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RIVERS AND LAKES—THEIR DISTRIBUTION, ORIGINS, AND FORMS
RIVERS AND LAKES—THEIR DISTRIBUTION, ORIGINS, AND FORMS I. Distribution of Fresh Waters II. Running Waters: Lotie Ecosystems III. Morphology and Flow in River Ecosystems A. Drainage Basin B. Water Influx and Movement C. Channel Morphology IV. Groundwater Fluxes to Lakes V. Geomorphology of Lake Basins A. Tectonic Basins B. Lakes Formed by Volcanic Activity C. Lakes Formed by Landslides D. Lakes Formed by Glacial Activity E. Solution Lakes
The amount of fresh water on earth is very small in comparison to the water of the oceans, but the fresh waters have much more rapid renewal times (cf. Table 1-1). On a volumetric basis, fresh water is concentrated in large, deep basins of several great lakes. About 20% of surface fresh water is contained in Lake Baikal of Siberian Russia. The number of individual depressions of smaller lakes and reservoirs is extremely large, how ever, and most of these lakes are located in temperate and subarctic regions of the Northern Hemisphere. Most lakes are shallow and geologically very transient. Catastrophic events of glacial, volcanic, and tectonic activities have aggregated many freshwater lakes into lake districts. The morphometry and geological sub strata of the drainage basins are very important because these properties influence sediment-water interactions, the resultant productivity, and the significance of littoral productivity to that of the river and entire lake ecosys tem. Shallow lakes, which have more sediment area per unit of water volume, are generally more productive
VI.
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VIII. IX.
F. Lake Basins Formed by River Activity G. Wind-Formed Lake Basins H. Basins Formed by Shoreline Activity I. Lakes of Organic Origin Morphology of Lake Basins A. Morphometric Parameters B. Hypsographic and Volume Curves Reservoirs A. Reservoir Characteristics B. Zonation in Reservoirs Comparative Geomorphological Characteristics Summary
than deep lakes, and a greater proportion of their total productivity is attributable to communities of the littoral and wetland areas of the land-water interface. I. DISTRIBUTION OF FRESH WATERS Inland waters cover less than 2 % of the earth's sur face, approximately 2.5 X 106 km 2 . About 20 lakes are extremely deep (in excess of 400 m), and a significant portion of the world's fresh water is contained in Lake Baikal, Siberian Russia (A = 31,500 km 2 ; zm = 1620 m; z = 740 m), the deepest lake of enormous volume (23,000 km 3 ). Like Lake Baikal, nearly all other ex tremely deep lakes are tectonic or volcanic in origin or have formed from fjords that have subsequently become fresh. Although a few lakes of glacial origin, such as the Laurentian Great Lakes and Great Slave Lake of Canada, have basins of great depth, few exceed a depth of 300 m. Most of the very deep lakes are found in 1R
The amount of fresh water on earth is very small in comparison to the water of the oceans, but the fresh waters have much more rapid renewal times (cf. Table 1-1). On a volumetric basis, fresh water is concentrated in large, deep basins of several great lakes. About 20% of surface fresh water is contained in Lake Baikal of Siberian Russia. The number of individual depressions of smaller lakes and reservoirs is extremely large, how ever, and most of these lakes are located in temperate and subarctic regions of the Northern Hemisphere. Most lakes are shallow and geologically very transient. Catastrophic events of glacial, volcanic, and tectonic activities have aggregated many freshwater lakes into lake districts. The morphometry and geological sub strata of the drainage basins are very important because these properties influence sediment-water interactions, the resultant productivity, and the significance of littoral productivity to that of the river and entire lake ecosys tem. Shallow lakes, which have more sediment area per unit of water volume, are generally more productive
VI.
VII.
VIII. IX.
F. Lake Basins Formed by River Activity G. Wind-Formed Lake Basins H. Basins Formed by Shoreline Activity I. Lakes of Organic Origin Morphology of Lake Basins A. Morphometric Parameters B. Hypsographic and Volume Curves Reservoirs A. Reservoir Characteristics B. Zonation in Reservoirs Comparative Geomorphological Characteristics Summary
than deep lakes, and a greater proportion of their total productivity is attributable to communities of the littoral and wetland areas of the land-water interface. I. DISTRIBUTION OF FRESH WATERS Inland waters cover less than 2 % of the earth's sur face, approximately 2.5 X 106 km 2 . About 20 lakes are extremely deep (in excess of 400 m), and a significant portion of the world's fresh water is contained in Lake Baikal, Siberian Russia (A = 31,500 km 2 ; zm = 1620 m; z = 740 m), the deepest lake of enormous volume (23,000 km 3 ). Like Lake Baikal, nearly all other ex tremely deep lakes are tectonic or volcanic in origin or have formed from fjords that have subsequently become fresh. Although a few lakes of glacial origin, such as the Laurentian Great Lakes and Great Slave Lake of Canada, have basins of great depth, few exceed a depth of 300 m. Most of the very deep lakes are found in 1R