Lakes and rivers in Mongolia
Mongolia’s water resources are divided into three drainage basins: the Arctic Ocean, the Pacific Ocean, and the Central Asian inland basins with no external drainage. 85% of Mongolia's surface water resources are freshwater.
In Mongolia's western and northern regions, the per capita water resources are about 50,000 cubic meters, which is 4-5 times higher than the global average. However, in the Gobi desert region, the per capita water resource is 10 times less than the global average. About 60% of river flow leaves the country, with the remaining portion seeping into the ground and replenishing groundwater reserves.
HYDROLOGY OF MONGOLIAScale: 1:12 000 000
LAKES AND WATER BODIES: Mongolia has 4,196 lakes and water bodies, of which 16 have areas larger than 100 square kilometers. Lakes make up 83.7% of the total water resources. However, a 2010 study found that around 1,200 lakes and water bodies have dried up. The following are the top 10 largest lakes:
Uvs Lake: Uvs Lake has an area of 3,350 square kilometers and is located at 759 meters above sea level. Its length is 84 km, its width is 79 km, and its depth is 10-20 meters, making it a relatively shallow lake. It is the largest lake in the northeastern part of Uvs province, with no external drainage.
Uvs Lake
Saltwater Lake: Known for being five times saltier than sea water. A total of 38 rivers and streams, including the Tes, Narain, Kharkhiraa, Turgen, Sags, and Borshoo, flow into the lake.
Flora and Fauna: Species such as the Altai Osman fish and spotted minnow inhabit the lake. Along the shores, reed grass, bulrush, bushes, willows, and various other plants grow.
Significance: Uvs Lake is a unique ecosystem with rare environmental features, playing a vital role in preserving the ecological balance.
Khuvsgul Lake
Size and Depth: The lake covers 2,620 sq. km and reaches a maximum depth of 262 meters. It is the second largest freshwater lake in the world by water clarity.
Tectonic Origin: The lake’s shores are deeply indented, with numerous bays, peninsulas, and islands due to tectonic formations.
Geography: It stretches 133.4 km from north to south and is 39.5 km wide. Surrounded by towering mountains, the northern slopes form cliffs up to 40-50 meters high. Khuvsgul Lake is fed by 46 rivers and streams, draining an area of 5,300 sq. km. Four islands, namely Khadan Khui, Dalain Khui, Modon Khui, and Baga Khui, dot the lake, with Dalain Khui being the largest.
Khar-Us Lake
Shallow Waters: With a surface area of 1,852 sq. km and a maximum depth of only 4.5 meters, this tectonic lake is relatively shallow.
Islands and Channels: It contains more than 10 islands, the largest being Agbash, which divides the lake into northern and southern parts. A channel named Lun-Yum connects these parts, stretching 50-100 meters wide and over 20 km long.
River Source: Khar-Us Lake receives water from a drainage area of 70,450 sq. km, with 70% of this area associated with the Khovd River.
Khyargas Lake
Size and Depth: Covering 1,407 sq. km and sitting at 1,028 meters above sea level, Khyargas Lake is 75 km long and 31 km wide. Its depth ranges from 40-50 meters, with a maximum depth of 80 meters.
Geographic Features: The lake’s shoreline is heavily indented, with narrow peninsulas such as the 7-km-long Nuur's Peninsula and the 4-km-long Chaachargana and Mogoina peninsulas.
Drainage Area: It is part of a large drainage basin spanning 170,000 sq. km, which covers the Altai and Khangai mountain ranges. Various rivers flow into the lake, eventually draining into the Airag Lake and from there into Khyargas Lake via the single Nuuriin Kholoi. The lake features soft, sandy shores to the north and rocky islands to the south. Khyargas Lake supports a rich ecosystem of fish, including Altai Osman, Khadyran, Osmand, dwarf Osman, and several species of minnows and carp.
Buir Lake
Size: Buir Lake spans 615 sq. km, making it the largest lake in Eastern Mongolia. It stretches 40 km from northeast to southwest and has a width of 21 km.
Depth and Shoreline: The average depth is 6-10 meters, and the southern shore is characterized by dunes formed by tidal surges, rising 3-5 meters high. These dunes create small ponds between them, some of which are connected to the main lake.
Water Source: Buir Lake is fed by the Halh River and drains into the Orshuun River. Dense reeds and willows grow along the shores.
Fish Resources: With highly fresh and clean water containing elements like hydrocarbonates, sodium chloride, and calcium, the lake supports a rich population of fish. Fishing serves as a key livelihood for many local residents.
