Which one of the following lakes of India is a salt-water lake ?

1. Introduction to Indian Hydrography and Drainage (basic)

Welcome to your journey into Indian Geography! To truly master the topic of lakes and wetlands, we must first understand the hydrographic framework of India. Think of India's drainage system as a vast network of biological plumbing that has evolved over millions of years. This system is the outcome of three factors: the physiographic units (mountains, plains, and plateaus), the nature of the rocks, and the patterns of precipitation (rainfall and snowmelt) INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.), Drainage System, p.19.

In India, we broadly classify our drainage into two major groups based on their mode of origin: the Himalayan (Extra-Peninsular) Drainage and the Peninsular Drainage Geography of India, Majid Husain (McGrawHill 9th ed.), The Drainage System of India, p.5. This distinction is crucial because it dictates why some rivers (and the lakes they feed) are permanent, while others are seasonal. For instance, the Peninsular system is much older and more "mature" than the Himalayan one, characterized by broad, shallow valleys that have reached a state of equilibrium INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.), Drainage System, p.23.

A key concept you'll encounter is the Water Divide. In the Peninsular region, the Western Ghats act as a massive structural wall, forcing most major rivers like the Godavari, Krishna, and Kaveri to flow eastward into the Bay of Bengal, while only short, swift rivulets dash westward into the Arabian Sea INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.), Drainage System, p.23. Understanding this tilt of the Indian landmass helps us predict where large deltas, wetlands, and coastal lakes are likely to form.

Feature	Himalayan Drainage	Peninsular Drainage
Nature of Flow	Perennial (water year-round from glaciers and rain).	Seasonal (dependent almost entirely on monsoon rain).
Maturity	Youthful; actively eroding deep gorges.	Mature; broad, graded shallow valleys.
Major Systems	Indus, Ganga, Brahmaputra.	Mahanadi, Godavari, Krishna, Kaveri.

Sources: INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.), Drainage System, p.19; INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.), Drainage System, p.23; Geography of India, Majid Husain (McGrawHill 9th ed.), The Drainage System of India, p.5

2. Geological Origins: How Indian Lakes are Formed (intermediate)

To understand Indian lakes, we must look at the diverse geological forces that carved the subcontinent's landscape. In the north, the Himalayan lakes primarily owe their existence to glacial action. As massive glaciers moved, they eroded the bedrock to create deep basins (sometimes called cirques). When these glaciers retreated, the basins filled with snowmelt to form freshwater bodies like Bhimtal and Nainital CONTEMPORARY INDIA-I, Chapter 3, p.22. Interestingly, small mountain lakes that collect in these glacial basins are specifically known as Tarns, such as the Gangabal lake in Kashmir Geography of India, Chapter 3, p.28. However, not all Himalayan lakes are glacial; Wular Lake in Jammu and Kashmir, India's largest freshwater lake, was formed by tectonic activity—the shifting and folding of the Earth's crust CONTEMPORARY INDIA-I, Chapter 3, p.22. Moving to the plains and arid regions, different processes take over. In the Indo-Gangetic and Brahmaputra plains, meandering rivers often shift their courses. Over time, a river loop can become so sharp that the water cuts through the narrow neck, leaving behind a crescent-shaped Oxbow lake Physical Geography by PMF IAS, Fluvial Landforms, p.200. In contrast, the arid landscape of Rajasthan hosts lakes of inland drainage. These are often seasonal and saline, such as the Sambhar Lake. Because these lakes sit in depressions (like those in the Aravalli Range) and lack an outlet to the sea, minerals accumulate as water evaporates, making them vital for salt production CONTEMPORARY INDIA-I, Chapter 3, p.22.

To help you distinguish between these origins, consider this comparison:

Formation Type	Mechanism	Key Example
Glacial	Erosion by moving ice filled with snowmelt.	Gangabal, Bhimtal
Tectonic	Fracturing or subsidence of the Earth's crust.	Wular Lake
Fluvial (Oxbow)	River meanders being cut off from the main channel.	Kanwar Lake (Bihar)
Inland Drainage	Depressions in arid regions with high evaporation.	Sambhar Lake

Sources: CONTEMPORARY INDIA-I, Drainage, p.22; Geography of India, The Drainage System of India, p.28; Physical Geography by PMF IAS, Fluvial Landforms and Cycle of Erosion, p.200

3. Coastal Ecosystems: Lagoons and Backwaters (intermediate)

To understand India's coastline, we must first distinguish between Inland and Coastal Wetlands. While inland wetlands include things like ox-bow lakes and marshes, coastal wetlands are those specifically influenced by the sea, such as estuaries, mangroves, and lagoons Environment and Ecology, Majid Hussain, MAJOR BIOMES, p.27.

A Lagoon is a shallow body of water separated from a larger body of water (usually the ocean) by a narrow landform, such as reefs, barrier islands, sandbanks, or spits. In India, these are primarily formed by the deposition of sandbars along the coast. Notable examples include Chilika Lake in Odisha (the largest coastal salt-water lake in India), Pulicat Lake on the Andhra Pradesh-Tamil Nadu border, and Kolleru Lake (which, though historically a lagoon, is now slightly inland due to deltaic growth) Geography of India, Majid Husain, The Drainage System of India, p.28 CONTEMPORARY INDIA-I, Geography, Class IX . NCERT, Drainage, p.22.

