How does the Volga River change after the Kama River joins it?

After the Kama River joins the Volga River at the Samara Reservoir, the Volga becomes a "mighty river". This confluence marks the beginning of the lower Volga, which flows southwestward along the foot of the Volga Hills toward Volgograd.1

Hydrologically, this point is significant because more than 90 percent of the river's annual runoff occurs above the confluence with the Kama. Additionally, the climate along the river changes after this junction; while the upper and middle courses lie within a temperate zone, the region from the Kama southward is characterized by hot, dry summers and cold winters with little snow.23