The water resources of the Republic of Armenia amount to approximately 8.5 billion cubic meters. The greater part of these resources is formed by atmospheric precipitation falling within the territory of the republic, while only about 1.4 billion cubic meters are replenished from neighboring areas, primarily through the waters of the border river Araks.
The average annual amount of atmospheric precipitation across the republic is about 600 mm, which corresponds to roughly 18.0 billion cubic meters of water per year. Of this volume, 55% (around 10.0 billion m³) evaporates, 39% (approximately 7.0 billion m³) is transformed into surface runoff, and 6% (about 1.0 billion m³) infiltrates into the soil, forming groundwater flow that gradually feeds springs and small rivers.
Rivers
There are 9,480 rivers within the territory of the republic. Of these, 9,100 are up to 10 km in length, 318 are 10–25 km long, 57 are 26–100 km long, and only five rivers—Araks, Akhuryan, Debed, Hrazdan, and Vorotan—exceed 101 km in length.
The rivers of Armenia belong to the drainage basins of the Kura and Araks rivers. The Araks basin covers 76% of the territory of the republic, while the Kura basin accounts for 24%. The watershed runs along the crests of the Javakheti, Pambak, Areguni, and Sevan mountain ranges.
The hydrographic network of Armenia is unevenly distributed. The average density of the river network is 0.31 km per km². The most developed river network is found in the Kura basin and in the folded-block mountains of Syunik, where climatic conditions are relatively humid. In contrast, much of the Araks basin has a less developed river network due to the fractured nature of volcanic rocks, limited atmospheric precipitation, and intense evaporation. In Syunik and the northeastern regions of the republic, river network density reaches 1.5–2 km per km²; on volcanic plateaus it is 0.5–0.6 km per km², while on the Ararat Plain it is only about 0.2 km per km². The highest river network density in Armenia is observed in Zangezur.
Armenian rivers are mainly fed by snowmelt, rainfall, and groundwater. The most important component of river feeding is groundwater (30–50%), which results in an unstable flow regime. Flooding occurs primarily from April to June, when precipitation reaches its maximum and snowmelt takes place. During this period, 50–70% of the annual runoff passes through river channels. Flooding is weaker in autumn, while in summer and winter rivers become shallow. In summer, due to hot and dry climatic conditions, especially in the Araks basin, many rivers experience significant shallowing. Owing to relatively mild winter temperatures and rapid flow, rivers generally do not freeze.
Rivers that are predominantly fed by lakes and springs have a relatively more stable regime.
The vast majority of Armenia’s rivers are mountainous in character. They originate in high or medium-altitude mountains, have steep gradients, and therefore high flow velocities. Flowing through narrow and deep gorges, they form rapids and waterfalls. The most well-known waterfalls are Jermuk (in the Arpa River basin), Shaki (on a tributary of the Vorotan), and Trchkan (on the Chichkan, a tributary of the Pambak).
Due to their steep gradients, rivers perform intense erosional work, eroding and transporting millions of tons of rock material.
Most river waters have low to moderate bicarbonate mineralization. The least mineralized waters are found in volcanic regions and are considered the most suitable for drinking.
The rivers of the republic are not navigable, but they are rich in hydroelectric resources and are of great importance, particularly for irrigation.
Lakes
The Republic of Armenia has a relatively small number of lakes—about 90 lakes and ponds. All of them are freshwater and vary in origin. There are tectono-volcanic, tectonic, volcanic, crater, glacial, and other types of lakes.
Among the largest lakes is Lake Sevan. In addition to Sevan, the republic has a number of small lakes (with a total water volume of about 0.5 km³) that are also located at high elevations and are distinguished by exceptional water clarity and transparency.
Lake Sevan is of tectonic origin and is situated at an altitude of approximately 1,900 meters above sea level. The surface area of its water mirror is 1,275 km², the volume is about 35 billion m³, and the maximum depth reaches approximately 85 meters. The lake is fed by 28 small rivers flowing into it and by atmospheric precipitation. The Hrazdan River originates from Lake Sevan. Endemic Sevan trout (ishkhan) and whitefish introduced from Lake Ladoga reproduce in the lake.
After Lake Sevan, the second-largest water body in the republic is Lake Arpi, located at an elevation of 2,020 meters above sea level. It is fed by springs and small rivers. Near the outlet, on the Akhuryan River, a 10-meter-high dam was constructed, which raised the lake level and increased the stored water volume to 105 million m³. After the transformation of Lake Arpi into a reservoir, its surface area increased fourfold and now amounts to about 20 km².
The remaining lakes of the republic are much smaller. Lake Akna, located on the near-summit plateau of the Gegham Mountains, is of volcanic origin. Crater lakes of volcanic origin include those of Azhdahak and Armaghan. Glacial lakes include Kari (Mount Aragats), Sev, Al (Syunik Highlands), and Kapuyt (Zangezur Range). Lake Parz (Tavush Region) was formed by a landslide dam. Lake Aygr (Metsamor) originated as a result of springs emerging from deep layers of the Earth’s crust.
Reservoirs
Approximately two dozen reservoirs have been constructed on large and water-rich rivers for energy production, irrigation, domestic, and other purposes. The total volume of water stored in all reservoirs of the republic exceeds 1 billion m³.
The largest reservoirs include Akhuryan (525 million m³), Spandaryan (276 million m³), as well as the reservoirs of Lake Arpi, Azat, Kechut, and Aparan.
Artesian Basins
Artesian basins are an important component of the republic’s hydrographic network. Their waters are formed between impermeable clay layers. The largest reserves are found in the Ararat artesian basin, which is recharged by waters from the mountains surrounding the Ararat Depression. Its long-term reserves are estimated at approximately 28 billion m³, nearly equal to the current water reserves of Lake Sevan. Smaller artesian basins are also known in Shirak, Masrik, Pambak, and Sisian.
The mineralization of artesian waters is low. They are used not only for irrigation and drinking water supply, but also for fish farming.
Wetlands
Wetlands are not widespread within the territory of the republic. Small areas occur in the Sevan basin, on the Lori volcanic plateau, and in the Akhuryan Depression. Most wetlands consist of waterlogged soils that turn into meadows during the second half of summer.
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