In the state of Kerala, these coastal lagoons have a unique regional identity and are known as Backwaters or Kayals. The Vembanad Lake is the most famous example; it is the largest lake in Kerala and is separated from the Arabian Sea by a narrow barrier island Geography of India, Majid Husain, The Drainage System of India, p.31. These backwaters are not just geographical features but are vital to the local economy and culture. They serve as essential Inland Waterways for transport and are world-renowned for tourism and the Vallamkali (Nehru Trophy Boat Race) INDIA PEOPLE AND ECONOMY, TEXTBOOK IN GEOGRAPHY FOR CLASS XII, Transport and Communication, p.82.

Feature	Description	Key Examples
Lagoon	Formed by sandbars/spits blocking sea water.	Chilika (Odisha), Pulicat (Andhra/TN)
Backwater (Kayal)	Regional name for lagoons in Kerala; used for navigation.	Vembanad, Ashtamudi

Sources: Environment and Ecology, Majid Hussain, MAJOR BIOMES, p.27; Geography of India, Majid Husain, The Drainage System of India, p.28, 31; CONTEMPORARY INDIA-I, Geography, Class IX . NCERT, Drainage, p.22; INDIA PEOPLE AND ECONOMY, TEXTBOOK IN GEOGRAPHY FOR CLASS XII, Transport and Communication, p.82

4. Conservation and Policy: The Ramsar Convention (exam-level)

The Ramsar Convention, signed in 1971 in the Iranian city of Ramsar, is the only global environmental treaty that provides a framework for the conservation and 'wise use' of a specific ecosystem — wetlands. It defines wetlands broadly, ranging from lakes and rivers to underground aquifers, mangroves, and even human-made sites like reservoirs. Unlike strict 'no-touch' conservation models, the convention’s philosophy is built on the 'Wise Use' principle: the maintenance of the wetland's ecological character through the implementation of ecosystem-based approaches, allowing for sustainable utilization for the benefit of mankind.

India became a contracting party to the convention on February 1, 1982 Environment, Shankar IAS Academy, International Organisation and Conventions, p.398. Since then, the country has significantly expanded its network of 'Wetlands of International Importance' (Ramsar Sites). To qualify, a site must meet at least one of nine criteria, such as supporting vulnerable species or regularly supporting 20,000 or more waterbirds. In India, these sites are incredibly diverse, reflecting our varied geography:

• High-altitude wetlands: Like Chandratal and Renuka in Himachal Pradesh Geography of India, Majid Husain, Natural Vegetation and National Parks, p.53.
• Inland freshwater lakes: Such as Loktak in Manipur (famous for its floating phumdis) and Bhoj in Madhya Pradesh Geography of India, Majid Husain, Natural Vegetation and National Parks, p.54.
• Coastal/Marine systems: Including the vast Vembanad Kol in Kerala and Chilika Lake in Odisha.

Proper management involves close coordination between national implementing units and other international frameworks like the Convention on Biological Diversity (CBD) Environment, Shankar IAS Academy, International Organisation and Conventions, p.398. For sites facing immediate ecological threats due to human interference or pollution, the convention maintains the Montreux Record — a register of wetland sites where changes in ecological character have occurred, are occurring, or are likely to occur. In India, Keoladeo Ghana National Park and Loktak Lake are currently on this record.

Feature	Description
Core Philosophy	Wise Use (Sustainable utilization)
India Joined	1982
Smallest Site	Renuka Wetland, Himachal Pradesh
Largest Site	Sundarbans (or Vembanad Kol by area of water body)

Sources: Environment, Shankar IAS Academy, International Organisation and Conventions, p.398; Geography of India, Majid Husain, Natural Vegetation and National Parks, p.53-54

5. Freshwater Lakes of the Himalayan and Peninsular Regions (intermediate)

When we study India's freshwater lakes, we divide them geographically because their origin stories are vastly different. In the Himalayan region, most freshwater lakes are glacial in origin. These were formed when massive glaciers carved out deep hollows in the landscape, which then filled with snowmelt as the climate warmed. However, a notable exception is the Wular Lake in Jammu and Kashmir. Unlike its glacial neighbors, Wular is primarily a result of tectonic activity, making it the largest natural freshwater lake in India CONTEMPORARY INDIA-I, Drainage, p.22. It acts as a crucial reservoir for the River Jhelum and is the site of the Tulbul Project, which helps regulate water levels for navigation Geography of India, The Drainage System of India, p.32.

Moving to the Kumaun Division of Uttarakhand, we find a distinct cluster of freshwater lakes like Bhimtal, Nainital, and Sattal. Bhimtal is famous for its picturesque island at the center, while Sattal (literally 'seven lakes') is an interconnected group of water bodies that serves as a vital habitat for migratory birds Geography of India, The Drainage System of India, p.31. Beyond the Himalayas, freshwater lakes are also found in unique settings, such as Nakki Lake in Rajasthan, which is a rare high-altitude freshwater lake in an otherwise semi-arid region, and Loktak Lake in Manipur, famous for its floating islands called 'phumdis'.

