Hydrography
The river is mostly fed by melting snow (60–70%); the contribution of precipitation is relatively minor. Most of its annual discharge (65%) occurs during the spring floods, which occur in March–April near the mouth and in late April–June upstream; 30% drain during the summer-autumn and 5% in winter. During the floods, the river widens to above 10 km near Uralsk and to several tens kilometers near the mouth. Water level is highest in later April upstream and in May downstream. Its fluctuation is 3–4 m in the upper stream, 9–10 m in the middle of the river and about 3 m in the delta. The average water discharge is 104 m3/s near Orenburg, 400 m3/s at the Kushum village (76.5 km from the mouth); maximum discharge is 14,000 m3/s and the lowest is 1.62 m3/s. Average turbidity is 280 g/m3 at Orenburg and 290 g/m3 near Kushum 290. The river freezes at the source in early November and in the middle and lower reaches in late November. It opens in the lower reaches in late March and in early April in the upper reaches. The ice drift is relatively short.
The average depth is 1–1.5 m near the source, it increases in the middle reaches and especially near the mouth. The density of underwater vegetation also increases from the south to the mouth, so as the richness of the fauna. The bottom in the upper stream is rocky, with pebble and sand; it changes to silt-sand and occasionally clay downstream. The basin is asymmetrical – its left side from the river is 2.1 times larger in area than the right side; however, the right side is more important for feeding the river. The density of the tributaries is 0.29 km/km2 in the right and 0.19 km/km2 in the left side of the basin. The right-side tributaries are typical mountain rivers whereas the left-side tributaries have flatland character. About 200 km from the mouth there is a dangerous spot for shipping called Kruglovskaya prorva (Russian: Кругловская прорва meaning Kruglovsk abyss). Here the river narrows and creates a strong vortex over a deep pit. The climate is continental with frequent and strong winds. Typical annual precipitation is 530 mm.
Read more about this topic: Ural River