Why does the Volga River lose water below Volgograd?

Below the city of Volgograd, the Volga River loses approximately 2 percent of its water volume due to evaporation.1

Beyond this localized loss, the overall discharge of the river at its mouth has been significantly diminished compared to natural conditions. This broader reduction is primarily attributed to water loss from impoundment in reservoirs, evaporation from those artificial water bodies, and the diversion of water for irrigation purposes. These human-made alterations to the river's hydrology have also contributed to a long-term decline in the level of the Caspian Sea.2