From an ecological perspective, these lakes are often classified by their nutrient content. For instance, the Dal Lake in Srinagar is considered eutrophic, meaning it is highly nutrient-rich, which often leads to dense aquatic plant growth Environment and Ecology, MAJOR BIOMES, p.26. In the Peninsular region, while many large water bodies are man-made reservoirs, natural freshwater lakes like Kolleru (Andhra Pradesh) play a massive role in supporting local biodiversity and fisheries.

Feature	Himalayan Freshwater Lakes	Peninsular/Other Freshwater Lakes
Primary Origin	Glacial erosion or Tectonic shifts.	Deltaic depressions, Tectonic, or Man-made.
Key Examples	Wular, Dal, Bhimtal, Sattal.	Kolleru, Nakki, Loktak (Northeast).
Water Source	Snowmelt and Perennial rivers.	Monsoon rains and Ground seepage.

Sources: CONTEMPORARY INDIA-I, Drainage, p.22; Geography of India, The Drainage System of India, p.32; Geography of India, The Drainage System of India, p.31; Environment and Ecology, MAJOR BIOMES, p.26

6. Saline and Brackish Water Systems of India (exam-level)

To understand the saline and brackish water systems of India, we must first look at why some water bodies accumulate salt while others remain fresh. In humid regions like the Himalayas, lakes are often of glacial origin or formed by tectonic activity (like Wular Lake); these stay fresh because they have a constant inflow of meltwater and an outlet to carry minerals away CONTEMPORARY INDIA-I, NCERT, Drainage, p.22. However, in arid and semi-arid regions, we find endorheic basins (inland drainage systems) where water does not reach the sea. In these basins, high evaporation rates cause minerals and salts brought by rivers to concentrate over time, leading to high salinity Physical Geography by PMF IAS, Ocean temperature and salinity, p.519.
In India, these systems are broadly categorized into two types: Inland Saline Lakes and Coastal Brackish Lagoons.

• Inland Saline Systems: Primarily found in the Rajasthan Plains. These include Playas—small, temporary hollows or depressions on the desert surface—and Dhands Geography of India, Majid Husain, The Drainage System of India, p.28. The most significant example is Sambhar Lake. Located in a depression of the Aravalli Range near Jaipur, it is India's largest inland salt lake and a designated Ramsar site. It is economically vital, producing nearly 10% of India's salt through evaporation ponds Geography of India, Majid Husain, The Drainage System of India, p.31.
• Coastal Brackish Systems: These are lagoons like Chilika (Odisha) and Pulicat (Andhra Pradesh/Tamil Nadu). Unlike inland lakes, their salinity comes from a mix of seawater and fresh river water. While Chilika is the largest brackish water lake in India overall, it is a coastal feature, distinct from the inland systems of the desert.

Feature	Inland Saline Lake (e.g., Sambhar)	Coastal Brackish Lake (e.g., Chilika)
Source of Salt	Terrestrial minerals + High evaporation	Mixing of Sea water + River water
Drainage	Inland/Endorheic (no outlet to sea)	Connected to the sea (Lagoon)
Key Example	Sambhar, Didwana, Pachpadra	Chilika, Pulicat, Vembanad

Sources: CONTEMPORARY INDIA-I, NCERT, Drainage, p.22; Geography of India, Majid Husain, The Drainage System of India, p.28, 31; Physical Geography by PMF IAS, Ocean temperature and salinity, p.519

7. Solving the Original PYQ (exam-level)

This question serves as a direct application of your studies on the drainage systems of India and the classification of water bodies by salinity. As you have learned, the origin of a lake—whether glacial, tectonic, or aeolian—largely determines its chemical composition. In the arid and semi-arid regions of Western India, inland drainage and high rates of evaporation often lead to the formation of saline basins. This question tests your ability to map those theoretical concepts to specific geographical entities across the Indian landscape.

To arrive at the answer, you must evaluate the location and origin of each option. Sambhar Lake is the correct choice because it is situated in a depression within the Aravalli Range of Rajasthan and lacks an outlet to the sea, making it India's largest inland salt-water lake. As noted in NCERT Class IX: Contemporary India-I, these inland saline lakes are of great economic importance for salt production. By recognizing that Sambhar is a Ramsar site and a major source of India's salt, you can confidently identify it as the saline outlier among the choices.

The UPSC often includes geographical traps to test the depth of your conceptual clarity. A common pitfall here is Nakki Lake; because it is located in Rajasthan (Mount Abu), students might reflexively categorize it as salty, but it is actually a freshwater lake. Similarly, Bhimtal and Rewalsar are located in the Himalayan and sub-Himalayan belts (Uttarakhand and Himachal Pradesh respectively). As highlighted in Geography of India by Majid Husain, most lakes in the Himalayan region are of freshwater origin due to snowmelt and glacial activity, which immediately allows you to eliminate them from the list of salt-water candidates.