Which one of the following rivers thrice forks into two streams and reunites a few miles farther on, thus forming the islands of Srirangappattanam, Sivasamudram and Srirangam ?

1. Introduction to Peninsular River Systems (basic)

Welcome to your first step in mastering the Peninsular River System. To understand these rivers, we must first recognize that they are geologically much older than the Himalayan rivers. While the Himalayan rivers are young and still carving deep valleys, the Peninsular rivers flow through broad, largely-graded shallow valleys, indicating they have reached a stage of maturity INDIA PHYSICAL ENVIRONMENT, Geography Class XI, p.23. This is a fundamental distinction: the North is a land of youthful energy, while the South is a land of stable, ancient drainage.

The character of these rivers is defined by their regime—the seasonal pattern of their water flow. Unlike the perennial Himalayan rivers that receive water from both melting snow and rain, Peninsular rivers are almost exclusively monsoonal. They depend on seasonal rainfall, meaning their water levels fluctuate significantly throughout the year Geography of India, Majid Husain, p.22. Furthermore, the Western Ghats serve as the primary water divide; since these mountains are situated close to the western coast, most major rivers are forced to flow eastward across the plateau to reach the Bay of Bengal.

Feature	Himalayan Rivers	Peninsular Rivers
Nature	Perennial (Snow + Rain)	Seasonal (Rain only)
Age	Young and Active	Old and Mature
Valleys	Deep V-shaped Gorges	Broad and Shallow

The current orientation of these rivers was shaped by three major geological events: the subsidence of the western flank into the sea, the upheaval of the Himalayas which created rift valleys (trough faults) where the Narmada and Tapi flow, and a slight tilting of the entire Peninsular block towards the southeast. This tilt is the reason why rivers like the Mahanadi, Godavari, Krishna, and Kaveri flow toward the Bay of Bengal INDIA PHYSICAL ENVIRONMENT, Geography Class XI, p.23.

Sources: INDIA PHYSICAL ENVIRONMENT, Geography Class XI, Drainage System, p.23; Geography of India, Majid Husain, The Drainage System of India, p.22

2. East-Flowing vs. West-Flowing Rivers (basic)

To understand the Peninsular drainage system, we must first look at the Water Divide. In Peninsular India, this divide is formed by the Western Ghats, which run north-to-south very close to the western coast. Because the Deccan Plateau has a general tilt from west to east, most major rivers originate near the Western Ghats and flow across the plateau to reach the Bay of Bengal NCERT Class IX, Drainage, p.21.

Rivers like the Mahanadi, Godavari, Krishna, and Kaveri follow this eastward path. These rivers are characterized by their gentle gradients as they cross the broad plateau, allowing them to carry and deposit significant amounts of sediment. By the time they reach the sea, they "fan out" to form deltas—fertile, triangular landforms made of alluvial deposits. For instance, the Kaveri is known for forming a prominent quadrilateral delta in the Thanjavur district Physical Geography by PMF IAS, Fluvial Landforms and Cycle of Erosion, p.208.

In contrast, the West-flowing rivers tell a different story. While there are numerous small streams, the Narmada and Tapi are the only long rivers that flow west. These rivers do not form deltas. Instead, they flow through rift valleys and meet the Arabian Sea via estuaries—semi-enclosed coastal bodies where freshwater from the river mixes with salty seawater Environment (Shankar IAS), Aquatic Ecosystem, p.45. Because they flow through hard rock terrains with a steep gradient, they lack the sediment load necessary to build deltas.

