Fresh and salt lakes are examples. Lakes: drainage and drainless, fresh and salty. Learning new material

Geography lesson in 6th grade

Teacher: Neborak T.I.

Lesson topic: "Blue Eyes of the Planet" ( Lakes).

Target: get acquainted with the diversity of lakes on our planet and their origin.

Tasks:

educational: to form students’ ideas about the lake, types of lake basins, drainage and drainageless, fresh and salt lakes;

developing: development of individual cognitive interests among students;

educational : to cultivate in students a sense of love for their Motherland, pride in their land.

Lesson type: explanation of new material.

Upon completion of the lesson the student should:

Know: what is a lake? types of lake basins; drainage and drainageless, salt and fresh lakes;

Be able to: show lakes on the map.

Technologies: lesson using ICT and problem-based learning.

Equipment:

TSO means: computer, projector, screen.

Didactic and visual material: Route sheets, textbooks, map of the hemispheres and physical map of Russia, atlases, slides are shown in parallel.

Lesson steps: 1. Organizational

2. Studying new material with step-by-step reinforcement.

3. Lesson summary.

4. Homework

During the classes.

1. Organizational.

Hello guys! Today I will teach the geography lesson - Tatyana Ilyinichna Neborak. I hope that our cooperation will be not only pleasant, but also fruitful.

2. Studying new material.

(against the background of music).

Teacher. Listen and guess the riddle that will tell us the topic of today's lesson. Slide No. 1.

There is a mirror in the middle of the field.

The glass is blue, the frame is green.

Young mountain ash trees look at it,

Their colored ones, directing their scarves

Young birch trees look at him,

Adjusting your hair in front of him.

Both the month and the stars - everything is reflected in it...

What is this mirror called? (Lake).

Teacher. Right. This lake. The topic of our lesson is “The Blue Eyes of the Planet.” (Lakes). Slide number 2.

Teacher. Throughout the lesson we will consider the following questions:

The variety of lakes on our planet and their origin;

Which lakes are called drainage and which are drainless;

Let's get acquainted with the concepts of salt and fresh lakes. Slide number 3.

Teacher. Today we will take notes in class not in notebooks, but in Route Sheets, ( Appendix No. 1) which are on your desk. Slide number 4.

Teacher. Our educational road is long and therefore we hit the road without delay.

Teacher. Guys, how many of you have seen the lake? Hands up.

Teacher. I invite you to close your eyes for a few seconds and imagine a lake. (Music). Now let’s open our eyes and tell you what we saw. Before my eyes, the lake was round and shallow. What words do you associate it with? (small and large, deep and shallow, etc.). (Children's answers)

Exercise. Try to formulate a definition of the concept of “lake”.

(Children answer).

Teacher. Let's compare it with the definition that the authors of the textbook offer us. p. 95. Who was the first to find the definition?

A lake is a closed body of water formed on the land surface in a natural depression.

We write down the definition in the Route Sheet. Slide number 5.

Teacher. This depression is called a lake basin.

Teacher. Guys, the lake is not part of the ocean, like the sea. (explanation)

Teacher. We have already found out that a lake is a natural depression or lake basin formed on the earth’s surface. What natural processes and phenomena can lead to the formation of lake basins? Yes, the question is difficult, but we will now try to answer it.

For further work we will need the atlases on page 16 " Physical card Russia."

Teacher. So, pay attention to the screen.

Teacher's story.

Tectonic in troughs (residual). They were formed due to the slow subsidence of vast areas of the earth's crust, which were filled with water. (Aral, and the largest lake in the world - Caspian). Slide No. 6,7.

2. Tectonic in faults. When moving sections earth's crust cracks formed and filled with water. As a rule, such lakes are very deep. (Tanganyika, Nyasa on the African mainland. What do you think, there are such lakes in Russia). - Most deep lake- Baikal. It is unique. In fame and glory he has no equal. Nai great depth- 1620m. Baikal contains one tenth of the fresh waters of the entire Earth. In terms of water transparency, Baikal ranks first in the world. 336 rivers and rivulets flow into the lake, and only Angara flows out. Slide No. 8,9.

3. The lakes are of glacial origin and were formed on the site of depressions deepened by a glacier. (Onega. Ladoga This lake has a glorious history: during the Great Patriotic War, the Road of Life passed along its ice - the country’s only connection with besieged Leningrad).

Slide No. 10,11.

4. Dams were formed as a result of a collapse or shedding of rocks into a river valley. An example is Lake Sarez in the Pamirs.

(Student's story). On a February night in 1911, the residents of Bartang woke up from an incredible roar coming from the bowels of the earth. The roar was accompanied by a deafening stone crash. It seemed that somewhere above an invisible genie was raging, breaking the Pamir giant. Giant rock fragments were flying from the peaks. The frightened people felt as if they were on choppy waves; the soil moved underfoot. There was a strong earthquake. And clouds of large dust swirled over the village of Usa for several days. And when the dust cleared, in the riverbed people saw a miraculous stone wall half a kilometer high. A wall formed from fragments of rocks blocked a stormy river. This is how Lake Sarez was born in the Pamirs.” Slide No. 12,13.

5. Volcanic. Their lake basins are located in the crater extinct volcanoes. (Kronotskoye, Kurilskoye.) Slide No. 14,15.

6. Oxbow lakes are often found in river floodplains; they are the remnants of former river channels. These lakes are small, so they are not indicated on the map. They have an arched shape. Slide number 16.

7. Karst. Easily soluble rocks (limestone, salt, etc.) are found in the earth’s crust and on its surface. When they dissolve, voids, caves, and basins are formed on the earth’s surface, which are filled with water. (Many in the Urals, Caucasus). Slide number 17.

Dynamic pause. (Close screen)

Teacher. The Route Sheets contain a table “Types of lake basins”. Working with the textbook pp. 96-97 and relying on the material that I told you, you fill out the table. We will work in pairs. I gave you cards in advance on which only one type of origin of lake basins is written. You will describe it.

Guys, pay attention to the example of filling. Slide number 18.

Basin type	Reason for formation
Tectonic in troughs	Subsidence of vast areas of the earth's crust	Aral, Caspian
Tectonic in faults	Subsidence of sections of the earth's crust along a fault	Baikal, Nyasa, Tanganyika.
Glacial	The basin is deepened by ancient glaciers.	Onega, Ladoga.
Zaprudnye	The river bed is blocked by a landslide or a flow of hardened lava.	Sarez.
Volcanic	Craters of extinct volcanoes	Kronotskoye, Kurilskoye.
Karst	It is formed after the collapse of the top layer covering the underground cavity and fills it with water.
	Sections of the former river bed that have changed their direction.	Small ones are not indicated on the maps.

