Glossary of Lake-Related Terms

A short, exam-focused glossary of the technical vocabulary this book uses repeatedly — worth a final read-through, since objective questions occasionally test the term directly ("which of the following describes a lake with no outlet?") rather than any specific lake's name.

• Endorheic — a drainage basin with no outlet to the ocean; water leaves only by evaporation or seepage. Applies to the Caspian Sea, Dead Sea, Aral Sea, Sambhar Lake, Pangong Tso, and Tso Moriri, among others in this book.
• Brackish — water that is saltier than freshwater but less salty than seawater, typically from the mixing of seawater and freshwater in a lagoon or estuary. Applies to Chilika, Pulicat, and Vembanad.
• Playa — a dry, flat lakebed (a salt pan) that only intermittently fills with water. Lake Eyre in Australia is the standard world example.
• Limnic eruption — a rare, sudden, catastrophic release of dissolved gas (usually CO₂) from deep lake water, capable of asphyxiating life over a wide area. Applies to Lake Kivu, Lake Nyos, and Lake Monoun.
• Moraine — debris (rock, soil, sediment) deposited directly by a glacier; a moraine can dam a valley and impound a glacial lake. Relevant to the formation of many Himalayan glacial lakes and to the mechanism behind most GLOFs.
• Caldera — a large depression formed when a volcano's magma chamber empties and its summit collapses inward; a caldera lake (like Crater Lake or Lake Toba) forms when this depression fills with water.
• Graben — a depressed block of the Earth's crust bordered by parallel faults, common in rift-valley and tectonic settings; Lake Tahoe's basin is a hybrid graben-and-glacial example.
• Phumdi — a naturally occurring floating mat of vegetation, soil, and organic matter, unique in Indian usage to Loktak Lake, Manipur.
• Oxbow lake — a crescent-shaped lake formed when a meandering river cuts off and abandons one of its own loops. Kanwar Lake (Kabar Tal), Bihar, is this book's standard large Indian example.
• Trophic status — a lake's nutrient level and biological productivity, classified as oligotrophic (nutrient-poor, clear), mesotrophic (moderate), or eutrophic (nutrient-rich, often algae-choked).
• Eutrophication — the process by which a lake becomes nutrient-overloaded (usually from sewage, agricultural runoff, or detergent phosphates), triggering excessive algal growth and oxygen depletion. Lake Erie's mid-20th-century crisis and Lake Winnipeg's ongoing one are this book's standard examples.
• Ramsar site — a wetland formally designated under the Ramsar Convention as a Wetland of International Importance; a treaty-level recognition, not a domestic legal-protection category by itself.
• Reservoir — an artificial lake created by damming a river, typically for irrigation, drinking water, flood control, or hydropower.
• GLOF (Glacial Lake Outburst Flood) — the sudden release of a glacial lake's impounded water after its natural (usually moraine) dam fails, sending a destructive flood surge downstream.

Memory hook: "Fourteen terms, fourteen precise definitions — when a question uses the term instead of the lake's name, this glossary is the answer key."

Practice Recall: Before reading on, define "endorheic" and "brackish" in one sentence each, and name one lake from this book that exemplifies each term.

Answer: Endorheic — a closed basin with no outlet, water lost only to evaporation (e.g., the Caspian Sea or Sambhar Lake); Brackish — water saltier than fresh but less salty than seawater, from mixing at a lagoon (e.g., Chilika Lake).