock after the establishment of its consequent river (main drainage pattern). The rivers from Satpura and Vindhyan ranges flow northward towards the river Ganga. This is because of the northward slope of Peninsula in the Great Plains. Chambal, Ken, Betwa, Tons, and Son river are the subsequent drainage of the Ganga Drainage system.

Obsequent Rivers

The river stream formed or adjusted due to some rock structure. These streams may or may not be perpendicular to the subsequent stream (rivers).  This flows in the opposite direction to the original consequent stream. The northward stream (from lesser Himalayas) joins Sun Kosi as the Obsequent stream. These streams flow opposite the direction of Ganga and Yamuna.

Resequent Rivers

The recently originated stream started due to the cycle of erosion in a folded structure are called Resequent rivers. These develop in response to the new base level.

Dendritic drainage pattern


The Drainage system of India 

The Drainage system of India is purely controlled by the geographical condition of the Indian Subcontinent. Based on origin, the drainage system of India (Rivers of India) is divided into two categories:

Himalayan Drainage System of India

The Himalayan drainage system of India contains Indus, Ganga, Brahmaputra, and their tributaries. The basin or catchment area of Ganga is the largest in India. Indus and Brahmaputra are the longest rivers of this drainage system but these rivers are being shared by neighboring countries as well. The Longest River in India is river Ganga. The Himalayan rivers of India have long routes from their originating source to the Oceans or sea. These rivers perform heavy soil erosional activity in the upper region of routes (Himalayan Regions) and carry a large amount of sand and silt along to the plains.

Major rivers of India
Major Rivers of India

Himalayan rivers have perennial flow. Their valleys are deep due to vertical erosion. With perennial flow and deep valleys, in the Himalayan course, these rivers are useful for Hydro Power Production and in plains for Navigation. The Himalayan rivers form Meanders as their flow is serpentine. The Himalayan drainage system is Antecedent in nature as these rivers are older than the Himalayan mountain ranges. Indus, Brahmaputra, Sutlej, and Arun-Kosi originate from Tibet and cut across the Himalayan mountain ranges to flow into the plains.

Climate of India
Classification of Drainage System of India| Image Credit: Internet

Peninsular Rivers of India is a type of drainage system based on the flow of the river, peninsular rivers are classified as East flowing peninsular rivers, West flowing Peninsular rivers, and Inland Drainage.

East Flowing Peninsular Rivers

Mahanadi (Odisha), Godavari, Krishna (Andhra Pradesh) & Kaveri (Tamil Nadu). The Godavari has the largest basin and it is the second-largest basin of India after Ganga. So it is called Dakshinganga.

These rivers are consequent. Their flow is southeast along the slope of the Indian Peninsular. These rivers are seasonal as their flow is over hard metamorphic rocks. With low altitudes and slopes, these rivers are involved in lateral erosion. With lateral erosion, their valleys are wide and shallow. With seasonal flow and wide and shallow valleys, these rivers are neither useful for hydric power nor navigation. Formations of meanders are restricted.

West Flowing Peninsular Rivers

Narmada and Tapi are important west-flowing rivers. These rivers flow into rift valleys which are linear, deep, narrow, and steep (which is why their course is almost like a straight line). Rift valleys are formed due to the Down faulting of rocks (Endogenetic Forces). This is why their flow is opposite to the slope of the Peninsula [the slope of the Indian is south-east ward]. Narmada is the longest west flowing river.

Inland Drainage System

If the ultimate flow of water is not to the sea, it is called an Inland Drainage System. Luni forms an inland drainage system. Its flow is into the Rann Of Kutch in Gujarat. The Rann of Kutch is a saline and marshy area.