Teacher. Did you complete the task? Now let's create a general table.

(Those interested in groups report on the work done).

Teacher. Guys, do you know the name of the lakes in the Kargat region? (eastern part of Lake Ubinskoye, Kargan, Malye and Bolshiye Toroki, Atkul, Kankul, Kayly, Bizyura). The lakes in our area are the remnants of an ancient lake system. Slide number 19.

Teacher. A lake is a depression filled with water. Where do you think the water in these depressions comes from? What do the lakes feed on? (atmospheric precipitation, groundwater, water of inflowing rivers). Slide No. 20,21.

Teacher. All lakes can be divided into 2 groups based on water inflow and outflow.

In the diagram you can see lakes and rivers. Please note that rivers can flow into and out of lakes .

Children's answers.

Teacher. We have two new concepts: drainage and drainless lakes. Let's try to formulate definitions. Slide number 22.

A sewage lake is a lake into which rivers flow in and out (or only flow out)

Endorheic lakes are lakes into which rivers only flow.

Teacher. What type of lake do you think Lake Baikal belongs to? (children's answers)

Why? (children's answers)

Examples of sewage lakes are also Onega and Lake Ladoga.

What type of lake is the Aral Sea-lake? (children's answers)

Why? (children's answers)

Examples of closed lakes are also the Caspian and Balkhash.

Write examples of lakes in the table. Slide number 23.

	Baikal, Onega, Ladoga
Drainless	Caspian, Balkhash, Aral

Teacher. Lakes differ not only in water flow, but also in the presence of salts. Let's remember, what is salinity? (amount of minerals in 1 liter of water). And what is it expressed in? (in ppm-thousandths of a number). Slide No. 24,25.

Teacher. All lakes can be divided into two groups based on salinity: fresh - up to 1%; salty - from 1%o to 35%o. Fresh ones are indicated on the map in blue, salted ones in pink.

Teacher: Find Lake Balkhash in the atlases. Pay attention to its color. Part of the lake is colored blue, and the other pink. Why do you think? (saline lakes are most often drainless, since minerals brought by rivers gradually accumulate in the lakes)

Teacher. Is Lake Baikal fresh or salty? ? (Children's answers)

Exercise: Write examples of lakes in the table.

	Baikal, Ladoga, etc.
	Balkhash, Caspian, Dead (270 ppm)

Student messages about Dead Lake. Slide number 26. Listen to what a person who has visited its shores says about one of the saltiest lakes, Dead Lake: “We stood on a deserted shore, the dull appearance of which evoked sadness: a dead land - no grass, no birds. On the other side of the lake, reddish mountains rose steeply from the green water. We decided to go for a swim, but they dissuaded us. We just washed ourselves with water as thick as brine. After a few minutes, my face and hands were covered with a white coating of salt, and an unbearably bitter taste remained on my lips. Sometimes fish swim from the Jordan River into the Dead Lake. She dies within a minute. We found one such fish washed up on the shore. It was hard as a stick, in a strong salty shell.”

Teacher. How do people use lakes? Slide number 28.(fishing, for navigation, raising waterfowl, extracting salt, the coast of lakes is a favorable area not only for life, but also for recreation and restoration of health).

Teacher. Lakes have been used by humans since ancient times. But today, like other bodies of water, many lakes are polluted with oil products, industrial and household waste, and pesticides from fields. The “blue eyes” of the planet, including the lakes of the Kargat region, ask for help from people, shedding pure tears.

Slide number 29. Even the tiniest lake filled with “living water” should be treated as a most valuable gift in order to convey this cup of priceless life-giving moisture to the future generation.

3. Lesson summary.

Teacher. Our lesson is coming to an end. I would like to know how fruitful it was. Answer the questions: what new did you learn? what did you learn? Start your answers with... Slide number 30.

I found out…

I can…

4. Homework. Slide No. 31. Now pay attention to homework. Read 31 paragraphs, describe the lake Baikal according to a standard plan (on route sheets). Prepare reports about unusual lakes in the world (optional). (they don’t write it in the diary because homework written down on route sheets).

And also, I would like to know the attitude of each of you to the lesson. Choose the emoticon that most clearly reflects your mood. And I, in turn, will give you my emoticons as a keepsake of this lesson.

Thank you for the lesson. Slide number 32.

Route sheet

Lesson topic: “ Blue eyes of the planet”(lakes).

Lake - _____________________________________________________________________

_____________________________________________________________________________

Types of lake basins

Basin type	Reason for formation	Examples
Tectonic in troughs (residual)
Tectonic in faults
Glacial
Zaprudnye
Volcanic
Karst

By flow and inflow of water


Drainless

By salinity

Fresh up to 1%o
Salted from 1% and above

Homework: read the text of the textbook, paragraph 31, using the plan to describe Lake Baikal, prepare reports about unusual lakes (optional).

Fill out the table:

Description of Lake Baikal according to a standard plan

Lake description plan	Characteristics of the lake
1. Title
2. On what continent is it located and in what part of it?
3. Between what meridians and parallels is it located?
4. Origin of the basin
5. Waste or drainless. Inflowing and outflowing rivers
6. Salty or fresh

Unusual lakes of the world: ink lake, pan lake, burning lake, ghost lake, asphalt lake, sweet lake.

A lake is one of the components of the hydrosphere, the water shell of the Earth. Lakes are bodies of water that have arisen naturally. They represent a kind of bowl (lake bed), filled to the brim with water. There are more than five million lakes on Earth, total area which is more than 2.7 million sq. kilometers.

The science of planetology defines a lake as an object, stable

existing in time and space and filled with liquid matter. The size of the lake, according to the same science, is average between the sea and the pond. If we consider lakes from a geographic point of view, they are depressions in the earth's surface into which water flows and accumulates. It is important to know that such bodies of water are not part of the World Ocean.

The chemical composition of lake water is considered quite stable. The water in the lakes practically does not circulate, so the filling liquid is renewed quite rarely. Lakes perform an important function - they hold water in their basins and release them at different periods of time.

Such reservoirs have significant thermal inertia, and therefore help moderate the climate in the surrounding areas. In lakes, processes of accumulation of sediments (minerals and minerals) constantly occur, which in turn form bottom sediments. During the subsequent development of the reservoir, bottom sediments can be transformed into land, swamps or mountain sediments.