The following table summarizes the structural differences between these two systems:

Feature	East-Flowing Rivers	West-Flowing Rivers
Outlet	Bay of Bengal	Arabian Sea
Landform at Mouth	Deltas (e.g., Godavari Lobate, Kaveri Quadrilateral)	Estuaries (e.g., Narmada, Tapi)
Basin Size	Generally larger (Godavari is the largest in the Peninsula)	Generally smaller Geography of India (Majid Husain), The Drainage System of India, p.4
Examples	Mahanadi, Godavari, Krishna, Kaveri, Damodar	Narmada, Tapi, Sabarmati, Mahi

Sources: NCERT Class IX, Drainage, p.21; Environment (Shankar IAS), Aquatic Ecosystem, p.45; Physical Geography by PMF IAS, Fluvial Landforms and Cycle of Erosion, p.208; Geography of India (Majid Husain), The Drainage System of India, p.4

3. The Godavari and Krishna Basins (intermediate)

Welcome back! In our journey through the Peninsular rivers, we now arrive at the two absolute giants of the Deccan: the Godavari and the Krishna. These rivers are the lifelines of Central and Southern India, and understanding their drainage patterns is crucial for any civil services aspirant.

The Godavari, often revered as the 'Dakshin Ganga' (Ganges of the South) due to its massive size and age, is the largest Peninsular river system. It originates from the slopes of the Western Ghats at Trimbak Plateau near Nasik, Maharashtra Contemporary India-I NCERT, Drainage, p.21. Stretching approximately 1,465 km, its basin is immense, covering nearly 10% of India's total geographical area. A key detail to remember is its tributary system: while it has many left-bank tributaries like the Purna, Wardha, and Indravati, the Manjira stands out as its only significant right-bank tributary Geography of India (Majid Husain), The Drainage System of India, p.21. Notably, the Pranhita is not a single stream from the start; it is the combined flow of the Wardha, Penganga, and Wainganga.

Just south of the Godavari lies the Krishna River. Rising from a spring near Mahabaleshwar, it flows for about 1,400 km before reaching the Bay of Bengal Contemporary India-I NCERT, Drainage, p.22. While the Godavari is longer, the Krishna is equally vital for irrigation and power. Its major tributaries include the Tungabhadra (its largest), the Bhima, and the Musi (on which Hyderabad stands). Interestingly, while many Indian rivers form arcuate deltas, the Krishna is known for building a fertile bird-foot delta, similar to the Mississippi River in the USA Geography of India (Majid Husain), The Drainage System of India, p.21.

Feature	The Godavari	The Krishna
Source	Trimbak Plateau (Nasik)	Mahabaleshwar
Major Tributaries	Pranhita, Indravati, Manjira, Sabari	Tungabhadra, Bhima, Musi, Koyna
Basin States	MH, MP, CH, OR, TL, AP	MH, KN, TL, AP

Sources: Contemporary India-I NCERT, Drainage, p.21-22; Geography of India (Majid Husain), The Drainage System of India, p.21

4. Interstate River Water Disputes (intermediate)

In a federal structure like India, rivers are the lifeblood of the economy, but they do not respect political boundaries. Most Peninsular rivers, such as the Cauvery, Krishna, and Godavari, flow through multiple states, leading to inevitable conflicts over water sharing. To manage these 'hydro-political' tensions, the Constitution of India provides a specific mechanism under Article 262. This article is unique because it allows Parliament to provide for the adjudication of disputes relating to waters of inter-state rivers and specifically empowers Parliament to exclude the jurisdiction of the Supreme Court and all other courts in such matters Introduction to the Constitution of India, INTER-STATE RELATIONS, p.407. Following this constitutional mandate, the Parliament enacted two critical laws in 1956 to manage these disputes. While one focuses on cooperation and planning, the other focuses on legal resolution when negotiations fail. It is important to distinguish between the two:

Feature	River Boards Act (1956)	Inter-State River Water Disputes Act (1956)
Primary Purpose	Regulation and development of inter-state rivers and river valleys.	Adjudication (legal resolution) of actual disputes between states.
Mechanism	Establishment of River Boards to advise state governments.	Setting up of an ad hoc Tribunal to hear the dispute.
Nature of Decision	Advisory and recommendatory.	The decision of the tribunal is final and binding Indian Polity, Inter-State Relations, p.167.

