Why rivers, the lifeline of the nation, must flow

India is blessed with many rivers that provide its population with resources for irrigation, industry, domestic purposes, hydroelectricity, transportation, fishing, fertile land for agriculture, etc. However, these rivers are facing growing challenges such as pollution, flooding, water scarcity, and interstate disputes. 

The river interlinking project presents an ambitious solution to such challenges by connecting India’s major rivers to address regional water disparities and improve water availability for agriculture and domestic use.  

To understand the scope of such initiatives, it is important to explore India’s river systems: How are rivers formed, how many river systems exist, and what theories explain their formation? 

India’s river systems

There are various ways of classifying Indian river systems, such as based on catchment size, origin and orientation to the sea. Broadly, they are classified into Himalayan rivers, which include the Indus, Ganga and Brahmaputra and their tributaries, and the Peninsular rivers based on their origin. 

There are differences between the two river systems based on their source of water, regime, flow etc. Himalayan rivers are perennial, fed by glaciers and monsoon, and have two maxima or peak flow periods – one during summer due to glacial melt and the second during the southwest monsoon. They have relatively larger basins and meandering courses as they pass through soft sedimentary rocks. 

On the other hand, Peninsular rivers are mostly seasonal and have only one maxima or peak flow during the monsoon, except for the Kaveri, which also receives water from the northeast monsoon. These rivers have smaller basins and relatively straighter courses due to the presence of hard peninsular rocks. 

Evolution of the Himalayan rivers

The evolution of the Himalayan rivers is explained by theories like the Indo-Brahma/Siwalik River theory of E.H. Pascoe and the Multiple River theory. The Indo-Brahma River theory suggests that a large river once flowed from Assam to Punjab and possibly extended to Sind.

The theory also postulates that the present-day Indus and Brahmaputra rivers were part of this ancient river system and were separated later. The separation happened due to geological events like the Potwar Plateau upheaval in the western Himalayas during the Pleistocene age, headward erosion by tributaries of the Indo-Brahma River, and the development of the Malda trough.

Many geological events have also contributed to the current drainage pattern of Peninsular India. The subsidence of the western flank of the Peninsula during the late Tertiary period and the tilting of the peninsular landmass towards the southeast resulted in the asymmetrical drainage of the Peninsular rivers primarily towards the eastern flank.

What theories on the formation of rivers say

Theories related to the formation of rivers and the morphological features they create are part of broader landscape development theories. One of the most influential theories is W.M. Davis’s Cycle of Erosion (1889), which laid emphasis on the role of structure, process, and stage (time) in landscape evolution. Davis proposed that after an initial rapid uplift, the landscape goes through a complete cycle of development consisting of three stages: youth, maturity, and old age.

However, Davis’s theory was contested by W. Penck, who rejected the role of time and stated that geomorphic forms are shaped by the phase and rate of uplift in relation to the rate of degradation. Other notable theories include G.K. Gilbert’s Equilibrium Concept, L.C. King’s Uniform development of landforms in varying environmental conditions, J.T. Hack’s Dynamic Equilibrium Theory, and Morisawa’s Tectono-geomorphic model. 

Stages of river landform development

True stability of geological conditions is rare due to factors like complications of geological structure, diastrophic history, and climatic variations. However, in case of the ideal fluvial (river) cycle, a general sequence of processes and landform development is followed. It is important to note that the duration of different stages is not uniform. 

Youth Stage  

In this stage, the formation of V-shaped valleys, where valley deepening is more dominant than valley widening, occurs. Fluvial erosion primarily involves downcutting (valley deepening) and lateral erosion (valley widening). Both of these occur through solution/corrasion, abrasion, attrition, and hydraulic action.

Landforms like canyons (such as Grand Canyon in Colorado) and gorges are some of the features of this stage. Lakes and swamps may form in areas near local base levels of erosion. The presence of rapids and waterfalls is also typical of this stage due to the presence of resistant rocks.

Maturity Stage 

In this stage, the river attains a profile of equilibrium, with valley widening becoming more dominant than valley deepening, giving it a U-shape. Interstream divide becomes ridge-shaped. Depositional features like alluvial fans (for example Kosi River Fan) and cones can be seen as the river enters the plains from the mountains. Meanders and oxbow lakes (such as Kanwar Lake) become prominent in this stage. 

Old Stage

Fewer tributaries are present in this stage. Very wide valleys with a gentle slope develop, and interstream areas are reduced in height. The river carries a finer load, and deposition becomes dominant. Lakes, swamps, and marshes are common in floodplain areas (such as Ganga-Yamuna floodplains). Levee formation and braided river flow can also be observed. Peneplanation and delta formation (for example Sundarbans Delta) are common features of this stage. 

However, fluvial cycles are rarely uninterrupted, as various factors can cause interruptions, including volcanic activity, climatic changes, and positive or negative shifts in the base level of erosion. Rejuvenation of the fluvial cycle can also take place due to factors like subsidence of the sea floor, glaciation, uplift of the landmass, or an increase in water volume of rivers.

Examples of rejuvenation include the development of nick points in the river profile due to tectonic activity, valley-in-valley topography, paired terraces, incised meanders, and uplifted peneplains. Such interruptions in the fluvial cycle lead to topographical discordance, where older landforms persist before the development of younger forms. 

Challenges and government initiatives 

Rivers of India face several issues, like pollution, flooding, water scarcity, and interstate disputes. Pollution is primarily caused by the dumping of sewage, plastic, and municipal and industrial waste. Flooding results from both natural factors (such as increased rainfall due to climate change) and human activities (such as deforestation, encroachment of floodplains, poor drainage, sudden dam releases, and embankment failures).

Water scarcity primarily occurs due to vagaries of the monsoon, while interstate disputes arise over water-sharing, such as in river basins like Cauvery, Krishna, Godavari, and Narmada.

Various measures have been taken by the government to tackle these issues. To tackle pollution and clean rivers, schemes like the National River Conservation Plan and Namami Ganga were launched. The Water (Prevention and Control of Pollution) Act, 1974 was also enacted to regulate pollution. Programmes like AMRUT and the Smart Cities Mission focus on improving sewerage infrastructure.

The Flood Management Programme was launched during the 10th Plan to address the issues of flood-affected states through measures like drainage works and the construction of embankments. Government schemes like Jal Shakti Abhiyan and MGNREGS (which include water conservation and rainwater harvesting structures) aim to tackle water scarcity. The Inter-State River Water Disputes Act (1956) was enacted to resolve disputes over river water sharing.

The National Waterways Act, 2016 was introduced to ease the burden on road and rail transport by designating 111 waterways as National Waterways. A National Perspective Plan for the interlinking of rivers was also prepared by the Ministry of Irrigation in 1980, though its implementation depends on the consensus of the concerned states.

Post Read Questions

How are Indian river systems classified? What are the major differences between Himalayan and Peninsular rivers?

What are the main theories related to the formation of rivers and their morphological features?

What are the key features of the youth, maturity and old stages in river development?

What is the Inter-State River Water Disputes Act, and how does it resolve water-sharing conflicts?

How does the National Perspective Plan for the interlinking of rivers aim to address water management issues in India?

(Raj Shekhar is pursuing his Ph.D. in Geography from Jawaharlal Nehru University.)

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