Streams and rivers have a longitudinal zonation or profile (Fig. 4.12) instead of horizontal in lakes and ponds. lilies and Botosaneanu (1963) have recognized two major subdivisions of a river course: the steep and torrential upper course ("rithron ") and the flat, slow-flowing lower course ("potamon "). However, a true rhithron having water temperature below 20°C, may be often absent [...]
Lakes in temperate latitudes exhibit marked seasonal temperature changes which may be described as follows: Winter: During winter the coldest water forms ice at 0°C (32°F) and floats at the surface. The water at increasing depth below the ice is progressively warmer and denser. The heaviest water, at the bottom of the lake, has a winter temperature of 4°C and [...]
Lake Eutrophication: Types and Effects Eutrophication is the process by which lakes are enriched naturally or, more usually, by human activity. As a result, an oligotrophic lake ("underfed" or "nutrient poor") may become eutrophic ("well-fed" or "nutrient rich") in due course of time. The key nutrients responsible for eutrophication are nitrogen and phosphorus. Excess nutrients come from a variety of [...]