A watershed is a concept that hydrology is actively studying. What is the essence and significance of this concept for science? What types of watersheds are distinguished by scientists? The answers to these questions are in our article.
The watershed is ... Definition
There are tens of thousands of rivers on our planet. And each of them collects water from a specific area. A watershed is a conditional line drawn on the earth's surface. Before determining the essence of this concept, you should familiarize yourself with some other terms. We are talking about two hydrological concepts: the river system and the river basin.
A river system is a water system consisting of a main river and all its tributaries. By a river basin is meant the territory from which all water (both surface and underground) flows into a specific river system. Now we can give a logical and understandable definition of the concept of a river watershed.
A watershed is a line that delimits neighboring river basins. In mountainous or hilly areas, it is more pronounced, and in the plains it is more weak. In the mountains, watershed lines often run along ridges and ridges. In this case, the runoff of water and precipitation is directed in different directions from the ridge (along opposite slopes).
Within the lowlands, the watershed can be fuzzy in relief. Moreover, in such areas its line may even shift in one direction or another with time or depending on the season.
The main types of watersheds
The watershed dividing the basins of different oceans or designating areas of inland continental runoff is called continental. For example, in America, this line runs along the highest ridges and peaks of the Cordillera and the Andean Mountains.
In Europe, the most important watersheds are the Alps, the Scandinavian mountains, as well as the Valdai Upland. Within the limits of the last form of relief, three major rivers originate: the Volga, the Dnieper and the Western Dvina. Moreover, each of them carries its waters to different seas - to the Caspian, Black and Baltic, respectively.
In addition, it is customary to distinguish underground and surface watersheds. The first of them delimits underground drainage basins, and the second - surface. And they do not always coincide with each other.
Sometimes the concept of a watershed is used to distinguish between separate large forms of the Earth's relief. For example, Orinoco is a river that is a watershed between the Guiana Plateau and the Andes in South America. However, such a formulation is not entirely correct from the point of view of hydrological science.
Watershed study
The study of the conditional topographic lines described above is of great scientific and practical importance. Especially when it comes to the active development of human geographical space.
So, when designing bridges, dams or power plants on a river, you just need to have an idea of how the dividing lines in a particular region go. Even more important is a detailed study of the watersheds when planning large reservoirs. This is necessary in order to maximally accurately calculate the amount of possible filling of the future reservoir.
Volga river basin and its watershed
The Volga is the largest river system in Europe, including over 150 thousand watercourses: rivers, permanent and drying streams. The drainage basin of this river occupies a huge area - 1.36 million square meters. km This territory is comparable in size to states such as Peru or Mongolia. Within the Volga river basin there are 30 constituent entities of the Russian Federation, one region of Kazakhstan and dozens of large cities (in particular, Moscow, Ryazan, Tver, Orel, Kazan, Astrakhan, Perm and others).
The Volga watershed runs along the Central Russian Upland in the west, the hills of the Northern Uval in the north, along the western slopes of the Ural Mountains, the General Syrt Upland and the Caspian Lowland in the south.