Under the Inter-State River Water Disputes Act, when a state government requests the Central government to refer a dispute to a tribunal, and the Centre is of the opinion that the matter cannot be settled by negotiations, a Water Disputes Tribunal is constituted. These tribunals are temporary (ad hoc) and composed of judges nominated by the Chief Justice of India. Once the tribunal gives its award, it carries the same force as an order of the Supreme Court, ensuring a legal conclusion to the technical and emotional battle over water Introduction to the Constitution of India, INTER-STATE RELATIONS, p.407.

Sources: Introduction to the Constitution of India, INTER-STATE RELATIONS, p.407; Indian Polity, Inter-State Relations, p.167

5. Hydrology of the Kaveri River (intermediate)

The Kaveri (Cauvery) river is often hailed as the 'Ganges of the South,' not just for its spiritual significance, but for its unique hydrological behavior. Unlike most Peninsular rivers that run nearly dry during the summer, the Kaveri maintains a relatively constant flow throughout the year. This 'perennial' nature is due to its strategic geographical position. The river's upper catchment area in Karnataka receives heavy rainfall from the South-West Monsoon (June to September), while its lower catchment area in Tamil Nadu benefits from the North-East Monsoon (October to December). This dual-monsoon supply ensures that the river carries water with significantly less fluctuation than its neighbors like the Krishna or Godavari INDIA PHYSICAL ENVIRONMENT, Drainage System, p.24. Rising at an elevation of 1,341m in the Brahmagiri hills of Kodagu, Karnataka, the river travels approximately 800 km before emptying into the Bay of Bengal. Its basin is shared primarily between Tamil Nadu (approx. 56%) and Karnataka (approx. 41%), with a tiny fraction (3%) in Kerala Geography of India, The Drainage System of India, p.38. As the river descends from the Mysore Plateau, it creates a spectacular landscape of gorges and waterfalls, most notably the Hogenakkal Falls, which marks the end of its plateau journey. Before reaching the plains, the river also bifurcates to form famous riverine islands such as Srirangapatna and Sivasamudram. The Kaveri's efficiency as an irrigation lifeline is bolstered by its numerous tributaries. On the left bank, it is joined by the Hemavati, Shimsa, and Arkavati. On the right bank, the Lakshman-Tirath, Kabini, Bhavani, and Amravati provide significant volume. As the river nears its end in the Thanjavur district of Tamil Nadu, it 'fans out' into a massive quadrant-delta, transforming the region into the 'Granary of South India' Geography of India, The Drainage System of India, p.21.

Sources: INDIA PHYSICAL ENVIRONMENT, Drainage System, p.24; Geography of India, The Drainage System of India, p.38; Geography of India, The Drainage System of India, p.21

6. River Landforms: Braiding and Riverine Islands (exam-level)

When we think of a river, we often imagine a single, continuous flow of water. However, as a river reaches the later stages of its journey—especially as it transitions from a plateau or mountain to the plains—it often changes its character. A braided river consists of a complex network of channels that split and rejoin, separated by small, often temporary islands called braid bars. This happens primarily because the river's energy decreases, but its sediment load remains high.

There are two critical factors that lead to this "braiding" effect:

• Low Gradient: As the slope (gradient) becomes extremely gentle, the water flows more leisurely and loses the power to push its heavy "luggage" of silt and sand forward FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Landforms and their Evolution, p.51.
• Sediment Overload: When the river carries more sediment than it can transport, the excess material is deposited in the middle of the channel. These deposits form bars that force the water to divert and find new paths, creating a "braided" appearance Physical Geography by PMF IAS, Fluvial Landforms and Cycle of Erosion, p.197.

When these deposits become large and stable enough to support vegetation or habitation, they are called riverine islands. While the Brahmaputra's Majuli is the most famous example in India CONTEMPORARY INDIA-I, Physical Features of India, p.11, this phenomenon is a defining feature of several Peninsular rivers as well. For example, the Kaveri (Cauvery) River is noted for its tendency to "fan out" and form islands like Sivasamudram and Srirangam as it enters the plains. In its lower course, the river splits into numerous channels known as distributaries, creating a rich, fertile delta landscape.

