The Ala-Archa (; also Alarcha, ) is a river in Alamüdün District, Chüy Region, Kyrgyzstan, flowing through Bishkek. It belongs to the Chu river system and is traditionally regarded as a left tributary of the Chu. The river is long and has a drainage basin of .
Course The Ala-Archa rises from glaciers on the northern slope of the Kyrgyz Ala-Too. Its upper course flows through a narrow mountain gorge. After the confluence with the Kashka-Suu river, the river emerges into the Baytik Depression.
Below Chon-Aryk, the river flows north through Bishkek. Settlements along its course include Kashka-Suu, Tash-Döbö, Ortolysh, Chon-Aryk, Orto-Say and Mayevka.
Its main tributaries include the Ak-Sai, Teke-Tör, Top-Karagai, Tuyuk-Suu, Jindi-Suu, Adygene and Kashka-Suu.
Hydrology The Ala-Archa is fed mainly by glaciers and snow. Its high-water period begins in May and continues until late September. The mean annual discharge is , with a recorded maximum of and a minimum of .
The drainage basin contains five lakes and 33 glaciers with a combined area of .
Environment The upper basin of the Ala-Archa lies within Ala Archa National Park, which was established in 1976 to protect the mountain landscapes and ecosystems of the upper Ala-Archa valley.
The protected area includes juniper woodlands, patches of spruce forest, subalpine and alpine meadows, and riparian vegetation. More than 600 species of higher plants have been recorded within the park.
The Ala-Archa is the principal river of the park, with tributaries including the Ak-Sai and Adygene.
Water use The waters of the Ala-Archa are extensively used for irrigation. Two reservoirs have been constructed on the Ala-Archa. The Upper Ala-Archa Reservoir is situated near Kashka-Suu, while the Lower Ala-Archa Reservoir lies on the lower course of the river north of Bishkek. Because of water abstraction for irrigation, the Ala-Archa normally does not reach the Chu River.
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