Khar Lake
Area: 575 sq. km
Elevation: 1,132 meters above sea level
Dimensions: 37 km long, 17-23 km wide, average depth of 4 meters
Inflow: Khar Lake receives excess water from Khar Us Lake via the Chonokharykh River. A portion of its excess water is discharged into Dörgön Lake through the Khomi Canal, while another part flows into the Zavkhan River via the Taggan Teeg River.
Achit Lake
Area: 311 sq. km
Elevation: 1,464 meters above sea level
Dimensions: 30 km long, 16 km wide
Inflow: Achit Lake drains from a catchment area of 10,500 sq. km. It is fed by several rivers originating from the significant branches of the Mongolian Altai Mountain Range, including the Sihlem and Turgen Mountains, as well as from snow and glaciers. The lake discharges its excess water into the Khovd River through a single river called the Usan Canal.
Dörgön Lake
Area: 305 sq. km
Dimensions: 24 km long, with a maximum width of 17 km and an average width of 13 km
Depth: The deepest part of Dörgön Lake reaches 27 meters, with an average depth of 14.3 meters
Location: This lake is adjacent to Khar Lake, and a small lake called Nogoong Lake lies between them. Dörgön Lake is connected to Khar Lake via the Khomi Canal and to other bodies of water through the Mergeni Neck. The lake has no islands or peninsulas.
Boentsagaan Lake
Area: 252 sq. km
Elevation: 1,336 meters above sea level
Dimensions: 24 km long, 16 km wide
Characteristics: The shores of Boentsagaan Lake are low and sandy. It is fed by the Baidrag River, which originates from the southern slopes of the Hangai Mountains; however, it has no outflow. The water is classified as alkaline, containing bicarbonates, sulfates, chlorides, sodium, and magnesium.
Uureg Lake
Area: 238 sq. km
Elevation: 1,426 meters above sea level
Dimensions: 19 km long, 18 km wide
Characteristics: Uureg Lake is a round lake located in a closed basin between the Tsagaan Shiveet and Turgen Mountains. Its shores are slightly sloping, and there are no islands or bays. The lake is fed by temporary rivers, including the Tsagaan Shuvuut and Tsagduul, as well as by the Kharig River, which has a permanent flow. Uureg Lake has no outflow, and due to high evaporation rates, the water is saline.
Rivers
Mongolia's water resources are composed of 10.5% from glaciers and 5.8% from river water. There are approximately 65,000 km of permanent rivers and streams, with over 9,600 springs recorded. According to a 2010 study, 870 rivers and 2,300 springs have dried up. Here are some of the major rivers that rank in the top 10:
Selenge River
Description: The Selenge River is considered the largest river in Mongolia due to its extensive catchment area. It is formed by the confluence of the Delger River, which originates from the Khovsgol Mountains, and the Ider River, which starts from the Hangai Mountains.
Length: The Selenge River flows for 992 km before it drains into Lake Baikal, of which 593 km is within Mongolia.
Dimensions: The width of the river ranges from 70 to 250 meters, and its depth is generally around 4-5 meters in the deeper sections.
Major tributary: The largest tributary is the Orkhon River.
Orkhon River
Description: The Orkhon River is 1,124 km long and originates from the main ridge of the Hangai Mountains, specifically from the southern slopes of Mount Suvarga. It collects numerous small and large streams before flowing into the Selenge River.
Dimensions: The width usually ranges from 10 to 60 meters, but can expand up to 120-150 meters in the lower sections, where the flow slows significantly. The dominant depth is about 1.5 meters, while in deeper areas it can reach 2.5-4 meters.
Tributaries: It is fed by rivers such as Tamir, Khogshin Orkhon, Tuul, Kharaa, Sharyn, and Yeruu.
Kherlen River
Description: The Kherlen River originates from the southern slopes of the Khentii Mountains. It is named Kherlen from the confluence of Bogd Mountain and the Tsagaan River.
Length: It flows for 1,090 km through the provinces of Töv, Khentii, and Dornod, eventually draining into Dalai Lake in China, making its total length 1,264 km.
Flow characteristics: Starting from elevated terrain, the river has a swift current, but becomes more gentle around the Delgerkhaan area.
Ecology: The river is home to various fish species, including taimen, grayling, and several others. Important historical sites along the Kherlen River include Kherlen's countryside island, Aurag Mountain, and Kherlentoon Mountain. The Mongolian people have historically regarded the Kherlen River as favorable to men, referring to it as "King Kherlen."