Large lakes can have a mitigating effect on the climatic conditions of adjacent areas. Lakes existing on the planet are classified according to several criteria. They can be above-ground and underground, mountainous, riverine, crater-shaped, or collapsed. They can be anthropogenic, that is, artificial and natural. According to their water balance, they are divided into waste and non-waste.

Endorheic lakes

There are many land areas on Earth with river systems that are not connected to the World Ocean. River basins located in such areas are called drainage basins. And the bottom of such pools is, as a rule, a closed lake. Science gives the following definition: an endorheic lake is a body of water that has no outlet underground and no surface drainage. Simply put, one or more rivers may flow into such reservoirs, but none of them flows out.

Drainless lakes form in areas with arid climates, where moisture is much lower than evaporation. Endorheic lakes are scattered throughout the planet; they are found on all continents, even in Antarctica. There such lakes are located on the territory of Victoria Land and the McMurdo Dry Valley.

The most famous are Fryxell, Vostok, Ellsworth, Don Juan. The area of Lake Fryxell is 7 square kilometers, and its entire surface is constantly covered with ice about 5 meters thick. Vostok is the largest subglacial freshwater lake in Antarctica. Its uniqueness lies in the fact that for several million years it was isolated from the surface of the Earth. Don Juan - not at all big lake, is interesting, first of all, because on this moment claims to be the saltiest lake in the world. The salt content in Lake Fryxell is more than 40%, the salinity of the famous Dead Sea– slightly less than 35%. Due to the high salt content, the reservoir does not freeze even at a temperature of -53 degrees.

Another amazing fact o Fixell: its waters contain a lot of nitrous oxide, which appears as a result of the activity of microorganisms. Meanwhile, scientists were unable to detect a single microorganism in the waters of the lake.

Lake Wanda- another one of the mysteries of Antarctica. The fact is that, despite the low ambient temperatures, the waters of the lake always maintain a temperature of about +26 degrees. The reason was unknown until recently, and only very recently scientists discovered that the water is simply heated by the Sun. This happens because the ice above the lake has the shape of a lens, which means it focuses the sun’s heat.

In Australia, such reservoirs include Eyre, Corangamite, George, Torrens. In North America - Pyramid Lake, Sevier, Mona, Atitlan. The inland basin is most of Central and Western Asia. Sasykkol, Balkhash, Zhalanoshkol, Issyk-Kul are located precisely in this territory. Caspian and Aral Sea by origin they are not seas, but residual lakes, relics formed after the disappearance of the ancient Tethys Ocean.

Baikal- the largest freshwater lake in Russia, it is the deepest in the world. The water in it is so clean and transparent that you can find objects at a depth of 40 meters. This lake is one of the oldest on Earth; it was formed 20-25 million years ago. 336 rivers flow into it, but only one flows out - the Angara. Thus, Baikal is a waste lake.

Endorheic lakes are almost always salty. This is explained by the fact that rivers that could carry this salt do not flow from them.

Sewage lakes

Sewage lakes include lakes that have a flow (usually rivers). Most lakes of this type are located in areas with a temperate and humid climate. It is interesting that several rivers can flow into such reservoirs, but only one can flow out. Dissolved substances (for example, salt) are removed from waters using wastewater. However, in some lakes, water exchange may be slow, leading to salt accumulation and other biochemical processes. The way the water changes in a reservoir determines the amount of water in the lake, its chemical composition and the ability to self-clean.

One of the subtypes of waste lakes are flow-through lakes. They differ in that the outflowing river carries away approximately the same amount of water as the inflowing one brings. The flow-through ones include Chudskoye, Kubenskoye, Zaisan. Water consumption in such lakes occurs mainly due to runoff and evaporation. Flow in these lakes is one of the most important characteristics, as it affects filling, composition and water exchange. The largest lake on our planet is the Caspian Sea. Despite the presence of the word “sea” in the name, technically the Caspian is not one. The fact is that the sea is part of the World Ocean. If completely separated from the ocean by land, then it is a lake. The area of the Caspian Lake is 371,000 square kilometers.

Fresh lakes

Lakes are divided into several categories based on different characteristics. Based on mineralization, they are divided into fresh, ultra-fresh, brackish and saline. Freshwater lakes include those lakes whose salt content is minimal, that is, less than 1%. Freshwater lakes can be either wastewater or flowing. Drainless - always salty.
There are tens of thousands of freshwater lakes on the planet, some of them have truly amazing characteristics, have a unique location and most interesting story. In the country of Nicaragua, for example, there is a lake with the same name. It has tectonic origin, an area of about 8 thousand square kilometers. The uniqueness of Nicaragua is that it is the only freshwater lake on our planet where sharks live. The distance from the lake to the Pacific Ocean is very short, so scientists assume that previously the territory where the reservoir is located was a sea bay.

Another amazing creation of nature is Lake Titicaca. It is located at an altitude of 4000 meters above sea level, and was also once part of the world's oceans. More than three hundred rivers flow into it, most of which flow from glaciers. Titicaca was studied by scientists who came to the conclusion that thousands of years ago the lake was much lower - at an altitude of about 250 meters. Then the reservoir was a sea bay, and its waters are still inhabited mainly by marine species crustaceans and fish.
Freshwater lakes located in a hot thermal zone are distinguished by the fact that the water at their surface is warm. As depth increases, water temperature decreases. The name of this phenomenon is direct thermal stratification. Interestingly, lakes that are located in the cold zone have water with the lowest temperature (about 0 degrees Celsius), but the greater the depth, the higher the temperature. If the temperature in a body of water is distributed in this way, it is called reverse thermal stratification.

Interesting Facts:

If you pay attention to the geographical map of the world, you will notice that some lakes are indicated in blue, while others are indicated in purple. This is explained simply - fresh lakes are marked blue, salty lakes are purple.
There are more fresh lakes on our planet than salt lakes.
The largest freshwater lake on the planet is located in North America. This is Lake Superior, it is part of the Great Lakes group.
There are also some kind of “record holders” for salinity. These are considered water bodies whose salt content is more than 25 grams per liter. Examples - Tuz (Türkiye), Air (Australia), Dus-Khol (Tuva).
The least saline lakes are those located in mountain glaciers.
One of the saltiest is Lake Tuz. It is 80 km long and about 45 km wide. When the lake overflows, it becomes huge - up to 25 thousand square kilometers. The salt content in its waters reaches 322 grams per liter of water.
The saltiest and deepest is the Dead Sea. Its depth in some places reaches 400 meters. The salt content in it is 437 grams per liter of water.
There are quite a few on the planet amazing lakes. For example, Balkhash, one part of which is salty and the other is fresh. And Lake Chad, located in Africa, is fresh at the top and salty closer to the bottom. This is explained by the fact that fresh water (rain) when entering the lake does not mix with salt water. Thus, Lake Chad has two layers.
The largest basins, in which lakes subsequently formed, are of tectonic origin.

