Rivers and Lakes of Northern Asia. Undrained Areas

     Rivers are unevenly distributed in Asia. In the wetter regions flow large and deep rivers. In the dry regions of Central and South­western Asia, on the other hand, rivers are few and shallow. The greater part of the large rivers rise in the high mountains and branch off in different directions towards the seas that wash the coasts of Asia.

Fig. 85. Lake Baikal. The picturesque mountainous shores of the enormous lake are covered with forests.

In Central Asia there are vast undrained areas whose rivers do not reach the sea. but either end in salt lakes or disappear in the sands.
Rivers and Lakes ol Northern Asia. There are many large rivers in Northern Asia. The largest are the Ob, the Yenisei and the Lena, each of which is longer than Europe's greatest river, the Volga.
Siberian rivers are frozen for the greater part of the year. Spring sets in earlier in the south, and the upper reaches of the rivers begin to melt and flood there when winter is still in full swing in the north. The blocks of ice coming downstream are detained by the solid ice of the lower reaches. There occur jams that cause the rivers to rise and overflood their banks.
The O b rises in the Altai. After descending the mountains this noble river continues calmly across the West Siberian Lowland, dividing into branches in some places, overflowing in others. It falls into a broad inlet (bay) of the Kara Sea. The Ob's chief tributary is the Irtish.
The Yenisei, too, rises in a range of mountains in the south of Siberia. In its upper reaches it is a rapid mountain stream, but as it continues across the eastern edge of the West Siberian Lowland it puts on the appearance of a plain-river. The Yenisei takes in many tributaries and finally, a wide and deep stream, falls into the Kara Sea east of the Ob. The name itself, Yenisei, means 'big water'.
The Angara, the Yenisei's largest tributary, has its source in Lake Baikal.
Lake Baikal is bordered by high, mountainous shores. This large lake was formed as a result of a sinking of the earth's crust. It is almost twice the size of Lake Ladoga and is the deepest lake in the world (1,620m.). In volume of water it ranks second after the Caspian. Over 300 rivers and rivulets fall into Lake Baikal, but only one, the Angara, leaves it.
Lake Baikal is very beautiful. On still and sunny days its waters are bright greenish-blue, their transparency reflecting the sur­rounding cliffs. In windy weather, however, Lake Baikal is dark and threatening, storming angrily against the rocky shores.
The Lena rises on the slopes of .a range bordering Lake Baikal on the west. It flows across the edge of the Central Siberian Plateau and falls into the Laptev Sea, forming a giant delta.
It is impossible to overestimate the importance of North Sibe­ria's rivers as channels of communication when we consider its enor­mous size and the lack of railways. Especially has this importance increased after the opening of the Northern Shipping Route. Car­goes are transported to the mouths of the rivers by sea, and from there up the rivers to the interior of Siberia. So deep is the Yenisei in its lower course that large seagoing steamers can travel far up it.

Siberia: The Lena River.

Siberian rivers are rich in water-power, especially the Angara. The world's largest hydroelectric power-dams are now being built on the Yenisei and Angara Rivers.

rous salt lakes, or salines, in these areas have no outlets. Local rivers either feed them with their waters or disappear in the sands.
Across the Turan Lowland flow the Syr Darya and the full-bodied Amu Darya. Both rivers rise in the mountains -the Syr Darya in the Tien Shan, the Amu Darya in the Pamirs and Hindu Kush. In their upper reaches they rush swiftly through the mountain gorges, but slow down upon reaching the plain. They both fall into a large though shallow salt lake called the Aral Sea.
In the west the Turan Lowland borders on the Caspian Sea. Like the Aral Sea, the Caspian has no links with other seas and is really a lake—the largest in the world. It was formerly connected with the Sea of Azov by the Kuma-Manych Depression. Considering its size, depth (about 1,000 metres) and salinity, the Caspian deserves to be called a sea (though it is three times less salt than the ocean).
Much fish is caught in the Caspian Sea. There is seal, too. Oil is extracted, not only along the shores, but from the bottom of the sea as well.
North of the Tien Shan there is a large but shallow lake— Lake Balkhash. It has no outlet, and its water, especially in its eastern part, is salt and unfit to drink.
Among the lofty Tien Shan ranges lies a large, deep and brackish lake — Issyk Kul (over 700 metres deep). Small streams flow into it from the mountains, not a single effluent leaving it.

areas with a rich vegetation, cultivated fields and dense populations. Canals are built to drain water from the rivers for watering the crops. Without artificial irrigation agriculture in these desert areas would be almost impossible.
In the desert areas of Turan in the U.S.S.R. large-scale irrigation work is being carried on. Big reservoirs are being built. Canals from the Syr Darya, Arnu Darya and other rivers are used to water the fields. The amount of watered lands is thus being steadily increased.
Questions and Assignments.

• Mark and name on the outline map the rivers and lakes of
  Northern Asia and the undrained areas.
• Draw a sketch of Lake Baikal, doubling the scale in comparison
  with that of the map of Asia in your Atlas. Now compare the sizes of
  Lake Ladoga on the map of Europe and Lake Baikal on your sketch.