Tuul River
Description: The Tuul River originates from the Baga Khentii Mountain Range and flows through several provinces including Khentii, Töv, Bulgan, and Selenge, covering 819 km before emptying into the Orkhon River near Bayantsogt Mountain.
Feeding streams: It is nourished by about 20 smaller rivers. The upper section is rocky, while the area around Ulaanbaatar is lush with reed beds.
Flooding history: The water level used to be much higher, leading to timber being transported by river during the 1950s. The river has experienced significant flooding in 1934, 1959, 1966, and 1967, causing considerable damage. The Tuul River is historically significant and is often mentioned in the Secret History of Mongolia. The Mongolian people have long regarded the Tuul River as favorable to women, referring to it as "Lady Tuul."
Zavkhan River
Description: The Zavkhan River flows from both sides of Mount Otgontenger, the highest peak of the Hangai Mountains.
Length: It stretches for 808 km, with its source considered to be the confluence of the Buoyant and Shar-Us Rivers, which originate from the southern slopes of the Hangai Mountains.
Lake basin: The river basin contains numerous lakes formed by glacial deposits, the largest being Khukh Lake at 20 sq. km. These lakes are interconnected and discharge their excess water into the Zavkhan River.
Tributaries: The largest tributary, Shuragai River, joins from the western side.
Tes River
Description: The Tes River originates from the Bulnai Mountains and flows into Uvs Lake, with a total length of 568 km.
Feeding streams: Several streams flowing from the Tagna Mountains feed into the Tes River, increasing its water volume downstream.
Swamp area: The river flows through a vast swamp area created by the confluence of rivers, known as the "Jargalant Swamp."
Cultural significance: The Tes River is respected by locals as the "Patriotic River," as it flows out of Mongolia into Russia and then back into Uvs Lake. It typically branches out into several streams at its lower reaches, forming marshy areas. The river's depth ranges from 0.3 to 2.5 meters.
Khovd River (continued)
These two rivers flow into Khar-Us Lake, crossing the Khoton and Khurgan Lakes while collecting water from several other rivers and streams. The lakes—Tolbo, Tal, Dayan, Khoton, Khurgan, and Achit—feed their excess water into the Khovd River. The depth of the river ranges from 1.5 to 3 meters.
Eg River
The Eg River is the only river that originates from Lake Khuvsgul, beginning at a place called Nuuryn Khooloi in the southern part of Lake Khuvsgul and flows 475 km until it meets the eastern side of the Selenge River.
The Eg River flows through high mountains and widens to 40-70 meters when it merges with the Uuriin River. Its depth varies from 0.3 to 3.5 meters. Several rivers such as Tavt, Tarvagatain, and Kharlan feed into it, creating beautiful natural locations known as Eg, Eg-Uuri, Eg-Tarvagatain, and Eg-Selenge confluences.
Idre River
The Idre River originates from the Khangai Mountains and flows through the narrow valley between the Bulnai and Tarvagatai mountains. The river is 452 km long and has a drainage area of 24,555 sq.km. The average width of the river is 40-60 meters, and its depth ranges from 0.7 to 2 meters. Over 30 fast-flowing rivers and streams feed into it, with the largest being the Chuluut River.
Onon River
In terms of water resources, the Onon River ranks second after the Selenge River. It begins from a location with hot springs in the Onon Valley of the Khetain Mountains, at an elevation of 1,950 meters, and flows 445 km to the national border before joining the Ingetai River in Russia to form the Shilka River. The river's width ranges from 80 to 160 meters, with an average depth of 0.5 to 3 meters. Because its source is at a high elevation, it has a steep drop and a fast flow. The Onon River basin is rich in forests, vegetation, and marshes, hosting a variety of rare and important fish species such as Hilem, tul, zeveg, khelti, red cisco, horse fish, gutar, white hader, Amaryn turkhai, sugas, and buluu tsagaan. The Onon River is mentioned over 30 times in the Secret History of Mongolia.
Potanin Glacier
During the Quaternary period, about two million years ago, the climate became colder, leading to snow accumulation that did not melt during the summer, eventually forming glaciers. At that time, glaciers were abundant in the Altai, Khangai, and Khetain Mountains, with the largest remaining glacier in the Mongolian Altai being the Potanin Glacier, which is 20 km long and 5 km wide. Notably, in 1983, a detailed study of Mongolia's glaciers was conducted by geographer N. Dashzeveg, engineer P. Khishigsuren, and R. Evelkhan, who, based on satellite and land surveys and previous research, estimated the total area of glaciers in Mongolia to be 659 sq.km.