Lakes are depressions in land filled with water, formed naturally and occupy about 2% of all land. On the territory of Russia there is the deepest lake - Baikal and the most large lake in the world – Caspian.

People use lakes for water supply. The lakes serve as routes of communication and contain a lot of fish. Valuable minerals were found at the bottom of some lakes: iron ores, salts, sapropel. The shores of the lakes are equipped for people’s recreation; sanatoriums and rest houses have been built there.

Types of lakes

Based on the nature of their flow, lakes are divided into:

a) drainless;

b) waste.

Many rivers flow into and out of flowing lakes, for example, Lake Onega and Lake Ladoga. A drainage lake is a lake that is replenished with water from a large number of rivers, but only one river originates from it. This type includes lakes Baikal and Teletskoye. Endorheic lakes are located mainly in arid areas and in the tundra; not a single river flows from them. Representatives of such lakes are the Caspian, Aral, and Balkhash.

Lake depressions arose as a result of various natural processes. Depressions that arose under the influence of the internal forces of the Earth are called endogenous. These include tectonic and volcanic. Most of the world's large lakes have this origin. Lakes resulting from activities external forces, are called exogenous, these are mainly small lakes. Tectonic basins formed in places where sections of the earth's crust subsided. They could have formed as a result of faults along cracks in the earth's crust or flexure of its layers. The following lakes were formed in tectonic basins: Aral - due to the deflection of the earth's layers, and Baikal, Superior, Huron, Michigan, Tanganyika- due to discharges.

Volcanic basins are volcanic craters, depressions on the surface of lava flows, or flat areas covered by lava flows. Kronotskoye Lake in Kamchatka, lakes in New Zealand, Kuril Islands and the islands of Java.

Lake basins of exogenous origin are also diverse. Oxbow lakes, found in river valleys and having an oblong shape, arose in the places of former river beds. Lakes are of glacial origin, formed as a result of the long-standing advance of glaciers onto land, that is, during the Ice Age. They were formed due to the movement of glaciers, which plowed huge furrows on the earth's surface, filling with water. Such glacial lakes narrow and elongated in shape, they are found in Canada, Finland, and northwestern Russia. In places where the retreating glacier left its debris, wide, shallow, oval-shaped lakes arose. Many such lakes are found in northern Europe and North America, for example, Ladozhskoye, Bolshoye Medvezhye.

In areas where water-soluble rocks - limestone, dolomite and gypsum - are found, basins of karst origin are often formed. Water fills the voids in the earth's crust, forming karst lakes, many of which are very deep, for example, Svityaz. Thermokarst basins, formed as a result of uneven thawing of permafrost, are often found in the tundra and taiga.

Dammed lakes arose in the mountains when, as a result of strong earthquakes, rivers were blocked by rubble or lava flows. This is how Lake Tana in Africa was formed. And in the Pamirs in 1911, right before people’s eyes, Lake Sarez was formed when, during an earthquake, mountain range collapsed into the river valley and blocked it with a dam more than 500 m high.

A lot of basins - artificial reservoirs - are created by man. Thus, on many large rivers of our country (Volga, Angara, Yenisei), large reservoirs have been created due to the construction of dams on them, therefore, the flow of these rivers is regulated.

Many lake basins are of mixed origin. For example, Lakes Ladoga and Onega are of tectonic origin, but their basins underwent changes under the influence of glaciers and rivers. The remnants of ancient seas, which, due to vertical shifts of the earth's crust, were cut off from the ocean by land, are called relict lakes. Conventionally, they are called seas, they include Caspian lake– remnant of large sea basin, the largest lake in the world (area about 371 thousand km2), and the Aral Sea.

The sources of lake water are underground springs, precipitation and rivers flowing into them. Part of the water evaporates from the surface of the lake, goes to underground drainage, and is carried out of the lake into rivers. Due to the inflow and outflow, the water level fluctuates, and therefore the area of the lakes changes. Thus, Lake Chad in Africa in the rainy season has an area of up to 26 thousand km2, and in the dry season it decreases to 12 thousand km2.

The water level in the lake changes due to climatic conditions, namely when water evaporates from its surface or the volume of precipitation falls in the lake basin decreases. The water level in the lake can also change due to tectonic shifts.

Lake waters contain a lot of dissolved substances and, depending on their amount in the water, lakes are divided into: fresh, brackish and saline. Fresh lakes contain less than 1% dissolved salts, brackish lakes contain more than 1% dissolved salts, and salt lakes contain more than 24.7% dissolved salts.

Fresh water lakes include flowing and waste lakes, since the influx of fresh water in them exceeds the flow rate. Endorheic lakes are mainly salty or brackish. The salinity in these lakes increases due to less water inflow relative to its outflow. Salt lakes are located in the steppe and desert zones (Baskunchak, Elton, Mertvoe, Bolshoye Solenoye and a number of others). Some lakes contain high soda content, for example, the soda lakes of Southwestern Siberia.

Life of the lakes

Lakes develop depending on changes in environmental conditions. A lot of inorganic and organic substances enter the lakes, brought by river water and temporary water flows that accumulate at the bottom. Remains of vegetation are also deposited at the bottom, gradually filling the basins. As a result of such accumulations, lakes become shallow and can turn into swamps. The lakes are located zonally. In Russia, the largest number of lakes are located in areas of ancient glaciation: in Karelia, on the Kola Peninsula. Here the lakes are flowing with fresh water and quickly overgrow. There are very few lakes in the steppe and forest-steppe zones of the southern regions. In the desert zone there are drainless salt lakes, which dry up over time, forming salt marshes. In all belts there are tectonic lakes that have greater depth, so changes in them are difficult to discern.

Let's remember: What sources feed the lakes? What is evaporation? Keywords:feeding lakes, drainage and drainage lakes, fresh and salt lakes.

1. Drainage and drainage lakes. The lakes are fed by river and underground runoff and precipitation. Depending on the water flow, lakes can be drained or drainless. Lakes that have river flow, that is, from which rivers flow, are S t o t e s lakes, and lakes that have no flow - wasteless. Drainage lakes are located mainly in areas of excess moisture, while drainage lakes are located in areas of insufficient moisture.

The level of lakes does not remain constant due to the inflow and outflow of water, it changes. Particularly large fluctuations in lake levels are observed in arid and dry areas. This is associated with changes in the areas of lakes.