To help you distinguish between the different ways a river "bends" or "splits" in its mature stage, look at this comparison:

Feature	Braided Channel	Meandering Channel
Appearance	Interconnected network of multiple channels.	A single channel flowing in a winding, S-shaped loop.
Key Cause	High sediment load and low slope.	Lateral erosion on gentle gradients FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Landforms and their Evolution, p.51.
Typical Landform	Riverine islands and braid bars.	Ox-bow lakes and point bars.

Sources: FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Landforms and their Evolution, p.51; Physical Geography by PMF IAS, Fluvial Landforms and Cycle of Erosion, p.197; CONTEMPORARY INDIA-I, Physical Features of India, p.11

7. The Specific Geography of the Kaveri Islands (exam-level)

The Kaveri River, often revered as the 'Ganga of South India', exhibits a unique geographical phenomenon among Peninsular rivers: the formation of large, habitable riverine islands. Unlike many other rivers that simply flow in a single channel until they reach a delta, the Kaveri has a habit of bifurcating (splitting) and then reuniting, effectively 'wrapping' itself around large landmasses. This occurs primarily as the river descends from the Mysore Plateau and enters the plains of Tamil Nadu Geography of India, The Drainage System of India, p.21. These islands are not just geographical curiosities; they have served as centers of power, spirituality, and early industrial innovation.

There are three primary islands formed by the Kaveri, often categorized by their upstream-to-downstream sequence:

• Srirangapatna: Located just 20 km from Mysore, this island was a strategic fortress and the capital of Tipu Sultan. It is formed where the river splits and rejoins shortly before reaching the Krishnaraja Sagar dam.
• Sivasamudram: Further downstream, the river drops nearly 100 meters, creating the famous twin waterfalls of Gaganachukki and Bharachukki. This site is historic for hosting India’s first major hydro-electric power station, commissioned in 1902 to supply power to the Kolar Gold Fields Environment and Ecology, Distribution of World Natural Resources, p.9.
• Srirangam: Located near Tiruchirappalli, the river splits into two branches: the northern Coleroon (Kollidam) and the southern Kaveri. The land between them forms the Srirangam island, home to one of the largest functioning Hindu temples in the world.

Because the Kaveri receives rainfall from both the Southwest Monsoon (summer) and the Retreating/Northeast Monsoon (winter), it maintains a more consistent flow than most Peninsular rivers, allowing these island ecosystems to thrive year-round Geography of India, The Drainage System of India, p.21.

Sources: Geography of India, The Drainage System of India, p.21; Environment and Ecology, Distribution of World Natural Resources, p.9

8. Solving the Original PYQ (exam-level)

Now that you have mastered the drainage patterns and river morphology of the Peninsular plateau, this question serves as the perfect test of your ability to apply that theory to real-world geography. You previously learned how rivers change their behavior as they transition from high-gradient plateaus to flatter plains; the "forking and reuniting" described here is a classic example of an anastomosing pattern. This specific geomorphological feature creates riverine islands, which historically became centers of power and pilgrimage. To solve this, you must synthesize your knowledge of state-wise river courses with these specific historical landmarks.

Your reasoning should follow the spatial trail of the islands: Srirangappattanam and Sivasamudram are located in Karnataka, while Srirangam is situated much further downstream near Tiruchirappalli in Tamil Nadu. The only major East-flowing river that traverses both these states and is celebrated for these three sacred bifurcations is the Cauvery. As highlighted in Geography of India by Majid Husain, the river is unique for its braided channels and distributaries that "fan out" to form a quadrant-delta, a process that begins well before it reaches the coast. Therefore, (A) Cauvery is the correct answer.

UPSC often uses the Godavari and Krishna as distractors because they are the largest rivers in the South; however, their island formations (like the Konaseema region) do not match this specific three-island sequence. The Tungabhadra, while geographically significant, is a tributary and does not maintain the volume or length required to form such distinct, large-scale islands across two different states. The trap here is thinking all major deltas are the same—always look for the specific island names to anchor your choice to the correct river basin.