Goh Cheng Leong Chapter 9: Lakes YouTube Lecture Handouts Geography
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Goh Cheng Leong Chapter 9: Lakes
- Hollows of land where water accumulates β vary in size, shape, depth and mode of formation
- Caspian Sea (760 miles long; 3215 ft deep & area of 143,550 square miles β bigger than Malaysia)
- Can be temporary or permanent
- Fresh water lakes β Lake Geneva, Lake Poyang, Great Lakes of America
- Inland drainage β region of low precipitation and intense evaporation β high salinity like Dead Sea (250 parts per thousand) ; Great Salt Lake in Utah
- Low salinity β Black Sea which received many rivers
- Desert β lakes known as playas
- Lakes dry up in regions of unreliable rainfall
- In hot desert β lake disappear by evaporation, percolation and outflow
Formation of Lakes
Formed by Earth Movement
- Tectonic Lakes β warping, sagging, bending and fracturing β lake Titicaca (in intermontane plateau of Andes) β highest lake in world; Caspian Sea (largest lake β 5 times larger than Lake Superior)
- Rift Valley Lakes β faulting and sinking of land between faults & water collects in trough β East African rift Valley (Zambia, Malawi, Tanzania, Kenya and Ethiopia β extending along Red Sea to Israel and Jordan) β includes Lake Tanganyika (worldΥs deepest lake) , Malawi, Edward, Rudolf, Albert and Dead Sea (worldΥs lowest lake β 1286 BSL)
Formed by Glaciation
Cirque Lakes or Tarn Lakes β arm chaired as Red Tarn in Lake District. Ribbon lakes like Lake Ullswater long and deep
Kettle Lakes β outwash plain by melting of stagnant ice β irregular and uneven morainic surface β meres of Shropshire in England and Orkney in Scotland
Rock-Hollow Lakes β formed by ice scouring when ice sheets scoop the surface β found in Finland (country known as Soumi or land of lakes by Finns with more than 35,000 lakes)
Lakes formed by morainic damming of valleys - morainic debris when water accumulates behind the barrier (both lateral and terminal moraines) β Lake Windermere of Lake District in England
Lakes by Deposition of glacial drifts β in poor drainage with drumlins and intervening depressions as in County Down in Northern Ireland
Formed by Volcanic Activity
Crater and Caldera Lakes β volcanic explosion of top cone of volcano β can be enlarged into caldera β Crater Lake, USA; Lake Toba in North Sumatra & Lake Avernus near Naples
- Lava Blocked Lake β in volcanic areas it solidifies as Jordan valley forming Sea of Galilee (inland elongated lake)
- By subsidence of Volcanic Land surface β shallow depression as Myvatn of Iceland
Formed by Erosion
- Karst lakes β solvent action of rain water on limestone carves out solution hollows β these are clogged with debris β collapse of limestone roofs β long narrow lakes as Lac de Chaillexon in Jura Mountains.
- Polje donΥt have surface outlet and contain lakes β during wet period cover floor by shrink in dry periods β Lake Scutari in Yugoslavia
- Solution is important in rock salt β meres of Cheshire, England
- Wind deflated lakes - in desert create playas and salt lakes β Qattara Depression in Egypt; Great Basin in Utah, USA
Formed by Deposition
Due to river deposits β ox bow lakes in flood plains of Mississippi, USA and Rio Grande, Mexico
Due to Marine deposits β isolate lagoons along coast by building spits and bars β in deltas of Nile and Ganga. In East Germany and Poland these are called haffs. Strong offshore winds push coastal sanddunes landwards and enclose as marshy lagoons β in Landes of SW France
Due to Landslide, Scree and Avalanches β barrier lakes which are short lived due to loose fragments that pile across valleys. Lake Gormire in Yorkshire blocked by landslides and Ffynnon Frech on Snowdon blocked by screes
Formed by Human or Biological Activities
Man made lakes β artificial lakes by concrete dam and reservoir β Lake Mead above Hoover dam on Colorado River, USA
Made by Animals - beavers β Beaver lake in yellow Stone National park, USA
Ornamental lakes β Lake Gardens in Kuala Lumpur, Taiping lakes
Mining lakes β tin mining created many lakes in West Malaysia
Fishing Lakes β created by inland fish culture
Lakes and Man
Means of communication: Great Lakes- . Lawrence waterways in USA β arteries of commerce.
Tonnage through Sault Ste. Marie Canal or Soo Canal between Lake Huron and Superior is greater than combined annual tonnage of Suez and Panama Canals
Economic and Industrial development: early settlements and town sites, industries, raw material and fuels are handled by HOMES (in USA) ; Yangtze basin with industrial development of Wuhan (Wuchang, Hanyang and Hankow)
Water Storage: Domestic water supplies like Britain Lake Thirlmere supplies to Manchester; Loch Katrine to Glasgow; Lake Vyrnwy (in Wales) to Liverpool. Okhla Reservoir to Delhi. Veterna, Vihar and Tulsi lakes to Bombay
HEP Generation: Niagara River from L. Erie to Ontario has regular supply to power stations while Catawba River in Carolinas has little water during dry seasons as it does not flow from lake.
Abu Bakar Dam of Cameron Highlands supplies to central west Malaysia. Aswan Dam on Nile & Lloyd Barrage on Indus at Sukkur suffers from similar defects
Agricultural Defects: thick fertile alluvium will be formed β Vale of Pickering in Yorkshire or Red River valley of Canada (former site of lake Agassiz) . Dams for irrigation β Sennar dam on Blue Nile in Sudan; Burrinjick Dam on Murrumbidgee in Australia; Hirakund Dam on Mahanadi
Regulating River Flows: Steady flow of river is maintained by absorbing excess water in rainy season. Poyang and Tung Ting on Yangtze Kiang, Tonle Sap on Mekong, Lake Constance on upper Rhine.
Artificial reservoirs on Hoover Dam on Colorado River and also Bhakra Nangal on Sutlej Rivers.
Moderation and Climate: Water in lakes cools the air in summer by absorbing heat and warms in winter by releasing heat. East of Lake Erie, Ontario and Huron has milder winter than west as oncoming winds are warmed and frosts are minimized.
Lake Peninsula has grapes and fruit farming. Large lakes like Lake Michigan and Caspian Sea exert influence on cloudiness of the region.
Source of Food: protein by fresh water fish. Sturgeon in Caspian Sea; salmon and trout in Great Lakes & Tonle Sap in Cambodia. Amateur fishing in lakes is rewarding pastime. Fish breeding in China and Japan.
Sources of Minerals: high salinity like common salt. Borax is mined in salt lakes of Mojave Desert. Gypsum in Cheshire & potash in Stassfurt near Berlin
Tourist Attraction and Health Resorts: Lake Geneva, Lucerne, Lugano, Como, Placid, Vaner, Vatter, Taiping.
β Manishika