** During the rainy season of wet years, the Australian Lake Eyre North is a large body of water with an area of up to 9,300 km 2, and during the dry seasons of dry years, water is stored only in a few bays of the southern part of the lake.

Fresh and salt lakes. Based on the amount of dissolved substances, lakes are divided into fresh(salt content less than 1 g per liter of water), salty(from 1 to 24 g of salts per liter) and salty, or MINERAL(salt content more than 24 g per liter of water). In lakes with high salinity, salts precipitate. Usually wastewater lakes are fresh, since the water in them is constantly renewed. Endorheic lakes are most often brackish or saline. This happens because the water flow of such lakes is dominated by evaporation. All minerals brought by rivers and groundwater remain and accumulate in the reservoir.

**One of the largest salt lakes on Earth is the Great Salt Lake in North America (salinity from 137 to 300 0/00) (Fig. 131). The saltiest lake in the world is the Dead Sea - maximum salinity is 310 ppm.

As a result of sediment deposition and overgrowth by vegetation, the lakes gradually become shallow and then turn into swamps. They, like rivers, are the most important natural wealth. Lakes are used for navigation, water supply, fishing, irrigation, recreation, treatment, and the production of various substances.

1. What types of lakes are there in terms of water flow and salinity? 2. Why is the water in endorheic lakes most often brackish or salty? 3. Name the largest lake in your area. How is it used by the local population?

Practical work.

Divide these lakes into two groups (drainage and non-drainage): Baikal, Caspian Sea, Ladoga, Onega, Victoria, Tanganyika, Aral Sea, Chad, Air North.

Draw a drainage and a drainless lake?

3. Describe one of the world’s lakes on the map according to the plan (see Appendix 2).

& 45. Glaciers

Let's remember: What land waters have we studied? Remember what glaciers are. Name the properties of ice .

Keywords:snow, glaciers, continental and mountain glaciers, moraine

1. Glaciers and their formation. Accumulations of ice on the earth's surface are glaciers. They do not contain the same ice that covers our rivers and lakes in winter.

* On Earth, glaciers cover an area of about 16.1 million km2, which is approximately 11% of the land area. Glaciers are found in all latitudes, but the largest area of glaciation occurs in the polar regions.

Glaciers are formed as a result of the accumulation and transformation of solid atmospheric precipitation, mainly snow. If more snow falls than can melt, it accumulates, compacts and turns into clear, bluish ice.

Rice. 132. Scheme of the glacier structure

* The height at which as much snow falls in a year as it melts is called the snow boundary (line). In tropical latitudes, the snow line is located at an altitude of 5000 - 6000 m and drops to ocean level in polar latitudes. Below this limit, less snow falls throughout the year than can melt, and therefore its accumulation is impossible. Higher up, due to the low temperature, snowfall exceeds its melting, snow accumulates and transforms into ice. This is where the glacier feeds. From here the ice, being a plastic substance, flows down in the form of a glacial tongue (Fig. 132).

Glaciers are moving slowly. The speed of movement of glaciers in most mountainous countries ranges from 20 to 80 cm per day or 100 to 300 m per year. In the ice sheets of Greenland and Antarctica, ice moves even more slowly - from 3 to 30 cm per day (10 - 130 m per year).

2. Cover and mountain glaciers. Glaciers are divided into cover and mountain.

Coverings, or m a t e r i c s , glaciers occupy the surface of the land regardless of its relief, which does not affect the shape of the glacier (Fig. 133). They have a flat-convex surface in the form of domes or shields. Ice accumulates in the middle part and slowly spreads to the sides. Glacier tongues often descend to the coastal part of the ocean, as, for example, in Antarctica. In this case, blocks of ice break off from it, turning into floating ice mountains - icebergs (Fig. 134).

Rice. 134. Formation of icebergs

The height of icebergs above the water surface is on average 70 - 100 m, most of them are under water.

** One of the icebergs off the coast of Antarctica was 45 km wide and 170 km long with an ice thickness of more than 200 m.

Icebergs move under the influence of currents and winds to warmer latitudes, where they melt. They are dangerous for navigation. Modern ships are equipped with means of detecting them.

Continental ice sheets are developed in Antarctica and Greenland, on the islands of the Arctic Ocean. Ice sheets once covered much of Europe, North Asia and North America.

Rice. 133. Ice sheet of Antarctica

* Continental glaciers occupy 98.5% of the area of modern glaciation. Antarctica is almost entirely covered with ice (the area not covered with ice is 5% of the total). The average thickness of the ice cover of Antarctica is 2200 m, the maximum is 4776 m. The powerful ice sheet is carried by the island of Greenland .

MOUNTAIN GLACIERS, unlike integumentary ones, are smaller in size and have a variety of shapes. The shape of mountain glaciers is determined by the relief. Some, like caps, cover the peaks, others are located in bowl-shaped depressions on the slopes, and others fill mountain valleys (Fig. 135).

Rice. 135. Mountain glaciers

*The most common are valley mountain glaciers, which move from feeding areas along mountain valleys down. They can receive tributaries and have icefalls. The thickness of mountain glaciers is usually 200 - 400 m. The world's largest mountain glaciers are the Malaspina glacier in Alaska in North America (100 km long) and the Fedchenko glacier in the Pamirs in Asia (71 km).

3. The importance of glaciers. Glaciers have large reserves of fresh water. They contain many times more water than rivers and lakes combined. Mountain glaciers often feed streams and rivers.

Glaciers, like flowing waters, change the topography of land. During their movement, they develop glacial valleys, expand and deepen them, erase irregularities that impede their movement, demolish loose rocks, transport and deposit various materials in other places. At the same time, the work of glaciers occurs where there are no rivers - in high mountain and polar countries.

The solid material that glaciers transport and deposit is called sea. The moraine consists of sand, sandy loam, loam, clay, gravel, boulders and is deposited when glaciers melt. It makes up moraine plains, ridges, hills, and hills (Fig. 136).

1. What natural formations are called glaciers? 2. What is a snow line? 3. How do continental (cover) glaciers differ from mountain glaciers? 4. What is the importance of glaciers? 5*. Show on a pie chart the relationship between continental and mountain glaciers.

On geographical maps the lakes are colored either blue or lilac. Blue color means that the lake is fresh, and lilac means that it is salty.

The salinity of water in lakes varies. Some lakes are so saturated with salts that it is impossible to drown in them, and they are called mineral lakes. In others, the water tastes only slightly salty. The concentration of dissolved substances depends on what kind of water the rivers bring to them. If the climate is humid and the rivers are full of water, the lakes are fresh. In deserts there is little precipitation, rivers often dry up or there are none at all, which is why the lakes are salty.

