Hunan province, China

The river bank, where fresh water flows, was the first place where people began to settle. Rivers, large and small, became poiletsy and feed of humanity. After all, we know perfectly well that without fresh water, all life on the planet cannot exist. And the river also gave food, so people tried for a long time not to move away from fresh water.

In ancient times, rivers were the main means of communication. It is for this reason that tribes settled along the banks of many rivers, cities were born. Even now, navigable rivers make it possible to establish transport links between coastal cities and settlements. Now man has learned to use the energy of river waters. Thousands of hydroelectric power stations have been built on the rivers.

The rivers are called the blue arteries of the earth. They cover the entire globe as if with a blue web. Rivers play a huge role in the lives of all people inhabiting the planet. People have long used the water of rivers for their own purposes. The rivers used for irrigation of land, for the transportation of goods, along the banks of full-flowing rivers arose the first agricultural areas in China and Egypt. Mountain rivers are characterized by fast flowing, clean and cool water. Mountain rivers feed on melting glaciers and snow. They have a high energy potential; it is particularly efficient to produce electricity on rivers flowing from high-mountain lakes. On the mountain rivers can be found waterfalls.

Rivers, as a rule, do not have a constant depth. They alternate sections with relatively large depths (lines) and shallow (rolls). If over the entire length and width of the river to measure the depth, and find the deepest sections of the river, then you can make a line of the greatest depths, it is called the thalweg. As a rule, river vessels go precisely along this line, since it is impossible to let the ship run aground. This safe way for ships is called fairway. It is especially good when the line of the greatest depths coincides with the line of the fastest current (rod), but this does not always happen.

To protect himself from misfortune, man built houses on high places or on high foundations along rivers, and also began a detailed study of the rivers near which he had to live. To do this, it was necessary to find out how the rivers receive food, where they start. And, as it turned out, the river is a complex formation, many factors are involved in the formation of the water flow.

The extraordinary generosity of deltaic soils, which restore their fertility during frequent river flooding, has become one of the main reasons for the flourishing of ancient states and the mighty civilizations of Egypt in the Nile delta, Assyria and Babylon on the lands of the fertile lowlands between Tigris and Euphrates. But modern deltas also play a big role in human life. Delta deposits are very fertile and favorable for farming. As a result, there is now a very high population density in these areas.

Spilling any river, although it sometimes delivers great inconvenience to people, is good for the soil, since along with water, many useful substances that fertilize the soil are brought. It is very well seen on the longest river Nile. This river receives water from the rains on the equator. When bottling in the middle and lower reaches, the river provides enough water to feed the soil. That is why agriculture in the Nile Valley has long been well developed, and the life of the bulk of the population is concentrated. In addition, the rivers are good transport routes, which carry a lot of different cargoes. And the constructed hydroelectric power stations give rather cheap electric power.

In the north of China, in the Amur basin on sod-podzolic soils, taiga forests grow with the participation of Daurian larch, Korean cedar and other coniferous and broad-leaved species. To the south, to the Qinling Range, there are both deciduous and mixed forests. Here, oak, linden, maple, walnut, and several species are represented. South of Qinling, a zone of subtropical forests stretches, where there are several species of laurel, camellia, magnolia, Masson pine and cunningamia. Numerous deciduous species grow in the mountains. In the extreme south and west of Yunnan, tropical forests and savannas dominate, consisting of mesophilic and humid tropical associations.

Western China differs significantly from eastern China by the uniformity of its forms: under conditions of low moisture and poor saline soils, mainly xerophytes grow - perennial drought-resistant shrubs and shrubs. A number of desert territories are characterized by sparse vegetation cover. The richest vegetation is represented here in the cereal and herbaceous steppes of the Western Prihingan. To the west, as precipitation decreases, the dry steppes, onion and wormwood-tyrse desert steppes, real deserts with desert soils and vegetation succeed each other. The vast deserts of the Gobi, Alashan, Takla-Makan deserts are the realm of moving sands, rocky deserts. The vegetation here is extremely poor, represented by shrubs and hodgepodge, sometimes with cereals. Areas that are completely devoid of vegetation are frequent.

From Alashani to the Dzungar Depression, in the depressions among the sands, along the river valleys, rare groves are found where variegated poplar and desert elm grow. In the mountain valleys of the Eastern Tien Shan and Kunlun there are forests where spruce, juniper and others grow. Qinghai-Tibet Plateau is an alpine cold desert. Plants are represented here by a small number of species adapted to extreme conditions of survival: low temperatures, strong winds, and abundant solar radiation. It was the lack of vegetable fuel in high mountain conditions that predetermined the spread of a specific funeral rite here - the dismemberment of a corpse into feed for wild animals. To the east, where the climate is milder, more moisture, there are mountain meadows and steppes, and in the Brahmaputra valley there are coniferous forests.

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