Hydrology lakes – Statopedia
5.1 Classification and water balance of lakes
Lakes are referred to as water-filled basins or depressions of the earth’s surface, which has no direct connection with the sea (ocean) and characterized by slow water exchange.
In the development of the lake can be divided in three phases :
the lake basin remains almost unchanged, the existing deposits have not have a noticeable impact on his couch;
– formed coastal shoal, there is a Delta at the confluence of the rivers develop water vegetation;
– roughness of the smoothed basin of sedimentation due to products of destruction of coast and slopes of the deltas extends onshore shallow, reduced depth, vegetation covers almost the entire surface of the lake.
In the future it turns into a small pond with the widespread development of vegetation, of which the underwater part goes to the surface and turns the lake into a swamp.
The origin of the lakes can be dammed, hollows and mixed.
Dammed lakes are formed due to the overlap of the river valley by a cave with sediment, the detrital material of the retreating glacier.
Hollow lake, depending on the circumstances and causes of the education basin are tectonic, volcanic, deflationary, glacial, karst and thermokarst.
Lakes in tectonic basins were formed by tectonic processes (abrupt changes in the earth’s crust), for example during earthquakes. Tectonic lakes are very deep (lake Baikal, lake Sevan, Issyk-Kul, etc.).
Volcanic lakes appear under the action of volcanic forces, for example, Kuril lake, Chronicle, etc.
Deflation lakes are formed as a result of the blowing of rocks and in depressions between the dunes and dunes. Their basins are usually shallow.
Glacial lakes are the result of the action of glaciers, which once covered vast areas of continents (oz. Seliger).
Karst lakes are the result of chemical activity of groundwater and surface water. These lakes occur in the basin of the Northern Dvina, Volga and Onega watershed, in the Nizhny Novgorod region, Mari and Bashkir republics.
Thermokarst lakes occur as a result of flooding of the cavities on the surface of the earth, formed in areas of permafrost due to melting of subsurface layers or lenses of ice (lakes of Yakutia).
Mixed lakes are formed from the combined effects of different reasons. For example, lacustrine basin of tectonic origin was subjected to the action of glaciers, which influenced its formation (lake Ladoga and lake Onega). The basin of the lake dam type may be prepared by the processes of weathering, activity surface water and groundwater.
The lakes are divided into two categories . sewage and closed.
Sewage lakes are characterized by the fact that the incoming surface water and groundwater are consumed for food resulting from their rivers, as well as for evaporation and filtration. Waste lake can have a perennial flow year-round or only during the period of the greatest influx (temporary sewage lakes).
In the particular case when one of flowing into the rivers lake water of the same order as that of the river flowing from it, the lake is called flow. The river flowing from the lake, has a smaller amplitude of fluctuation of levels (and costs); the hydrographs of these rivers are more flattened and spread than the available hydrographs of the rivers. The lake serves as a natural regulator of the regime stemming from the river.
Inland lakes spend of incoming water in them mainly for evaporation and partly to seepage into the ground.
The composition of the lake water are divided into fresh and salt, or mineral. Sewage lakes as a rule, are fresh. In the inland lake the evaporation of pure water, and salts remain in it. Therefore, the water in the inland lake continuously mineralized (becomes saline), and the faster, the greater the concentration of salts in water bringing it.
In b.The USSR has more than 2.8 million lakes, the total area of which is about 490 thousand km (excluding the Caspian and Aral lakes, which is considered inland seas). Small lake, with water surface area less than 1 km , consists of 99.2 %. Fourteen lakes with a water surface area more than 1000 km, are among the greatest lakes in the world. In the lakes are concentrated 27.2 thousand km of water. Of these, 23 thousand km of this is lake Baikal.
Waste water balance of the lake . that is, the ratio of the arrival and flow of water can be represented as:
where surface and groundwater inflow into the lake;
condensation of water vapor on the surface of the lake;
– precipitation on the lake surface;
– surface and underground flow from the lake;
– evaporation from the lake surface;
– accumulation of water in the lake.
All members of the water balance equation expressed in the form of a layer of water.
Endorheic lakes in the runoff from the lake is missing, water is mainly consumed for evaporation.