Among the world's largest lakes, most are fresh. This is due to the fact that the water in them is flowing and does not stagnate, which means that the salts brought by rivers are carried away by them into the seas and oceans.

The freshest lakes on the planet are Baikal in Asia, Onega and Ladoga in Eastern Europe, and Verkhneye in North America. But the freshest of them should still be considered Lake Benern - the largest of the lakes in Western Europe. Its water is closest to distilled water, with slightly more soluble minerals in Lake Baikal and Lake Onega.

Freshwater lake with the largest water surface area - Lake Superior - one of the Great Lakes North America. Its area is 83,350 square kilometers.

Mountain glacial lakes, whose waters are fed by glaciers and snowfields, are especially poor in salts.

If the reservoir is not flowing, then the water in it becomes first slightly brackish and then salty.

The saltiest lakes on our planet can be considered lakes in which the salt content per liter of water is more than 25 grams. Such lakes, in addition to Lake Tuz in Turkey, include Lake Eyre in Australia, the Dead Sea on the Arabian Peninsula, Molla-Kara in Turkmenistan, Lake Dus-Khol in Tuva and others.

In the center of Turkey, south of Ankara, at an altitude of 900 meters above sea level, there is a lake on which you can walk in the summer. This closed lake Tuz has a length of 80 kilometers, a width of about forty-five kilometers and an average depth of two meters. It is not only small, but also very salty - up to three hundred and twenty-two kilograms of salt per ton of water. In spring, due to winter and spring precipitation, the lake overflows and increases almost seven times, occupying a huge area of 25,000 square kilometers. In summer, when the water evaporates, the lake becomes very small, and a dense crust of salt forms on its surface, ranging from a few centimeters to two meters thick.

The Dead Sea is the deepest and saltiest of the salt lakes. Its greatest depth is over 400 meters, and it is located 395 meters below the level of the World Ocean. One liter of Dead Sea water contains 437 grams of salt.

Some of the lakes are brackish-fresh. The most amazing of them is Lake Balkhash. Its western part is fresh, and its eastern part is brackish. The reason for this uniqueness is that the Ili River flows into the western part of the lake, and the eastern part is surrounded by deserts, where the water evaporates very strongly. Therefore on geographical maps the western part of Balkhash is shown in blue, and the eastern part in lilac.

The huge Lake Chad, located on the outskirts of the Sahara, is fresh at the top and brackish at the bottom. Fresh river and rain water, entering the lake, does not mix with brackish water, but seems to float on it. Freshwater fish live in the upper layer, and sea fish that entered the lake in ancient times stay near the bottom.

The lake is very shallow (from 2 to 4 meters deep). Its shores are flat and swampy, and the desert approaches them closely from the north. The hot sun dried out all the northern and eastern tributaries of Chad, turning them into waterless channels - wadis. And only the Shari and Lagoni rivers flowing into it from the south feed the “Saharan Sea” with their waters. For a long time Lake Chad, or Nghi Boul as it was called local residents, was considered drainless, which was its main mystery. Typically, large, shallow, and endorheic lakes on Earth have completely salty water, while the top layer of Lake Chad is fresh. The riddle turned out to be simple.

About 900 kilometers northeast of Chad is the vast Bodélé Basin, which lies approximately 80 meters below lake level. A hidden underground water stream stretched towards her from the lake. Thus, through underground flow, Lake Chad slowly but constantly renews its waters, preventing them from becoming salty.

Lake Mogilnoye is even more amazing. It is located on the island of Kildin, near north coast Kola Peninsula, and has a depth of 17 meters. The lake consists of several layers - “floors”. The first “floor” at the bottom of the lake, almost lifeless, consists of liquid silt and is saturated with hydrogen sulfide. The second “floor” is distinguished by a cherry color - this color is given to it by purple bacteria. They are like a filter that traps hydrogen sulfide rising from the bottom. The “third” floor is a “piece of the sea” hidden in the depths of the lake. This is ordinary sea water, and its salinity here is the same as in the sea. This layer is filled with life, jellyfish, sea crustaceans, stars, sea anemones, sea bass, and cod live here. They just look much smaller than their counterparts in the sea. The fourth “floor” is intermediate: the water in it is no longer sea, but also not fresh, but slightly brackish. The fifth “floor” is a six-meter layer of clean spring water, suitable for drinking. The fauna here is typical for freshwater lakes.

The unusual structure is explained by the history of the lake. It is very ancient and was formed on the site of a sea bay. Mogilnoye Lake is separated from the sea only by a small bridge. At high tide sea water seeps through it in the place where the “marine” layer is located. And the distribution of water in the lake by layers is due to the fact that salty water, being heavier, is at the bottom, and fresh, lighter water is at the top. That's why they don't mix. Oxygen does not reach the depths of the lake, and the bottom layers are contaminated with hydrogen sulfide.

An unusual lake called Drutso is located in Tibet. Locals consider it magical. Every 12 years, the water in the lake changes: it becomes either fresh or salty.

Anyone who was on the beach could see that the water in the sea tasted salty. But where does salt come from if fresh water enters the ocean through rains, rivers, etc.? Why is the sea salty and has it always been like this - time to figure it out!

How is water salinity determined?

Salinity refers to the salt content in water. Most often, salinity is measured in " ppm » (‰). Permille is one thousandth of a number. Let's give an example: a water salinity of 27 ‰ will mean that one liter of water (this is approximately 1000 grams) contains 27 grams of salt.

Water with an average salinity of 0.146 ‰ is considered fresh.

Average The salinity of the World Ocean is 35 ‰. What makes water salty is sodium chloride, also known as table salt. Among other salts, its share in sea water is the highest.

The saltiest sea is the Red Sea. Its salinity is 41‰.

Where does salt come from in the seas and oceans?

Scientists still disagree about whether seawater was originally salty or acquired such properties over time. Depending on the versions, different sources of the appearance of salts in the World Ocean are considered.

Rains and rivers

Fresh water always has a small amount of salts, and rainwater is no exception. It always contains traces of dissolved substances that were captured during its passage through the atmosphere. Getting into the soil, rainwater washes away a small amount of salts and eventually carries them to lakes and seas. From the surface last water evaporates intensely, falls again in the form of rain and brings new minerals from the land. The sea is salty because all the salts remain in it.

The same principle applies to rivers. Each of them is not completely fresh, but contains small amounts of salts captured on land.

