Inventory Of The Morphometric And Limnologic Characteristics Of The Large Lakes Of The World

An inventory of the distribution, origin, morphometry, and limnologic characteristics of the world's large lakes has been undertaken. Natural lakes, fresh and salt, with a surface area greater than 500 km are included; 253 such lakes have been identified. Large lakes occur on all continents except Antarctica, but nearly half of them (48 percent) are found in North America and most of these lie above the 40th parallel, attesting to the scouring action of continental glaciers. Tectonic belts, such as the Rift Valley of east Africa and the Lake Baikal region of Siberia, are the second most common loci of large lakes. Tabular morphometric data include surface area, drainage basin, elevation, mean and maximum depth, volume, length and breadth, shoreline length and development ratio, and orientation of longest axis. These data show that the large lakes of the world occupy a surface area of slightly over 1,400,000 km and they have an estimated volume of 179,000 km. Large lakes account for approximately 90 percent of the total surface area and volume of water held in all lakes of the world. Climatic and limnologic data include precipitation, evaporation, basin runoff, water quality, and biological productivity. Seventy-five percent of the large lakes are fresh, with the remaining 25 percent ranging from brackish to hypersaline. The tropical, freshwater lakes of Africa are the most biologically productive.