| Usa | |
|---|---|
  Mouth location in theKomi Republic | |
| Location | |
| Country | Komi Republic Russia |
| Physical characteristics | |
| Source | |
| • location | The northernUral Mountains |
| Mouth | Pechora |
• coordinates | 65°57′55″N56°56′01″E / 65.9653°N 56.9336°E /65.9653; 56.9336 |
| Length | 565 km (351 mi) |
| Basin size | 93,600 km2 (36,100 sq mi) |
| Discharge | |
| • average | 1,310 m3/s (46,000 cu ft/s) |
| Basin features | |
| Progression | Pechora→Barents Sea |
TheUsa (Russian:Уса́;Komi:Усва,Usva) is a river in the northeast corner of European Russia that drains the Polar Urals southwest into thePechora. The Polar Urals tend to the northeast and the Usa runs parallel to them. It is in theKomi Republic ofRussia and the largesttributary of the Pechora, which it joins from theright. It is 565 kilometres (351 mi) long, with adrainage basin of 93,600 square kilometres (36,100 sq mi).[1]
The Usa has an average discharge of 1,310 cubic metres per second (46,000 cu ft/s), but this varies from a maximum of 21,500 cubic metres per second (760,000 cu ft/s) in June to a minimum of 43.9 cubic metres per second (1,550 cu ft/s) in April.
The Usa valley has been inhabited for 40,000 years, as evidenced by the archaeological siteMamontovaya Kurya (Russian: Мамонтовой Курьи, "the mammoth curve").[2]
With theRussian conquest of Siberia it became one of the main routes into Siberia. The route ran from the Pechora, which connects to other rivers in northern Russia, up the Usa, across the low Kamen Portage and down the Sob River toOb River where there were customhouses at the Sob barrier andObdorsk. During the short summer season this route was preferred by west-bound travellers since most of the sailing was down-river. For other Ural crossings seeVerkhoturye.
The river has its sources in the northernUral Mountains, at the southern end of thePolar Urals, and it flows towards the southwest, roughly parallel to the mountain range. The main river is formed by the confluence of the Bolshaya Usa (Large Usa) and the Malaya Usa (Little Usa) some 30 km east ofVorkuta. The two tributaries are steep, with many rapids and waterfalls. After the confluence the main river is calm, with only a few rapids in its upper sections. Its banks here are high and cliff-like, but further downriver they become lower, wooded and boggy, except for a section around the settlement of Adak (Russian: Адак), where the river cuts through the Chernyshov Hills.
Below the settlement of Sivomaskinsky (Russian: Сивомаскинский) the river gets much wider, and in its lower reaches it is from 700 to 2,000 metres (2,300 to 6,600 ft) wide. It also starts forming meanders and sand islands, and it keeps this appearance all the way to its mouth. Some 30 kilometres (19 mi) from its mouth lies the town ofUsinsk and the river port of Parma. The Usa flows into the Pechora River at the settlement ofUst-Usa.
It freezes over in October or November and is icebound until the spring thaw begins in May or June. Its largest tributaries are, from the left:Yelets,Lemva,Bolshaya Synya,Bolshoy Kochmes andKosyu, and from the right:Vorkuta,Syoyda,Adzva andKolva.
The river is navigable 325 kilometres (202 mi) upstream from its mouth, and there are river ports at Abez, Petrun, Makarikha, Parma and Ust-Usa. Within the Usa basin is the largePechora coalfield, and in its lower parts, by the town of Usinsk, there are several big petroleum and natural gas fields.