Confirmation of the theory - salt lakes

Proof that salt comes through rivers are the most saline lakes: Bolshoye Salt Lake and the Dead Sea. Both are about 10 times saltier than seawater. Why are these lakes salty?, while most of the world's lakes are not?

Lakes are usually temporary storage areas for water. Rivers and streams bring water to lakes, and other rivers carry it away from these lakes. That is, water comes in from one end and leaves from the other.

The Great Salt Lake, the Dead Sea and other salt lakes have no outlets. All the water that flows into these lakes leaves only through evaporation. When water evaporates, dissolved salts remain in bodies of water. Thus, some lakes are salty because:

the rivers carried salt to them;
the water in the lakes evaporated;
the salt remained.

Over many years, salt in the lake water has accumulated to its current level.

Interesting fact: The density of salt water in the Dead Sea is so high that it practically pushes a person out, preventing him from sinking.

The same process made the seas salty. Rivers carry dissolved salts to the ocean. Water evaporates from the oceans to fall again as rain and replenish rivers, but the salts remain in the ocean.

Hydrothermal processes

Rivers and rain are not the only source of dissolved salts. Not long ago, they were discovered on the ocean floor hydrothermal vents. They represent places where seawater has seeped into the rocks of the Earth's crust, become hotter, and is now flowing back into the ocean. Along with it comes a large amount of dissolved minerals.

Submarine volcanism

Another source of salts in the oceans is underwater volcanism - volcanic eruption underwater. It is similar to the previous process in that seawater reacts with hot volcanic products and dissolves some of the mineral components.

Earth's bodies of water arose for various reasons. Their creators are water, wind, glaciers, tectonic forces. The water washed out a basin on the surface of the earth, the wind blew out a depression, the glacier plowed out and polished the depression, a mountain collapse dammed the river valley - and so the bed of the future reservoir was ready. The depressions will be filled with water and a lake will appear.

Lakes globe are divided into two large groups - fresh and salt water bodies. If less than one gram of salts are dissolved in one liter of water, the water is considered fresh; if there are more salts, then it is salty.

Lakes have very different salinities - from fractions of a gram to several tens and hundreds of grams per liter of water. There are, for example, reservoirs whose water is so saturated with salts that it surpasses ocean water in this regard (35 grams of salts per liter of water); Such lakes are called mineral lakes. All this depends on what tribute the rivers bring them. If the climate is humid and the rivers are full of water, it means that the rocks in the catchment area are well washed, and therefore river and lake waters are weakly mineralized.

In drier climates, where precipitation is scarce and rivers are shallow, their waters contain significantly more salts. That is why salt (mineral) lakes are most widespread in deserts. A striking example of this is Central Kazakhstan, where there are few fresh lakes, and salt lakes are found almost at every turn. And yet, among the world's greatest lakes, fresh water bodies predominate.

They are flowing, the water in them does not stagnate, salts brought by rivers are discharged into the ocean or sea. But if you make such a reservoir without drainage, it will become salty after some time. Take, for example, the Caspian Sea. This huge body of water became largely salty because it did not have access to the ocean. There have been many similar cases on Earth.

Some of the lakes are brackish-fresh. The most amazing of them is Lake Balkhash. Its western part is fresh, and its eastern part is brackish. The reason for this uniqueness is that the Ili River flows into the western part of the lake, and the eastern part is surrounded by deserts, where the water evaporates very strongly. Therefore, on geographical maps the western part of Balkhash is shown blue, and the eastern part is shown lilac.

The lake is very shallow (from 2 to 4 meters deep). Its shores are flat and swampy, and the desert approaches them closely from the north. The hot sun dried out all the northern and eastern tributaries of Chad, turning them into waterless channels - wadis. And only the Shari and Lagoni rivers flowing into it from the south feed the “Sahara Sea” with their waters. For a long time, Lake Chad, or Nghi-Bul, as the locals call it, was considered drainless, which was its main mystery. Typically, large, shallow, and endorheic lakes on Earth have completely salty water, while the top layer of Lake Chad is fresh. The riddle turned out to be simple.

About 900 kilometers northeast of Chad is the vast Bodélé Basin, which lies about 80 meters below lake level. A hidden underground water stream stretched towards her from the lake. Thus, through underground flow, Lake Chad slowly but constantly renews its waters, preventing them from becoming salty.

Lake Mogilnoye is even more amazing. It is located on the island of Kildin, near the northern coast of the Kola Peninsula, and has a depth of 17 meters. The lake consists of several layers - “floors”. The first “floor” at the bottom of the lake, almost lifeless, consists of liquid silt and is saturated with hydrogen sulfide. The second “floor” is distinguished by a cherry color - this color is given to it by purple bacteria. They are like a filter that traps hydrogen sulfide rising from the bottom. The “third” floor is a “piece of the sea” hidden in the depths of the lake. This is ordinary sea water, and its salinity here is the same as in the sea. This layer is filled with life, jellyfish, sea crustaceans, stars, sea anemones, sea bass, and cod live here. They just look much smaller than their counterparts in the sea. The fourth “floor” is intermediate: the water in it is no longer sea, but also not fresh, but slightly brackish. The fifth “floor” is a six-meter layer of clean spring water, suitable for drinking. Animal world here is common for freshwater lakes.

The unusual structure is explained by the history of the lake. It is very ancient and was formed on the site of a sea bay. Mogilnoye Lake is separated from the sea only by a small bridge. At high tide, seawater seeps through where the "sea" layer is located. And the distribution of water in the lake by layers is due to the fact that salty water, being heavier, is at the bottom, and fresh, lighter water is at the top. That's why they don't mix. Oxygen does not reach the depths of the lake, and the bottom becomes contaminated with hydrogen sulfide.

