How does the Angara River change the size and flow of the Yenisey River?

The confluence of the Angara River significantly alters the physical characteristics of the Yenisey River.

Following the confluence, the river undergoes the following changes:

• Width: The riverbed expands dramatically, increasing from a width of 870 yards (800 metres) above the confluence to 3,000 yards (2,700 metres) below it.1
• Depth: The depth of the river increases to between 32 and 56 feet (10 and 17 metres).1
• Flow Velocity: The velocity of the river's flow drops by 50 percent or more.1

Because the Angara has a greater volume at its mouth than the Yenisey does above their meeting point, it is sometimes considered the true upper course of the main river rather than a mere tributary. Additionally, the two rivers possess distinct water qualities; the middle Yenisey is highly turbid during spring and summer, while the Angara is limpid. These two streams flow within the same bed without mingling for approximately 9 miles (14 km) after they meet.12