WATER OF LAND Option 1 1. A water stream flowing in a depression created by it - a channel: a) lake; b) current; c) river; d) flow. 2. The place where the river flows

into another river, sea or lake: a) tributary; b) mouth; c) waterfall; d) lake. 3. This river is so vast, you need to swim for several months to understand how much the water here dominates the Earth. Not every sea has its depth - more than 90 meters. The river really seems like a sea: after all, standing on one bank, you cannot see the other at all. About which river we're talking about? a) Volga; b) Limpopo; c) Lena; d) Amazon. 4. The highest waterfall in the world: a) Angel; b) Iguazu; c) Victoria; d) Ilya-Muromets. 5. The part of the bottom of a river valley that is flooded during a river flood is called: a) bank; b) meadow; c) floodplain; d) flood. 6. In the past, this lake was connected to the ocean and was a sea. Now it is the largest lake on the planet. a) Baikal; b) Upper; c) Ladoga; d) Caspian. 7. Name the longest river in the world: a) Mississippi; b) Rhine; c) Nile; d) Amazon; d) Lena. 8. Which of these lakes is Australian? a) Air; b) Victoria; c) Baikal; d) Michigan. WATER OF LAND Option 2 1. Drainage area of the river and its tributaries: a) flood; b) river system; c) river basin; d) source. 2. The deepest river in our country: a) Lena; b) Volga; c) Yenisei; d) Cupid. 3. Where is it located? Niagara Falls? a) in Asia; b) in Europe; c) in the USA. 4. Voids washed out by water in easily soluble rocks are called: a) springs; b) ravines; c) caves. 5. Find a match: 1. Sewage lake; 2. Endorheic lake. a) Baikal; b) Chad; c) Caspian; d) Aral; d) Upper. 6. On which bank of the great Russian river is the city of Kamyshin located? a) on the left; b) on the right. 7. Select the rivers of Africa: a) Yenisei; b) Congo; c) Nile; d) Mississippi; e) Niger; e) Volga. 8. Which lakes have the following coordinates? Match: 1. 7° south. sh.; 30° E. 2. 53° N. sh.; 105° E. 3. 62° N. sh.; 32° east d. a) Baikal; b) Tanganyika; c) Ladoga. WATER OF LAND Option 3 1. The place where a river begins is called its: a) tributary; b) source; c) by the riverbed; d) threshold. 2. The basin of this lake appeared 15–20 million years ago. This is one of the oldest lakes in the world. Some scientists see it as a nascent ocean. It is called the “well of the planet”, as this lake is the deepest in the world. What lake are we talking about? a) Upper; b) Victoria; c) Nyasa; d) Baikal. 3. Which lakes have the following coordinates? Match: 1. 12° S. sh.; 35th century d.; 2. 48° N. sh.; 88° W d.; 3. 28° S sh.; 137° E. d. a) Upper; b) Air; c) Nyasa. 4. Select artificial reservoirs from the listed water bodies: a) Volga-Don Canal; b) Aral Sea; c) Tsimlyansk reservoir; d) Suez Canal; d) pond; e) Bering Strait. g) Parana River. 5. Match the rivers and the continents through which they flow: 1. Africa; 2. North America; 3. Australia; 4. Eurasia; 5. South America. a) Ob; b) Congo; c) Murray; d) Parana; d) Colorado. 6. A sudden rise in the water level in a river is: a) flood; b) flood; c) low water; d) floodplain. 7. Determine where the mouth of the Angara River is: a) Caspian Sea; b) Lena River; c) Lake Baikal; d) the Yenisei River. 8. Lakes from which rivers originate are called: a) waste lakes; b) drainless; c) fresh. please help me with the correct answers!!

This deepest continental body of water contains one-fifth of the fresh water on Earth (excluding glaciers). More than 300 rivers flow into and out of the lake

why lakes are salty and others are fresh and got the best answer

Answer from Rain Wives[guru]
On geographical maps the lakes are colored either blue or lilac. Blue color means that the lake is fresh, and lilac means that it is salty.
The salinity of water in lakes varies. Some lakes are so saturated with salts that it is impossible to drown in them, and they are called mineral lakes. In others, the water tastes only slightly salty. The concentration of dissolved substances depends on what kind of water the rivers bring to them. If the climate is humid and the rivers are full of water, the lakes are fresh. In deserts there is little precipitation, rivers often dry up or there are none at all, which is why the lakes are salty.
Among the world's largest lakes, most are fresh. This is due to the fact that the water in them is flowing and does not stagnate, which means that the salts brought by rivers are carried away by them into the seas and oceans.
The freshest lakes on the planet are Baikal in Asia, Onega and Ladoga in Eastern Europe, and Verkhneye in North America. But the freshest of them should still be considered Lake Benern - the largest of the lakes Western Europe. Its water is closest to distilled water, with slightly more soluble minerals in Lake Baikal and Lake Onega.
The freshwater lake with the largest water surface area - Lake Superior - is one of the Great Lakes of North America. Its area is 83,350 square kilometers.
Mountain glacial lakes, whose waters are fed by glaciers and snowfields, are especially poor in salts.
If the reservoir is not flowing, then the water in it becomes first slightly brackish and then salty.
The saltiest lakes on our planet can be considered lakes in which the salt content per liter of water is more than 25 grams. Such lakes, in addition to Lake Tuz in Turkey, include Lake Eyre in Australia, the Dead Sea on the Arabian Peninsula, Molla-Kara in Turkmenistan, Lake Dus-Khol in Tuva and others.
In the center of Turkey, south of Ankara, at an altitude of 900 meters above sea level, there is a lake on which you can walk in the summer. This closed lake Tuz has a length of 80 kilometers, a width of about forty-five kilometers and an average depth of two meters. It is not only small, but also very salty - up to three hundred and twenty-two kilograms of salt per ton of water. In spring, due to winter and spring precipitation, the lake overflows and increases almost seven times, occupying a huge area of 25,000 square kilometers. In summer, when the water evaporates, the lake becomes very small, and a dense crust of salt forms on its surface, ranging from a few centimeters to two meters thick.
The Dead Sea is the deepest and saltiest of the salt lakes. Its greatest depth is over 400 meters, and it is located 395 meters below the level of the World Ocean. One liter of Dead Sea water contains 437 grams of salt.
Some of the lakes are brackish-fresh. The most amazing of them is Lake Balkhash. Its western part is fresh, and its eastern part is brackish. The reason for this uniqueness is that the Ili River flows into the western part of the lake, and the eastern part is surrounded by deserts, where the water evaporates very strongly. Therefore, on geographical maps the western part of Balkhash is shown blue, and the eastern part is shown lilac.
The huge Lake Chad, located on the outskirts of the Sahara, is fresh at the top and brackish at the bottom. Fresh river and rain water, entering the lake, does not mix with brackish water, but seems to float on it. Freshwater fish live in the upper layer, and sea fish that entered the lake in ancient times stay at the bottom.
Source:

Answer from Department for interaction with POVK[newbie]
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Answer from Albina Sapitsyna[active]
PATAMU))))))

Answer from Katya Shubina[newbie]
Not quite right with the drain. but the point is in recharging lakes if the lake is fed from a salty spring ( mineral spring) then it is salty, for example Lake Yarovoye is itself salty and there is a lake nearby Hot key fresh. Nearby it is 10-15 meters away.

Answer from Victoria Volgina[newbie]
Water becomes salty in endorheic lakes in hot, arid climates. Due to high evaporation, salts contained in the water accumulate in the lake, making it salty.